/**
 * TASKMATE - Claude Assistant Routes
 * ====================================
 * REST-Endpunkte und Session-Manager fuer den Claude-Assistenten
 *
 * Kommuniziert ueber HTTP mit dem Claude-Proxy (SSE-Streaming)
 * Proxy-URL: http://172.20.0.1:3100/api/chat
 */

const express = require('express');
const router = express.Router();
const http = require('http');
const { getDb } = require('../database');
const logger = require('../utils/logger');

// ============================================================================
// SESSION MANAGER
// ============================================================================

// Aktive Sessions: userId -> { claudeSessionId, busy, sessionId, socket, currentRequest, timeout }
const activeSessions = new Map();

const SESSION_TIMEOUT_MS = 30 * 60 * 1000; // 30 Minuten

/**
 * Erlaubte Benutzer fuer den Assistenten (lowercase)
 */
const ALLOWED_ASSISTANT_USERS = new Set([
  'hendrik', 'monami',
  'hendrik_gebhardt@gmx.de', 'momohomma@googlemail.com'
]);

function hasAssistantAccess(user) {
  const username = (user.username || '').toLowerCase();
  const displayName = (user.displayName || '').toLowerCase();
  return ALLOWED_ASSISTANT_USERS.has(username) || ALLOWED_ASSISTANT_USERS.has(displayName);
}

/**
 * Berechtigungs-Middleware: Nur Hendrik und Monami duerfen den Assistenten nutzen
 */
function requireAssistantAccess(req, res, next) {
  if (!hasAssistantAccess(req.user)) {
    return res.status(403).json({ error: 'Kein Zugriff auf den Assistenten' });
  }
  next();
}

/**
 * Socket-Berechtigung pruefen
 */
function checkSocketAccess(socket) {
  return hasAssistantAccess(socket.user);
}

/**
 * Timeout zuruecksetzen fuer eine Session
 */
function resetTimeout(userId) {
  const session = activeSessions.get(userId);
  if (!session) return;

  if (session.timeout) {
    clearTimeout(session.timeout);
  }

  session.timeout = setTimeout(() => {
    logger.info(`[Assistant] Session-Timeout fuer User ${userId} - wird beendet`);
    stopSession(userId);
  }, SESSION_TIMEOUT_MS);
}

/**
 * Proxy-URL und Token
 */
const PROXY_URL = 'http://172.20.0.1:3100/api/chat';
const PROXY_TOKEN = process.env.PROXY_TOKEN || '';

/**
 * Claude-Session aktivieren (kein Prozess - der wird erst bei sendMessage gestartet)
 */
function startSession(userId, sessionId, socket) {
  const existing = activeSessions.get(userId);

  // Gleiche Session: Nur Socket aktualisieren
  if (existing && existing.sessionId === sessionId) {
    existing.socket = socket;
    resetTimeout(userId);
    socket.emit('assistant:status', {
      sessionId,
      status: existing.busy ? 'thinking' : 'active'
    });
    return;
  }

  // Andere Session: bestehende aufraemen
  if (existing) {
    if (existing.currentRequest) {
      try { existing.currentRequest.destroy(); } catch (e) {}
    }
    if (existing.timeout) clearTimeout(existing.timeout);
  }

  const sessionData = {
    claudeSessionId: null,
    busy: false,
    sessionId,
    socket,
    currentRequest: null,
    timeout: null
  };

  activeSessions.set(userId, sessionData);
  resetTimeout(userId);

  logger.info(`[Assistant] Session ${sessionId} aktiviert fuer User ${userId}`);
  socket.emit('assistant:status', { sessionId, status: 'active' });

  // TaskContext als erste Nachricht senden
  try {
    const db = getDb();
    const dbSession = db.prepare('SELECT task_context FROM assistant_sessions WHERE id = ?').get(sessionId);
    if (dbSession && dbSession.task_context) {
      sendMessage(userId, dbSession.task_context, socket);
    }
  } catch (err) {
    logger.error(`[Assistant] TaskContext-Fehler: ${err.message}`);
  }
}

/**
 * Nachricht an Claude senden (HTTP-Request an Proxy mit SSE-Streaming)
 */
function sendMessage(userId, message, socket) {
  const session = activeSessions.get(userId);
  if (!session) throw new Error('Keine aktive Session');
  if (session.busy) throw new Error('Assistent verarbeitet noch eine Nachricht');

  session.busy = true;
  session.socket = socket;

