sundog-calculator/src/js/calculator.js

        /**
         * Dog Calorie Calculator - iframe version
         * by Canine Nutrition and Wellness
         */

        class DogCalorieCalculator {
            constructor() {
                this.currentMER = 0;
                this.currentMERMin = 0; // For range calculations
                this.currentMERMax = 0; // For range calculations
                this.isImperial = false;
                this.theme = this.getThemeFromURL() || CALCULATOR_CONFIG.defaultTheme;
                this.scale = this.getScaleFromURL() || CALCULATOR_CONFIG.defaultScale;
                this.foodSources = [];
                this.maxFoodSources = CALCULATOR_CONFIG.maxFoodSources;
                this.mealsPerDay = 2;
                this.showPerMeal = false;
                this.init();
            }

            init() {
                this.applyTheme();
                this.applyScale();
                this.initializeFoodSources();
                this.bindEvents();
                this.updateUnitLabels();
                this.setupIframeResize();
                
                // Show the calculator with fade-in
                const container = document.getElementById('dogCalculator');
                container.classList.add('loaded');
            }

            getThemeFromURL() {
                const urlParams = new URLSearchParams(window.location.search);
                const theme = urlParams.get('theme');
                return ['light', 'dark', 'system'].includes(theme) ? theme : null;
            }

            getScaleFromURL() {
                const urlParams = new URLSearchParams(window.location.search);
                const scale = parseFloat(urlParams.get('scale'));
                return (!isNaN(scale) && scale >= CALCULATOR_CONFIG.minScale && scale <= CALCULATOR_CONFIG.maxScale) ? scale : null;
            }

            applyTheme() {
                const container = document.getElementById('dogCalculator');
                container.classList.remove('theme-light', 'theme-dark', 'theme-system');
                container.classList.add('theme-' + this.theme);
            }

            applyScale() {
                const container = document.getElementById('dogCalculator');
                if (!container) return;

                // Clamp scale between min and max for usability
                const clampedScale = Math.max(CALCULATOR_CONFIG.minScale, Math.min(CALCULATOR_CONFIG.maxScale, this.scale));
                
                if (clampedScale !== 1.0) {
                    container.style.transform = `scale(${clampedScale})`;
                    container.style.transformOrigin = 'top center';
                    
                    // Recalculate height for parent without adding artificial margins
                    setTimeout(() => {
                        this.sendHeightToParent();
                    }, 100);
                }
            }

            // Food Source Management Methods
            initializeFoodSources() {
                this.addFoodSource();
                this.updateAddButton();
            }

            addFoodSource() {
                if (this.foodSources.length >= this.maxFoodSources) {
                    return;
                }

                const id = this.generateFoodSourceId();
                const foodSource = {
                    id: id,
                    name: `Food Source ${this.foodSources.length + 1}`,
                    energy: '',
                    energyUnit: this.isImperial ? 'kcalcup' : 'kcal100g',
                    percentage: this.foodSources.length === 0 ? 100 : 0,
                    isLocked: false
                };

                this.foodSources.push(foodSource);
                this.redistributePercentages();
                this.renderFoodSource(foodSource);
                this.updateAddButton();
                this.updateRemoveButtons();
                this.refreshAllPercentageUI();
            }

            removeFoodSource(id) {
                if (this.foodSources.length <= 1) {
                    return; // Cannot remove the last food source
                }

                const index = this.foodSources.findIndex(fs => fs.id === id);
                if (index === -1) return;

                this.foodSources.splice(index, 1);
                
                // Remove the DOM element
                const element = document.getElementById(`foodSource-${id}`);
                if (element) {
                    element.remove();
                }

                // Redistribute percentages among remaining sources
                this.redistributePercentages();
                this.updateFoodSourceNames();
                this.updateAddButton();
                this.updateRemoveButtons();
                this.refreshAllPercentageUI();
            }

            generateFoodSourceId() {
                return 'fs_' + Date.now() + '_' + Math.random().toString(36).substr(2, 5);
            }

            redistributePercentages() {
                const count = this.foodSources.length;
                if (count === 0) return;

                // Only redistribute among unlocked sources
                const unlockedSources = this.foodSources.filter(fs => !fs.isLocked);
                const lockedSources = this.foodSources.filter(fs => fs.isLocked);
                
                // Calculate total locked percentage
                const totalLockedPercentage = lockedSources.reduce((sum, fs) => sum + fs.percentage, 0);
                
                // Available percentage for unlocked sources
                const availablePercentage = 100 - totalLockedPercentage;
                
                if (unlockedSources.length > 0) {
                    const equalPercentage = Math.floor(availablePercentage / unlockedSources.length);
                    const remainder = availablePercentage - (equalPercentage * unlockedSources.length);

                    unlockedSources.forEach((fs, index) => {
                        fs.percentage = equalPercentage + (index < remainder ? 1 : 0);
                    });
                }

                // Update the UI sliders and inputs
                this.refreshAllPercentageUI();
            }

            // OBSOLETE METHODS - Replaced by new validation system
            // Keeping for reference but these are no longer used
            
            /*
            updatePercentageInputs() {
                this.foodSources.forEach(fs => {
                    const slider = document.getElementById(`percentage-slider-${fs.id}`);
                    const input = document.getElementById(`percentage-input-${fs.id}`);
                    const display = document.getElementById(`percentage-display-${fs.id}`);
                    
                    if (slider) slider.value = fs.percentage;
                    if (input) input.value = fs.percentage;
                    if (display) display.textContent = `${fs.percentage}%`;
                });
                
                // Update constraints after values are set
                this.updatePercentageConstraints();
            }

            updatePercentageConstraints() {
                this.foodSources.forEach(fs => {
                    const slider = document.getElementById(`percentage-slider-${fs.id}`);
                    const input = document.getElementById(`percentage-input-${fs.id}`);
                    
                    if (!slider || !input) return;
                    
                    // Always keep full 0-100 scale for all sliders
                    slider.max = 100;
                    input.max = 100;
                    
                    if (fs.isLocked) {
                        // Locked sources can't be changed
                        slider.disabled = true;
                        input.disabled = true;
                    } else {
                        // Calculate the maximum this source can have
                        const lockedSources = this.foodSources.filter(other => other.id !== fs.id && other.isLocked);
                        const totalLockedPercentage = lockedSources.reduce((sum, other) => sum + other.percentage, 0);
                        const maxAllowed = 100 - totalLockedPercentage;
                        
                        // Re-enable 
                        slider.disabled = false;
                        input.disabled = false;
                        
                        // Store max allowed for validation (we'll check this in event handlers)
                        slider.dataset.maxAllowed = maxAllowed;
                        input.dataset.maxAllowed = maxAllowed;
                        
                        // If current value exceeds max, adjust it
                        if (fs.percentage > maxAllowed) {
                            fs.percentage = maxAllowed;
                            slider.value = maxAllowed;
                            input.value = maxAllowed;
                            document.getElementById(`percentage-display-${fs.id}`).textContent = `${maxAllowed}%`;
                        }
                    }
                });
            }

            adjustPercentages(changedId, newPercentage) {
                const changedIndex = this.foodSources.findIndex(fs => fs.id === changedId);
                if (changedIndex === -1) return;

                const oldPercentage = this.foodSources[changedIndex].percentage;
                const difference = newPercentage - oldPercentage;
                
                this.foodSources[changedIndex].percentage = newPercentage;

                // Only redistribute among unlocked sources (excluding the changed one)
                const otherUnlockedSources = this.foodSources.filter((fs, index) => 
                    index !== changedIndex && !fs.isLocked
                );
                
                // If this is the only unlocked source, force it to fill remaining percentage
                if (otherUnlockedSources.length === 0) {
                    const lockedSources = this.foodSources.filter((fs, index) => 
                        index !== changedIndex && fs.isLocked
                    );
                    const totalLockedPercentage = lockedSources.reduce((sum, fs) => sum + fs.percentage, 0);
                    const requiredPercentage = 100 - totalLockedPercentage;
                    
                    // Force the changed source to the required percentage
                    this.foodSources[changedIndex].percentage = requiredPercentage;
                    this.updatePercentageInputs();
                    this.updateFoodCalculations();
                    return;
                }

                // Calculate total locked percentage (excluding the changed source)
                const lockedSources = this.foodSources.filter((fs, index) => 
                    index !== changedIndex && fs.isLocked
                );
                const totalLockedPercentage = lockedSources.reduce((sum, fs) => sum + fs.percentage, 0);
                
