document.addEventListener('DOMContentLoaded', () => {
    const chatForm = document.getElementById('chat-form');
    const userInput = document.getElementById('user-input');
    const chatContainer = document.getElementById('chat-container');
    const sendBtn = document.getElementById('send-btn');
    const clearChatBtn = document.getElementById('clear-chat');

    let chatHistory = []; // Store conversation history

    // Auto-resize textarea
    userInput.addEventListener('input', function() {
        this.style.height = 'auto';
        this.style.height = (this.scrollHeight > 150 ? 150 : this.scrollHeight) + 'px';
        if (this.value.trim() === '') {
            sendBtn.disabled = true;
        } else {
            sendBtn.disabled = false;
        }
    });

    // Handle Enter key (Shift+Enter for new line)
    userInput.addEventListener('keydown', function(e) {
        if (e.key === 'Enter' && !e.shiftKey) {
            e.preventDefault();
            if (!sendBtn.disabled) {
                chatForm.requestSubmit();
            }
        }
    });

    clearChatBtn.addEventListener('click', () => {
        if (confirm('Are you sure you want to clear the chat history?')) {
            chatHistory = [];
            chatContainer.innerHTML = '';
            addMessage('system', 'Hello! I am LocalFoodAI, your completely local nutrition and menu assistant. How can I help you today?');
        }
    });

    chatForm.addEventListener('submit', async (e) => {
        e.preventDefault();
        const message = userInput.value.trim();
        if (!message) return;

        // Reset input
        userInput.value = '';
        userInput.style.height = 'auto';
        sendBtn.disabled = true;

        // Add user message to UI
        addMessage('user', message);
        chatHistory.push({ role: 'user', content: message });

        // Add loading indicator
        const loadingId = addTypingIndicator();

        try {
            const token = localStorage.getItem('localFoodToken');
            // Fetch response from backend
            const response = await fetch('/chat', {
                method: 'POST',
                headers: { 
                    'Content-Type': 'application/json',
                    'Authorization': `Bearer ${token}`
                },
                body: JSON.stringify({ messages: chatHistory })
            });

            if (response.status === 401) {
                setLoggedOutState();
                addMessage('system', 'Your session has expired. Please log in again.');
                return;
            }

            if (!response.ok) {
                throw new Error(`HTTP error! status: ${response.status}`);
            }

            // Remove loading indicator
            removeElement(loadingId);

            // Create new bot message container
            const botMessageId = 'msg-' + Date.now();
            const botContentEl = addMessage('system', '', botMessageId);

            let botFullResponse = '';

            // Handle Server-Sent Events (Streaming)
            const reader = response.body.getReader();
            const decoder = new TextDecoder('utf-8');
            let done = false;

            while (!done) {
                const { value, done: readerDone } = await reader.read();
                done = readerDone;
                if (value) {
                    const chunk = decoder.decode(value, { stream: true });
                    // Split the chunk by double newline to get individual SSE messages
                    const lines = chunk.split('\n\n');
                    for (const line of lines) {
                        if (line.startsWith('data: ')) {
                            const dataStr = line.substring(6);
                            if (dataStr.trim() === '') continue;
                            try {
                                const data = JSON.parse(dataStr);
                                if (data.error) {
                                    botContentEl.innerHTML += `<br><span style="color:#f85149">Error: ${data.error}</span>`;
                                } else if (data.content !== undefined) {
                                    botFullResponse += data.content;
                                    // Basic text to HTML conversion
                                    botContentEl.innerHTML = formatText(botFullResponse);
                                    chatContainer.scrollTop = chatContainer.scrollHeight;
                                }
                            } catch (err) {
                                console.error('Error parsing SSE data:', err, dataStr);
                            }
                        }
                    }
                }
            }

            // Save bot response to history once complete
            chatHistory.push({ role: 'assistant', content: botFullResponse });

