// Enhanced logging utility
class Logger {
    constructor() {
        this.logs = [];
        this.maxLogs = 1000;
    }

    log(level, message, data = null) {
        const timestamp = new Date().toISOString();
        const logEntry = {
            timestamp,
            level,
            message,
            data,
            url: window.location.href
        };

        this.logs.push(logEntry);
        if (this.logs.length > this.maxLogs) {
            this.logs.shift();
        }

        const consoleMethod = level === 'error' ? 'error' : level === 'warn' ? 'warn' : 'log';
        console[consoleMethod](`[${timestamp}] ${level.toUpperCase()}: ${message}`, data || '');

        // Save to localStorage for persistence
        try {
            localStorage.setItem('devden_logs', JSON.stringify(this.logs));
        } catch (e) {
            console.warn('Failed to save logs to localStorage:', e);
        }
    }

    info(message, data = null) { this.log('info', message, data); }
    warn(message, data = null) { this.log('warn', message, data); }
    error(message, data = null) { this.log('error', message, data); }

    exportLogs() {
        const blob = new Blob([JSON.stringify(this.logs, null, 2)], { type: 'application/json' });
        const url = URL.createObjectURL(blob);
        const a = document.createElement('a');
        a.href = url;
        a.download = `devden_logs_${new Date().toISOString().split('T')[0]}.json`;
        a.click();
        URL.revokeObjectURL(url);
    }

    clearLogs() {
        this.logs = [];
        localStorage.removeItem('devden_logs');
    }
}

const logger = new Logger();

// Load existing logs from localStorage
try {
    const savedLogs = localStorage.getItem('devden_logs');
    if (savedLogs) {
        logger.logs = JSON.parse(savedLogs);
        logger.info('Loaded existing logs from localStorage', { count: logger.logs.length });
    }
} catch (e) {
    logger.warn('Failed to load existing logs from localStorage:', e);
}

const loginScreen = document.getElementById("loginScreen");
const welcomeScreen = document.getElementById("welcomeScreen");
const chatScreen = document.getElementById("chatScreen");
const chatMessages = document.getElementById("chatMessages");
const welcomeInput = document.getElementById("welcomeInput");
const chatInput = document.getElementById("chatInput");
const loginBtn = document.getElementById("loginBtn");

// API URL is same as frontend (nginx proxies /api and /auth to backend)
const API_URL = window.location.origin;

let isInChat = false;

// Auth functions
function getToken() {
  try {
    const token = localStorage.getItem("devden_token");
    logger.info('Retrieved token from localStorage', { hasToken: !!token });
    return token;
  } catch (error) {
    logger.error('Failed to retrieve token from localStorage', error);
    return null;
  }
}

function setToken(token) {
  try {
    localStorage.setItem("devden_token", token);
    logger.info('Token saved to localStorage');
  } catch (error) {
    logger.error('Failed to save token to localStorage', error);
  }
}

function clearToken() {
  try {
    localStorage.removeItem("devden_token");
    logger.info('Token cleared from localStorage');
  } catch (error) {
    logger.error('Failed to clear token from localStorage', error);
  }
}

function showLoginScreen() {
  try {
    loginScreen.classList.remove("hidden");
    welcomeScreen.classList.add("hidden");
    chatScreen.classList.add("hidden");
    logger.info('Switched to login screen');
  } catch (error) {
    logger.error('Failed to show login screen', error);
  }
}

function showWelcomeScreen() {
  try {
    loginScreen.classList.add("hidden");
    welcomeScreen.classList.remove("hidden");
    chatScreen.classList.add("hidden");
    welcomeInput.focus();
    logger.info('Switched to welcome screen');
  } catch (error) {
    logger.error('Failed to show welcome screen', error);
  }
}

function switchToChat() {
  try {
    loginScreen.classList.add("hidden");
    welcomeScreen.classList.add("hidden");
    chatScreen.classList.remove("hidden");
    chatInput.focus();
    isInChat = true;
    logger.info('Switched to chat screen');
  } catch (error) {
    logger.error('Failed to switch to chat screen', error);
  }
}

