const http = require('http');
const fs   = require('fs');
const path = require('path');
const { WebSocketServer } = require('ws');

const PORT     = parseInt(process.env.PORT, 10) || 8080;
const ROOT_DIR = path.resolve(__dirname, '..');

// ─── Static file server ────────────────────────────────────────────────

const MIME = {
  '.html': 'text/html',
  '.js':   'application/javascript',
  '.css':  'text/css',
  '.json': 'application/json',
  '.png':  'image/png',
  '.jpg':  'image/jpeg',
  '.jpeg': 'image/jpeg',
  '.gif':  'image/gif',
  '.svg':  'image/svg+xml',
  '.ico':  'image/x-icon',
};

const httpServer = http.createServer((req, res) => {
  let urlPath = decodeURIComponent(req.url.split('?')[0]);
  if (urlPath === '/') urlPath = '/index.html';

  const filePath = path.join(ROOT_DIR, urlPath);

  // Prevent path traversal
  if (!filePath.startsWith(ROOT_DIR)) {
    res.writeHead(403);
    res.end();
    return;
  }

  fs.readFile(filePath, (err, data) => {
    if (err) {
      res.writeHead(404);
      res.end('Not found');
      return;
    }
    const ext  = path.extname(filePath).toLowerCase();
    const mime = MIME[ext] || 'application/octet-stream';
    res.writeHead(200, { 'Content-Type': mime });
    res.end(data);
  });
});

// ─── WebSocket server ──────────────────────────────────────────────────

const wss = new WebSocketServer({ server: httpServer });

// Room storage: roomCode -> { state, players: Map<playerId, ws>, claims: Map<groupId, playerId>, nextPlayerId }
const rooms = new Map();

let globalPlayerId = 1;

wss.on('connection', (ws) => {
  let playerId = null;
  let roomCode = null;

  ws.on('message', (raw) => {
    let msg;
    try {
      msg = JSON.parse(raw);
    } catch {
      return;
    }

    switch (msg.type) {

      // ─── Room lifecycle ────────────────────────────────────────

      case 'create_room': {
        roomCode = msg.roomCode;
        playerId = globalPlayerId++;

        rooms.set(roomCode, {
          state:        msg.state,
          players:      new Map([[playerId, ws]]),
          claims:       new Map(), // groupId -> playerId
          nextPlayerId: playerId + 1,
        });

        send(ws, {
          type:     'room_created',
          roomCode,
          playerId,
        });

        console.log(`Room ${roomCode} created by player ${playerId}`);
        break;
      }

      case 'join_room': {
        roomCode = msg.roomCode;
        const room = rooms.get(roomCode);

        if (!room) {
          send(ws, { type: 'error', message: 'Room not found' });
          return;
        }

        playerId = room.nextPlayerId++;
        room.players.set(playerId, ws);

        // Build claims list as { pieceId -> playerId } for the joiner
        const claimsList = {};
        for (const [gid, pid] of room.claims) {
          claimsList[gid] = pid;
        }

        // Build player list
        const playerList = Array.from(room.players.keys());

        send(ws, {
          type:     'room_joined',
          roomCode,
          playerId,
          state:    room.state,
          players:  playerList,
          claims:   claimsList,
        });

        // Notify existing players
        broadcast(room, playerId, {
          type:     'player_joined',
          playerId,
        });

        console.log(`Player ${playerId} joined room ${roomCode}`);
        break;
      }

      // ─── Piece interaction ─────────────────────────────────────

      case 'claim': {
        const room = rooms.get(roomCode);
        if (!room) return;

        const pieceId = msg.pieceId;

        // Find which group this piece belongs to using the room state
        const groupId = findGroupForPiece(room.state.groups, pieceId);
        if (groupId === null) return;

        // Check if any piece in this group is already claimed
        if (room.claims.has(groupId)) {
          const heldBy = room.claims.get(groupId);
          if (heldBy !== playerId) {
            send(ws, { type: 'claim_denied', pieceId, heldBy });
            return;
          }
        }

        room.claims.set(groupId, playerId);