        } catch (error) {
            console.error('Chat error:', error);
            removeElement(loadingId);
            addMessage('system', 'Sorry, there was an error communicating with the local LLM. Make sure the server and Ollama are running.');
        } finally {
            sendBtn.disabled = false;
            userInput.focus();
        }
    });

    function addMessage(role, content, id = null) {
        const msgDiv = document.createElement('div');
        msgDiv.className = `message ${role}`;
        if (id) msgDiv.id = id;

        const avatarDiv = document.createElement('div');
        avatarDiv.className = 'avatar';
        avatarDiv.textContent = role === 'user' ? '👤' : '🤖';

        const contentDiv = document.createElement('div');
        contentDiv.className = 'message-content';
        contentDiv.innerHTML = formatText(content);

        msgDiv.appendChild(avatarDiv);
        msgDiv.appendChild(contentDiv);
        chatContainer.appendChild(msgDiv);
        chatContainer.scrollTop = chatContainer.scrollHeight;

        return contentDiv;
    }

    function addTypingIndicator() {
        const id = 'typing-' + Date.now();
        const msgDiv = document.createElement('div');
        msgDiv.className = 'message system';
        msgDiv.id = id;

        const avatarDiv = document.createElement('div');
        avatarDiv.className = 'avatar';
        avatarDiv.textContent = '🤖';

        const contentDiv = document.createElement('div');
        contentDiv.className = 'message-content typing-indicator';
        contentDiv.innerHTML = `
            <div class="typing-dot"></div>
            <div class="typing-dot"></div>
            <div class="typing-dot"></div>
        `;

        msgDiv.appendChild(avatarDiv);
        msgDiv.appendChild(contentDiv);
        chatContainer.appendChild(msgDiv);
        chatContainer.scrollTop = chatContainer.scrollHeight;

        return id;
    }

    function removeElement(id) {
        const el = document.getElementById(id);
        if (el) el.remove();
    }

    function formatText(text) {
        if (!text) return '';
        // Very basic markdown parsing for bold, italics, code, and newlines
        let formatted = text
            .replace(/&/g, "&amp;")
            .replace(/</g, "&lt;")
            .replace(/>/g, "&gt;")
            .replace(/\n/g, "<br>")
            .replace(/\*\*(.*?)\*\*/g, "<strong>$1</strong>") // bold
            .replace(/\*(.*?)\*/g, "<em>$1</em>") // italic
            .replace(/`(.*?)`/g, "<code style='background:rgba(255,255,255,0.1);padding:2px 4px;border-radius:4px'>$1</code>"); // inline code
        return formatted;
    }

    // Authentication & Session Logic
    const authScreen = document.getElementById('auth-screen');
    const chatApp = document.getElementById('chat-app');
    
    const loginForm = document.getElementById('login-form');
    const registerForm = document.getElementById('register-form');
    
    const showRegisterLink = document.getElementById('show-register');
    const showLoginLink = document.getElementById('show-login');
    
    const loginError = document.getElementById('login-error');
    const regError = document.getElementById('reg-error');
    const regSuccess = document.getElementById('reg-success');
    
    const logoutBtn = document.getElementById('nav-logout-btn');
    const userGreeting = document.getElementById('user-greeting');

    // Check session on load
    const savedUser = localStorage.getItem('localFoodUser');
    const savedToken = localStorage.getItem('localFoodToken');
    if (savedUser && savedToken) {
        setLoggedInState(savedUser, savedToken);
    }

    async function setLoggedInState(username, token) {
        localStorage.setItem('localFoodUser', username);
        localStorage.setItem('localFoodToken', token);
        userGreeting.textContent = `Welcome, ${username}`;
        
        authScreen.classList.add('fade-out');
        setTimeout(() => {
            authScreen.style.display = 'none';
            chatApp.style.display = 'flex';
            chatApp.classList.add('fade-in');
            userInput.focus();
        }, 500);

