// import { randomInt } from "./deps.ts";

const SERVER_VERSION = "0.2.0";
// TODO: version comparison

type ID = string;

// app state
const allLobbies = new Map<ID, Lobby>();
const allClients = new Map<ID, Client>();
// TODO: client index by id?

interface DataMessage {
  type: string;
}

type ServerDataObject = Record<
  "peerId" | string,
  string | number | symbol | null | boolean
>;
type ServerData = ServerDataObject[] | ServerDataObject | string | boolean;
type Message = string | DataMessage;

const buildMessage = (
  type: string,
  data: ServerData | ServerData[],
) => {
  if (Array.isArray(data)) return { type, data };
  else if (typeof data === "object") return { type, ...data };
  return `${type}:${data}`;
};

class Client {
  id: ID;
  peerId: number | null;
  name: string;
  socket: WebSocket;
  lobby: Lobby | null;

  constructor(socket: WebSocket) {
    this.id = crypto.randomUUID();
    this.socket = socket;
    this.peerId = null;
    this.name = "Client";
    this.lobby = null;

    allClients.set(this.id, this);
  }

  isConnected() {
    return this.socket.readyState == WebSocket.OPEN;
  }

  remove() {
    this.lobbyLeave();
    if (this.isConnected()) {
      this.socket.close();
    }
    allClients.delete(this.id);
  }

  send(message: Message) {
    try {
      if (this.isConnected()) {
        this.socket.send(
          typeof message === "object"
            ? ("json:" + JSON.stringify(message))
            : message,
        );
      }
    } catch (e) {
      console.error(
        `Failed to send on socket ${this.socket} to client ${this.id}: ${
          JSON.stringify(e)
        }`,
      );
      this.remove();
    }
  }

  ping() {
    this.send(buildMessage("ping", {}));
  }

  peerList() {
    if (!this.lobby) {
      this.send(
        buildMessage(
          "info",
          "you cannot request a list of peers unless you are in a lobby",
        ),
      );
      return;
    }
    const peers: {
      id: ID;
      name: string;
      peerId: number | null;
    }[] = [];
    this.lobby.clients.forEach(({ id, name, peerId }) =>
      peers.push({ id, name, peerId })
    );
    this.send(buildMessage("peer_data", peers));
    // TODO: chunk async?
  }

  lobbyList() {
    const netLobbies: {
      id: ID;
      name: string;
      maxPlayers: number;
      locked: boolean;
      currentPlayers: number;
    }[] = [];
    allLobbies.forEach((lobby) => netLobbies.push(lobby.toData()));
    this.send(buildMessage("lobby_data", netLobbies));
  }

  lobbyNew(lobby: Lobby) {
    // if the client is already in a lobby, do not send them lobby updates
    if (this.lobby) return;
    this.send(
      buildMessage("lobby_data", [lobby.toData()]),
    );
  }

  lobbyDelete({ id }: Lobby) {
    if (this.lobby) return;
    this.send(buildMessage("lobby_delete", { id }));
  }

  lobbyCreate(opts?: Partial<Lobby>) {
    if (this.lobby) {
      this.send(
        buildMessage(
          "info",
          `cannot create lobby: already in lobby ${this.lobby.id}`,
        ),
      );
      return;
    }
    new Lobby(this, opts?.name || `${this.name}'s lobby`, opts?.maxPlayers);
  }

  lobbyJoin(lobby: Lobby) {
    if (this.lobby) {
      this.send(
        buildMessage(
          `info`,
          `cannot join lobby: already in lobby ${this.lobby.id}`,
        ),
      );
      return;
    }
    this.lobby = lobby;
    lobby.addClient(this);
    this.send(
      buildMessage("lobby_joined", {
        ...this.lobby.toData(),
        peerId: this.peerId,
      }),
    );
  }

  lobbyLeave() {
    const leavingLobby = this.lobby;
    if (!leavingLobby) {
      this.send(`[info] cannot leave lobby (not in a lobby)`);
      return;
    }
    this.peerId = null;
    this.lobby = null;
    if (this.isConnected()) {
      this.send(buildMessage("lobby_left", { id: leavingLobby.id }));
    }
    leavingLobby.removeClient(this);
  }
}

class Lobby {
  id: ID;
  name: string;
  clients: Map<ID, Client>;
  hostClientId: ID;
  maxPlayers: number;
  locked: boolean;

