const express = require('express');
const { prisma } = require('../utils/db');
const { authenticate } = require('../middleware/auth');
const { getIO } = require('../socket');

const router = express.Router();

// POST /api/matches - Create a match request
router.post('/', authenticate, async (req, res, next) => {
  try {
    const { targetUserId, eventSlug } = req.body;
    const requesterId = req.user.id;

    // Validation
    if (!targetUserId || !eventSlug) {
      return res.status(400).json({
        success: false,
        error: 'targetUserId and eventSlug are required',
      });
    }

    if (requesterId === targetUserId) {
      return res.status(400).json({
        success: false,
        error: 'Cannot create match with yourself',
      });
    }

    // Find event by slug
    const event = await prisma.event.findUnique({
      where: { slug: eventSlug },
      select: { id: true, name: true },
    });

    if (!event) {
      return res.status(404).json({
        success: false,
        error: 'Event not found',
      });
    }

    // Check if both users are participants
    const [requesterParticipant, targetParticipant] = await Promise.all([
      prisma.eventParticipant.findUnique({
        where: {
          userId_eventId: {
            userId: requesterId,
            eventId: event.id,
          },
        },
      }),
      prisma.eventParticipant.findUnique({
        where: {
          userId_eventId: {
            userId: targetUserId,
            eventId: event.id,
          },
        },
      }),
    ]);

    if (!requesterParticipant) {
      return res.status(403).json({
        success: false,
        error: 'You must be a participant of this event',
      });
    }

    if (!targetParticipant) {
      return res.status(400).json({
        success: false,
        error: 'Target user is not a participant of this event',
      });
    }

    // Check if match already exists (in either direction)
    const existingMatch = await prisma.match.findFirst({
      where: {
        eventId: event.id,
        OR: [
          { user1Id: requesterId, user2Id: targetUserId },
          { user1Id: targetUserId, user2Id: requesterId },
        ],
      },
    });

    if (existingMatch) {
      return res.status(400).json({
        success: false,
        error: 'Match already exists with this user',
        match: existingMatch,
      });
    }

    // Create match
    const match = await prisma.match.create({
      data: {
        user1Id: requesterId,
        user2Id: targetUserId,
        eventId: event.id,
        status: 'pending',
      },
      include: {
        user1: {
          select: {
            id: true,
            username: true,
            avatar: true,
            firstName: true,
            lastName: true,
          },
        },
        user2: {
          select: {
            id: true,
            username: true,
            avatar: true,
            firstName: true,
            lastName: true,
          },
        },
        event: {
          select: {
            id: true,
            slug: true,
            name: true,
          },
        },
      },
    });

    // Emit socket event to target user
    try {
      const io = getIO();
      const targetSocketRoom = `user_${targetUserId}`;
      io.to(targetSocketRoom).emit('match_request_received', {
        matchId: match.id,
        from: {
          id: match.user1.id,
          username: match.user1.username,
          avatar: match.user1.avatar,
          firstName: match.user1.firstName,
          lastName: match.user1.lastName,
        },
        event: {
          slug: match.event.slug,
          name: match.event.name,
        },
        createdAt: match.createdAt,
      });
    } catch (socketError) {
      console.error('Failed to emit match request notification:', socketError);
    }

    res.status(201).json({
      success: true,
      data: match,
    });
  } catch (error) {
    // Handle unique constraint violation
    if (error.code === 'P2002') {
      return res.status(400).json({
        success: false,
        error: 'Match already exists with this user for this event',
      });
    }
    next(error);
  }
});

// GET /api/matches - List matches for current user (optionally filtered by event)
router.get('/', authenticate, async (req, res, next) => {
  try {
    const userId = req.user.id;
    const { eventSlug, status } = req.query;

    // Build where clause
    const where = {
      OR: [
        { user1Id: userId },
        { user2Id: userId },
      ],
    };

    // Filter by event if provided
    if (eventSlug) {
      const event = await prisma.event.findUnique({
        where: { slug: eventSlug },
        select: { id: true },
      });

      if (!event) {
        return res.status(404).json({
          success: false,
          error: 'Event not found',
        });
      }

      where.eventId = event.id;
    }

    // Filter by status if provided
    if (status) {
      where.status = status;
    }