                // Available percentage for unlocked sources
                const availablePercentage = 100 - newPercentage - totalLockedPercentage;
                
                const totalUnlockedPercentage = otherUnlockedSources.reduce((sum, fs) => sum + fs.percentage, 0);
                
                if (totalUnlockedPercentage === 0) {
                    // If all other unlocked sources are 0, distribute equally
                    const equalShare = Math.floor(availablePercentage / otherUnlockedSources.length);
                    const remainder = availablePercentage - (equalShare * otherUnlockedSources.length);
                    
                    otherUnlockedSources.forEach((fs, index) => {
                        fs.percentage = equalShare + (index < remainder ? 1 : 0);
                    });
                } else {
                    // Distribute proportionally among unlocked sources
                    const scale = availablePercentage / totalUnlockedPercentage;
                    
                    let distributedTotal = 0;
                    otherUnlockedSources.forEach((fs, index) => {
                        if (index === otherUnlockedSources.length - 1) {
                            // Last item gets the remainder to ensure exact 100%
                            fs.percentage = availablePercentage - distributedTotal;
                        } else {
                            fs.percentage = Math.round(fs.percentage * scale);
                            distributedTotal += fs.percentage;
                        }
                    });
                }

                this.updatePercentageInputs();
                this.updateFoodCalculations();
            }
            */

            // New validation system methods
            validatePercentageChange(sourceId, requestedValue) {
                // Find the source being changed
                const changedSource = this.foodSources.find(fs => fs.id === sourceId);
                if (!changedSource) {
                    return { isValid: false, reason: 'Source not found' };
                }

                // If the source is locked, no change allowed
                if (changedSource.isLocked) {
                    return { isValid: false, reason: 'Source is locked' };
                }

                // Ensure requested value is within bounds
                const clampedValue = Math.max(0, Math.min(100, requestedValue));

                // Calculate locked and other unlocked totals
                const lockedSources = this.foodSources.filter(fs => fs.id !== sourceId && fs.isLocked);
                const otherUnlockedSources = this.foodSources.filter(fs => fs.id !== sourceId && !fs.isLocked);
                
                const totalLocked = lockedSources.reduce((sum, fs) => sum + fs.percentage, 0);

                // Check if the only unlocked source
                if (otherUnlockedSources.length === 0) {
                    // This is the only unlocked source, must fill remaining percentage
                    const requiredPercentage = 100 - totalLocked;
                    return {
                        isValid: true,
                        actualValue: requiredPercentage,
                        affectedSources: [{ id: sourceId, newPercentage: requiredPercentage }],
                        reason: 'Only unlocked source, forced to fill remainder'
                    };
                }

                // Calculate available percentage for redistribution
                const availableForOthers = 100 - clampedValue - totalLocked;
                
                // Check if redistribution is possible
                if (availableForOthers < 0) {
                    // Cannot accommodate this value
                    const maxAllowed = 100 - totalLocked;
                    return {
                        isValid: true,
                        actualValue: maxAllowed,
                        affectedSources: this.calculateRedistribution(sourceId, maxAllowed, otherUnlockedSources),
                        reason: 'Value clamped to maximum allowed'
                    };
                }

                // Calculate redistribution
                const affectedSources = this.calculateRedistribution(sourceId, clampedValue, otherUnlockedSources);
                
                return {
                    isValid: true,
                    actualValue: clampedValue,
                    affectedSources: affectedSources,
                    reason: 'Valid change'
                };
            }

            calculateRedistribution(sourceId, newValue, otherUnlockedSources) {
                const result = [{ id: sourceId, newPercentage: newValue }];
                
                if (otherUnlockedSources.length === 0) {
                    return result;
                }

                // Calculate total locked percentage
                const lockedSources = this.foodSources.filter(fs => fs.id !== sourceId && fs.isLocked);
                const totalLocked = lockedSources.reduce((sum, fs) => sum + fs.percentage, 0);
                
                // Available percentage for other unlocked sources
                const availableForOthers = 100 - newValue - totalLocked;
                
                // Current total of other unlocked sources
                const currentOtherTotal = otherUnlockedSources.reduce((sum, fs) => sum + fs.percentage, 0);
                
                if (currentOtherTotal === 0 || availableForOthers === 0) {
                    // Distribute equally among other unlocked sources
                    const equalShare = Math.floor(availableForOthers / otherUnlockedSources.length);
                    const remainder = availableForOthers - (equalShare * otherUnlockedSources.length);
                    
                    otherUnlockedSources.forEach((fs, index) => {
                        const newPercentage = equalShare + (index < remainder ? 1 : 0);
                        result.push({ id: fs.id, newPercentage });
                    });
                } else {
                    // Distribute proportionally
                    const scale = availableForOthers / currentOtherTotal;
                    let distributedTotal = 0;
                    
                    otherUnlockedSources.forEach((fs, index) => {
                        let newPercentage;
                        if (index === otherUnlockedSources.length - 1) {
                            // Last item gets remainder to ensure exact total
                            newPercentage = availableForOthers - distributedTotal;
                        } else {
                            newPercentage = Math.round(fs.percentage * scale);
                            distributedTotal += newPercentage;
                        }
                        result.push({ id: fs.id, newPercentage });
                    });
                }
                
                return result;
            }

            applyValidatedChanges(validationResult) {
                if (!validationResult.isValid) {
                    return false;
                }
                
                // Apply all percentage changes
                validationResult.affectedSources.forEach(change => {
                    const source = this.foodSources.find(fs => fs.id === change.id);
                    if (source) {
                        source.percentage = change.newPercentage;
                    }
                });
                
                return true;
            }

            refreshAllPercentageUI() {
                this.foodSources.forEach(fs => {
                    // Update all UI elements from single source of truth
                    const slider = document.getElementById(`percentage-slider-${fs.id}`);
                    const input = document.getElementById(`percentage-input-${fs.id}`);
                    const display = document.getElementById(`percentage-display-${fs.id}`);
                    
                    if (slider) slider.value = fs.percentage;
                    if (input) input.value = fs.percentage;
                    if (display) display.textContent = `${fs.percentage}%`;
                    
                    // Update constraints and disabled states
                    this.updateSliderConstraints(fs);
                });
                
                // Update food calculations
                this.updateFoodCalculations();
            }

            updateSliderConstraints(foodSource) {
                const slider = document.getElementById(`percentage-slider-${foodSource.id}`);
                const input = document.getElementById(`percentage-input-${foodSource.id}`);
                
                if (!slider || !input) return;
                
                // Always keep 0-100 scale
                slider.max = 100;
                input.max = 100;
                
                if (foodSource.isLocked) {
                    slider.disabled = true;
                    input.disabled = true;
                } else {
                    // Calculate maximum allowed and store for validation
                    const maxAllowed = this.calculateMaxAllowed(foodSource.id);
                    slider.disabled = (maxAllowed <= 0);
                    input.disabled = (maxAllowed <= 0);
                    slider.dataset.maxAllowed = maxAllowed;
                    input.dataset.maxAllowed = maxAllowed;
                }
            }

            calculateMaxAllowed(sourceId) {
                const lockedSources = this.foodSources.filter(fs => fs.id !== sourceId && fs.isLocked);
                const otherUnlockedSources = this.foodSources.filter(fs => fs.id !== sourceId && !fs.isLocked);
                
                const totalLocked = lockedSources.reduce((sum, fs) => sum + fs.percentage, 0);
                
                // If this is the only unlocked source, it must take up the remainder
                if (otherUnlockedSources.length === 0) {
                    return 100 - totalLocked;
                }
                
                // Otherwise, maximum is 100 minus locked percentages
                return Math.max(0, 100 - totalLocked);
            }

            updateFoodSourceNames() {
                this.foodSources.forEach((fs, index) => {
                    // Only update if the name is still the default pattern
                    if (fs.name.match(/^Food Source \d+$/)) {
                        fs.name = `Food Source ${index + 1}`;
                        const titleElement = document.getElementById(`food-title-${fs.id}`);
                        if (titleElement) {
                            titleElement.value = fs.name;
                        }
                    }
                });
            }

            updateAddButton() {
                const addBtn = document.getElementById('addFoodBtn');
                
                if (addBtn) {
                    const remaining = this.maxFoodSources - this.foodSources.length;
                    const buttonText = addBtn.querySelector('span:last-child');
                    
                    if (remaining <= 0) {
                        // Disable button and show max reached message
                        addBtn.disabled = true;
                        if (buttonText) {
                            buttonText.textContent = `Maximum ${this.maxFoodSources} sources reached`;
                        }
                    } else {
                        // Enable button with normal text
                        addBtn.disabled = false;
                        if (buttonText) {
                            buttonText.textContent = 'Add another food source';
                        }
                    }
                }
            }

            updateRemoveButtons() {
                // Show/hide remove buttons based on whether we have more than one source
                const hasMultipleSources = this.foodSources.length > 1;
                
                this.foodSources.forEach(fs => {
                    const removeBtn = document.getElementById(`remove-${fs.id}`);
                    if (removeBtn) {
                        removeBtn.style.display = hasMultipleSources ? 'block' : 'none';
                    }
                });
            }

            renderFoodSource(foodSource) {
                const container = document.getElementById('foodSources');
                if (!container) return;

                const cardHTML = `
                    <div class="dog-calculator-food-source-card" id="foodSource-${foodSource.id}">
                        <div class="dog-calculator-food-source-header">
                            <input type="text" class="dog-calculator-food-source-name-input" id="food-title-${foodSource.id}" value="${foodSource.name}" placeholder="Enter food name" maxlength="50" title="Click to edit food source name">
                            <button class="dog-calculator-remove-food-btn" id="remove-${foodSource.id}" type="button" title="Remove this food source" style="display: ${this.foodSources.length > 1 ? 'block' : 'none'}">×</button>
                        </div>
                        