  _shouldNotify: boolean;

  constructor(host: Client, name?: string, maxPlayers = 20) {
    this.id = crypto.randomUUID();
    this.hostClientId = host.id;
    this.clients = new Map<ID, Client>();
    this.name = name || this.id;
    this.maxPlayers = maxPlayers;
    this.locked = false;

    this._shouldNotify = true;

    allLobbies.set(this.id, this);
    host.peerId = 1;
    host.lobbyJoin(this);
    this.notify();
  }

  toData() {
    return {
      id: this.id,
      name: this.name,
      maxPlayers: this.maxPlayers,
      locked: this.locked,
      currentPlayers: this.clients.size,
    };
  }

  update(
    requestor: Client,
    newValues: { name?: string; maxPlayers?: number; locked?: boolean },
  ) {
    if (requestor.peerId === 1) {
      for (const k in newValues) {
        switch (k) {
          case "name":
            if (newValues?.name) this.name = newValues.name;
            break;
          case "maxPlayers":
            if (
              newValues?.maxPlayers && typeof newValues.maxPlayers === "number"
            ) {
              this.maxPlayers = newValues.maxPlayers;
            }
            break;
          case "locked":
            if (newValues?.locked) this.locked = newValues.locked;
            break;
        }
      }
      this.notify();
    } else {
      requestor.send(
        "[info] you cannot update this lobby (you are not the host!)",
      );
    }
  }

  notify() {
    if (!this._shouldNotify) return;
    allClients.forEach((client) => client.lobbyNew(this));
  }

  remove() {
    this._shouldNotify = false;
    allLobbies.delete(this.id);
    allClients.forEach((client) => client.lobbyDelete(this));
    this.clients.forEach((client) => {
      client.lobbyLeave();
    });
  }

  broadcast(message: Message) {
    this.clients.forEach((client) => client.send(message));
  }

  addClient(client: Client) {
    if (!client.peerId) {
      const arr = new Int32Array(1);
      crypto.getRandomValues(arr);
      client.peerId = Math.abs(arr[0]);
    }
    client.send(buildMessage("init_peer", client.peerId.toString()));
    this.broadcast(
      buildMessage("peer_data", [{
        id: client.id,
        name: client.name,
        peerId: client.peerId,
      }]),
    );
    client.send(
      buildMessage(
        "peer_data",
        Array.from(this.clients.values()).map(
          ({ id, name, peerId }) => ({ id, name, peerId }),
        ),
      ),
    );
    this.clients.set(client.id, client);
    this.notify();
  }

  removeClient({ id }: Client) {
    this.clients.delete(id);
    this.broadcast(buildMessage("peer_left", [{ id }]));
    if (id === this.hostClientId) {
      console.warn("Host left!");
      this.remove();
    }
    this.notify();
  }

  getPeer(peerId: number): Client | null {
    for (const [_id, client] of this.clients) {
      if (client.peerId == peerId) return client;
    }
    return null;
  }
}

interface ClientMessage {
  type:
    | "candidate"
    | "offer"
    | "answer"
    | "init"
    | "lobby_create"
    | "update_lobby";
  data: ServerDataObject;
}

function parseMessage(message: string): { type: string; data?: ServerData } {
  const trimmedMessage = message.trim();
  if (trimmedMessage.startsWith("json:")) {
    const { type, ...data } = JSON.parse(trimmedMessage.substr(5));
    return { type, data };
  } else {
    const splitAt = trimmedMessage.indexOf(":");
    if (splitAt > 0) {
      return {
        type: trimmedMessage.substr(0, splitAt),
        data: trimmedMessage.substr(splitAt + 1),
      };
    } else {
      return { type: trimmedMessage };
    }
  }
}

