/**
 * JCHAT Web Application
 * Main application logic for the JMAP-based chat client
 */

class JChatApp {
    constructor() {
        this.jmapClient = new JMAPClient(JChatConfig.API_BASE_URL);
        this.conversations = new Map();
        this.messages = new Map();
        this.currentConversationId = null;
        this.currentUser = null; // Will be set after authentication
        this.authToken = this.getStoredToken();
        this.states = {
            conversation: '0',
            message: '0'
        };
        
        // UI Elements
        this.elements = {};
        this.bindElements();
        this.bindEvents();
        
        // Initialize the application
        this.init();
    }

    bindElements() {
        this.elements = {
            connectionStatus: document.getElementById('connectionStatus'),
            conversationList: document.getElementById('conversationList'),
            chatHeader: document.getElementById('chatHeader'),
            messagesContainer: document.getElementById('messagesContainer'),
            messageInputArea: document.getElementById('messageInputArea'),
            messageInput: document.getElementById('messageInput'),
            sendButton: document.getElementById('sendButton')
        };
    }

    bindEvents() {
        // Send message on button click
        this.elements.sendButton.addEventListener('click', () => this.sendMessage());
        
        // Send message on Enter (but not Shift+Enter)
        this.elements.messageInput.addEventListener('keydown', (e) => {
            if (e.key === 'Enter' && !e.shiftKey) {
                e.preventDefault();
                this.sendMessage();
            }
        });

        // Auto-resize textarea
        this.elements.messageInput.addEventListener('input', () => {
            this.autoResizeTextarea(this.elements.messageInput);
        });

        // Enable/disable send button based on input
        this.elements.messageInput.addEventListener('input', () => {
            const hasText = this.elements.messageInput.value.trim().length > 0;
            this.elements.sendButton.disabled = !hasText;
        });
    }

    async init() {
        try {
            this.updateConnectionStatus('Connecting...', 'connecting');
            
            // Check if user is authenticated
            if (!this.authToken || !await this.verifyAuthentication()) {
                // Show login/registration prompt
                this.showAuthenticationPrompt();
                return;
            }
            
            // Initialize JMAP session
            await this.jmapClient.init(this.authToken);
            console.log('JMAP session initialized:', this.jmapClient.session);
            
            // Load initial data
            await this.loadConversations();
            
            this.updateConnectionStatus('Connected', 'connected');
            
            // Start polling for updates (in production, use EventSource/WebSockets)
            this.startPolling();
            
        } catch (error) {
            console.error('Failed to initialize application:', error);
            if (error.message.includes('unauthorized') || error.message.includes('401')) {
                // Authentication error - show login
                this.clearStoredToken();
                this.showAuthenticationPrompt();
            } else {
                this.updateConnectionStatus('Connection failed', 'disconnected');
                this.showError('Failed to connect to chat server. Please refresh the page to try again.');
            }
        }
    }

    // Authentication methods
    getStoredToken() {
        return localStorage.getItem('jchat_auth_token');
    }

    storeToken(token) {
        localStorage.setItem('jchat_auth_token', token);
        this.authToken = token;
    }

    clearStoredToken() {
        localStorage.removeItem('jchat_auth_token');
        this.authToken = null;
    }

    async verifyAuthentication() {
        if (!this.authToken) return false;
        
        try {
            const response = await fetch(`${JChatConfig.API_BASE_URL}/auth/me`, {
                method: 'GET',
                headers: {
                    'Authorization': `Bearer ${this.authToken}`,
                    'Content-Type': 'application/json'
                }
            });

            if (response.ok) {
                const data = await response.json();
                this.currentUser = data.user;
                return true;
            } else {
                return false;
            }
        } catch (error) {
            console.error('Auth verification failed:', error);
            return false;
        }
    }

    showAuthenticationPrompt() {
        // Decide whether to show login or register modal
        // For simplicity, always show register modal first
        showModal('registerModal');
    }

    async performLogin() {
        const email = document.getElementById('loginEmail').value.trim();
        const password = document.getElementById('loginPassword').value;

        if (!email || !password) {
            this.showLoginError('Please fill in all fields');
            return;
        }

        try {
            const response = await fetch(`${JChatConfig.API_BASE_URL}/auth/login`, {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json'
                },
                body: JSON.stringify({
                    email: email,
                    password: password
                })
            });

            const data = await response.json();

            if (response.ok) {
                // Store token and user info
                this.storeToken(data.token);
                this.currentUser = data.user;
                
