import { test, expect } from "vitest";
import { spawn } from "node:child_process";
import path from "node:path";
import { buildApp } from "../src/app.js";
import { loadConfig } from "../src/config.js";

const FAKE = path.resolve("../harness/tests/fake_pi/fake_pi_rpc.mjs");
const SCRIPT = path.resolve("../harness/tests/fake_pi/scripts/f1_disambiguation.json");

// Legge dallo stream SSE finche' `predicate(acc)` e' vero o scade il timeout.
async function readUntil(
  reader: ReadableStreamDefaultReader<Uint8Array>,
  predicate: (acc: string) => boolean,
  timeoutMs: number,
): Promise<string> {
  const dec = new TextDecoder();
  let acc = "";
  const deadline = Date.now() + timeoutMs;
  while (Date.now() < deadline) {
    const res: any = await Promise.race([
      reader.read(),
      new Promise((r) => setTimeout(() => r({ timeout: true }), deadline - Date.now())),
    ]);
    if (res.timeout || res.done) break;
    acc += dec.decode(res.value);
    if (predicate(acc)) return acc;
  }
  return acc;
}

test("loop F1: crea sessione → SSE riceve il widget → risponde → il modello riparte (follow-up)", async () => {
  const app = buildApp(loadConfig({
    THT_HARNESS_DIR: "../harness", THT_LEGACY_WORKSPACE_MODE: "local",
  }), {
    thtRunner: {
      ollamaEnsure: async () => ({ ok: true }),
      searchPack: async () => {},
      sessionNew: async () => ({ id: "s1" }),
      sessionShow: async (_id: string) => ({ id: "s1", interaction_language: "en", provider: undefined, model: undefined, thinking: undefined }),
      sessionList: async () => [],
    } as any,
    spawnFn: () => spawn("node", [FAKE, SCRIPT]) as any,
  });
  await app.listen({ port: 0, host: "127.0.0.1" });
  const base = `http://127.0.0.1:${(app.server.address() as any).port}`;

  // 1. Create session — spawns fake-pi, sends prompt, fake-pi emits widget
  const created = await fetch(`${base}/sessions`, {
    method: "POST",
    headers: { "content-type": "application/json" },
    body: JSON.stringify({ workspace: "w", question: "q", interactionLanguage: "en" }),
  });
  expect(created.status).toBe(200);

  // 2. Small delay to let fake-pi process the prompt and fill pendingWidget
  await new Promise((r) => setTimeout(r, 50));

  // 3. SSE: the pending widget is re-emitted on subscribe
  const es = await fetch(`${base}/sessions/s1/events`);
  const reader = es.body!.getReader();
  const first = await readUntil(reader, (t) => t.includes("ui_request"), 2000);
  expect(first).toContain("ui_request");

  // 4. POST response — widget id is "u1" from f1_disambiguation.json (id INTERNO del descriptor)
  const resp = await fetch(`${base}/sessions/s1/response`, {
    method: "POST",
    headers: { "content-type": "application/json" },
    body: JSON.stringify({ ui_response: { id: "u1", choices: ["a"] } }),
  });
  expect(resp.status).toBe(204);

  // 5. Prova del fix: la risposta deve essere correlata sull'id RPC di Pi, cosi' ctx.ui.input
  //    si risolve e il modello produce il follow-up. Col bug, la risposta veniva scartata e
  //    nessun follow-up arrivava ("stuck senza output").
  const after = await readUntil(reader, (t) => t.includes("Procedo."), 2000);
  expect(after).toContain("Procedo.");
  await reader.cancel();

  await app.close();
}, 10000);