// events
function onMessage(client: Client, ev: MessageEvent) {
  // TODO: log who from? IPs etc.?
  const msg = parseMessage(ev.data);
  if (msg.type === "pong") return;
  console.log("Client Message Received", msg);
  switch (msg.type) {
    case "init":
      if (msg.data && (msg.data as { name: string })["name"]) {
        client.name = (msg.data as { name: string }).name.toString();
      }
      client.send(buildMessage("init", {
        id: client.id,
        peerId: client.peerId,
        name: client.name,
        serverVersion: SERVER_VERSION,
      }));
      break;
    case "lobby_create":
      client.lobbyCreate(msg.data as Partial<Lobby>);
      break;
    case "lobby_leave":
      client.lobbyLeave();
      break;
    case "request_lobby_list":
      client.lobbyList();
      break;
    case "request_peer_list":
      client.peerList();
      break;
    case "update_display_name":
      if (msg.data) client.name = msg.data.toString();
      break;
    case "lobby_join":
      if (msg.data) {
        const lobby = allLobbies.get(msg.data.toString());
        if (lobby) {
          client.lobbyJoin(lobby);
        } else {
          client.send(buildMessage("info", `count not find lobby ${msg.data}`));
        }
      }
      break;
    case "update_lobby":
      if (client.lobby) {
        if (typeof (msg.data) === "object") {
          client.lobby.update(client, msg.data as Partial<Lobby>);
        }
      } else {
        client.send(
          buildMessage(
            "info",
            "failed to update lobby info: you are not in a lobby",
          ),
        );
      }
      break;
    case "candidate":
      /* falls through */
    case "answer":
      /* falls through */
    case "offer": {
      if (!client.lobby) return;
      if (typeof msg.data !== "object") return;
      const webrtcMessage = (msg.data as { peerId?: number });
      if (!webrtcMessage.peerId || typeof webrtcMessage.peerId !== "number") {
        return;
      }
      console.log(
        `Received WebRTC Negotiation Message (type: ${msg.type}, from: ${client.peerId}, to: ${webrtcMessage.peerId})...`,
      );
      const destClient = client.lobby.getPeer(webrtcMessage.peerId);
      if (!destClient || !destClient.peerId) return;
      webrtcMessage.peerId = client.peerId as number;
      destClient.send(buildMessage(msg.type, webrtcMessage));
      break;
    }
    default:
      console.debug("Unknown message: ", msg);
      break;
  }
}

function onSocketOpen(client: Client, _ev: Event) {
  console.log("New Client", client.id);
}

function onClientLeave(client: Client) {
  client.remove();
}

function onSocketClose(client: Client, _ev: Event) {
  console.log("Client Socket Close");
  onClientLeave(client);
}

function onSocketError(client: Client, _ev: Event) {
  console.log("Client Socket Error");
  onClientLeave(client);
}

setInterval(() => {
  allLobbies.forEach((lobby) => {
    if (lobby.clients.size <= 0) lobby.remove();
  });
  allClients.forEach((client) => client.ping());
}, 5000);

const PORT = parseInt(Deno.env.get("PORT") || "80");
console.log("Listening on port", PORT);
const listener = Deno.listen({ port: PORT });
for await (const conn of listener) {
  (async () => {
    const server = Deno.serveHttp(conn);
    for await (const { respondWith, request } of server) {
      try {
        const { socket, response } = Deno.upgradeWebSocket(request);
        const client = new Client(socket);
        socket.onmessage = (ev) => onMessage(client, ev);
        socket.onopen = (ev) => onSocketOpen(client, ev);
        socket.onclose = (ev) => onSocketClose(client, ev);
        socket.onerror = (ev) => onSocketError(client, ev);
        respondWith(response);
      } catch (e) {
        console.log("Could not add client for unhandled reason:", e);
        respondWith(
          new Response("400 Bad Request", {
            status: 400,
            headers: { "content-type": "text/html" },
          }),
        );
      }
    }
  })();
}