import express from 'express';
import { query } from '../db/index.js';
import { authMiddleware } from '../middleware/auth.js';
import { asyncHandler, AppError } from '../middleware/errorHandler.js';

const router = express.Router();

// Get all challenges for the current user
router.get('/', authMiddleware, asyncHandler(async (req, res) => {
  const challenges = await query(
    `SELECT 
      c.*,
      u.username as creator_username,
      cp.status as participation_status,
      (SELECT COUNT(*) FROM predictions WHERE challenge_id = c.id AND status = 'validated' AND user_id = ?) as my_points
    FROM challenges c
    INNER JOIN users u ON c.created_by = u.id
    LEFT JOIN challenge_participants cp ON cp.challenge_id = c.id AND cp.user_id = ?
    WHERE c.created_by = ? OR cp.user_id IS NOT NULL
    ORDER BY c.created_at DESC`,
    [req.user.userId, req.user.userId, req.user.userId]
  );

  res.json({ challenges });
}));

// Get a single challenge with details
router.get('/:id', authMiddleware, asyncHandler(async (req, res) => {
  const challengeId = req.params.id;

  // Get challenge details
  const challenges = await query(
    `SELECT c.*, u.username as creator_username
     FROM challenges c
     INNER JOIN users u ON c.created_by = u.id
     WHERE c.id = ?`,
    [challengeId]
  );

  if (challenges.length === 0) {
    throw new AppError('Challenge not found', 404);
  }

  const challenge = challenges[0];

  // Check if user has access
  const access = await query(
    `SELECT * FROM challenge_participants 
     WHERE challenge_id = ? AND user_id = ? AND status = 'accepted'`,
    [challengeId, req.user.userId]
  );

  if (challenge.created_by !== req.user.userId && access.length === 0) {
    throw new AppError('Access denied', 403);
  }

    // Get participants with their points
    const participants = await query(
      `SELECT 
        u.id, u.username, u.email,
        cp.status,
        (SELECT COUNT(*) FROM predictions WHERE challenge_id = ? AND user_id = u.id AND status = 'validated') as points
       FROM challenge_participants cp
       INNER JOIN users u ON cp.user_id = u.id
       WHERE cp.challenge_id = ?
       ORDER BY points DESC`,
      [challengeId, challengeId]
    );

    // Get creator's points
    const creatorPoints = await query(
      `SELECT COUNT(*) as points FROM predictions 
       WHERE challenge_id = ? AND user_id = ? AND status = 'validated'`,
      [challengeId, challenge.created_by]
    );

  res.json({
    challenge,
    participants,
    creator_points: creatorPoints[0].points
  });
}));

// Create a new challenge
router.post('/', authMiddleware, asyncHandler(async (req, res) => {
  const { title, cover_image_url, tmdb_id, media_type } = req.body;

  if (!title) {
    throw new AppError('Title is required', 400);
  }

    const result = await query(
      'INSERT INTO challenges (title, cover_image_url, tmdb_id, media_type, created_by) VALUES (?, ?, ?, ?, ?)',
      [title, cover_image_url || null, tmdb_id || null, media_type || 'movie', req.user.userId]
    );

    const challenge = {
      id: result.insertId,
      title,
      cover_image_url,
      tmdb_id,
      media_type,
      created_by: req.user.userId,
      creator_username: req.user.username
    };

  res.json({ challenge });
}));

// Invite users to a challenge
router.post('/:id/invite', authMiddleware, asyncHandler(async (req, res) => {
  const challengeId = req.params.id;
  const { user_ids, emails } = req.body;

  // Verify user owns the challenge or is a participant
  const challenges = await query(
    'SELECT * FROM challenges WHERE id = ?',
    [challengeId]
  );

  if (challenges.length === 0) {
    throw new AppError('Challenge not found', 404);
  }

  const challenge = challenges[0];

  if (challenge.created_by !== req.user.userId) {
    // Check if user is an accepted participant
    const participation = await query(
      'SELECT * FROM challenge_participants WHERE challenge_id = ? AND user_id = ? AND status = "accepted"',
      [challengeId, req.user.userId]
    );

    if (participation.length === 0) {
      throw new AppError('Only challenge participants can invite others', 403);
    }
  }

    const invitedUsers = [];

    // Invite by user IDs
    if (user_ids && Array.isArray(user_ids)) {
      for (const userId of user_ids) {
        try {
          await query(
            'INSERT INTO challenge_participants (challenge_id, user_id, status) VALUES (?, ?, "pending")',
            [challengeId, userId]
          );
          invitedUsers.push(userId);
        } catch (err) {
          // Ignore duplicate key errors
        }
      }
    }

    // Invite by emails
    if (emails && Array.isArray(emails)) {
      for (const email of emails) {
        const users = await query('SELECT id FROM users WHERE email = ?', [email]);
        if (users.length > 0) {
          try {
            await query(
              'INSERT INTO challenge_participants (challenge_id, user_id, status) VALUES (?, ?, "pending")',
              [challengeId, users[0].id]
            );
            invitedUsers.push(users[0].id);
          } catch (err) {
            // Ignore duplicate key errors
          }
        }
      }
    }

  res.json({ invited: invitedUsers.length });
}));

// Accept/reject challenge invitation
router.post('/:id/respond', authMiddleware, asyncHandler(async (req, res) => {
  const challengeId = req.params.id;
  const { status } = req.body; // 'accepted' or 'rejected'

  if (!['accepted', 'rejected'].includes(status)) {
    throw new AppError('Invalid status', 400);
  }

  await query(
    'UPDATE challenge_participants SET status = ?, responded_at = NOW() WHERE challenge_id = ? AND user_id = ?',
    [status, challengeId, req.user.userId]
  );

  res.json({ status });
}));

export default router;