  // User-Nachricht in DB speichern
  try {
    const db = getDb();
    db.prepare(`
      INSERT INTO assistant_messages (session_id, role, content)
      VALUES (?, 'user', ?)
    `).run(session.sessionId, message);
  } catch (err) {
    logger.error(`[Assistant] DB-Fehler (user msg): ${err.message}`);
  }

  socket.emit('assistant:status', { sessionId: session.sessionId, status: 'thinking' });

  logger.info(`[Assistant] Proxy-Aufruf fuer Session ${session.sessionId} (resume: ${session.claudeSessionId || 'nein'})`);

  // HTTP-Request an Proxy
  const postData = JSON.stringify({
    message,
    resumeSessionId: session.claudeSessionId || null
  });

  const url = new URL(PROXY_URL);
  const options = {
    hostname: url.hostname,
    port: url.port,
    path: url.pathname,
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'X-Proxy-Token': PROXY_TOKEN,
      'Content-Length': Buffer.byteLength(postData)
    }
  };

  const req = http.request(options, (res) => {
    let fullOutput = '';
    let buffer = '';
    let currentEvent = null;

    res.setEncoding('utf8');

    res.on('data', (chunk) => {
      buffer += chunk;
      const lines = buffer.split('\n');
      buffer = lines.pop(); // Unvollstaendige Zeile behalten

      for (const line of lines) {
        // SSE event-Zeile
        if (line.startsWith('event: ')) {
          currentEvent = line.substring(7).trim();
          continue;
        }

        // SSE data-Zeile
        if (line.startsWith('data: ')) {
          const dataStr = line.substring(6);

          if (currentEvent === 'done') {
            // Done-Event: Enthaelt claudeSessionId
            try {
              const json = JSON.parse(dataStr);
              if (json.sessionId) {
                session.claudeSessionId = json.sessionId;
                logger.info(`[Assistant] Claude-SessionId gesetzt: ${json.sessionId}`);
              }
            } catch (e) {
              logger.warn(`[Assistant] Done-Event Parse-Fehler: ${e.message}`);
            }
            currentEvent = null;
            continue;
          }

          if (currentEvent === 'error') {
            // Error-Event
            try {
              const json = JSON.parse(dataStr);
              logger.error(`[Assistant] Proxy-Fehler: ${json.error || dataStr}`);
              if (socket.connected) {
                socket.emit('assistant:status', {
                  sessionId: session.sessionId,
                  status: 'error',
                  error: json.error || 'Proxy-Fehler'
                });
              }
            } catch (e) {
              logger.error(`[Assistant] Proxy-Fehler (raw): ${dataStr}`);
            }
            currentEvent = null;
            continue;
          }

          // Normales Text-Event
          try {
            const json = JSON.parse(dataStr);
            const text = json.text || json.content || '';
            if (text) {
              fullOutput += text;
              if (socket.connected) {
                socket.emit('assistant:output', { sessionId: session.sessionId, content: text });
              }
            }
          } catch (e) {
            // Kein valides JSON - Rohtext verwenden
            if (dataStr.trim()) {
              fullOutput += dataStr;
              if (socket.connected) {
                socket.emit('assistant:output', { sessionId: session.sessionId, content: dataStr });
              }
            }
          }
          currentEvent = null;
        }
      }
    });

    res.on('end', () => {
      // Restlichen Buffer verarbeiten
      if (buffer.trim()) {
        const lines = buffer.split('\n');
        for (const line of lines) {
          if (line.startsWith('data: ')) {
            const dataStr = line.substring(6);
            try {
              const json = JSON.parse(dataStr);
              const text = json.text || json.content || '';
              if (text) {
                fullOutput += text;
                if (socket.connected) {
                  socket.emit('assistant:output', { sessionId: session.sessionId, content: text });
                }
              }
            } catch (e) {}
          }
        }
      }