                        <div class="dog-calculator-input-group">
                            <div class="dog-calculator-form-group">
                                <label for="energy-${foodSource.id}">Energy Content:</label>
                                <input type="number" id="energy-${foodSource.id}" min="1" step="1" placeholder="Enter energy content" value="${foodSource.energy}">
                            </div>
                            <div class="dog-calculator-form-group">
                                <label for="energy-unit-${foodSource.id}">Unit:</label>
                                <select id="energy-unit-${foodSource.id}" class="dog-calculator-unit-select">
                                    <option value="kcal100g" ${foodSource.energyUnit === 'kcal100g' ? 'selected' : ''}>kcal/100g</option>
                                    <option value="kcalkg" ${foodSource.energyUnit === 'kcalkg' ? 'selected' : ''}>kcal/kg</option>
                                    <option value="kcalcup" ${foodSource.energyUnit === 'kcalcup' ? 'selected' : ''}>kcal/cup</option>
                                    <option value="kcalcan" ${foodSource.energyUnit === 'kcalcan' ? 'selected' : ''}>kcal/can</option>
                                </select>
                            </div>
                        </div>
                        <div id="energy-error-${foodSource.id}" class="dog-calculator-error dog-calculator-hidden">Please enter a valid energy content</div>

                        <div class="dog-calculator-percentage-group">
                            <label class="dog-calculator-percentage-label" for="percentage-slider-${foodSource.id}">
                                Percentage of Diet: <span id="percentage-display-${foodSource.id}">${foodSource.percentage}%</span>
                                <span class="dog-calculator-lock-icon unlocked" id="lock-${foodSource.id}" title="Lock this percentage">🔒</span>
                            </label>
                            <div class="dog-calculator-percentage-input-group">
                                <input type="range" id="percentage-slider-${foodSource.id}" class="dog-calculator-percentage-slider" 
                                       min="0" max="100" value="${foodSource.percentage}">
                                <input type="number" id="percentage-input-${foodSource.id}" class="dog-calculator-percentage-input" 
                                       min="0" max="100" value="${foodSource.percentage}">
                            </div>
                        </div>
                    </div>
                `;

                container.insertAdjacentHTML('beforeend', cardHTML);
                
                // Bind events for the new food source
                this.bindFoodSourceEvents(foodSource.id);
            }

            bindFoodSourceEvents(id) {
                // Name input events
                const nameInput = document.getElementById(`food-title-${id}`);
                
                // Energy input events
                const energyInput = document.getElementById(`energy-${id}`);
                const energyUnitSelect = document.getElementById(`energy-unit-${id}`);
                const percentageSlider = document.getElementById(`percentage-slider-${id}`);
                const percentageInput = document.getElementById(`percentage-input-${id}`);
                const removeBtn = document.getElementById(`remove-${id}`);
                const lockBtn = document.getElementById(`lock-${id}`);

                if (nameInput) {
                    nameInput.addEventListener('input', () => {
                        const newName = nameInput.value.trim() || `Food Source ${this.foodSources.findIndex(fs => fs.id === id) + 1}`;
                        this.updateFoodSourceData(id, 'name', newName);
                        this.updateFoodCalculations(); // This will refresh the food amount breakdown with new names
                    });
                    
                    nameInput.addEventListener('blur', () => {
                        // If field is empty, restore default name
                        if (!nameInput.value.trim()) {
                            const defaultName = `Food Source ${this.foodSources.findIndex(fs => fs.id === id) + 1}`;
                            nameInput.value = defaultName;
                            this.updateFoodSourceData(id, 'name', defaultName);
                            this.updateFoodCalculations();
                        }
                    });
                }

                if (energyInput) {
                    energyInput.addEventListener('input', () => {
                        this.updateFoodSourceData(id, 'energy', energyInput.value);
                        
                        // Auto-select cups when entering energy for kcal/cup
                        const foodSource = this.foodSources.find(fs => fs.id === id);
                        if (foodSource && foodSource.energyUnit === 'kcalcup' && parseFloat(energyInput.value) > 0) {
                            const unitSelect = document.getElementById('unit');
                            const cupsButton = document.getElementById('cupsButton');
                            
                            // First check if cups button will be enabled after update
                            const willEnableCups = this.foodSources.some(fs => 
                                fs.energyUnit === 'kcalcup' && fs.energy && parseFloat(fs.energy) > 0
                            );
                            
                            if (willEnableCups && unitSelect) {
                                // Set cups BEFORE updating calculations
                                unitSelect.value = 'cups';
                                unitSelect.setAttribute('value', 'cups');
                                this.setActiveUnitButton('cups');
                                
                                // Enable the cups button manually since we know it will be valid
                                if (cupsButton) {
                                    cupsButton.disabled = false;
                                    cupsButton.title = 'Show amounts in cups';
                                }
                            }
                            
                            // Now update calculations with cups already selected
                            this.updateFoodCalculations();
                        } else {
                            this.updateFoodCalculations();
                        }
                    });
                    energyInput.addEventListener('blur', () => this.validateFoodSourceEnergy(id));
                }

                if (energyUnitSelect) {
                    energyUnitSelect.addEventListener('change', () => {
                        this.updateFoodSourceData(id, 'energyUnit', energyUnitSelect.value);
                        
                        // Auto-select the most appropriate unit based on energy unit
                        const unitSelect = document.getElementById('unit');
                        const energyInput = document.getElementById(`energy-${id}`);
                        
                        if (unitSelect) {
                            switch(energyUnitSelect.value) {
                                case 'kcalcup':
                                    // Check if we have energy value to enable cups
                                    const foodSource = this.foodSources.find(fs => fs.id === id);
                                    if (foodSource && foodSource.energy && parseFloat(foodSource.energy) > 0) {
                                        // Set cups BEFORE updating calculations
                                        unitSelect.value = 'cups';
                                        unitSelect.setAttribute('value', 'cups');
                                        this.setActiveUnitButton('cups');
                                        
                                        // Enable the cups button manually
                                        const cupsButton = document.getElementById('cupsButton');
                                        if (cupsButton) {
                                            cupsButton.disabled = false;
                                            cupsButton.title = 'Show amounts in cups';
                                        }
                                    }
                                    this.updateFoodCalculations();
                                    break;
                                case 'kcal100g':
                                    // For kcal/100g, select grams
                                    unitSelect.value = 'g';
                                    this.setActiveUnitButton('g');
                                    this.updateFoodCalculations();
                                    break;
                                case 'kcalkg':
                                    // For kcal/kg, also select grams (or could be kg)
                                    unitSelect.value = 'g';
                                    this.setActiveUnitButton('g');
                                    this.updateFoodCalculations();
                                    break;
                                case 'kcalcan':
                                    // For kcal/can, use grams as default (or ounces in imperial)
                                    unitSelect.value = this.isImperial ? 'oz' : 'g';
                                    this.setActiveUnitButton(unitSelect.value);
                                    this.updateFoodCalculations();
                                    break;
                            }
                        } else {
                            // No unit select, just update calculations
                            this.updateFoodCalculations();
                        }
                    });
                }

                if (percentageSlider) {
                    percentageSlider.addEventListener('input', () => {
                        const requestedValue = parseInt(percentageSlider.value);
                        const result = this.validatePercentageChange(id, requestedValue);
                        
                        if (result.isValid) {
                            this.applyValidatedChanges(result);
                        }
                        // Always refresh to ensure valid state
                        this.refreshAllPercentageUI();
                    });
                }

                if (percentageInput) {
                    percentageInput.addEventListener('change', () => {
                        const requestedValue = parseInt(percentageInput.value) || 0;
                        const result = this.validatePercentageChange(id, requestedValue);
                        
                        if (result.isValid) {
                            this.applyValidatedChanges(result);
                        }
                        this.refreshAllPercentageUI();
                    });
                }

                if (removeBtn) {
                    removeBtn.addEventListener('click', () => this.removeFoodSource(id));
                }

                if (lockBtn) {
                    lockBtn.addEventListener('click', () => this.toggleLock(id));
                }
            }

            toggleLock(id) {
                const foodSource = this.foodSources.find(fs => fs.id === id);
                if (!foodSource) return;

                // Check if we're trying to lock the last unlocked source
                const unlockedSources = this.foodSources.filter(fs => !fs.isLocked);
                if (unlockedSources.length === 1 && unlockedSources[0].id === id) {
                    // Cannot lock the last unlocked source
                    alert('At least one food source must remain flexible for percentage adjustments.');
                    return;
                }

