import path from 'path';
import { fileURLToPath } from 'url';
import { createServer } from 'http';
import express from 'express';
import cors from 'cors';
import cookieParser from 'cookie-parser';
import rateLimit from 'express-rate-limit';
import dotenv from 'dotenv';
import { Server } from 'socket.io';
import natsAdapter from '@mickl/socket.io-nats-adapter';
const { createAdapter } = natsAdapter;
import { connectNats, getNatsConnection } from './lib/nats.js';
import pokerRoutes from './routes/poker.js';
import jiraRoutes from './routes/jira.js';
import roomRoutes from './routes/rooms.js';
import {
  getSessionSnapshot,
  revealIfComplete,
  forceReveal,
  saveScopedEstimate,
  submitVote
} from './services/pokerService.js';
import {
  joinRoom,
  leaveRoom,
  getRoomMembers,
  getRoomMemberCount,
  isRoomMember
} from './services/roomService.js';
import { updateIssueEstimate } from './services/jiraService.js';
import { getSocketUser } from './middleware/auth.js';
import { safeError } from './lib/errors.js';
import {
  register,
  websocketConnections,
  votesTotal,
  sessionsSavedTotal,
  httpRequestsTotal,
  httpRequestDuration,
  trackUniqueUser,
  trackUniqueTenant
} from './lib/metrics.js';

dotenv.config();

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const isProd = process.env.NODE_ENV === 'production';

const app = express();
const httpServer = createServer(app);

const port = Number(process.env.PORT || 4010);
if (isProd && !process.env.FRONTEND_URL) {
  throw new Error('FRONTEND_URL must be set in production.');
}
const frontendUrl = process.env.FRONTEND_URL || 'http://localhost:5174';
const corsOptions = { origin: frontendUrl, credentials: true };

function isAllowedOrigin(origin) {
  if (!origin) return true; // same-origin requests omit the Origin header
  return origin === frontendUrl;
}

app.disable('x-powered-by');
app.use((_req, res, next) => {
  res.setHeader('X-Content-Type-Options', 'nosniff');
  res.setHeader('X-Frame-Options', 'DENY');
  res.setHeader('Referrer-Policy', 'no-referrer');
  res.setHeader('Permissions-Policy', 'geolocation=(), microphone=(), camera=()');
  res.setHeader('Content-Security-Policy', [
    "default-src 'self'",
    "script-src 'self'",
    "style-src 'self' 'unsafe-inline' https://fonts.googleapis.com",
    `connect-src 'self' wss://${isProd ? new URL(frontendUrl).host : '*'}`,
    "img-src 'self' https://*.atl-paas.net https://*.atlassian.com https://*.gravatar.com https://*.wp.com data:",
    "font-src 'self' https://fonts.gstatic.com",
    "object-src 'none'",
    "base-uri 'self'",
    "form-action 'self'",
    "frame-ancestors 'none'"
  ].join('; '));
  if (isProd) {
    res.setHeader('Strict-Transport-Security', 'max-age=31536000; includeSubDomains');
  }
  next();
});

app.use(cors(corsOptions));
app.use(cookieParser());
app.use(express.json({ limit: '1mb' }));
app.use('/api/', rateLimit({ windowMs: 60_000, max: 100, standardHeaders: true, legacyHeaders: false }));

// Prometheus metrics endpoint (no auth, before rate limiter)
app.get('/metrics', async (_req, res) => {
  res.set('Content-Type', register.contentType);
  res.end(await register.metrics());
});

app.get('/api/health', (_req, res) => {
  res.json({ status: 'ok' });
});

// HTTP metrics middleware
app.use((req, res, next) => {
  if (req.path === '/metrics' || req.path === '/api/health') return next();
  const end = httpRequestDuration.startTimer();
  res.on('finish', () => {
    const route = req.route?.path || req.path;
    httpRequestsTotal.inc({ method: req.method, route, status: res.statusCode });
    end({ method: req.method, route });
  });
  next();
});

app.use('/api/poker', pokerRoutes);
app.use('/api/jira', jiraRoutes);
app.use('/api/poker/rooms', roomRoutes);

if (isProd) {
  const distPath = path.resolve(__dirname, '../../frontend/dist');
  app.use(express.static(distPath));
  app.get('*', (req, res) => {
    if (req.path.startsWith('/api/')) return res.status(404).json({ error: 'Not found' });
    res.sendFile(path.join(distPath, 'index.html'));
  });
}

const io = new Server(httpServer, {
  transports: ['websocket'],
  cors: corsOptions,
  allowRequest: (req, callback) => {
    if (isAllowedOrigin(req.headers.origin)) {
      callback(null, true);
      return;
    }
    callback('Origin not allowed', false);
  }
});