async function checkAuth() {
  logger.info('Starting auth check');
  const token = getToken();
  if (!token) {
    logger.info('No token found, showing login screen');
    showLoginScreen();
    return;
  }

  try {
    logger.info('Making auth check request to /api/auth/me');
    const response = await fetch(`${API_URL}/api/auth/me`, {
      headers: { Authorization: `Bearer ${token}` },
    });

    logger.info('Auth check response received', {
      status: response.status,
      statusText: response.statusText,
      ok: response.ok
    });

    if (response.ok) {
      const userData = await response.json();
      logger.info('Auth check successful', { user: userData });
      showWelcomeScreen();
    } else {
      const errorText = await response.text();
      logger.warn('Auth check failed', {
        status: response.status,
        statusText: response.statusText,
        response: errorText
      });
      clearToken();
      showLoginScreen();
    }
  } catch (error) {
    logger.error('Auth check request failed', {
      error: error.message,
      stack: error.stack
    });
    showLoginScreen();
  }
}

async function handleLogin() {
  logger.info('Login button clicked, starting login process');

  try {
    loginBtn.disabled = true;
    loginBtn.textContent = "Checking auth config...";
    logger.info('Disabled login button and updated text');

    // Check if auth is configured
    logger.info('Checking auth configuration via /api/auth/status');
    const statusResponse = await fetch(`${API_URL}/api/auth/status`);
    const statusData = await statusResponse.json();

    logger.info('Auth status response', {
      status: statusResponse.status,
      configured: statusData.configured
    });

    if (!statusData.configured) {
      const errorMsg = "Authentication not configured. Please set ENTRA_TENANT_ID, ENTRA_CLIENT_ID, and ENTRA_CLIENT_SECRET in your .env file.";
      logger.error('Auth not configured', { response: statusData });
      alert(errorMsg);
      loginBtn.disabled = false;
      loginBtn.textContent = "Sign in with Microsoft";
      return;
    }

    loginBtn.textContent = "Getting auth URL...";
    logger.info('Auth configured, requesting login URL from /api/auth/login');

    // Get auth URL and redirect
    const response = await fetch(`${API_URL}/api/auth/login`);
    const data = await response.json();

    logger.info('Login URL response', {
      status: response.status,
      hasAuthUrl: !!data.auth_url,
      authUrl: data.auth_url ? data.auth_url.substring(0, 100) + '...' : null
    });

    if (data.auth_url) {
      loginBtn.textContent = "Redirecting...";
      logger.info('Redirecting to Microsoft OAuth URL');
      window.location.href = data.auth_url;
    } else {
      throw new Error("No auth URL returned");
    }
  } catch (error) {
    logger.error('Login process failed', {
      error: error.message,
      stack: error.stack
    });
    alert("Login failed: " + error.message);
    loginBtn.disabled = false;
    loginBtn.textContent = "Sign in with Microsoft";
  }
}

async function handleCallback() {
  logger.info('Starting OAuth callback processing', { url: window.location.href });

  const params = new URLSearchParams(window.location.search);
  const code = params.get("code");
  const sessionState = params.get("session_state");
  const error = params.get("error");
  const errorDescription = params.get("error_description");

  logger.info('Parsed URL parameters', {
    hasCode: !!code,
    hasSessionState: !!sessionState,
    hasError: !!error,
    codeLength: code ? code.length : 0,
    sessionState: sessionState,
    error: error,
    errorDescription: errorDescription
  });