                // Toggle lock state
                foodSource.isLocked = !foodSource.isLocked;
                this.updateLockIcon(id);
                this.updateLockStates();
                this.refreshAllPercentageUI();
            }

            updateLockIcon(id) {
                const foodSource = this.foodSources.find(fs => fs.id === id);
                const lockIcon = document.getElementById(`lock-${id}`);
                
                if (!lockIcon || !foodSource) return;

                if (foodSource.isLocked) {
                    lockIcon.classList.remove('unlocked');
                    lockIcon.classList.add('locked');
                    lockIcon.title = 'Unlock this percentage';
                } else {
                    lockIcon.classList.remove('locked');
                    lockIcon.classList.add('unlocked');
                    lockIcon.title = 'Lock this percentage';
                }
            }

            updateLockStates() {
                const unlockedSources = this.foodSources.filter(fs => !fs.isLocked);
                
                // Update lock icon states - disable lock for last unlocked source
                this.foodSources.forEach(fs => {
                    const lockIcon = document.getElementById(`lock-${fs.id}`);
                    if (lockIcon) {
                        if (!fs.isLocked && unlockedSources.length === 1) {
                            lockIcon.classList.add('disabled');
                            lockIcon.title = 'Cannot lock - at least one source must remain flexible';
                        } else {
                            lockIcon.classList.remove('disabled');
                            lockIcon.title = fs.isLocked ? 'Unlock this percentage' : 'Lock this percentage';
                        }
                    }
                });
                
                // Update percentage constraints based on lock states
                this.refreshAllPercentageUI();
            }

            updateFoodSourceData(id, field, value) {
                const foodSource = this.foodSources.find(fs => fs.id === id);
                if (foodSource) {
                    foodSource[field] = value;
                }
            }

            validateFoodSourceEnergy(id) {
                const energyInput = document.getElementById(`energy-${id}`);
                const energyUnitSelect = document.getElementById(`energy-unit-${id}`);
                const errorElement = document.getElementById(`energy-error-${id}`);
                
                if (!energyInput || !energyUnitSelect || !errorElement) return;
                
                const energy = parseFloat(energyInput.value);
                const unit = energyUnitSelect.value;
                
                let minValue = 1;
                switch (unit) {
                    case 'kcal100g': minValue = 1; break;
                    case 'kcalkg': minValue = 10; break;
                    case 'kcalcup': minValue = 50; break;
                    case 'kcalcan': minValue = 100; break;
                }
                
                if (!this.validateInput(energy, minValue)) {
                    errorElement.classList.remove('dog-calculator-hidden');
                } else {
                    errorElement.classList.add('dog-calculator-hidden');
                }
            }

            bindEvents() {
                const weightInput = document.getElementById('weight');
                const dogTypeSelect = document.getElementById('dogType');
                const daysInput = document.getElementById('days');
                const unitSelect = document.getElementById('unit');
                const unitToggle = document.getElementById('unitToggle');
                const addFoodBtn = document.getElementById('addFoodBtn');

                if (weightInput) {
                    weightInput.addEventListener('input', () => this.updateCalorieCalculations());
                    weightInput.addEventListener('blur', () => this.validateWeight());
                }
                
                if (dogTypeSelect) dogTypeSelect.addEventListener('change', () => this.updateCalorieCalculations());
                
                if (daysInput) {
                    daysInput.addEventListener('input', () => {
                        this.updateDayLabel();
                        this.updateFoodCalculations();
                    });
                    daysInput.addEventListener('blur', () => this.validateDays());
                }
                
                if (unitSelect) unitSelect.addEventListener('change', () => this.updateFoodCalculations());

                // Unit button event listeners
                const unitButtons = document.querySelectorAll('.dog-calculator-unit-btn');
                unitButtons.forEach(button => {
                    button.addEventListener('click', (e) => {
                        const selectedUnit = e.target.dataset.unit;
                        this.setActiveUnitButton(selectedUnit);
                        // Update hidden select to trigger existing logic
                        if (unitSelect) {
                            unitSelect.value = selectedUnit;
                            this.updateFoodCalculations();
                        }
                    });
                });
                
                if (unitToggle) unitToggle.addEventListener('change', () => this.toggleUnits());

                if (addFoodBtn) addFoodBtn.addEventListener('click', () => this.addFoodSource());

                // Feeding configuration event listeners
                const showDaily = document.getElementById('showDaily');
                const showPerMeal = document.getElementById('showPerMeal');
                const mealsPerDayInput = document.getElementById('mealsPerDay');
                const mealInputGroup = document.getElementById('mealInputGroup');

                if (showDaily) {
                    showDaily.addEventListener('change', () => {
                        if (showDaily.checked) {
                            this.showPerMeal = false;
                            if (mealInputGroup) mealInputGroup.style.display = 'none';
                            this.updateDayLabel();
                            this.updateFoodCalculations();
                        }
                    });
                }

                if (showPerMeal) {
                    showPerMeal.addEventListener('change', () => {
                        if (showPerMeal.checked) {
                            this.showPerMeal = true;
                            if (mealInputGroup) mealInputGroup.style.display = 'inline-flex';
                            this.updateDayLabel();
                            this.updateFoodCalculations();
                        }
                    });
                }

                if (mealsPerDayInput) {
                    mealsPerDayInput.addEventListener('input', () => {
                        const meals = parseInt(mealsPerDayInput.value);
                        if (meals && meals >= 1 && meals <= 10) {
                            this.mealsPerDay = meals;
                            if (this.showPerMeal) {
                                this.updateDayLabel();
                                this.updateFoodCalculations();
                            }
                        }
                    });

                    mealsPerDayInput.addEventListener('blur', () => {
                        if (!mealsPerDayInput.value || parseInt(mealsPerDayInput.value) < 1) {
                            mealsPerDayInput.value = 2;
                            this.mealsPerDay = 2;
                            if (this.showPerMeal) {
                                this.updateDayLabel();
                                this.updateFoodCalculations();
                            }
                        }
                    });
                }

                // Modal event listeners
                const shareBtn = document.getElementById('shareBtn');
                const shareModalClose = document.getElementById('shareModalClose');

                if (shareBtn) shareBtn.addEventListener('click', () => this.showShareModal());
                if (shareModalClose) shareModalClose.addEventListener('click', () => this.hideShareModal());

                // Share buttons
                const shareFacebook = document.getElementById('shareFacebook');
                const shareTwitter = document.getElementById('shareTwitter');
                const shareLinkedIn = document.getElementById('shareLinkedIn');
                const shareEmail = document.getElementById('shareEmail');
                const shareCopy = document.getElementById('shareCopy');

                if (shareFacebook) shareFacebook.addEventListener('click', () => this.shareToFacebook());
                if (shareTwitter) shareTwitter.addEventListener('click', () => this.shareToTwitter());
                if (shareLinkedIn) shareLinkedIn.addEventListener('click', () => this.shareToLinkedIn());
                if (shareEmail) shareEmail.addEventListener('click', () => this.shareViaEmail());
                if (shareCopy) shareCopy.addEventListener('click', () => this.copyShareLink());

                // Embed copy buttons removed (embedding disabled)

                // Close modals on outside click
                const shareModal = document.getElementById('shareModal');

                if (shareModal) {
                    shareModal.addEventListener('click', (e) => {
                        if (e.target === shareModal) this.hideShareModal();
                    });
                }

                // Embed modal removed
            }

            toggleUnits() {
                const toggle = document.getElementById('unitToggle');
                this.isImperial = toggle.checked;
                
                this.updateUnitLabels();
                this.convertExistingValues();
                this.updateCalorieCalculations();
            }

            updateUnitLabels() {
                const metricLabel = document.getElementById('metricLabel');
                const imperialLabel = document.getElementById('imperialLabel');
                const weightLabel = document.getElementById('weightLabel');
                const weightInput = document.getElementById('weight');
                const unitSelect = document.getElementById('unit');

                if (metricLabel && imperialLabel) {
                    metricLabel.classList.toggle('active', !this.isImperial);
                    imperialLabel.classList.toggle('active', this.isImperial);
                }

                if (this.isImperial) {
                    if (weightLabel) weightLabel.textContent = "Dog's Weight (lbs):";
                    if (weightInput) {
                        weightInput.placeholder = "Enter weight in lbs";
                        weightInput.min = "0.2";
                        weightInput.step = "0.1";
                    }
                    if (unitSelect) {
                        unitSelect.innerHTML = '<option value="oz">ounces (oz)</option>' +
                            '<option value="lb">pounds (lb)</option>' +
                            '<option value="g">grams (g)</option>' +
                            '<option value="kg">kilograms (kg)</option>';
                        unitSelect.value = 'oz'; // Auto-select ounces for imperial
                        this.setActiveUnitButton('oz'); // Sync unit buttons
                    }
                    