        // Load persisted chat history and macro targets from the server
        await loadChatHistory();
        await loadMacroTargets();
    }

    async function loadChatHistory() {
        const token = localStorage.getItem('localFoodToken');
        if (!token) return;

        try {
            const response = await fetch('/api/chat/history', {
                headers: { 'Authorization': `Bearer ${token}` }
            });

            if (response.status === 401) {
                setLoggedOutState();
                return;
            }

            if (response.ok) {
                const data = await response.json();
                if (data.history && data.history.length > 0) {
                    // Clear initial welcome message if we have real history
                    chatContainer.innerHTML = '';
                    chatHistory = []; // Reset local state
                    
                    data.history.forEach(msg => {
                        addMessage(msg.role, msg.content);
                        chatHistory.push({ role: msg.role, content: msg.content });
                    });
                }
            }
        } catch (err) {
            console.error("Failed to load chat history:", err);
        }
    }

    async function loadMacroTargets() {
        const token = localStorage.getItem('localFoodToken');
        if (!token) return;

        const dashboard = document.getElementById('macro-dashboard');
        try {
            const response = await fetch('/api/macros/targets', {
                headers: { 'Authorization': `Bearer ${token}` }
            });

            if (response.ok) {
                const data = await response.json();
                document.getElementById('macro-calories').textContent = `${data.calories} kcal`;
                document.getElementById('macro-protein').textContent  = `${data.protein_g} g`;
                document.getElementById('macro-carbs').textContent    = `${data.carbs_g} g`;
                document.getElementById('macro-fat').textContent      = `${data.fat_g} g`;
                if (dashboard) dashboard.style.display = 'flex';
            }
        } catch (err) {
            console.error('Failed to load macro targets:', err);
        }
    }

    async function setLoggedOutState() {
        const token = localStorage.getItem('localFoodToken');
        if (token) {
            try {
                await fetch('/api/logout', {
                    method: 'POST',
                    headers: { 'Authorization': `Bearer ${token}` }
                });
            } catch (err) {
                console.error("Error during logout:", err);
            }
        }

        // Clear chat memory and interface so the next user doesn't see old messages
        chatHistory = [];
        chatContainer.innerHTML = '';
        addMessage('system', 'Hello! I am LocalFoodAI, your completely local nutrition and menu assistant. How can I help you today?');

        localStorage.removeItem('localFoodUser');
        localStorage.removeItem('localFoodToken');
        chatApp.style.display = 'none';
        chatApp.classList.remove('fade-in');
        const dashboard = document.getElementById('macro-dashboard');
        if (dashboard) dashboard.style.display = 'none';
        
        authScreen.style.display = 'block';
        setTimeout(() => {
            authScreen.classList.remove('fade-out');
        }, 50);
        loginForm.reset();
        registerForm.reset();
        loginError.textContent = '';
        regError.textContent = '';
    }

    logoutBtn.addEventListener('click', () => {
        setLoggedOutState();
    });

    // Toggles
    showRegisterLink.addEventListener('click', (e) => {
        e.preventDefault();
        loginForm.style.display = 'none';
        registerForm.style.display = 'block';
    });
    
    showLoginLink.addEventListener('click', (e) => {
        e.preventDefault();
        registerForm.style.display = 'none';
        loginForm.style.display = 'block';
    });

    // Login Submission
    loginForm.addEventListener('submit', async (e) => {
        e.preventDefault();
        loginError.textContent = '';
        const submitBtn = document.getElementById('login-submit-btn');
        submitBtn.disabled = true;

        const username = document.getElementById('login-username').value;
        const password = document.getElementById('login-password').value;

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

            const data = await response.json();

            if (!response.ok) {
                loginError.textContent = data.detail || 'Login failed.';
            } else {
                setLoggedInState(data.username, data.token);
            }
        } catch (err) {
            loginError.textContent = 'Server error. Is the backend running?';
        } finally {
            submitBtn.disabled = false;
        }
    });

    // Registration Submission
    registerForm.addEventListener('submit', async (e) => {
        e.preventDefault();
        regError.textContent = '';
        regSuccess.textContent = '';
        const submitBtn = document.getElementById('reg-submit-btn');
        submitBtn.disabled = true;

        const username = document.getElementById('reg-username').value;
        const password = document.getElementById('reg-password').value;
        const confirmInfo = document.getElementById('reg-confirm').value;

        if (password !== confirmInfo) {
            regError.textContent = "Passwords do not match.";
            submitBtn.disabled = false;
            return;
        }