                // Close modal and initialize app
                closeModal('loginModal');
                this.init(); // Restart initialization
            } else {
                this.showLoginError(data.detail || 'Login failed');
            }
        } catch (error) {
            console.error('Login error:', error);
            this.showLoginError('Login failed. Please try again.');
        }
    }

    async performRegistration() {
        const email = document.getElementById('registerEmail').value.trim();
        const displayName = document.getElementById('registerDisplayName').value.trim();
        const password = document.getElementById('registerPassword').value;
        const confirmPassword = document.getElementById('registerConfirmPassword').value;

        if (!email || !displayName || !password || !confirmPassword) {
            this.showRegisterError('Please fill in all fields');
            return;
        }

        if (password !== confirmPassword) {
            this.showRegisterError('Passwords do not match');
            return;
        }

        if (password.length < 8) {
            this.showRegisterError('Password must be at least 8 characters long');
            return;
        }

        try {
            const response = await fetch(`${JChatConfig.API_BASE_URL}/auth/register`, {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json'
                },
                body: JSON.stringify({
                    email: email,
                    displayName: displayName,
                    password: password
                })
            });

            const data = await response.json();

            if (response.ok) {
                // Store token and user info
                this.storeToken(data.token);
                this.currentUser = data.user;
                
                // Close modal and initialize app
                closeModal('registerModal');
                this.init(); // Restart initialization
            } else {
                this.showRegisterError(data.detail || 'Registration failed');
            }
        } catch (error) {
            console.error('Registration error:', error);
            this.showRegisterError('Registration failed. Please try again.');
        }
    }

    showLoginModal() {
        closeModal('registerModal');
                    showModal('loginModal');
        // Clear any previous errors
        document.getElementById('loginError').style.display = 'none';
    }

    showRegisterModal() {
        closeModal('loginModal');
                    showModal('registerModal');
        // Clear any previous errors
        document.getElementById('registerError').style.display = 'none';
    }

    showLoginError(message) {
        const errorDiv = document.getElementById('loginError');
        errorDiv.textContent = message;
        errorDiv.style.display = 'block';
    }

    showRegisterError(message) {
        const errorDiv = document.getElementById('registerError');
        errorDiv.textContent = message;
        errorDiv.style.display = 'block';
    }

    async logout() {
        try {
            await fetch(`${JChatConfig.API_BASE_URL}/auth/logout`, {
                method: 'POST',
                headers: {
                    'Authorization': `Bearer ${this.authToken}`,
                    'Content-Type': 'application/json'
                }
            });
        } catch (error) {
            console.error('Logout error:', error);
        } finally {
            // Clear local state regardless of server response
            this.clearStoredToken();
            this.currentUser = null;
            this.conversations.clear();
            this.messages.clear();
            this.currentConversationId = null;
            
            // Show authentication prompt
            this.showAuthenticationPrompt();
        }
    }

    updateConnectionStatus(text, status) {
        this.elements.connectionStatus.textContent = text;
        this.elements.connectionStatus.className = `connection-status status-${status}`;
    }

    async loadConversations() {
        try {
            // Query all conversations
            const queryResult = await this.jmapClient.queryConversations({}, [{
                property: 'lastMessageAt',
                isAscending: false
            }]);

            if (queryResult.ids.length > 0) {
                // Get conversation details
                const conversationsResult = await this.jmapClient.getConversations(queryResult.ids);
                
                // Update local state
                conversationsResult.list.forEach(conv => {
                    this.conversations.set(conv.id, conv);
                });

                this.states.conversation = conversationsResult.state;
            }

            this.renderConversationList();
            
        } catch (error) {
            console.error('Failed to load conversations:', error);
            this.showError('Failed to load conversations.');
        }
    }

    async createConversation(title, description = '') {
        try {
            this.showStatus('Creating conversation...', 'info');
            
            const result = await this.jmapClient.createConversation({
                title: title,
                description: description || null,
                participantIds: [this.currentUser] // Add current user as participant
            });
            
            this.showStatus('Conversation created successfully!', 'success');
            