                    // Update energy units for all food sources to kcal/cup for imperial
                    this.foodSources.forEach(fs => {
                        if (fs.energyUnit === 'kcal100g') {
                            fs.energyUnit = 'kcalcup';
                            const energyUnitSelect = document.getElementById(`energy-unit-${fs.id}`);
                            if (energyUnitSelect) {
                                energyUnitSelect.value = 'kcalcup';
                            }
                        }
                    });
                } else {
                    if (weightLabel) weightLabel.textContent = "Dog's Weight (kg):";
                    if (weightInput) {
                        weightInput.placeholder = "Enter weight in kg";
                        weightInput.min = "0.1";
                        weightInput.step = "0.1";
                    }
                    if (unitSelect) {
                        unitSelect.innerHTML = '<option value="g">grams (g)</option>' +
                            '<option value="kg">kilograms (kg)</option>' +
                            '<option value="oz">ounces (oz)</option>' +
                            '<option value="lb">pounds (lb)</option>';
                        unitSelect.value = 'g'; // Auto-select grams for metric
                        this.setActiveUnitButton('g'); // Sync unit buttons
                    }
                    
                    // Update energy units for all food sources to kcal/100g for metric
                    this.foodSources.forEach(fs => {
                        if (fs.energyUnit === 'kcalcup') {
                            fs.energyUnit = 'kcal100g';
                            const energyUnitSelect = document.getElementById(`energy-unit-${fs.id}`);
                            if (energyUnitSelect) {
                                energyUnitSelect.value = 'kcal100g';
                            }
                        }
                    });
                }
            }

            convertExistingValues() {
                const weightInput = document.getElementById('weight');

                if (weightInput && weightInput.value) {
                    const currentWeight = parseFloat(weightInput.value);
                    if (!isNaN(currentWeight)) {
                        if (this.isImperial) {
                            weightInput.value = this.formatNumber(currentWeight * 2.20462, 1);
                        } else {
                            weightInput.value = this.formatNumber(currentWeight / 2.20462, 1);
                        }
                    }
                }
            }

            getWeightInKg() {
                const weightInput = document.getElementById('weight');
                if (!weightInput || !weightInput.value) return null;
                
                const weight = parseFloat(weightInput.value);
                if (isNaN(weight)) return null;
                
                return this.isImperial ? weight / 2.20462 : weight;
            }


            calculateRER(weightKg) {
                return 70 * Math.pow(weightKg, 0.75);
            }

            calculateMER(rer, factor) {
                return rer * factor;
            }

            // Get the range multipliers for each life stage
            getLifeStageRange(factor) {
                // Define ranges based on the reference image
                const ranges = {
                    '3.0': { min: 3.0, max: 3.0 }, // Puppy 0-4 months (no range)
                    '2.0': { min: 2.0, max: 2.0 }, // Puppy 4m-adult OR Working light (no range for puppies)
                    '1.2': { min: 1.2, max: 1.4 }, // Adult inactive/obese
                    '1.6': { min: 1.4, max: 1.6 }, // Adult neutered/spayed
                    '1.8': { min: 1.6, max: 1.8 }, // Adult intact
                    '1.0': { min: 1.0, max: 1.0 }, // Weight loss (fixed)
                    '1.7': { min: 1.2, max: 1.8 }, // Weight gain (wide range)
                    '5.0': { min: 5.0, max: 5.0 }, // Working heavy (upper bound)
                    '1.1': { min: 1.1, max: 1.1 }  // Senior (no range)
                };
                
                const key = factor.toFixed(1);
                return ranges[key] || { min: factor, max: factor };
            }

            validateInput(value, min = 0, isInteger = false) {
                const num = parseFloat(value);
                if (isNaN(num) || num < min) return false;
                if (isInteger && !Number.isInteger(num)) return false;
                return true;
            }

            showError(elementId, show = true) {
                const errorElement = document.getElementById(elementId);
                if (errorElement) {
                    if (show) {
                        errorElement.classList.remove('dog-calculator-hidden');
                    } else {
                        errorElement.classList.add('dog-calculator-hidden');
                    }
                }
            }

            convertUnits(grams, unit, foodSource = null) {
                switch (unit) {
                    case 'kg':
                        return grams / 1000;
                    case 'oz':
                        return grams / 28.3495;
                    case 'lb':
                        return grams / 453.592;
                    case 'cups':
                        // For cups, we need to convert from grams worth of calories to cups
                        if (foodSource && foodSource.energyUnit === 'kcalcup' && foodSource.energy) {
                            // Get calories per 100g for this food
                            const caloriesPerGram = this.getFoodSourceEnergyPer100g(foodSource) / 100;
                            // Calculate total calories represented by these grams
                            const totalCalories = grams * caloriesPerGram;
                            // Divide by calories per cup to get number of cups
                            const caloriesPerCup = parseFloat(foodSource.energy);
                            return totalCalories / caloriesPerCup;
                        }
                        return null; // Cannot convert to cups without kcal/cup
                    default:
                        return grams;
                }
            }

            formatNumber(num, decimals = 0) {
                if (decimals === 0) {
                    return Math.round(num).toString();
                }
                return num.toFixed(decimals).replace(/\.?0+$/, '');
            }

            validateWeight() {
                const weightKg = this.getWeightInKg();
                if (weightKg !== null && weightKg < 0.1) {
                    this.showError('weightError', true);
                } else {
                    this.showError('weightError', false);
                }
            }


            validateDays() {
                const days = document.getElementById('days')?.value;
                if (days && !this.validateInput(days, 1, true)) {
                    this.showError('daysError', true);
                } else {
                    this.showError('daysError', false);
                }
            }

            updateDayLabel() {
                const days = document.getElementById('days')?.value;
                const dayLabel = document.getElementById('dayLabel');
                const mealNote = document.getElementById('mealNote');
                if (dayLabel && days) {
                    const numDays = parseInt(days);
                    dayLabel.textContent = numDays === 1 ? 'day' : 'days';
                }
                if (mealNote) {
                    if (this.showPerMeal && days) {
                        const numDays = parseInt(days);
                        const totalMeals = numDays * this.mealsPerDay;
                        mealNote.textContent = ` (${totalMeals} meal${totalMeals === 1 ? '' : 's'} total)`;
                        mealNote.style.display = 'inline';
                    } else {
                        mealNote.style.display = 'none';
                    }
                }
            }

            setActiveUnitButton(unit) {
                const unitButtons = document.querySelectorAll('.dog-calculator-unit-btn');
                unitButtons.forEach(button => {
                    button.classList.remove('active');
                    if (button.dataset.unit === unit) {
                        button.classList.add('active');
                    }
                });
            }

            updateCalorieCalculations() {
                const dogTypeSelect = document.getElementById('dogType');
                const calorieResults = document.getElementById('calorieResults');
                const rerValue = document.getElementById('rerValue');
                const merValue = document.getElementById('merValue');

                if (!dogTypeSelect || !calorieResults || !rerValue || !merValue) {
                    return;
                }

                const weightKg = this.getWeightInKg();
                const dogTypeFactor = dogTypeSelect.value;
                
                this.showError('weightError', false);
                
                if (!weightKg || weightKg < 0.1) {
                    const weightInput = document.getElementById('weight');
                    if (weightInput && weightInput.value) this.showError('weightError', true);
                    calorieResults.style.display = 'none';
                    return;
                }

                if (!dogTypeFactor) {
                    calorieResults.style.display = 'none';
                    return;
                }

                const factor = parseFloat(dogTypeFactor);
                
                const rer = this.calculateRER(weightKg);
                const mer = this.calculateMER(rer, factor);
                
                // Calculate range for MER
                const range = this.getLifeStageRange(factor);
                this.currentMERMin = this.calculateMER(rer, range.min);
                this.currentMERMax = this.calculateMER(rer, range.max);
                this.currentMER = mer; // Keep middle/selected value for compatibility
                
                rerValue.textContent = this.formatNumber(rer, 0) + ' cal/day';
                
                // Show MER as range if applicable
                if (range.min !== range.max) {
                    merValue.textContent = this.formatNumber(this.currentMERMin, 0) + '-' + 
                                         this.formatNumber(this.currentMERMax, 0) + ' cal/day';
                } else {
                    merValue.textContent = this.formatNumber(mer, 0) + ' cal/day';
                }
                calorieResults.style.display = 'block';
                
                this.updateFoodCalculations();
            }

            updateCupsButtonState() {
                const cupsButton = document.getElementById('cupsButton');
                if (!cupsButton) return;
                
                // Check if any food source has kcal/cup selected
                const hasKcalCup = this.foodSources.some(fs => 
                    fs.energyUnit === 'kcalcup' && fs.energy && parseFloat(fs.energy) > 0
                );
                
                if (hasKcalCup) {
                    cupsButton.disabled = false;
                    cupsButton.title = 'Show amounts in cups';
                } else {
                    cupsButton.disabled = true;
                    cupsButton.title = 'Available when using kcal/cup measurement';
                    