async function emitRoomMembers(roomId, cloudId) {
  const members = await getRoomMembers(roomId, cloudId);
  io.to(`room:${roomId}`).emit('room:members', { roomId, members });
}

async function emitSessionState(roomId, sessionId, tenantCloudId) {
  const snapshot = await getSessionSnapshot(sessionId, tenantCloudId);
  if (!snapshot) return;

  const memberCount = await getRoomMemberCount(roomId, tenantCloudId);

  io.to(`room:${roomId}`).emit('poker:vote-update', {
    sessionId,
    voteCount: snapshot.voteCount,
    votedUserKeys: snapshot.votedUserKeys,
    memberCount
  });

  if (snapshot.session.state === 'REVEALED' || snapshot.session.state === 'SAVED') {
    io.to(`room:${roomId}`).emit('poker:revealed', {
      sessionId,
      votes: snapshot.votesByUser,
      average: snapshot.session.averageEstimate,
      suggestedEstimate: snapshot.session.suggestedEstimate,
      savedEstimate: snapshot.session.savedEstimate
    });
  }
}

function socketThrottle(socket, limitPerMinute = 60) {
  const counts = new Map();
  return (event, handler) => {
    socket.on(event, async (...args) => {
      const now = Date.now();
      const entry = counts.get(event) || { count: 0, resetAt: now + 60_000 };
      if (now > entry.resetAt) { entry.count = 0; entry.resetAt = now + 60_000; }
      entry.count++;
      counts.set(event, entry);
      if (entry.count > limitPerMinute) {
        socket.emit('poker:error', { error: 'Too many requests, slow down.' });
        return;
      }
      await handler(...args);
    });
  };
}

io.on('connection', (socket) => {
  const user = getSocketUser(socket);
  if (!user || !user.jiraCloudId) {
    socket.emit('poker:error', { error: 'Not authenticated' });
    socket.disconnect(true);
    return;
  }
  socket.user = user;
  websocketConnections.inc();
  trackUniqueUser(user.jiraAccountId);
  trackUniqueTenant(user.jiraCloudId);

  // Use 'disconnecting' — socket.rooms is still populated (unlike 'disconnect')
  socket.on('disconnecting', async () => {
    websocketConnections.dec();
    const roomId = socket.roomId;
    if (!roomId) return;
    try {
      await leaveRoom(roomId, socket.user.jiraCloudId, socket.user.jiraAccountId);
      await emitRoomMembers(roomId, socket.user.jiraCloudId);
    } catch {
      // best-effort cleanup
    }
  });

  const throttled = socketThrottle(socket);

  throttled('room:join', async ({ roomId }) => {
    try {
      if (!roomId) {
        socket.emit('poker:error', { error: 'roomId is required.' });
        return;
      }

      await joinRoom(roomId, socket.user.jiraCloudId, {
        userKey: socket.user.jiraAccountId,
        userName: socket.user.displayName,
        avatarUrl: socket.user.avatarUrl || null
      });

      socket.join(`room:${roomId}`);
      socket.roomId = roomId;

      await emitRoomMembers(roomId, socket.user.jiraCloudId);
    } catch (error) {
      console.error('[socket] room:join failed:', error);
      socket.emit('poker:error', { error: safeError(error) });
    }
  });

  throttled('room:leave', async ({ roomId }) => {
    try {
      if (!roomId) return;
      await leaveRoom(roomId, socket.user.jiraCloudId, socket.user.jiraAccountId);
      socket.leave(`room:${roomId}`);
      socket.roomId = null;
      await emitRoomMembers(roomId, socket.user.jiraCloudId);
    } catch (error) {
      console.error('[socket] room:leave failed:', error);
      socket.emit('poker:error', { error: safeError(error) });
    }
  });

  throttled('poker:vote', async ({ sessionId, vote }) => {
    try {
      if (!sessionId) {
        socket.emit('poker:error', { error: 'sessionId is required.' });
        return;
      }

      const snapshot = await getSessionSnapshot(sessionId, socket.user.jiraCloudId);
      if (!snapshot) {
        socket.emit('poker:error', { error: 'Session not found.' });
        return;
      }

      const roomId = snapshot.session.roomId;
      if (!await isRoomMember(roomId, socket.user.jiraCloudId, socket.user.jiraAccountId)) {
        socket.emit('poker:error', { error: 'Join the room before voting.' });
        return;
      }