            // Reload conversations to include the new one
            await this.loadConversations();
            
            // Select the new conversation if possible
            if (result && result.id) {
                this.selectConversation(result.id);
            }
            
        } catch (error) {
            console.error('Failed to create conversation:', error);
            this.showError('Failed to create conversation: ' + error.message);
            throw error;
        }
    }

    async loadMessages(conversationId) {
        try {
            // Query messages for the conversation
            const queryResult = await this.jmapClient.queryMessages({
                inConversation: conversationId
            }, [{
                property: 'sentAt',
                isAscending: true
            }]);

            if (queryResult.ids.length > 0) {
                // Get message details
                const messagesResult = await this.jmapClient.getMessages(queryResult.ids);
                
                // Update local state
                messagesResult.list.forEach(msg => {
                    this.messages.set(msg.id, msg);
                });

                this.states.message = messagesResult.state;
            }

            this.renderMessages(conversationId);
            
        } catch (error) {
            console.error('Failed to load messages:', error);
            this.showError('Failed to load messages.');
        }
    }

    renderConversationList() {
        const conversations = Array.from(this.conversations.values());
        
        if (conversations.length === 0) {
            this.elements.conversationList.innerHTML = `
                <div class="loading">No conversations yet</div>
            `;
            return;
        }

        // Sort by last message time
        conversations.sort((a, b) => {
            const aTime = a.lastMessageAt || a.createdAt;
            const bTime = b.lastMessageAt || b.createdAt;
            return new Date(bTime) - new Date(aTime);
        });

        const html = conversations.map(conv => {
            const isActive = conv.id === this.currentConversationId;
            const title = conv.title || 'Untitled Conversation';
            const preview = 'No messages yet'; // In production, would show last message
            const time = this.formatTime(conv.lastMessageAt || conv.createdAt);
            
            return `
                <div class="conversation-item ${isActive ? 'active' : ''}" 
                     onclick="app.selectConversation('${conv.id}')">
                    <div class="conversation-title">${this.escapeHtml(title)}</div>
                    <div class="conversation-preview">${this.escapeHtml(preview)}</div>
                    <div class="conversation-meta">
                        <span>${conv.messageCount} messages</span>
                        <span>${time}</span>
                    </div>
                </div>
            `;
        }).join('');

        this.elements.conversationList.innerHTML = html;
    }

    async selectConversation(conversationId) {
        try {
            this.currentConversationId = conversationId;
            const conversation = this.conversations.get(conversationId);
            
            if (!conversation) {
                console.error('Conversation not found:', conversationId);
                return;
            }

            // Update UI
            this.elements.chatHeader.textContent = conversation.title || 'Untitled Conversation';
            this.elements.messageInputArea.style.display = 'flex';
            
            // Update conversation list highlighting
            this.renderConversationList();
            
            // Load messages for this conversation
            await this.loadMessages(conversationId);
            
        } catch (error) {
            console.error('Failed to select conversation:', error);
            this.showError('Failed to load conversation.');
        }
    }

    renderMessages(conversationId) {
        const conversationMessages = Array.from(this.messages.values())
            .filter(msg => msg.conversationId === conversationId)
            .sort((a, b) => new Date(a.sentAt) - new Date(b.sentAt));

        if (conversationMessages.length === 0) {
            this.elements.messagesContainer.innerHTML = `
                <div class="empty-state">
                    <h3>No messages yet</h3>
                    <p>Start the conversation by sending a message below</p>
                </div>
            `;
            return;
        }

        const html = conversationMessages.map(msg => {
            const isOwn = msg.senderId === this.currentUser;
            const senderName = msg.senderId || 'Unknown User'; // Use the senderId as the display name
            const avatar = senderName.charAt(0).toUpperCase();
            const time = this.formatTime(msg.sentAt);
            
            return `
                <div class="message ${isOwn ? 'own' : ''}">
                    <div class="message-avatar">${avatar}</div>
                    <div class="message-content">
                        ${!isOwn ? `<div class="message-sender">${this.escapeHtml(senderName)}</div>` : ''}
                        <div class="message-text">${this.formatMessageBody(msg.body, msg.bodyType)}</div>
                        <div class="message-time">${time}</div>
                    </div>
                </div>
            `;
        }).join('');

        this.elements.messagesContainer.innerHTML = html;
        