                    // If cups was selected, switch back to grams
                    const unitSelect = document.getElementById('unit');
                    if (unitSelect && unitSelect.value === 'cups') {
                        unitSelect.value = 'g';
                        this.setActiveUnitButton('g');
                    }
                }
            }

            updateFoodCalculations() {
                if (this.currentMER === 0) return;
                
                // Check if we have a range
                const hasRange = this.currentMERMin !== this.currentMERMax;
                
                const daysInput = document.getElementById('days');
                const unitSelect = document.getElementById('unit');
                const dailyFoodResults = document.getElementById('dailyFoodResults');
                const dailyFoodValue = document.getElementById('dailyFoodValue');
                const foodAmountsSection = document.getElementById('foodAmountsSection');
                const foodAmountsList = document.getElementById('foodAmountsList');
                const totalAmountDisplay = document.getElementById('totalAmountDisplay');
                const foodBreakdownResults = document.getElementById('foodBreakdownResults');
                const foodBreakdownList = document.getElementById('foodBreakdownList');
                const feedingConfig = document.getElementById('feedingConfig');
                
                // Update cups button state
                this.updateCupsButtonState();

                if (!daysInput || !unitSelect || !dailyFoodResults || !dailyFoodValue || !foodAmountsSection) {
                    return;
                }

                const days = daysInput.value;
                let unit = unitSelect.value;
                
                // Failsafe: if unit is empty string but cups button is active, use 'cups'
                if (!unit || unit === '') {
                    const activeButton = document.querySelector('.dog-calculator-unit-btn.active');
                    if (activeButton) {
                        unit = activeButton.dataset.unit || 'g';
                    } else {
                        unit = 'g'; // Default fallback
                    }
                }
                
                const unitLabel = unit === 'g' ? 'g' : unit === 'kg' ? 'kg' : unit === 'oz' ? 'oz' : unit === 'lb' ? 'lb' : 'cups';
                const decimals = unit === 'g' ? 0 : unit === 'kg' ? 2 : unit === 'cups' ? 1 : 1;
                
                // Debug: log what unit is being used
                console.log('UpdateFoodCalculations - unit:', unit, 'unitLabel:', unitLabel);
                
                // Determine frequency suffix for display
                const frequencySuffix = this.showPerMeal ? '/meal' : '/day';
                
                // Clear all food source errors first
                this.foodSources.forEach(fs => {
                    this.showError(`energy-error-${fs.id}`, false);
                });
                this.showError('daysError', false);

                // Validate days input
                if (!days || !this.validateInput(days, 1, true)) {
                    if (days) this.showError('daysError', true);
                    foodAmountsSection.style.display = 'none';
                    dailyFoodResults.style.display = 'none';
                    if (foodBreakdownResults) foodBreakdownResults.style.display = 'none';
                    if (feedingConfig) feedingConfig.style.display = 'none';
                    
                    // Hide unit buttons when validation fails
                    const unitButtons = document.getElementById('unitButtons');
                    if (unitButtons) unitButtons.style.display = 'none';
                    return;
                }

                const numDays = parseInt(days);
                
                // Calculate per-food breakdown
                const foodBreakdowns = [];
                let totalDailyGrams = 0;
                let hasValidFoods = false;

                this.foodSources.forEach(fs => {
                    const energyPer100g = this.getFoodSourceEnergyPer100g(fs);
                    
                    if (energyPer100g && energyPer100g > 0.1 && fs.percentage > 0) {
                        const dailyCaloriesForThisFood = (this.currentMER * fs.percentage) / 100;
                        // Calculate range values if applicable
                        const dailyCaloriesMin = hasRange ? (this.currentMERMin * fs.percentage) / 100 : dailyCaloriesForThisFood;
                        const dailyCaloriesMax = hasRange ? (this.currentMERMax * fs.percentage) / 100 : dailyCaloriesForThisFood;
                        
                        let dailyGramsForThisFood;
                        let dailyGramsMin, dailyGramsMax;
                        let dailyCupsForThisFood = null;
                        let dailyCupsMin, dailyCupsMax;
                        
                        // For kcal/cup, calculate cups directly from calories
                        if (fs.energyUnit === 'kcalcup' && fs.energy) {
                            const caloriesPerCup = parseFloat(fs.energy);
                            dailyCupsForThisFood = dailyCaloriesForThisFood / caloriesPerCup;
                            dailyCupsMin = dailyCaloriesMin / caloriesPerCup;
                            dailyCupsMax = dailyCaloriesMax / caloriesPerCup;
                            // We still need grams for total calculation, use approximation
                            dailyGramsForThisFood = (dailyCaloriesForThisFood / energyPer100g) * 100;
                            dailyGramsMin = (dailyCaloriesMin / energyPer100g) * 100;
                            dailyGramsMax = (dailyCaloriesMax / energyPer100g) * 100;
                        } else {
                            // For other units, calculate grams normally
                            dailyGramsForThisFood = (dailyCaloriesForThisFood / energyPer100g) * 100;
                            dailyGramsMin = (dailyCaloriesMin / energyPer100g) * 100;
                            dailyGramsMax = (dailyCaloriesMax / energyPer100g) * 100;
                        }
                        
                        // Calculate per-meal amounts if needed
                        const displayGrams = this.showPerMeal ? dailyGramsForThisFood / this.mealsPerDay : dailyGramsForThisFood;
                        const displayGramsMin = this.showPerMeal ? dailyGramsMin / this.mealsPerDay : dailyGramsMin;
                        const displayGramsMax = this.showPerMeal ? dailyGramsMax / this.mealsPerDay : dailyGramsMax;
                        
                        const displayCups = dailyCupsForThisFood !== null ? 
                            (this.showPerMeal ? dailyCupsForThisFood / this.mealsPerDay : dailyCupsForThisFood) : null;
                        const displayCupsMin = dailyCupsMin !== undefined ? 
                            (this.showPerMeal ? dailyCupsMin / this.mealsPerDay : dailyCupsMin) : null;
                        const displayCupsMax = dailyCupsMax !== undefined ? 
                            (this.showPerMeal ? dailyCupsMax / this.mealsPerDay : dailyCupsMax) : null;
                            
                        const displayCalories = this.showPerMeal ? dailyCaloriesForThisFood / this.mealsPerDay : dailyCaloriesForThisFood;
                        const displayCaloriesMin = this.showPerMeal ? dailyCaloriesMin / this.mealsPerDay : dailyCaloriesMin;
                        const displayCaloriesMax = this.showPerMeal ? dailyCaloriesMax / this.mealsPerDay : dailyCaloriesMax;
                        
                        foodBreakdowns.push({
                            name: fs.name,
                            percentage: fs.percentage,
                            dailyGrams: dailyGramsForThisFood,
                            dailyGramsMin: dailyGramsMin,
                            dailyGramsMax: dailyGramsMax,
                            displayGrams: displayGrams,
                            displayGramsMin: displayGramsMin,
                            displayGramsMax: displayGramsMax,
                            dailyCups: dailyCupsForThisFood,
                            dailyCupsMin: dailyCupsMin,
                            dailyCupsMax: dailyCupsMax,
                            displayCups: displayCups,
                            displayCupsMin: displayCupsMin,
                            displayCupsMax: displayCupsMax,
                            calories: dailyCaloriesForThisFood,
                            displayCalories: displayCalories,
                            displayCaloriesMin: displayCaloriesMin,
                            displayCaloriesMax: displayCaloriesMax,
                            isLocked: fs.isLocked,
                            hasEnergyContent: true,
                            hasRange: hasRange,
                            foodSource: fs  // Store reference for cups conversion
                        });
                        
                        totalDailyGrams += dailyGramsForThisFood;
                        hasValidFoods = true;
                    } else if (fs.percentage > 0) {
                        // Include food sources without energy content but show them as needing energy content
                        foodBreakdowns.push({
                            name: fs.name,
                            percentage: fs.percentage,
                            dailyGrams: 0,
                            displayGrams: 0,
                            dailyCups: null,
                            displayCups: null,
                            calories: 0,
                            displayCalories: 0,
                            isLocked: fs.isLocked,
                            hasEnergyContent: false,
                            foodSource: fs  // Store reference for cups conversion
                        });
                    }
                });

                if (!hasValidFoods) {
                    // Show errors for invalid food sources
                    this.foodSources.forEach(fs => {
                        const energyInput = document.getElementById(`energy-${fs.id}`);
                        if (energyInput && energyInput.value && (!this.getFoodSourceEnergyPer100g(fs) || this.getFoodSourceEnergyPer100g(fs) <= 0.1)) {
                            this.showError(`energy-error-${fs.id}`, true);
                        }
                    });
                    
                    dailyFoodResults.style.display = 'none';
                    if (foodBreakdownResults) foodBreakdownResults.style.display = 'none';
                    if (feedingConfig) feedingConfig.style.display = 'none';
                    