  // Check for OAuth errors
  if (error) {
    logger.error('OAuth error in callback URL', {
      error: error,
      errorDescription: errorDescription
    });
    alert(`Authentication failed: ${error} - ${errorDescription || 'Unknown error'}`);
    return false;
  }

  if (!code) {
    logger.warn('No authorization code found in callback URL');
    return false;
  }

  try {
    logger.info('Sending authorization code to backend /api/auth/callback');
    const response = await fetch(`${API_URL}/api/auth/callback`, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ code }),
    });

    logger.info('Callback response received', {
      status: response.status,
      statusText: response.statusText,
      ok: response.ok
    });

    if (!response.ok) {
      const errorData = await response.json();
      logger.error('Callback request failed', {
        status: response.status,
        error: errorData
      });
      throw new Error(errorData.detail || "Callback failed");
    }

    const data = await response.json();
    logger.info('Callback successful', {
      hasToken: !!data.token,
      hasUser: !!data.user,
      user: data.user
    });

    setToken(data.token);

    // Clean up URL
    logger.info('Cleaning up URL (removing query parameters)');
    window.history.replaceState({}, "", "/");

    return true;
  } catch (error) {
    logger.error('Callback processing failed', {
      error: error.message,
      stack: error.stack
    });
    alert("Authentication failed: " + error.message);
    return false;
  }
}

// Chat functions
function addMessage(text, type = "user") {
  const msg = document.createElement("div");
  msg.className = `message ${type}`;

  // Render markdown for bot messages, escape HTML for user messages
  const content = type === "assistant" ? renderMarkdown(text) : escapeHtml(text);
  msg.innerHTML = `<div class="message-text">${content}</div>`;

  chatMessages.appendChild(msg);

  // Add copy buttons to code blocks for assistant messages
  if (type === "assistant") {
    addCopyButtonsToCodeBlocks(msg);
  }

  scrollToBottom();
}

function showTyping() {
  const typing = document.createElement("div");
  typing.className = "message assistant";
  typing.id = "typing";
  typing.innerHTML = `
        <div class="message-text">
            <div class="typing">
                <span></span>
                <span></span>
                <span></span>
            </div>
        </div>
    `;
  chatMessages.appendChild(typing);
  scrollToBottom();
}

function hideTyping() {
  const typing = document.getElementById("typing");
  if (typing) typing.remove();
}

function scrollToBottom() {
  chatMessages.scrollTop = chatMessages.scrollHeight;
}

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

function renderMarkdown(text) {
  // Check if libraries are loaded
  if (typeof marked === 'undefined' || typeof DOMPurify === 'undefined') {
    logger.error('Markdown libraries not loaded', {
      markedAvailable: typeof marked !== 'undefined',
      dompurifyAvailable: typeof DOMPurify !== 'undefined'
    });
    return escapeHtml(text);
  }

  try {
    // Configure marked.js for optimal chat rendering
    marked.setOptions({
      breaks: true,        // Convert line breaks to <br>
      gfm: true,          // GitHub-flavored markdown
      headerIds: false,   // No IDs for headers
      mangle: false       // Don't obfuscate emails
    });

    // Parse markdown to HTML
    const rawHtml = marked.parse(text);

    // Sanitize HTML to prevent XSS attacks (include button element for copy functionality)
    const cleanHtml = DOMPurify.sanitize(rawHtml, {
      ALLOWED_TAGS: ['p', 'br', 'strong', 'em', 'u', 's', 'code', 'pre',
                     'a', 'ul', 'ol', 'li', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6',
                     'blockquote', 'hr', 'table', 'thead', 'tbody', 'tr', 'th', 'td', 'button'],
      ALLOWED_ATTR: ['href', 'target', 'rel', 'class']
    });

    return cleanHtml;
  } catch (error) {
    logger.error('Markdown rendering failed', error);
    return escapeHtml(text);
  }
}

function addCopyButtonsToCodeBlocks(element) {
  // Find all <pre> elements in the given element
  const preElements = element.querySelectorAll('pre');

  preElements.forEach((pre) => {
    // Skip if button already exists
    if (pre.querySelector('.copy-button')) {
      return;
    }

