// Websocket front door. Protocol (JSON messages):
//   client -> server:
//     {type:"create", name}                     create a room, become host
//     {type:"join", roomId, name}               join (or rejoin) a room
//     {type:"start"}                            host starts the game
//     {type:"command", command}                 a game Command for the engine
//   server -> client:
//     {type:"welcome"}                          on connect
//     {type:"room", roomId, players, hostId, started}
//     {type:"events", events}                   redacted for this recipient
//     {type:"state", view}                      redacted full view (after every change)
//     {type:"error", message}

import { WebSocketServer, WebSocket } from "ws";
import type { Command, PlayerId } from "@wizwar/engine";
import {
  createRoom,
  getRoom,
  joinRoom,
  redactFor,
  runCommand,
  startGame,
  viewForPlayer,
  type Room,
} from "./rooms";

const port = Number(process.env.PORT ?? 8787);
const wss = new WebSocketServer({ port });

interface Session {
  socket: WebSocket;
  playerId: PlayerId | null;
  roomId: string | null;
}

const sessions = new Set<Session>();

function send(socket: WebSocket, message: unknown): void {
  if (socket.readyState === WebSocket.OPEN) socket.send(JSON.stringify(message));
}

function roomInfo(room: Room) {
  return {
    type: "room",
    roomId: room.id,
    players: room.players,
    hostId: room.hostId,
    started: room.state !== null,
  };
}

function broadcast(room: Room, makeMessage: (playerId: PlayerId) => unknown): void {
  for (const s of sessions) {
    if (s.roomId === room.id && s.playerId) {
      send(s.socket, makeMessage(s.playerId));
    }
  }
}

function broadcastRoomState(room: Room): void {
  broadcast(room, (playerId) => roomInfo(room));
  if (room.state) {
    broadcast(room, (playerId) => ({ type: "state", view: viewForPlayer(room, playerId) }));
  }
}

wss.on("connection", (socket) => {
  const session: Session = { socket, playerId: null, roomId: null };
  sessions.add(session);
  send(socket, { type: "welcome", game: "wizwar" });

  socket.on("close", () => sessions.delete(session));

  socket.on("message", (data) => {
    let msg: Record<string, unknown>;
    try {
      msg = JSON.parse(data.toString());
    } catch {
      return send(socket, { type: "error", message: "invalid JSON" });
    }

    try {
      switch (msg.type) {
        case "create": {
          const name = String(msg.name ?? "").trim();
          if (!name) return send(socket, { type: "error", message: "name required" });
          const { room, token } = createRoom(name);
          session.playerId = name;
          session.roomId = room.id;
          send(socket, { type: "seat", playerId: name, token });
          broadcastRoomState(room);
          break;
        }
        case "join": {
          const name = String(msg.name ?? "").trim();
          const roomId = String(msg.roomId ?? "").trim();
          if (!name || !roomId) return send(socket, { type: "error", message: "name and roomId required" });
          const room = getRoom(roomId);
          if (!room) return send(socket, { type: "error", message: "no such room" });
          const result = joinRoom(room, name, typeof msg.token === "string" ? msg.token : null);
          if ("error" in result) return send(socket, { type: "error", message: result.error });
          session.playerId = name;
          session.roomId = room.id;
          send(socket, { type: "seat", playerId: name, token: result.token });
          broadcastRoomState(room);
          break;
        }
        case "start": {
          const room = session.roomId ? getRoom(session.roomId) : undefined;
          if (!room || !session.playerId) return send(socket, { type: "error", message: "not in a room" });
          if (session.playerId !== room.hostId) return send(socket, { type: "error", message: "only the host can start" });
          const result = startGame(room);
          if ("error" in result) return send(socket, { type: "error", message: result.error });
          broadcast(room, (playerId) => ({ type: "events", events: redactFor(result.events, playerId) }));
          broadcastRoomState(room);
          break;
        }
        case "command": {
          const room = session.roomId ? getRoom(session.roomId) : undefined;
          if (!room || !session.playerId) return send(socket, { type: "error", message: "not in a room" });
          const result = runCommand(room, session.playerId, msg.command as Command);
          if ("error" in result) return send(socket, { type: "error", message: result.error });
          broadcast(room, (playerId) => ({ type: "events", events: redactFor(result.events, playerId) }));
          broadcast(room, (playerId) => ({ type: "state", view: viewForPlayer(room, playerId) }));
          break;
        }
        default:
          send(socket, { type: "error", message: `unknown message type: ${String(msg.type)}` });
      }
    } catch (e) {
      send(socket, { type: "error", message: e instanceof Error ? e.message : "internal error" });
    }
  });
});

console.log(`wizwar server listening on ws://localhost:${port}`);