import { decode } from "./protocol";
import {
  type Client,
  getOrCreateSession,
  getSession,
  type WsData,
} from "./session";

const PORT = Number(process.env.PORT) || 4040;

function isValidRoomName(name: unknown): name is string {
  if (typeof name !== "string") return false;
  if (name.length === 0 || name.length > 64) return false;
  return /^[a-zA-Z0-9_-]+$/.test(name);
}

export const server = Bun.serve<WsData>({
  port: PORT,
  fetch(req, server) {
    const url = new URL(req.url);
    if (url.pathname === "/ws") {
      const upgraded = server.upgrade(req, {
        data: { room: null, client: null },
      });
      if (!upgraded) {
        return new Response("websocket upgrade failed", { status: 400 });
      }
      return;
    }
    return new Response("collabd running");
  },
  websocket: {
    open(ws) {
      // create client object once and store in ws.data
      const client: Client = { ws };
      ws.data.client = client;
      console.debug("client connected");
    },
    message(ws, raw) {
      const msg = decode(raw.toString());
      if (!msg) return;

      // reuse the client object from ws.data
      const client = ws.data.client;
      if (!client) return;

      switch (msg.type) {
        case "join": {
          if (!isValidRoomName(msg.room)) {
            try {
              ws.send(
                JSON.stringify({ type: "error", message: "invalid room name" }),
              );
            } catch (err) {
              console.debug("failed to send error to client:", err);
            }
            break;
          }
          const session = getOrCreateSession(msg.room);
          ws.data.room = msg.room;
          session.join(client);
          console.debug(`client joined room: ${msg.room}`);
          break;
        }
        case "leave": {
          if (ws.data.room) {
            const session = getSession(ws.data.room);
            session?.leave(client);
            ws.data.room = null;
          }
          break;
        }
        case "update": {
          if (ws.data.room) {
            const session = getSession(ws.data.room);
            session?.applyUpdate(new Uint8Array(msg.data), client);
          }
          break;
        }
        case "awareness": {
          if (ws.data.room) {
            const session = getSession(ws.data.room);
            if (session && "data" in msg) {
              session.broadcastAwareness(client, msg.data);
            }
          }
          break;
        }
      }
    },
    close(ws) {
      if (ws.data.room && ws.data.client) {
        const session = getSession(ws.data.room);
        session?.leave(ws.data.client);
      }
      console.debug("client disconnected");
    },
  },
});

console.log(`collabd listening on :${PORT}`);