    // Fetch matches
    const matches = await prisma.match.findMany({
      where,
      include: {
        user1: {
          select: {
            id: true,
            username: true,
            avatar: true,
            firstName: true,
            lastName: true,
          },
        },
        user2: {
          select: {
            id: true,
            username: true,
            avatar: true,
            firstName: true,
            lastName: true,
          },
        },
        event: {
          select: {
            id: true,
            slug: true,
            name: true,
            location: true,
            startDate: true,
            endDate: true,
          },
        },
        room: {
          select: {
            id: true,
          },
        },
      },
      orderBy: {
        createdAt: 'desc',
      },
    });

    // Transform matches to include partner info
    const transformedMatches = matches.map(match => {
      const isUser1 = match.user1Id === userId;
      const partner = isUser1 ? match.user2 : match.user1;
      const isInitiator = match.user1Id === userId;

      return {
        id: match.id,
        partner: {
          id: partner.id,
          username: partner.username,
          avatar: partner.avatar,
          firstName: partner.firstName,
          lastName: partner.lastName,
        },
        event: match.event,
        status: match.status,
        roomId: match.roomId,
        isInitiator,
        createdAt: match.createdAt,
      };
    });

    res.json({
      success: true,
      count: transformedMatches.length,
      data: transformedMatches,
    });
  } catch (error) {
    next(error);
  }
});

// GET /api/matches/:id - Get specific match
router.get('/:id', authenticate, async (req, res, next) => {
  try {
    const { id } = req.params;
    const userId = req.user.id;

    const match = await prisma.match.findUnique({
      where: { id: parseInt(id) },
      include: {
        user1: {
          select: {
            id: true,
            username: true,
            avatar: true,
            firstName: true,
            lastName: true,
          },
        },
        user2: {
          select: {
            id: true,
            username: true,
            avatar: true,
            firstName: true,
            lastName: true,
          },
        },
        event: {
          select: {
            id: true,
            slug: true,
            name: true,
            location: true,
            startDate: true,
            endDate: true,
          },
        },
        room: {
          select: {
            id: true,
          },
        },
      },
    });

    if (!match) {
      return res.status(404).json({
        success: false,
        error: 'Match not found',
      });
    }

    // Check authorization
    if (match.user1Id !== userId && match.user2Id !== userId) {
      return res.status(403).json({
        success: false,
        error: 'You are not authorized to view this match',
      });
    }

    // Transform match data
    const isUser1 = match.user1Id === userId;
    const partner = isUser1 ? match.user2 : match.user1;
    const isInitiator = match.user1Id === userId;

    res.json({
      success: true,
      data: {
        id: match.id,
        partner: {
          id: partner.id,
          username: partner.username,
          avatar: partner.avatar,
          firstName: partner.firstName,
          lastName: partner.lastName,
        },
        event: match.event,
        status: match.status,
        roomId: match.roomId,
        isInitiator,
        createdAt: match.createdAt,
      },
    });
  } catch (error) {
    next(error);
  }
});

// PUT /api/matches/:id/accept - Accept a pending match
router.put('/:id/accept', authenticate, async (req, res, next) => {
  try {
    const { id } = req.params;
    const userId = req.user.id;

    // Find match
    const match = await prisma.match.findUnique({
      where: { id: parseInt(id) },
      include: {
        user1: {
          select: {
            id: true,
            username: true,
            avatar: true,
          },
        },
        user2: {
          select: {
            id: true,
            username: true,
            avatar: true,
          },
        },
        event: {
          select: {
            id: true,
            slug: true,
            name: true,
          },
        },
      },
    });

    if (!match) {
      return res.status(404).json({
        success: false,
        error: 'Match not found',
      });
    }

    // Check authorization - only user2 can accept
    if (match.user2Id !== userId) {
      return res.status(403).json({
        success: false,
        error: 'Only the match recipient can accept',
      });
    }

    // Check status
    if (match.status !== 'pending') {
      return res.status(400).json({
        success: false,
        error: `Match is already ${match.status}`,
      });
    }

