// State Management
const state = {
    inventory: [],
    stats: {
        totalItems: 0,
        expiringSoon: 0,
        wasteAvoided: 0,
        moneySaved: 0
    },
    useMock: true
};

// Mock Data (Fallback)
const MOCK_INVENTORY = [
    { id: 1, name: 'Milk (Mock)', quantity: '1L', expiryDate: '2023-10-30', category: 'Dairy', price: 2.50 },
    { id: 2, name: 'Spinach (Mock)', quantity: '1 bag', expiryDate: '2023-10-26', category: 'Vegetables', price: 3.00 },
];

const MOCK_RECIPES = [
    { title: 'Mock Chicken Stir-fry', image: 'https://via.placeholder.com/300', ingredients: 'Chicken, Veggies' }
];

// Initialization
// Initialization
document.addEventListener('DOMContentLoaded', () => {
    // Check if backend is reachable or just load UI
    state.useMock = false; // We assume Python backend is primary now
    fetchInventory();
    setupFormListeners();

    // Hide N8N settings if present (optional UX polish)
    const settingsSection = document.getElementById('settings-section');
    if (settingsSection) {
        // We can inject a message or hide legacy N8N inputs here if we wanted
        // For now, we just leave it as is
    }
});

// Navigation
function showSection(sectionId) {
    const sections = ['dashboard', 'inventory', 'recipes', 'settings'];
    sections.forEach(id => document.getElementById(`${id}-section`).classList.add('hidden'));
    document.getElementById(`${sectionId}-section`).classList.remove('hidden');
    document.querySelectorAll('nav button').forEach(btn => btn.classList.remove('active'));

    if (sectionId === 'dashboard' || sectionId === 'inventory') {
        if (!state.useMock) fetchInventory();
        else updateUI();
    }
}

// Data Handling - Python API
async function apiRequest(endpoint, method = 'GET', data = null) {
    // If endpoint doesn't start with /, add it
    const path = endpoint.startsWith('/') ? endpoint : `/${endpoint}`;
    const url = `/api${path}`;

    const options = {
        method: method,
        headers: { 'Content-Type': 'application/json' }
    };

    if (data) {
        options.body = JSON.stringify(data);
    }

    const response = await fetch(url, options);
    if (!response.ok) {
        throw new Error(`Server Error: ${response.status}`);
    }
    return await response.json();
}

async function fetchInventory() {
    if (state.useMock) { updateUI(); return; } // Keep mock fallback for initial load if no URL was saved

    try {
        const data = await apiRequest('/get-items');
        state.inventory = data.items || [];
        updateUI();
    } catch (error) {
        console.error('API Error:', error);
        showToast('Backend not running? ' + error.message, 'error');
        // Fallback to mock data if API fails
        if (state.inventory.length === 0) {
            state.inventory = MOCK_INVENTORY;
            state.useMock = true; // Switch to mock mode
            updateUI();
        }
    }
}

async function addItem(itemData) {
    if (state.useMock) {
        state.inventory.push({ ...itemData, id: Date.now(), expiryDate: itemData.expiryDate || '2023-12-01' }); // Add ID for mock
        updateUI();
        showToast('Item added (Mock)!', 'success');
        return;
    }

    try {
        const result = await apiRequest('/add-item', 'POST', itemData);
        if (result.success) {
            showToast(`Item added! Expiry: ${result.expiryDate}`, 'success');
            fetchInventory();
        } else {
            showToast('Failed to add item: ' + (result.message || 'Unknown error'), 'error');
        }
    } catch (error) {
        console.error('Add Item Error:', error);
        showToast('Failed to add item.', 'error');
    }
}

async function getRecipeSuggestions() {
    const container = document.getElementById('recipes-container');
    container.innerHTML = '<div class="loader"></div>';

    if (state.useMock) {
        await new Promise(r => setTimeout(r, 1000));
        renderRecipes(MOCK_RECIPES);
        return;
    }

    try {
        const recipes = await apiRequest('/suggest-recipes', 'POST', {});
        renderRecipes(recipes);
    } catch (e) {
        console.error(e);
        container.innerHTML = '<p class="text-muted">Error fetching recipes. Showing mock recipes.</p>';
        setTimeout(() => renderRecipes(MOCK_RECIPES), 1000); // Fallback to mock recipes
    }
}

// Settings & Testing
function saveSettings() {
    const url = document.getElementById('config-webhook-url').value;
    updateConfig(url);
    showToast('Settings Saved! Reloading...', 'success');
    setTimeout(() => window.location.reload(), 1000);
}

async function testConnection() {
    const log = document.getElementById('connection-log');
    log.style.display = 'block';
    log.innerHTML = 'Testing connection...';

    // Explicitly testing 'get_items' action which matches the Switch node logic
    const payload = { action: 'get_items' };

    const url = document.getElementById('config-webhook-url').value;

    try {
        const response = await fetch(url, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify(payload)
        });

        if (response.ok) {
            const data = await response.json();
            log.innerHTML = `<span style="color: #10b981;">SUCCESS: Connected!</span><br>Response: ${JSON.stringify(data).slice(0, 50)}...`;
        } else {
            log.innerHTML = `<span style="color: #ef4444;">ERROR: Server returned ${response.status}</span>`;
        }
    } catch (e) {
        log.innerHTML = `<span style="color: #ef4444;">FAIL: ${e.name} - ${e.message}</span><br>Possible causes: CORS, Network, or Wrong URL.`;
    }
}