      const voteResult = await submitVote({
        sessionId,
        tenantCloudId: socket.user.jiraCloudId,
        userKey: socket.user.jiraAccountId,
        vote
      });
      if (!voteResult) {
        socket.emit('poker:error', { error: 'Unable to submit vote for this session.' });
        return;
      }
      votesTotal.inc();

      const memberCount = await getRoomMemberCount(roomId, socket.user.jiraCloudId);
      const reveal = await revealIfComplete(sessionId, socket.user.jiraCloudId, memberCount);

      await emitSessionState(roomId, sessionId, socket.user.jiraCloudId);

      if (reveal?.allVoted) {
        io.to(`room:${roomId}`).emit('poker:revealed', {
          sessionId,
          votes: reveal.votesByUser,
          average: reveal.average,
          suggestedEstimate: reveal.suggestedEstimate
        });
      }
    } catch (error) {
      console.error('[socket] poker:vote failed:', error);
      socket.emit('poker:error', { error: safeError(error) });
    }
  });

  throttled('poker:reveal', async ({ sessionId }) => {
    try {
      if (!sessionId) {
        socket.emit('poker:error', { error: 'sessionId is required.' });
        return;
      }

      const snapshot = await forceReveal(sessionId, socket.user.jiraCloudId);
      if (!snapshot) {
        socket.emit('poker:error', { error: 'Unable to reveal votes.' });
        return;
      }

      const roomId = snapshot.session.roomId;
      io.to(`room:${roomId}`).emit('poker:revealed', {
        sessionId,
        votes: snapshot.votesByUser,
        average: snapshot.session.averageEstimate,
        suggestedEstimate: snapshot.session.suggestedEstimate
      });

      await emitSessionState(roomId, sessionId, socket.user.jiraCloudId);
    } catch (error) {
      console.error('[socket] poker:reveal failed:', error);
      socket.emit('poker:error', { error: safeError(error) });
    }
  });

  throttled('poker:save', async ({ sessionId, estimate }) => {
    try {
      if (!sessionId) {
        socket.emit('poker:error', { error: 'sessionId is required.' });
        return;
      }

      const pre = await getSessionSnapshot(sessionId, socket.user.jiraCloudId);
      if (!pre) {
        socket.emit('poker:error', { error: 'Session not found.' });
        return;
      }
      const roomId = pre.session.roomId;

      if (!await isRoomMember(roomId, socket.user.jiraCloudId, socket.user.jiraAccountId)) {
        socket.emit('poker:error', { error: 'Join the room before saving.' });
        return;
      }

      const numericEstimate = Number(estimate);
      if (!Number.isFinite(numericEstimate)) {
        socket.emit('poker:error', { error: 'estimate must be a number.' });
        return;
      }

      const saved = await saveScopedEstimate({
        sessionId,
        estimate: numericEstimate,
        tenantCloudId: socket.user.jiraCloudId,
        userKey: socket.user.jiraAccountId
      });
      if (!saved) {
        socket.emit('poker:error', { error: 'Unable to save estimate for this session.' });
        return;
      }
      sessionsSavedTotal.inc();

      const issueRef = saved.session.issueId || saved.session.issueKey;
      try {
        await updateIssueEstimate(socket.user.jiraAccountId, issueRef, numericEstimate, saved.session.boardId);
      } catch (_jiraError) {
        // Jira update is best-effort so poker flow continues even when Jira is unavailable.
      }

      io.to(`room:${roomId}`).emit('poker:saved', {
        sessionId,
        estimate: numericEstimate,
        issueKey: saved.session.issueKey
      });

      io.to(`room:${roomId}`).emit('poker:ended', { sessionId });
    } catch (error) {
      console.error('[socket] poker:save failed:', error);
      socket.emit('poker:error', { error: safeError(error) });
    }
  });

  throttled('poker:kick', async ({ roomId, userKey }) => {
    try {
      if (!roomId || !userKey) {
        socket.emit('poker:error', { error: 'roomId and userKey are required.' });
        return;
      }
      await leaveRoom(roomId, socket.user.jiraCloudId, userKey);
      await emitRoomMembers(roomId, socket.user.jiraCloudId);
    } catch (error) {
      console.error('[socket] poker:kick failed:', error);
      socket.emit('poker:error', { error: safeError(error) });
    }
  });
});

async function start() {
  const nc = await connectNats();
  io.adapter(createAdapter(nc));

  httpServer.listen(port, () => {
    // eslint-disable-next-line no-console
    console.log(`Pokerface backend listening on :${port}`);
  });
}

start().catch((error) => {
  // eslint-disable-next-line no-console
  console.error('Failed to start server:', error);
  process.exit(1);
});