    // Create private chat room and update match in transaction
    const updatedMatch = await prisma.$transaction(async (tx) => {
      // Create private chat room
      const chatRoom = await tx.chatRoom.create({
        data: {
          type: 'private',
          eventId: match.eventId,
        },
      });

      // Update match status and link to chat room
      const updated = await tx.match.update({
        where: { id: parseInt(id) },
        data: {
          status: 'accepted',
          roomId: chatRoom.id,
        },
        include: {
          user1: {
            select: {
              id: true,
              username: true,
              avatar: true,
              firstName: true,
              lastName: true,
            },
          },
          user2: {
            select: {
              id: true,
              username: true,
              avatar: true,
              firstName: true,
              lastName: true,
            },
          },
          event: {
            select: {
              id: true,
              slug: true,
              name: true,
            },
          },
          room: {
            select: {
              id: true,
            },
          },
        },
      });

      return updated;
    });

    // Emit socket event to both users
    try {
      const io = getIO();
      const user1SocketRoom = `user_${match.user1Id}`;
      const user2SocketRoom = `user_${match.user2Id}`;

      const notification = {
        matchId: updatedMatch.id,
        roomId: updatedMatch.roomId,
        event: {
          slug: updatedMatch.event.slug,
          name: updatedMatch.event.name,
        },
      };

      io.to(user1SocketRoom).emit('match_accepted', {
        ...notification,
        partner: {
          id: updatedMatch.user2.id,
          username: updatedMatch.user2.username,
          avatar: updatedMatch.user2.avatar,
        },
      });

      io.to(user2SocketRoom).emit('match_accepted', {
        ...notification,
        partner: {
          id: updatedMatch.user1.id,
          username: updatedMatch.user1.username,
          avatar: updatedMatch.user1.avatar,
        },
      });
    } catch (socketError) {
      console.error('Failed to emit match accepted notification:', socketError);
    }

    // Transform response
    const isUser1 = updatedMatch.user1Id === userId;
    const partner = isUser1 ? updatedMatch.user2 : updatedMatch.user1;

    res.json({
      success: true,
      data: {
        id: updatedMatch.id,
        partner: {
          id: partner.id,
          username: partner.username,
          avatar: partner.avatar,
          firstName: partner.firstName,
          lastName: partner.lastName,
        },
        event: updatedMatch.event,
        status: updatedMatch.status,
        roomId: updatedMatch.roomId,
        isInitiator: isUser1,
        createdAt: updatedMatch.createdAt,
      },
    });
  } catch (error) {
    next(error);
  }
});

// DELETE /api/matches/:id - Reject or cancel a match
router.delete('/:id', authenticate, async (req, res, next) => {
  try {
    const { id } = req.params;
    const userId = req.user.id;

    // Find match
    const match = await prisma.match.findUnique({
      where: { id: parseInt(id) },
      include: {
        event: {
          select: {
            slug: true,
            name: true,
          },
        },
      },
    });

    if (!match) {
      return res.status(404).json({
        success: false,
        error: 'Match not found',
      });
    }

    // Check authorization - both users can delete
    if (match.user1Id !== userId && match.user2Id !== userId) {
      return res.status(403).json({
        success: false,
        error: 'You are not authorized to delete this match',
      });
    }

    // Cannot delete completed matches
    if (match.status === 'completed') {
      return res.status(400).json({
        success: false,
        error: 'Cannot delete completed matches',
      });
    }

    // Delete match (will cascade delete chat room if exists)
    await prisma.match.delete({
      where: { id: parseInt(id) },
    });

    // Emit socket event to the other user
    try {
      const io = getIO();
      const otherUserId = match.user1Id === userId ? match.user2Id : match.user1Id;
      const otherUserSocketRoom = `user_${otherUserId}`;

      io.to(otherUserSocketRoom).emit('match_cancelled', {
        matchId: match.id,
        event: {
          slug: match.event.slug,
          name: match.event.name,
        },
      });
    } catch (socketError) {
      console.error('Failed to emit match cancelled notification:', socketError);
    }

    res.json({
      success: true,
      message: 'Match deleted successfully',
    });
  } catch (error) {
    next(error);
  }
});

module.exports = router;