      // Komplette Antwort in DB speichern
      if (fullOutput) {
        try {
          const db = getDb();
          db.prepare(`
            INSERT INTO assistant_messages (session_id, role, content)
            VALUES (?, 'assistant', ?)
          `).run(session.sessionId, fullOutput);
        } catch (err) {
          logger.error(`[Assistant] DB-Fehler (assistant msg): ${err.message}`);
        }
      }

      logger.info(`[Assistant] Proxy-Antwort abgeschlossen fuer Session ${session.sessionId}`);

      session.busy = false;
      session.currentRequest = null;
      resetTimeout(userId);

      if (socket.connected) {
        if (res.statusCode !== 200 && !fullOutput) {
          socket.emit('assistant:status', {
            sessionId: session.sessionId,
            status: 'error',
            error: `Proxy-Fehler (HTTP ${res.statusCode})`
          });
        } else {
          socket.emit('assistant:status', { sessionId: session.sessionId, status: 'active' });
        }
      }
    });
  });

  req.on('error', (err) => {
    logger.error(`[Assistant] HTTP-Fehler: ${err.message}`);
    session.busy = false;
    session.currentRequest = null;

    if (socket.connected) {
      socket.emit('assistant:status', {
        sessionId: session.sessionId,
        status: 'error',
        error: `Verbindung zum Assistenten fehlgeschlagen: ${err.message}`
      });
    }
  });

  session.currentRequest = req;
  req.write(postData);
  req.end();
}

/**
 * Session beenden
 */
function stopSession(userId) {
  const session = activeSessions.get(userId);
  if (!session) return;

  logger.info(`[Assistant] Session ${session.sessionId} wird beendet fuer User ${userId}`);

  if (session.currentRequest) {
    try { session.currentRequest.destroy(); } catch (e) {}
  }
  if (session.timeout) clearTimeout(session.timeout);

  activeSessions.delete(userId);

  // DB aktualisieren
  try {
    const db = getDb();
    db.prepare(`
      UPDATE assistant_sessions SET status = 'ended', ended_at = CURRENT_TIMESTAMP
      WHERE id = ?
    `).run(session.sessionId);
  } catch (err) {
    logger.error(`[Assistant] DB-Fehler beim Beenden: ${err.message}`);
  }
}

// ============================================================================
// REST ENDPOINTS
// ============================================================================

// Alle Routen brauchen Assistant-Zugriff
router.use(requireAssistantAccess);

/**
 * GET /sessions - Alle Sessions des Users
 */
router.get('/sessions', (req, res) => {
  try {
    const db = getDb();
    const sessions = db.prepare(`
      SELECT id, user_id, title, status, task_context, created_at, ended_at
      FROM assistant_sessions
      WHERE user_id = ?
      ORDER BY created_at DESC
    `).all(req.user.id);

    res.json(sessions);
  } catch (err) {
    logger.error(`[Assistant] Fehler beim Laden der Sessions: ${err.message}`);
    res.status(500).json({ error: 'Fehler beim Laden der Sessions' });
  }
});

/**
 * GET /sessions/:id/messages - Alle Nachrichten einer Session
 */
router.get('/sessions/:id/messages', (req, res) => {
  try {
    const db = getDb();
    const sessionId = parseInt(req.params.id, 10);

    // Pruefen ob Session dem User gehoert
    const session = db.prepare(`
      SELECT id FROM assistant_sessions WHERE id = ? AND user_id = ?
    `).get(sessionId, req.user.id);

    if (!session) {
      return res.status(404).json({ error: 'Session nicht gefunden' });
    }

    const messages = db.prepare(`
      SELECT id, session_id, role, content, created_at
      FROM assistant_messages
      WHERE session_id = ?
      ORDER BY created_at ASC
    `).all(sessionId);

    res.json(messages);
  } catch (err) {
    logger.error(`[Assistant] Fehler beim Laden der Nachrichten: ${err.message}`);
    res.status(500).json({ error: 'Fehler beim Laden der Nachrichten' });
  }
});

/**
 * POST /sessions - Neue Session erstellen
 */
router.post('/sessions', (req, res) => {
  try {
    const db = getDb();
    const { title, taskContext } = req.body;

    const result = db.prepare(`
      INSERT INTO assistant_sessions (user_id, title, task_context)
      VALUES (?, ?, ?)
    `).run(req.user.id, title || 'Neue Session', taskContext || null);

    const session = db.prepare(`
      SELECT id, user_id, title, status, task_context, created_at, ended_at
      FROM assistant_sessions WHERE id = ?
    `).get(result.lastInsertRowid);

    logger.info(`[Assistant] Neue Session ${session.id} erstellt von ${req.user.username}`);
    res.status(201).json(session);
  } catch (err) {
    logger.error(`[Assistant] Fehler beim Erstellen der Session: ${err.message}`);
    res.status(500).json({ error: 'Fehler beim Erstellen der Session' });
  }
});