    // Create copy button
    const button = document.createElement('button');
    button.className = 'copy-button';
    button.textContent = 'Copy';

    // Add click handler
    button.addEventListener('click', async () => {
      const code = pre.querySelector('code');
      const text = code ? code.textContent : pre.textContent;

      try {
        await navigator.clipboard.writeText(text);
        button.textContent = 'Copied!';
        button.classList.add('copied');

        // Reset after 2 seconds
        setTimeout(() => {
          button.textContent = 'Copy';
          button.classList.remove('copied');
        }, 2000);
      } catch (error) {
        logger.error('Failed to copy code to clipboard', error);
        button.textContent = 'Failed';
        setTimeout(() => {
          button.textContent = 'Copy';
        }, 2000);
      }
    });

    // Add button to pre element
    pre.appendChild(button);
  });
}

async function sendMessage(text) {
  if (!text.trim()) return;

  if (!isInChat) {
    switchToChat();
  }

  addMessage(text, "user");
  chatInput.value = "";
  chatInput.disabled = true;

  showTyping();

  try {
    const token = getToken();
    const response = await fetch(`${API_URL}/api/chat/stream`, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        Authorization: `Bearer ${token}`,
      },
      body: JSON.stringify({
        message: text,
        provider: null,
      }),
    });

    if (response.status === 401) {
      hideTyping();
      clearToken();
      showLoginScreen();
      return;
    }

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

    hideTyping();

    // Create message element for streaming
    const msgDiv = document.createElement("div");
    msgDiv.className = "message assistant";
    const textDiv = document.createElement("div");
    textDiv.className = "message-text";
    msgDiv.appendChild(textDiv);
    chatMessages.appendChild(msgDiv);

    // Read stream
    const reader = response.body.getReader();
    const decoder = new TextDecoder();
    let assistantMessage = "";

    while (true) {
      const { done, value } = await reader.read();
      if (done) break;

      const chunk = decoder.decode(value);
      const lines = chunk.split("\n");

      for (const line of lines) {
        if (line.startsWith("data: ")) {
          const data = JSON.parse(line.slice(6));

          if (data.error) {
            textDiv.textContent = `Error: ${data.error}`;
            break;
          }

          if (data.chunk) {
            assistantMessage += data.chunk;
            textDiv.innerHTML = renderMarkdown(assistantMessage);
            scrollToBottom();
          }

          if (data.done) {
            // Add copy buttons to code blocks after streaming is complete
            addCopyButtonsToCodeBlocks(msgDiv);
            break;
          }
        }
      }
    }
  } catch (error) {
    hideTyping();
    addMessage(`Error: ${error.message}`, "assistant");
  } finally {
    chatInput.disabled = false;
    chatInput.focus();
  }
}

// Event listeners
loginBtn.addEventListener("click", handleLogin);

welcomeInput.addEventListener("keydown", (e) => {
  if (e.key === "Enter") {
    e.preventDefault();
    const text = welcomeInput.value.trim();
    if (text) {
      sendMessage(text);
    }
  }
});

chatInput.addEventListener("keydown", (e) => {
  if (e.key === "Enter") {
    e.preventDefault();
    sendMessage(chatInput.value);
  }
});

// Initialize
async function init() {
  logger.info('Application initialization started', {
    userAgent: navigator.userAgent,
    url: window.location.href,
    timestamp: new Date().toISOString()
  });

  // Check for CSS loading
  const styleLink = document.querySelector('link[rel="stylesheet"]');
  if (styleLink) {
    logger.info('CSS link found', { href: styleLink.href });
    styleLink.addEventListener('load', () => {
      logger.info('CSS loaded successfully');
    });
    styleLink.addEventListener('error', (e) => {
      logger.error('CSS failed to load', { href: styleLink.href, error: e });
    });
  } else {
    logger.error('CSS link not found in document');
  }