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

            const data = await response.json();

            if (!response.ok) {
                regError.textContent = data.detail || 'Registration failed.';
            } else {
                regSuccess.textContent = 'Account created! Logging in...';
                setTimeout(() => {
                    setLoggedInState(data.username, data.token);
                }, 1000);
            }
        } catch (err) {
            regError.textContent = 'Server error. Please try again later.';
        } finally {
            submitBtn.disabled = false;
        }
    });

    // --- Food Search Module Logic ---
    const searchInput = document.getElementById('food-search-input');
    const searchDropdown = document.getElementById('search-results-dropdown');
    const clearSearchBtn = document.getElementById('clear-search-btn');

    function debounce(func, delay) {
        let timeout;
        return function(...args) {
            clearTimeout(timeout);
            timeout = setTimeout(() => func(...args), delay);
        };
    }

    const performSearch = async (query) => {
        if (!query) {
            searchDropdown.style.display = 'none';
            return;
        }
        
        searchDropdown.style.display = 'block';
        searchDropdown.innerHTML = '<div class="search-loading">Searching local database...</div>';
        
        try {
            const token = localStorage.getItem('localFoodToken');
            const response = await fetch(`/api/food/search?q=${encodeURIComponent(query)}`, {
                headers: { 'Authorization': `Bearer ${token}` }
            });
            
            if (response.status === 401) {
                setLoggedOutState();
                addMessage('system', 'Your session has expired. Please log in again to use the food search.');
                searchDropdown.style.display = 'none';
                return;
            }

            if (!response.ok) {
                throw new Error(`HTTP error! status: ${response.status}`);
            }

            const data = await response.json();
            
            if (data.results && data.results.length > 0) {
                searchDropdown.innerHTML = '';
                data.results.forEach(item => {
                    const foodEl = document.createElement('div');
                    foodEl.className = 'food-item';
                    
                    const badgeStr = item.category === "Sourced Ingredient" ? "Raw Ingredient" : item.category;
                    
                    foodEl.innerHTML = `
                        <div class="food-item-header">
                            <span class="food-name">${item.name}</span>
                            <span class="food-badge">${badgeStr}</span>
                        </div>
                        <div class="food-macros">
                            <div class="macro-tag">Cal: <span>${item.calories}</span></div>
                            <div class="macro-tag">Pro: <span>${item.protein_g}g</span></div>
                            <div class="macro-tag">Fat: <span>${item.fat_g}g</span></div>
                            <div class="macro-tag">Carb: <span>${item.carbs_g}g</span></div>
                        </div>
                        <div class="food-item-footer">
                            <button class="details-btn" data-id="${item.id}">📊 Details</button>
                        </div>
                        <div class="details-panel" id="details-${item.id}">
                            <!-- Populated on demand -->
                        </div>
                    `;
                    
                    // Click on the header/name area auto-fills the chat
                    foodEl.querySelector('.food-item-header').addEventListener('click', (e) => {
                        e.stopPropagation();
                        userInput.value = `Can you build a meal around ${item.name} (${item.calories} cal, ${item.protein_g}g protein)?`;
                        userInput.focus();
                        userInput.style.height = 'auto'; // Reset
                        sendBtn.disabled = false;
                        searchDropdown.style.display = 'none';
                        searchInput.value = '';
                        clearSearchBtn.style.display = 'none';
                    });

                    // Click on the details button toggles the panel
                    foodEl.querySelector('.details-btn').addEventListener('click', (e) => {
                        e.stopPropagation();
                        const panel = document.getElementById(`details-${item.id}`);
                        toggleFoodDetails(item.id, panel, e.target);
                    });
                    
                    searchDropdown.appendChild(foodEl);
                });
            } else {
                searchDropdown.innerHTML = '<div class="search-empty">No matching foods found.</div>';
            }
        } catch (error) {
            console.error('Search error:', error);
            searchDropdown.innerHTML = '<div class="search-empty">Service currently unavailable. Please try again.</div>';
        }
    };

    const toggleFoodDetails = async (foodId, panel, btn) => {
        const isExpanded = panel.classList.contains('expanded');
        
        if (isExpanded) {
            panel.classList.remove('expanded');
            btn.textContent = '📊 Details';
            return;
        }