        // Scroll to bottom
        this.scrollToBottom();
    }

    async sendMessage() {
        const messageText = this.elements.messageInput.value.trim();
        
        if (!messageText || !this.currentConversationId) {
            return;
        }

        try {
            // Disable input while sending
            this.elements.messageInput.disabled = true;
            this.elements.sendButton.disabled = true;

            // Send the message
            const message = await this.jmapClient.sendMessage(
                this.currentConversationId,
                messageText,
                'text/plain',
                this.currentUser // Pass the current user as sender
            );

            // Add message to local state
            this.messages.set(message.id, message);

            // Clear input
            this.elements.messageInput.value = '';
            this.autoResizeTextarea(this.elements.messageInput);

            // Re-render messages
            this.renderMessages(this.currentConversationId);

            // Update conversation in list (message count, last message time, etc.)
            // In production, this would be handled by change notifications
            await this.loadConversations();

        } catch (error) {
            console.error('Failed to send message:', error);
            this.showError('Failed to send message. Please try again.');
        } finally {
            // Re-enable input
            this.elements.messageInput.disabled = false;
            this.elements.sendButton.disabled = false;
            this.elements.messageInput.focus();
        }
    }

    async createConversation(title, participantIds = []) {
        try {
            const conversation = await this.jmapClient.createConversation({
                title: title,
                participantIds: [this.currentUser, ...participantIds]
            });

            // Add to local state
            this.conversations.set(conversation.id, conversation);

            // Re-render conversation list
            this.renderConversationList();

            // Select the new conversation
            await this.selectConversation(conversation.id);

            return conversation;
            
        } catch (error) {
            console.error('Failed to create conversation:', error);
            this.showError('Failed to create conversation.');
            throw error;
        }
    }

    startPolling() {
        // Poll for changes every 5 seconds
        // In production, this should be replaced with EventSource/WebSockets
        setInterval(async () => {
            try {
                await this.checkForUpdates();
            } catch (error) {
                console.error('Failed to poll for updates:', error);
            }
        }, 5000);
    }

    async checkForUpdates() {
        try {
            // Check for conversation changes
            const convChanges = await this.jmapClient.getConversationChanges(this.states.conversation);
            if (convChanges.hasMoreChanges || convChanges.created.length > 0 || 
                convChanges.updated.length > 0 || convChanges.destroyed.length > 0 ||
                convChanges.newState !== this.states.conversation) {
                
                // Update our stored state
                this.states.conversation = convChanges.newState;
                await this.loadConversations();
            }

            // Check for message changes
            const msgChanges = await this.jmapClient.getMessageChanges(this.states.message);
            if (msgChanges.hasMoreChanges || msgChanges.created.length > 0 || 
                msgChanges.updated.length > 0 || msgChanges.destroyed.length > 0 ||
                msgChanges.newState !== this.states.message) {
                
                // Update our stored state
                this.states.message = msgChanges.newState;
                
                // Reload messages for current conversation
                if (this.currentConversationId) {
                    await this.loadMessages(this.currentConversationId);
                }
            }

        } catch (error) {
            // Don't spam console with polling errors
            if (error.message.includes('changes')) {
                console.debug('Polling error:', error);
            } else {
                console.error('Update check failed:', error);
            }
        }
    }