/**
 * DELETE /sessions/:id - Session loeschen
 */
router.delete('/sessions/:id', (req, res) => {
  try {
    const db = getDb();
    const sessionId = parseInt(req.params.id, 10);

    // Pruefen ob Session dem User gehoert
    const session = db.prepare(`
      SELECT id, user_id FROM assistant_sessions WHERE id = ? AND user_id = ?
    `).get(sessionId, req.user.id);

    if (!session) {
      return res.status(404).json({ error: 'Session nicht gefunden' });
    }

    // Wenn aktiver Prozess laeuft, zuerst beenden
    const activeSession = activeSessions.get(req.user.id);
    if (activeSession && activeSession.sessionId === sessionId) {
      stopSession(req.user.id);
    }

    // Session und zugehoerige Nachrichten loeschen (CASCADE)
    db.prepare('DELETE FROM assistant_sessions WHERE id = ?').run(sessionId);

    logger.info(`[Assistant] Session ${sessionId} geloescht von ${req.user.username}`);
    res.json({ success: true });
  } catch (err) {
    logger.error(`[Assistant] Fehler beim Loeschen der Session: ${err.message}`);
    res.status(500).json({ error: 'Fehler beim Loeschen der Session' });
  }
});

// ============================================================================
// SOCKET EVENT HANDLER (exportiert fuer server.js)
// ============================================================================

/**
 * Socket-Events registrieren
 */
function registerSocketEvents(socket) {
  const userId = socket.user.id;

  // assistant:start - Session aktivieren
  socket.on('assistant:start', (data) => {
    try {
      if (!checkSocketAccess(socket)) {
        socket.emit('assistant:status', { status: 'error', error: 'Kein Zugriff' });
        return;
      }

      const sessionId = data && data.sessionId;
      if (!sessionId) {
        socket.emit('assistant:status', { status: 'error', error: 'Keine Session-ID angegeben' });
        return;
      }

      // Pruefen ob Session existiert und dem User gehoert
      const db = getDb();
      const session = db.prepare(`
        SELECT id, user_id, status FROM assistant_sessions WHERE id = ? AND user_id = ?
      `).get(sessionId, userId);

      if (!session) {
        socket.emit('assistant:status', { status: 'error', error: 'Session nicht gefunden' });
        return;
      }

      // Beendete Session reaktivieren
      if (session.status === 'ended') {
        db.prepare(`UPDATE assistant_sessions SET status = 'active', ended_at = NULL WHERE id = ?`).run(sessionId);
      }

      startSession(userId, sessionId, socket);
    } catch (err) {
      logger.error(`[Assistant] Fehler beim Starten: ${err.message}`);
      socket.emit('assistant:status', { status: 'error', error: err.message });
    }
  });

  // assistant:message - Nachricht senden
  socket.on('assistant:message', (data) => {
    try {
      if (!checkSocketAccess(socket)) {
        socket.emit('assistant:status', { status: 'error', error: 'Kein Zugriff' });
        return;
      }

      const message = data && data.message;
      if (!message || typeof message !== 'string') {
        socket.emit('assistant:status', { status: 'error', error: 'Keine Nachricht angegeben' });
        return;
      }

      sendMessage(userId, message, socket);
    } catch (err) {
      logger.error(`[Assistant] Fehler beim Senden: ${err.message}`);
      socket.emit('assistant:status', { status: 'error', error: err.message });
    }
  });

  // assistant:stop - Session beenden
  socket.on('assistant:stop', () => {
    try {
      if (!checkSocketAccess(socket)) {
        socket.emit('assistant:status', { status: 'error', error: 'Kein Zugriff' });
        return;
      }

      stopSession(userId);
      socket.emit('assistant:status', { status: 'stopped' });
    } catch (err) {
      logger.error(`[Assistant] Fehler beim Stoppen: ${err.message}`);
      socket.emit('assistant:status', { status: 'error', error: err.message });
    }
  });

  // Bei Disconnect: aktive Session beenden
  socket.on('disconnect', () => {
    if (activeSessions.has(userId)) {
      logger.info(`[Assistant] Socket disconnect - Session wird beendet fuer User ${userId}`);
      stopSession(userId);
    }
  });
}

module.exports = router;
module.exports.registerSocketEvents = registerSocketEvents;
module.exports.stopSession = stopSession;