// A host with several routes connects through the first one that answers.
import { afterEach, describe, expect, it } from "bun:test";
import type { Server } from "bun";

import { T3Host } from "../src/t3/host.ts";

const ENVIRONMENT_ID = "env-laptop";
let servers: Server<undefined>[] = [];
afterEach(() => {
  for (const server of servers) server.stop(true);
  servers = [];
});

/**
 * Just enough of a T3 server: the descriptor, a ticket, config, and an empty shell snapshot.
 * While `state.up` is false its descriptor returns 503, like a route that is down.
 */
function fakeT3(state = { up: true }) {
  const server = Bun.serve({
    port: 0,
    fetch(req, srv) {
      const { pathname } = new URL(req.url);
      if (pathname === "/.well-known/t3/environment") {
        if (!state.up) return new Response("down", { status: 503 });
        return Response.json({ environmentId: ENVIRONMENT_ID, label: "framework-gib", serverVersion: "0.1.5", orchestrationProtocolVersion: 2 });
      }
      if (pathname === "/api/auth/websocket-ticket/rpc") return Response.json({ ticket: "t" });
      if (pathname === "/ws" && srv.upgrade(req)) return undefined;
      return new Response("not found", { status: 404 });
    },
    websocket: {
      message(ws, data) {
        const frame = JSON.parse(String(data)) as { _tag: string; id: string; tag: string };
        if (frame._tag !== "Request") return;
        if (frame.tag === "server.getConfig") {
          ws.send(JSON.stringify({ _tag: "Exit", requestId: frame.id, exit: { _tag: "Success", value: {} } }));
        } else if (frame.tag === "orchestration.subscribeShell") {
          const snapshot = { snapshotSequence: 1, projects: [], threads: [] };
          ws.send(JSON.stringify({ _tag: "Chunk", requestId: frame.id, values: [{ kind: "snapshot", snapshot }] }));
        }
      },
    },
  });
  servers.push(server);
  return `http://localhost:${server.port}`;
}

/** Resolves once `check` passes, polling every few milliseconds. */
async function until(check: () => boolean) {
  while (!check()) await Bun.sleep(5);
}

describe("T3Host routes", () => {
  it("falls back to the next route when the preferred one does not answer", async () => {
    const working = fakeT3();
    // Port 9 (discard) refuses connections, standing in for a LAN route that is down.
    const refused = "http://127.0.0.1:9";
    const spare = "https://t3laptop.example.org";
    const host = new T3Host({ id: ENVIRONMENT_ID, label: "Laptop", urls: [refused, working, spare], token: "x", environmentId: ENVIRONMENT_ID });
    host.start();
    await until(() => host.status === "online");
    expect(host.url).toBe(working);
    expect(host.routeAttempts.get(refused)).toMatchObject({ ok: false, error: "refused" });
    expect(host.routeAttempts.get(working)).toMatchObject({ ok: true, error: null });
    expect(host.routeAttempts.has(spare)).toBe(false);
    host.stop();
  });

  it("moves back to the preferred route on reconnect once it answers", async () => {
    const preferredState = { up: false };
    const preferred = fakeT3(preferredState);
    const fallback = fakeT3();
    const host = new T3Host({ id: ENVIRONMENT_ID, label: "Laptop", urls: [preferred, fallback], token: "x", environmentId: ENVIRONMENT_ID });
    host.start();
    await until(() => host.status === "online");
    expect(host.url).toBe(fallback);

    preferredState.up = true;
    host.reconnect();
    await until(() => host.status === "online" && host.url === preferred);
    expect(host.lastOnlineAt).not.toBeNull();
    host.stop();
  });
});