    // Utility methods
    formatTime(isoString) {
        if (!isoString) return '';
        const date = new Date(isoString);
        const now = new Date();
        
        if (date.toDateString() === now.toDateString()) {
            return date.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' });
        } else {
            return date.toLocaleDateString();
        }
    }

    formatMessageBody(body, bodyType) {
        if (bodyType === 'text/html') {
            // In production, would sanitize HTML
            return body;
        } else {
            // Convert plain text to HTML, preserving line breaks
            return this.escapeHtml(body).replace(/\n/g, '<br>');
        }
    }

    escapeHtml(text) {
        const div = document.createElement('div');
        div.textContent = text;
        return div.innerHTML;
    }

    autoResizeTextarea(textarea) {
        textarea.style.height = 'auto';
        textarea.style.height = Math.min(textarea.scrollHeight, 120) + 'px';
    }

    scrollToBottom() {
        this.elements.messagesContainer.scrollTop = this.elements.messagesContainer.scrollHeight;
    }

    showError(message) {
        // Simple error display - in production would use a proper notification system
        const errorDiv = document.createElement('div');
        errorDiv.className = 'error';
        errorDiv.textContent = message;
        
        document.body.appendChild(errorDiv);
        
        setTimeout(() => {
            document.body.removeChild(errorDiv);
        }, 5000);
    }
}

// Initialize the application when the DOM is loaded
let app;
document.addEventListener('DOMContentLoaded', () => {
    // Load user settings
    const savedUsername = localStorage.getItem('jchat_username');
    if (savedUsername) {
        document.getElementById('currentUser').textContent = savedUsername;
    }
    
    app = new JChatApp();
    window.jchatApp = app; // Make available globally for modal functions
    
    if (savedUsername) {
        app.currentUser = savedUsername;
    }
});

// Global functions for UI interactions
function showUserSettings() {
    const modal = document.getElementById('userSettingsModal');
    const input = document.getElementById('userDisplayName');
    input.value = localStorage.getItem('jchat_username') || '';
    modal.style.display = 'flex';
}

function showNewConversationDialog() {
    const modal = document.getElementById('newConversationModal');
    document.getElementById('newConversationTitle').value = '';
    document.getElementById('newConversationDescription').value = '';
    modal.style.display = 'flex';
}

function showModal(modalId) {
    document.getElementById(modalId).style.display = 'flex';
}

function closeModal(modalId) {
    document.getElementById(modalId).style.display = 'none';
}

function saveUserSettings() {
    const username = document.getElementById('userDisplayName').value.trim();
    if (username) {
        localStorage.setItem('jchat_username', username);
        document.getElementById('currentUser').textContent = username;
        closeModal('userSettingsModal');
        
        // Update the app's current user
        if (window.jchatApp) {
            window.jchatApp.currentUser = username;
        }
    }
}

async function createNewConversation() {
    const title = document.getElementById('newConversationTitle').value.trim();
    if (title) {
        const description = document.getElementById('newConversationDescription').value.trim();
        
        try {
            await window.jchatApp.createConversation(title, description);
            closeModal('newConversationModal');
        } catch (error) {
            console.error('Error creating conversation:', error);
            alert('Failed to create conversation. Please try again.');
        }
    }
}

// Authentication global functions
function showLoginModal() {
    if (window.jchatApp) {
        window.jchatApp.showLoginModal();
    }
}

function showRegisterModal() {
    if (window.jchatApp) {
        window.jchatApp.showRegisterModal();
    }
}

function performLogin() {
    if (window.jchatApp) {
        window.jchatApp.performLogin();
    }
}

function performRegistration() {
    if (window.jchatApp) {
        window.jchatApp.performRegistration();
    }
}

async function createNewConversation() {
    const title = document.getElementById('newConversationTitle').value.trim();
    const description = document.getElementById('newConversationDescription').value.trim();
    
    if (!title) {
        alert('Please enter a conversation title');
        return;
    }
    
    if (window.jchatApp) {
        try {
            await window.jchatApp.createConversation(title, description);
            closeModal('newConversationModal');
        } catch (error) {
            alert('Failed to create conversation: ' + error.message);
        }
    }
}

// Close modals when clicking outside
document.addEventListener('click', (e) => {
    if (e.target.classList.contains('modal')) {
        e.target.style.display = 'none';
    }
});

// Close modals with Escape key
document.addEventListener('keydown', (e) => {
    if (e.key === 'Escape') {
        const modals = document.querySelectorAll('.modal');
        modals.forEach(modal => {
            if (modal.style.display === 'flex') {
                modal.style.display = 'none';
            }
        });
    }
});

// For debugging in console
window.jchat = {
    get app() { return app; },
    get jmapClient() { return app?.jmapClient; }
};