        // If not loaded yet, fetch from API
        if (panel.innerHTML.trim() === '') {
            panel.innerHTML = '<div class="search-loading">Loading details...</div>';
            panel.classList.add('expanded'); // Show loading state
            
            try {
                const token = localStorage.getItem('localFoodToken');
                const response = await fetch(`/api/food/${foodId}`, {
                    headers: { 'Authorization': `Bearer ${token}` }
                });
                
                if (!response.ok) throw new Error("Failed to fetch details");
                
                const data = await response.json();
                renderFoodDetails(panel, data);
            } catch (err) {
                console.error(err);
                panel.innerHTML = '<div class="search-empty">Error loading details.</div>';
            }
        } else {
            panel.classList.add('expanded');
        }
        
        btn.textContent = '✖ Close';
    };

    const renderFoodDetails = (panel, data) => {
        panel.innerHTML = `
            <div class="nutrient-section">
                <div class="nutrient-section-title">Extended Nutrition</div>
                <div class="nutrient-grid">
                    <div class="nutrient-item"><span class="nutrient-label">Fiber</span><span class="nutrient-value">${data.extended.fiber_g}g</span></div>
                    <div class="nutrient-item"><span class="nutrient-label">Sugar</span><span class="nutrient-value">${data.extended.sugar_g}g</span></div>
                    <div class="nutrient-item"><span class="nutrient-label">Cholesterol</span><span class="nutrient-value">${data.extended.cholesterol_mg}mg</span></div>
                </div>
            </div>
            <div class="nutrient-section">
                <div class="nutrient-section-title">Vitamins</div>
                <div class="nutrient-grid">
                    <div class="nutrient-item"><span class="nutrient-label">Vitamin A</span><span class="nutrient-value">${data.vitamins.vitamin_a_iu}IU</span></div>
                    <div class="nutrient-item"><span class="nutrient-label">Vitamin C</span><span class="nutrient-value">${data.vitamins.vitamin_c_mg}mg</span></div>
                </div>
            </div>
            <div class="nutrient-section">
                <div class="nutrient-section-title">Minerals</div>
                <div class="nutrient-grid">
                    <div class="nutrient-item"><span class="nutrient-label">Calcium</span><span class="nutrient-value">${data.minerals.calcium_mg}mg</span></div>
                    <div class="nutrient-item"><span class="nutrient-label">Iron</span><span class="nutrient-value">${data.minerals.iron_mg}mg</span></div>
                    <div class="nutrient-item"><span class="nutrient-label">Potassium</span><span class="nutrient-value">${data.minerals.potassium_mg}mg</span></div>
                    <div class="nutrient-item"><span class="nutrient-label">Sodium</span><span class="nutrient-value">${data.minerals.sodium_mg}mg</span></div>
                </div>
            </div>
        `;
    };

    const handleSearchInput = debounce((e) => {
        const query = e.target.value.trim();
        if (query.length > 0) {
            clearSearchBtn.style.display = 'block';
            performSearch(query);
        } else {
            clearSearchBtn.style.display = 'none';
            searchDropdown.style.display = 'none';
        }
    }, 300);

    if (searchInput) {
        searchInput.addEventListener('input', handleSearchInput);
    }
    
    if (clearSearchBtn) {
        clearSearchBtn.addEventListener('click', () => {
            searchInput.value = '';
            clearSearchBtn.style.display = 'none';
            searchDropdown.style.display = 'none';
            searchInput.focus();
        });
    }

    document.addEventListener('click', (e) => {
        if (!e.target.closest('#food-search-module')) {
            if (searchDropdown) searchDropdown.style.display = 'none';
        }
    });

    // Initialize state
    sendBtn.disabled = true;
});