                    // Hide unit buttons when no valid foods
                    const unitButtons = document.getElementById('unitButtons');
                    if (unitButtons) unitButtons.style.display = 'none';
                    
                    // If we have any food sources without energy content, still show the breakdown section
                    if (foodBreakdowns.length > 0) {
                        // Show food amounts section with warnings for missing energy content
                        const unitLabel = unit === 'g' ? 'g' : unit === 'kg' ? 'kg' : unit === 'oz' ? 'oz' : 'lb';
                        
                        const foodAmountsHTML = foodBreakdowns.map(breakdown => {
                            const lockIndicator = breakdown.isLocked ? '<span class="dog-calculator-lock-indicator">🔒</span>' : '';
                            
                            return `
                                <div class="dog-calculator-food-amount-item">
                                    <div class="dog-calculator-food-amount-label">
                                        <span>${breakdown.name}</span>
                                        <span class="dog-calculator-food-percentage">${breakdown.percentage}%</span>
                                        ${lockIndicator}
                                    </div>
                                    <div class="dog-calculator-food-amount-value dog-calculator-warning" title="Enter energy content to calculate amount">
                                        ⚠️
                                    </div>
                                </div>
                            `;
                        }).join('');
                        
                        if (foodAmountsList) {
                            foodAmountsList.innerHTML = foodAmountsHTML;
                        }
                        
                        if (totalAmountDisplay) {
                            totalAmountDisplay.textContent = "Enter energy content for all foods";
                        }
                        
                        foodAmountsSection.style.display = 'block';
                        this.sendHeightToParent();
                    } else {
                        foodAmountsSection.style.display = 'none';
                    }
                    return;
                }

                // Update daily food results (total) - will be updated with proper units later
                dailyFoodResults.style.display = 'block';
                
                // Show feeding configuration when we have valid foods
                if (feedingConfig) {
                    feedingConfig.style.display = 'block';
                    
                    // Ensure "Per day" is checked when feeding config becomes visible
                    const showDaily = document.getElementById('showDaily');
                    if (showDaily && !showDaily.checked && !document.getElementById('showPerMeal').checked) {
                        showDaily.checked = true;
                    }
                }
                
                // Show unit buttons when daily results are shown
                const unitButtons = document.getElementById('unitButtons');
                if (unitButtons) unitButtons.style.display = 'flex';

                // Update per-food breakdown
                if (foodBreakdownList && foodBreakdowns.length > 1) {
                    const breakdownHTML = foodBreakdowns.map(breakdown => {
                        let valueContent;
                        if (breakdown.hasEnergyContent) {
                            if (unit === 'cups') {
                                // For cups, use the pre-calculated cups value if available
                                if (breakdown.displayCups !== null) {
                                    if (breakdown.hasRange && breakdown.displayCupsMin !== breakdown.displayCupsMax) {
                                        valueContent = `${this.formatNumber(breakdown.displayCupsMin, decimals)}-${this.formatNumber(breakdown.displayCupsMax, decimals)} ${unitLabel}${frequencySuffix}`;
                                    } else {
                                        valueContent = `${this.formatNumber(breakdown.displayCups, decimals)} ${unitLabel}${frequencySuffix}`;
                                    }
                                } else {
                                    valueContent = `<span class="dog-calculator-warning" title="Cups only available for foods with kcal/cup measurement">N/A</span>`;
                                }
                            } else {
                                // For other units (g, kg, oz, lb)
                                if (breakdown.hasRange && breakdown.displayGramsMin !== breakdown.displayGramsMax) {
                                    const minConverted = this.convertUnits(breakdown.displayGramsMin, unit);
                                    const maxConverted = this.convertUnits(breakdown.displayGramsMax, unit);
                                    valueContent = `${this.formatNumber(minConverted, decimals)}-${this.formatNumber(maxConverted, decimals)} ${unitLabel}${frequencySuffix}`;
                                } else {
                                    valueContent = `${this.formatNumber(this.convertUnits(breakdown.displayGrams, unit), decimals)} ${unitLabel}${frequencySuffix}`;
                                }
                            }
                        } else {
                            valueContent = `<span class="dog-calculator-warning" title="Enter energy content to calculate amount">⚠️</span>`;
                        }
                        
                        return `
                            <div class="dog-calculator-food-result-item">
                                <span class="dog-calculator-food-result-label">${breakdown.name} (${breakdown.percentage}%${breakdown.isLocked ? ' - locked' : ''}):</span>
                                <span class="dog-calculator-food-result-value">${valueContent}</span>
                            </div>
                        `;
                    }).join('');
                    
                    foodBreakdownList.innerHTML = breakdownHTML;
                    if (foodBreakdownResults) foodBreakdownResults.style.display = 'block';
                } else {
                    if (foodBreakdownResults) foodBreakdownResults.style.display = 'none';
                }

                // Generate individual food amount breakdown
                
                // Update daily food value with correct units
                const displayTotal = this.showPerMeal ? totalDailyGrams / this.mealsPerDay : totalDailyGrams;
                let convertedTotal;
                let totalDisplayText;
                
                if (unit === 'cups') {
                    console.log('Unit is cups, checking validity...');
                    // For cups, we can only show total if all foods with percentage > 0 have kcal/cup
                    const validForCups = foodBreakdowns.filter(b => b.percentage > 0)
                        .every(b => b.displayCups !== null && b.displayCups !== undefined);
                    
                    console.log('Valid for cups?', validForCups, 'Breakdowns:', foodBreakdowns);
                    
                    if (validForCups) {
                        // Calculate total cups using pre-calculated values
                        let totalCups = 0;
                        let totalCupsMin = 0;
                        let totalCupsMax = 0;
                        foodBreakdowns.forEach(breakdown => {
                            if (breakdown.percentage > 0 && breakdown.displayCups !== null) {
                                totalCups += breakdown.displayCups;
                                if (breakdown.hasRange) {
                                    totalCupsMin += breakdown.displayCupsMin || breakdown.displayCups;
                                    totalCupsMax += breakdown.displayCupsMax || breakdown.displayCups;
                                } else {
                                    totalCupsMin += breakdown.displayCups;
                                    totalCupsMax += breakdown.displayCups;
                                }
                            }
                        });
                        
                        if (hasRange && totalCupsMin !== totalCupsMax) {
                            totalDisplayText = `${this.formatNumber(totalCupsMin, decimals)}-${this.formatNumber(totalCupsMax, decimals)} ${unitLabel}${frequencySuffix}`;
                        } else {
                            totalDisplayText = this.formatNumber(totalCups, decimals) + ` ${unitLabel}${frequencySuffix}`;
                        }
                    } else {
                        totalDisplayText = 'Mixed units - see breakdown';
                    }
                } else {
                    // Calculate totals for ranges
                    if (hasRange) {
                        let totalGramsMin = 0;
                        let totalGramsMax = 0;
                        foodBreakdowns.forEach(breakdown => {
                            if (breakdown.percentage > 0 && breakdown.hasEnergyContent) {
                                totalGramsMin += breakdown.displayGramsMin || breakdown.displayGrams;
                                totalGramsMax += breakdown.displayGramsMax || breakdown.displayGrams;
                            }
                        });
                        
                        const convertedMin = this.convertUnits(totalGramsMin, unit);
                        const convertedMax = this.convertUnits(totalGramsMax, unit);
                        
                        if (totalGramsMin !== totalGramsMax) {
                            totalDisplayText = `${this.formatNumber(convertedMin, decimals)}-${this.formatNumber(convertedMax, decimals)} ${unitLabel}${frequencySuffix}`;
                        } else {
                            totalDisplayText = this.formatNumber(convertedMin, decimals) + ` ${unitLabel}${frequencySuffix}`;
                        }
                    } else {
                        convertedTotal = this.convertUnits(displayTotal, unit);
                        totalDisplayText = this.formatNumber(convertedTotal, decimals) + ` ${unitLabel}${frequencySuffix}`;
                    }
                }
                
                dailyFoodValue.textContent = totalDisplayText;
                
