const express = require("express");
const http = require("http");
const WebSocket = require("ws");
const { randomBytes } = require("crypto");

const app = express();
app.use(express.static("public"));

const server = http.createServer(app);
const wss = new WebSocket.Server({ server });

const board_wolf = { 0: [1, 2, 3], 1: [0, 2, 4, 5], 2: [0, 1, 3, 5], 3: [0, 2, 5, 6], 4: [1, 5, 7], 5: [1, 2, 3, 4, 6, 7, 8, 9], 6: [3, 5, 9], 7: [4, 5, 8, 10], 8: [5, 7, 9, 10], 9: [5, 6, 8, 10], 10: [7, 8, 9] };
const board_sheep = { 0: [1, 2, 3], 1: [2, 4, 5], 2: [1, 3, 5], 3: [2, 5, 6], 4: [5, 7], 5: [4, 6, 7, 8, 9], 6: [5, 9], 7: [8, 10], 8: [7, 9, 10], 9: [8, 10], 10: [] };

const rooms = {};

function broadcast(roomId) {
    const room = rooms[roomId];
    if (!room) return;
    room.players.forEach(p => {
        if (p.ws && p.ws.readyState === WebSocket.OPEN) {
            p.ws.send(JSON.stringify({ type: "state", game: room.game, yourRole: p.role }));
        }
    });
}

// Heartbeat: Check if clients are still alive every 30s
const interval = setInterval(() => {
    wss.clients.forEach(ws => {
        if (ws.isAlive === false) return ws.terminate();
        ws.isAlive = false;
        ws.ping();
    });
}, 30000);

wss.on("connection", (ws, req) => {
    const urlParams = new URLSearchParams(req.url.split('?')[1]);
    let roomId = urlParams.get("room");
    let sessionId = urlParams.get("sessionId");

    ws.isAlive = true;
    ws.on('pong', () => ws.isAlive = true);

    if (!roomId || !rooms[roomId]) {
        if (!roomId || roomId === "null") roomId = randomBytes(3).toString("hex");
        rooms[roomId] = {
            game: { wolf: 5, sheep: [0, 1, 3], turn: "sheep", moveCount: 0, winner: null },
            players: [],
            nextFirstRole: "sheep"
        };
    }

    const room = rooms[roomId];
    let player = room.players.find(p => p.sessionId === sessionId);

    if (!player && room.players.length >= 2) {
        ws.send(JSON.stringify({ type: "full" }));
        ws.close();
        return;
    }

    if (player) {
        player.ws = ws;
    } else {
        const role = room.players.length === 0 ? room.nextFirstRole : (room.nextFirstRole === "sheep" ? "wolf" : "sheep");
        player = { ws, role, sessionId };
        room.players.push(player);
    }

    ws.send(JSON.stringify({ type: "init", role: player.role, roomId }));
    broadcast(roomId);

    ws.on("message", msg => {
        let data = JSON.parse(msg);
        if (data.type === "restart") {
            room.players.forEach(p => p.role = (p.role === "wolf" ? "sheep" : "wolf"));
            room.nextFirstRole = room.nextFirstRole === "sheep" ? "wolf" : "sheep";
            room.game = { wolf: 5, sheep: [0, 1, 3], turn: "sheep", moveCount: 0, winner: null };
            broadcast(roomId);
        } else if (data.type === "leave") {
            room.players = room.players.filter(p => p.sessionId !== sessionId);
            if (room.players.length === 0) delete rooms[roomId];
        } else if (data.from !== undefined && data.to !== undefined) {
            handleMove(roomId, player.role, data);
        }
    });

    ws.on("close", () => {
        // We keep the player in the room for a while to allow reconnects
    });
});

function handleMove(roomId, role, { from, to }) {
    const room = rooms[roomId];
    if (!room || room.game.winner || room.game.turn !== role) return;
    const game = room.game;
    const allowed = (role === "wolf") ? board_wolf[from] : board_sheep[from];
    if (!allowed?.includes(to) || game.sheep.includes(to) || game.wolf === to) return;

    if (role === "wolf") { game.wolf = to; game.turn = "sheep"; }
    else { game.sheep[game.sheep.indexOf(from)] = to; game.turn = "wolf"; }
    
    game.moveCount++;
    game.winner = checkWinConditions(game);
    broadcast(roomId);
}

function checkWinConditions(game) {
    if (game.wolf === 0) return "wolf";
    if (game.moveCount >= 40) return "wolf";
    const canWolfMove = board_wolf[game.wolf].some(to => !game.sheep.includes(to));
    const canSheepMove = game.sheep.some(from => board_sheep[from].some(to => to !== game.wolf && !game.sheep.includes(to)));
    if (!canWolfMove) return "sheep";
    if (!canSheepMove && game.turn === "sheep") return "wolf";
    return null;
}

server.listen(3030, () => console.log("Server running on port 3030"));