  // Check DOM elements
  const elements = ['loginScreen', 'welcomeScreen', 'chatScreen', 'chatMessages', 'welcomeInput', 'chatInput', 'loginBtn'];
  elements.forEach(id => {
    const el = document.getElementById(id);
    if (!el) {
      logger.error(`Required DOM element not found: ${id}`);
    } else {
      logger.info(`DOM element found: ${id}`);
    }
  });

  try {
    // Check for OAuth callback first
    logger.info('Checking for OAuth callback parameters');
    const callbackSuccess = await handleCallback();

    if (callbackSuccess) {
      logger.info('OAuth callback processed successfully, showing welcome screen');
      showWelcomeScreen();
    } else {
      logger.info('No OAuth callback or callback failed, checking existing auth');
      await checkAuth();
    }
  } catch (error) {
    logger.error('Initialization failed', {
      error: error.message,
      stack: error.stack
    });
  }

  logger.info('Application initialization completed');
}

// Add global error handler
window.addEventListener('error', (event) => {
  logger.error('Global JavaScript error', {
    message: event.message,
    filename: event.filename,
    lineno: event.lineno,
    colno: event.colno,
    error: event.error
  });
});

window.addEventListener('unhandledrejection', (event) => {
  logger.error('Unhandled promise rejection', {
    reason: event.reason,
    promise: event.promise
  });
});

// Debug panel functionality
const debugPanel = document.getElementById('debugPanel');
const exportLogsBtn = document.getElementById('exportLogsBtn');
const clearLogsBtn = document.getElementById('clearLogsBtn');
const viewBackendLogsBtn = document.getElementById('viewBackendLogsBtn');
const closeDebugBtn = document.getElementById('closeDebugBtn');
const debugOutput = document.getElementById('debugOutput');

function showDebugPanel() {
  debugPanel.style.display = 'block';
  logger.info('Debug panel opened');
}

function hideDebugPanel() {
  debugPanel.style.display = 'none';
  logger.info('Debug panel closed');
}

function updateDebugOutput(text) {
  debugOutput.textContent = text;
  debugOutput.scrollTop = debugOutput.scrollHeight;
}

// Event listeners for debug panel
exportLogsBtn.addEventListener('click', () => {
  logger.exportLogs();
  updateDebugOutput('Frontend logs exported to download');
  logger.info('Logs exported via debug panel');
});

clearLogsBtn.addEventListener('click', () => {
  logger.clearLogs();
  updateDebugOutput('Logs cleared');
  logger.info('Logs cleared via debug panel');
});

viewBackendLogsBtn.addEventListener('click', async () => {
  try {
    updateDebugOutput('Loading backend logs...');
    const response = await fetch(`${API_URL}/logs`);
    if (response.ok) {
      const data = await response.json();
      if (data.logs) {
        updateDebugOutput(data.logs.join('\n'));
      } else if (data.error) {
        updateDebugOutput(`Error: ${data.error}`);
      }
    } else {
      updateDebugOutput(`Failed to load backend logs: ${response.status}`);
    }
  } catch (error) {
    updateDebugOutput(`Error loading backend logs: ${error.message}`);
    logger.error('Failed to load backend logs', error);
  }
});

closeDebugBtn.addEventListener('click', hideDebugPanel);

// Keyboard shortcuts
document.addEventListener('keydown', (e) => {
  // Ctrl+Shift+L: Export logs
  if (e.ctrlKey && e.shiftKey && e.key === 'L') {
    e.preventDefault();
    logger.exportLogs();
    logger.info('Logs exported via keyboard shortcut');
  }

  // Ctrl+Shift+D: Toggle debug panel
  if (e.ctrlKey && e.shiftKey && e.key === 'D') {
    e.preventDefault();
    if (debugPanel.style.display === 'none') {
      showDebugPanel();
    } else {
      hideDebugPanel();
    }
  }

  // Escape: Close debug panel
  if (e.key === 'Escape' && debugPanel.style.display !== 'none') {
    hideDebugPanel();
  }
});

init();