        // Broadcast claim to all players (including the claimer for confirmation)
        broadcastAll(room, {
          type:     'claim_ok',
          pieceId,
          playerId,
        });
        break;
      }

      case 'move': {
        const room = rooms.get(roomCode);
        if (!room) return;

        // Relay to all other players
        broadcast(room, playerId, {
          type:     'move',
          pieceId:  msg.pieceId,
          playerId,
          dx:       msg.dx,
          dy:       msg.dy,
        });
        break;
      }

      case 'release': {
        const room = rooms.get(roomCode);
        if (!room) return;

        // Update canonical state with new positions
        if (msg.positions) {
          const posMap = new Map(msg.positions.map(p => [p.id, p]));
          room.state.pieces.forEach(p => {
            const update = posMap.get(p.id);
            if (update) {
              p.x = update.x;
              p.y = update.y;
            }
          });
        }

        // Update canonical groups
        if (msg.groups) {
          room.state.groups = msg.groups;
        }

        // Release the claim
        const pieceId = msg.pieceId;
        const groupId = findGroupForPiece(room.state.groups, pieceId);
        if (groupId !== null) {
          room.claims.delete(groupId);
        }
        // Also clean up any old group claims by this player (groups may have merged)
        for (const [gid, pid] of room.claims) {
          if (pid === playerId) {
            room.claims.delete(gid);
          }
        }

        // Check completion
        const completed = room.state.groups.length === 1 &&
          room.state.groups[0].length === room.state.pieces.length;
        if (completed) {
          room.state.completed = true;
        }

        // Broadcast to all other players
        broadcast(room, playerId, {
          type:      'release',
          pieceId:   msg.pieceId,
          playerId,
          positions: msg.positions,
          groups:    msg.groups,
        });

        if (completed) {
          broadcastAll(room, { type: 'completed' });
        }
        break;
      }
    }
  });

  ws.on('close', () => {
    if (!roomCode || !playerId) return;
    const room = rooms.get(roomCode);
    if (!room) return;

    // Release all claims by this player
    for (const [gid, pid] of room.claims) {
      if (pid === playerId) {
        room.claims.delete(gid);
      }
    }

    room.players.delete(playerId);

    if (room.players.size === 0) {
      // Keep room alive for a while in case of reconnection
      setTimeout(() => {
        const r = rooms.get(roomCode);
        if (r && r.players.size === 0) {
          rooms.delete(roomCode);
          console.log(`Room ${roomCode} cleaned up (empty)`);
        }
      }, 5 * 60 * 1000); // 5 minutes
    } else {
      broadcast(room, playerId, {
        type:     'player_left',
        playerId,
      });
    }

    console.log(`Player ${playerId} left room ${roomCode}`);
  });
});

// ─── Helpers ───────────────────────────────────────────────────────────

function send(ws, obj) {
  if (ws.readyState === ws.OPEN) {
    ws.send(JSON.stringify(obj));
  }
}

function broadcast(room, excludePlayerId, obj) {
  const data = JSON.stringify(obj);
  for (const [pid, ws] of room.players) {
    if (pid !== excludePlayerId && ws.readyState === ws.OPEN) {
      ws.send(data);
    }
  }
}

function broadcastAll(room, obj) {
  const data = JSON.stringify(obj);
  for (const [, ws] of room.players) {
    if (ws.readyState === ws.OPEN) {
      ws.send(data);
    }
  }
}

/** Find the index of the group containing pieceId in the groups array. */
function findGroupForPiece(groups, pieceId) {
  for (let i = 0; i < groups.length; i++) {
    if (groups[i].includes(pieceId)) {
      return i;
    }
  }
  return null;
}

// ─── Start ─────────────────────────────────────────────────────────────

httpServer.listen(PORT, () => {
  console.log(`iPuzzle server running on http://localhost:${PORT}`);
});