// UI Helpers
function showToast(msg, type = 'info') {
    // Simple alert replacement
    const div = document.createElement('div');
    div.innerText = msg;
    div.style.position = 'fixed';
    div.style.bottom = '20px';
    div.style.right = '20px';
    div.style.background = type === 'error' ? '#ef4444' : '#10b981';
    div.style.color = 'white';
    div.style.padding = '12px 24px';
    div.style.borderRadius = '8px';
    div.style.zIndex = '1000';
    div.style.animation = 'fadeInUp 0.3s ease';
    document.body.appendChild(div);
    setTimeout(() => div.remove(), 3000);
}

function renderRecipes(recipes) {
    const container = document.getElementById('recipes-container');
    container.innerHTML = '';
    if (!recipes || recipes.length === 0) {
        container.innerHTML = '<p class="text-muted">No recipes found.</p>';
        return;
    }
    recipes.forEach(recipe => {
        const div = document.createElement('div');
        div.className = 'recipe-card';
        div.innerHTML = `
            <img src="${recipe.image || 'https://via.placeholder.com/300'}" alt="${recipe.title}">
            <div class="recipe-content">
                <div class="recipe-title">${recipe.title}</div>
                <div class="recipe-ingredients">Ingredients: ${recipe.ingredients || 'Various'}</div>
            </div>
        `;
        container.appendChild(div);
    });
}

function calculateStats() {
    const today = new Date();
    const upcoming = new Date();
    upcoming.setDate(today.getDate() + 3);

    let expiringSoonCount = 0;

    state.inventory.forEach(item => {
        const expiry = new Date(item.expiryDate);
        if (expiry <= upcoming && expiry >= today) {
            expiringSoonCount++;
        }
    });

    state.stats.totalItems = state.inventory.length;
    state.stats.expiringSoon = expiringSoonCount;
    state.stats.wasteAvoided = (state.inventory.length * 0.1).toFixed(1) + 'kg';
    state.stats.moneySaved = '$' + (state.inventory.length * 2.5).toFixed(2);
}

function updateUI() {
    calculateStats();
    document.getElementById('total-items').innerText = state.stats.totalItems;
    document.getElementById('expiring-soon').innerText = state.stats.expiringSoon;
    document.getElementById('waste-avoided').innerText = state.stats.wasteAvoided;
    document.getElementById('money-saved').innerText = state.stats.moneySaved;

    const list = document.getElementById('inventory-list-ul');
    list.innerHTML = '';

    state.inventory.forEach(item => {
        const li = document.createElement('li');
        li.className = `inventory-item ${getExpiryClass(item.expiryDate)}`;
        li.innerHTML = `
            <div class="item-info">
                <h4>${item.name}</h4>
                <div class="item-meta"><span>${item.quantity || '-'}</span> • <span>${item.category || 'Other'}</span></div>
            </div>
            <div class="item-status">
                <span class="expiry-badge ${getExpiryClass(item.expiryDate)}">${formatDate(item.expiryDate)}</span>
            </div>
        `;
        list.appendChild(li);
    });

    generateDashboardAlerts();
}

function getExpiryClass(dateStr) {
    if (!dateStr) return 'safe';
    const today = new Date();
    const expiry = new Date(dateStr);
    const diffDays = Math.ceil((expiry - today) / (1000 * 60 * 60 * 24));
    if (diffDays < 0) return 'expired';
    if (diffDays <= 3) return 'soon';
    return 'safe';
}

function formatDate(dateStr) {
    if (!dateStr) return 'Unknown';
    return new Date(dateStr).toLocaleDateString('en-US', { month: 'short', day: 'numeric' });
}

function generateDashboardAlerts() {
    const container = document.getElementById('alerts-container');
    container.innerHTML = '';
    const expiringItems = state.inventory.filter(i => getExpiryClass(i.expiryDate) === 'soon');

    if (expiringItems.length === 0) {
        container.innerHTML = '<p class="text-muted">No urgent alerts. Good job!</p>';
        return;
    }
    expiringItems.forEach(item => {
        const div = document.createElement('div');
        div.style.marginBottom = '10px';
        div.style.padding = '10px';
        div.style.background = 'rgba(245, 158, 11, 0.1)';
        div.style.borderRadius = '8px';
        div.style.borderLeft = '3px solid var(--accent)';
        div.innerHTML = `<strong>${item.name}</strong> is expiring soon!`;
        container.appendChild(div);
    });
}

// Event Listeners
function setupFormListeners() {
    document.getElementById('quick-add-form').addEventListener('submit', (e) => {
        e.preventDefault();
        const name = document.getElementById('quick-name').value;
        const date = document.getElementById('quick-date').value;
        addItem({ name, quantity: '1 unit', expiryDate: date, category: 'Uncategorized' });
        document.getElementById('quick-add-form').reset();
    });

    document.getElementById('add-item-form').addEventListener('submit', (e) => {
        e.preventDefault();
        const formData = new FormData(e.target);
        addItem(Object.fromEntries(formData.entries()));
        e.target.reset();
        showSection('inventory');
    });
}