                // Build HTML for individual food amounts
                const foodAmountsHTML = foodBreakdowns.map(breakdown => {
                    const lockIndicator = breakdown.isLocked ? '<span class="dog-calculator-lock-indicator">🔒</span>' : '';
                    
                    if (!breakdown.hasEnergyContent) {
                        // Show warning for food sources without energy content
                        return `
                            <div class="dog-calculator-food-amount-item">
                                <div class="dog-calculator-food-amount-label">
                                    <span>${breakdown.name}</span>
                                    <span class="dog-calculator-food-percentage">${breakdown.percentage}%</span>
                                    ${lockIndicator}
                                </div>
                                <div class="dog-calculator-food-amount-value dog-calculator-warning" title="Enter energy content to calculate amount">
                                    ⚠️
                                </div>
                            </div>
                        `;
                    } else {
                        // For multi-day calculations: show total amount for all days
                        let amountDisplay;
                        if (unit === 'cups') {
                            // For cups, use pre-calculated cups value
                            if (breakdown.dailyCups !== null) {
                                const totalCupsForDays = breakdown.dailyCups * numDays;
                                amountDisplay = `${this.formatNumber(totalCupsForDays, decimals)} ${unitLabel}`;
                            } else {
                                amountDisplay = `<span class="dog-calculator-warning" title="Cups only available for foods with kcal/cup measurement">N/A</span>`;
                            }
                        } else {
                            // For other units, calculate from grams
                            const totalGramsForDays = this.showPerMeal 
                                ? (breakdown.dailyGrams / this.mealsPerDay) * numDays * this.mealsPerDay
                                : breakdown.dailyGrams * numDays;
                            const convertedAmount = this.convertUnits(totalGramsForDays, unit);
                            amountDisplay = `${this.formatNumber(convertedAmount, decimals)} ${unitLabel}`;
                        }
                        
                        return `
                            <div class="dog-calculator-food-amount-item">
                                <div class="dog-calculator-food-amount-label">
                                    <span>${breakdown.name}</span>
                                    <span class="dog-calculator-food-percentage">${breakdown.percentage}%</span>
                                    ${lockIndicator}
                                </div>
                                <div class="dog-calculator-food-amount-value">
                                    ${amountDisplay}
                                </div>
                            </div>
                        `;
                    }
                }).join('');
                
                // Calculate and display total
                const totalFoodGrams = totalDailyGrams * numDays;
                
                // Update the display
                if (foodAmountsList) {
                    foodAmountsList.innerHTML = foodAmountsHTML;
                }
                
                if (totalAmountDisplay) {
                    if (unit === 'cups') {
                        // For cups total, check if all foods can be converted
                        const validForCups = foodBreakdowns.filter(b => b.percentage > 0)
                            .every(b => b.dailyCups !== null && b.dailyCups !== undefined);
                        
                        if (validForCups) {
                            // Calculate total cups using pre-calculated values
                            let totalCups = 0;
                            foodBreakdowns.forEach(breakdown => {
                                if (breakdown.percentage > 0 && breakdown.dailyCups !== null) {
                                    totalCups += breakdown.dailyCups * numDays;
                                }
                            });
                            totalAmountDisplay.textContent = `${this.formatNumber(totalCups, decimals)} ${unitLabel}`;
                        } else {
                            totalAmountDisplay.textContent = 'Mixed units - see individual amounts';
                        }
                    } else {
                        const totalConverted = this.convertUnits(totalFoodGrams, unit);
                        totalAmountDisplay.textContent = `${this.formatNumber(totalConverted, decimals)} ${unitLabel}`;
                    }
                }
                
                        foodAmountsSection.style.display = 'block';
                        this.sendHeightToParent();
            }

            getFoodSourceEnergyPer100g(foodSource) {
                if (!foodSource.energy || !foodSource.energyUnit) return null;
                
                const energy = parseFloat(foodSource.energy);
                if (isNaN(energy)) return null;
                
                const unit = foodSource.energyUnit;
                
                // Convert all units to kcal/100g for internal calculations
                switch (unit) {
                    case 'kcal100g':
                        return energy;
                    case 'kcalkg':
                        return energy / 10; // 1 kg = 10 × 100g
                    case 'kcalcup':
                        return energy / 1.2; // Assume 1 cup ≈ 120g for dry dog food
                    case 'kcalcan':
                        return energy / 4.5; // Assume 1 can ≈ 450g for wet dog food
                    default:
                        return energy;
                }
            }

            // Iframe auto-resize for allowed embeddings
            setupIframeResize() {
                // Only when embedded in an iframe
                if (window.top === window.self) return;
                
                // Initial send once UI is ready
                setTimeout(() => this.sendHeightToParent(), 50);
                
                // Monitor for content/attribute changes
                const observer = new MutationObserver(() => {
                    clearTimeout(this._resizeTimer);
                    this._resizeTimer = setTimeout(() => this.sendHeightToParent(), 100);
                });
                
                observer.observe(document.body, {
                    childList: true,
                    subtree: true,
                    attributes: true
                });
                
                // On viewport resize
                window.addEventListener('resize', () => this.sendHeightToParent());
            }

            sendHeightToParent() {
                if (!(window.parent && window.parent !== window)) return;
                const container = document.getElementById('dogCalculator');
                // Prefer visual height including transform scaling
                let height = 0;
                if (container) {
                    const rect = container.getBoundingClientRect();
                    height = Math.ceil(rect.height);
                } else {
                    height = Math.max(document.body.scrollHeight, document.documentElement.scrollHeight);
                }
                window.parent.postMessage({
                    type: 'dogCalculatorResize',
                    height: height
                }, '*');
            }

            // Modal functionality
            showShareModal() {
                const modal = document.getElementById('shareModal');
                const shareUrl = document.getElementById('shareUrl');
                if (modal && shareUrl) {
                    shareUrl.value = window.location.href;
                    // Use flex so content is centered within modal viewport
                    modal.style.display = 'flex';
                    // Sync modal scroll position with current page scroll so content is visible
                    try { modal.scrollTop = window.scrollY || document.documentElement.scrollTop || 0; } catch (e) {}
                    // Ensure the modal is visible even when the page is scrolled
                    // by recalculating parent iframe height (defensive)
                    this.sendHeightToParent();
                }
            }

            hideShareModal() {
                const modal = document.getElementById('shareModal');
                if (modal) modal.style.display = 'none';
                this.sendHeightToParent();
            }

            // Embed modal removed (embedding disabled)

            // Embed modal removed (embedding disabled)

            shareToFacebook() {
                const url = encodeURIComponent(window.location.href);
                window.open('https://www.facebook.com/sharer/sharer.php?u=' + url, '_blank', 'width=600,height=400');
            }

            shareToTwitter() {
                const url = encodeURIComponent(window.location.href);
                const text = encodeURIComponent('Check out this useful dog calorie calculator!');
                window.open('https://twitter.com/intent/tweet?url=' + url + '&text=' + text, '_blank', 'width=600,height=400');
            }

            shareToLinkedIn() {
                const url = encodeURIComponent(window.location.href);
                window.open('https://www.linkedin.com/sharing/share-offsite/?url=' + url, '_blank', 'width=600,height=400');
            }

            shareViaEmail() {
                const subject = encodeURIComponent('Dog Calorie Calculator');
                const body = encodeURIComponent('Check out this useful dog calorie calculator: ' + window.location.href);
                window.location.href = 'mailto:?subject=' + subject + '&body=' + body;
            }

            async copyShareLink() {
                const shareUrl = document.getElementById('shareUrl');
                const copyBtn = document.getElementById('shareCopy');
                
                if (shareUrl && copyBtn) {
                    try {
                        await navigator.clipboard.writeText(shareUrl.value);
                        const originalText = copyBtn.textContent;
                        copyBtn.textContent = 'Copied!';
                        copyBtn.classList.add('copied');
                        
                        setTimeout(() => {
                            copyBtn.textContent = originalText;
                            copyBtn.classList.remove('copied');
                        }, 2000);
                    } catch (err) {
                        // Fallback for older browsers
                        shareUrl.select();
                        document.execCommand('copy');
                    }
                }
            }

            // Embed code copy removed (embedding disabled)
        }

        // Initialize calculator when DOM is ready
        document.addEventListener('DOMContentLoaded', function() {
            // Allow embedding only from approved parent hosts
            if (window.top !== window.self) {
                const allowedHosts = ['caninenutritionandwellness.com', 'www.caninenutritionandwellness.com'];
                let parentAllowed = false;

                // Prefer document.referrer when available
                try {
                    if (document.referrer) {
                        const r = new URL(document.referrer);
                        parentAllowed = allowedHosts.includes(r.hostname);
                    }
                } catch (e) {}

                // Fallback: Chrome's ancestorOrigins (may be empty or absent)
                if (!parentAllowed && window.location.ancestorOrigins && window.location.ancestorOrigins.length) {
                    parentAllowed = Array.from(window.location.ancestorOrigins).some((originStr) => {
                        try {
                            const o = new URL(originStr);
                            return allowedHosts.includes(o.hostname);
                        } catch (e) {
                            return false;
                        }
                    });
                }

                if (!parentAllowed) {
                    document.body.innerHTML = '<div style="max-width:720px;margin:40px auto;padding:16px;border:1px solid #ddd;border-radius:8px;font-family:system-ui, -apple-system, Segoe UI, Roboto, sans-serif;color:#333;line-height:1.5;text-align:center;">Embedding of this calculator is only allowed on caninenutritionandwellness.com.</div>';
                    return;
                }
            }
            new DogCalorieCalculator();
        });