// Shared helpers for quiz portal stress tests.
// Boots a fresh uvicorn server, logs in as admin, creates quiz + session.
// Provides a Student class that wraps an authenticated WS + cookie state.

import { spawn } from "node:child_process";
import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { setTimeout as sleep } from "node:timers/promises";
import WebSocket from "ws";

const QUIZ_ROOT = "/home/ameer/RD/Projects/Apps/quiz";
const PORT_BASE = 8200;

export function nowMs() { return Date.now(); }
export function logLine(scenario, level, msg, extra = {}) {
  const rec = { ts: new Date().toISOString(), scenario, level, msg, ...extra };
  process.stdout.write(JSON.stringify(rec) + "\n");
}

export function pickRandom(arr) { return arr[Math.floor(Math.random() * arr.length)]; }
export function rand(min, max) { return Math.random() * (max - min) + min; }

// Boot a fresh server on its own port + DB. Returns { url, stop }.
export async function bootServer({ port, secret = "stress-secret-12345678", adminPw = "stresspw" } = {}) {
  const tmp = mkdtempSync(join(tmpdir(), "quiz-stress-"));
  const dbPath = join(tmp, "stress.db");
  const env = {
    ...process.env,
    QUIZ_DB_PATH: dbPath,
    QUIZ_SECRET_KEY: secret,
    QUIZ_ADMIN_PASSWORD: adminPw,
    QUIZ_HOST: "127.0.0.1",
    QUIZ_PORT: String(port),
    QUIZ_PUBLIC_URL: `http://127.0.0.1:${port}`,
  };
  const proc = spawn(
    `${QUIZ_ROOT}/.venv/bin/uvicorn`,
    ["app.main:app", "--host", "127.0.0.1", "--port", String(port), "--log-level", "warning"],
    { cwd: QUIZ_ROOT, env, stdio: ["ignore", "pipe", "pipe"] },
  );
  // Pipe server stderr to our stderr so panics are visible
  proc.stderr.on("data", chunk => process.stderr.write(`[server:${port}] ${chunk}`));

  const url = `http://127.0.0.1:${port}`;
  // Wait for /healthz
  const deadline = Date.now() + 20_000;
  while (Date.now() < deadline) {
    try {
      const r = await fetch(`${url}/healthz`);
      if (r.ok) {
        return {
          url,
          adminPw,
          stop: () => new Promise(res => {
            proc.once("exit", () => { rmSync(tmp, { recursive: true, force: true }); res(); });
            proc.kill("SIGTERM");
            // Hard-kill fallback
            setTimeout(() => proc.kill("SIGKILL"), 2000);
          }),
        };
      }
    } catch {}
    await sleep(150);
  }
  proc.kill("SIGKILL");
  throw new Error(`server on ${port} did not come up`);
}

// Cookie jar helper - parses Set-Cookie headers from fetch response.
export class CookieJar {
  constructor() { this.jar = new Map(); }
  ingest(response) {
    const raw = response.headers.getSetCookie?.() || (response.headers.get("set-cookie") ? [response.headers.get("set-cookie")] : []);
    for (const line of raw) {
      const [pair] = line.split(";");
      const eq = pair.indexOf("=");
      if (eq > 0) this.jar.set(pair.slice(0, eq).trim(), pair.slice(eq + 1).trim());
    }
  }
  header() {
    return [...this.jar.entries()].map(([k, v]) => `${k}=${v}`).join("; ");
  }
  get(name) { return this.jar.get(name); }
  set(name, value) { this.jar.set(name, value); }
  clear() { this.jar.clear(); }
}

export async function jsonReq(method, url, { jar, body, headers = {} } = {}) {
  const opts = { method, headers: { ...headers } };
  if (jar) opts.headers["Cookie"] = jar.header();
  if (body !== undefined) {
    opts.body = JSON.stringify(body);
    opts.headers["Content-Type"] = "application/json";
  }
  const r = await fetch(url, opts);
  if (jar) jar.ingest(r);
  let data = null;
  const txt = await r.text();
  try { data = txt ? JSON.parse(txt) : null; } catch { data = txt; }
  return { status: r.status, ok: r.ok, data, headers: r.headers };
}

// Build admin session: login + upload pool + create session. Returns { sid, jar }.
export async function setupSession(serverUrl, adminPw, pool) {
  const jar = new CookieJar();
  const login = await jsonReq("POST", `${serverUrl}/admin/login`, { jar, body: { password: adminPw } });
  if (!login.ok) throw new Error(`admin login failed: ${login.status} ${JSON.stringify(login.data)}`);
  const create = await jsonReq("POST", `${serverUrl}/admin/api/quizzes`, { jar, body: { pool_json: pool } });
  if (!create.ok) throw new Error(`quiz create failed: ${create.status} ${JSON.stringify(create.data)}`);
  const sess = await jsonReq("POST", `${serverUrl}/admin/api/sessions`, { jar, body: { quiz_id: create.data.quiz_id } });
  if (!sess.ok) throw new Error(`session create failed: ${sess.status} ${JSON.stringify(sess.data)}`);
  return { sid: sess.data.sid, jar };
}

// Student wrapper: join + connect WS + collect messages.
export class Student {
  constructor(serverUrl, sid, studentId, name) {
    this.serverUrl = serverUrl;
    this.sid = sid;
    this.studentId = studentId;
    this.name = name;
    this.jar = new CookieJar();
    this.ws = null;
    this.messages = [];
    this.lastMsgByType = {};
    this.events = new EventTarget();
    this.closed = false;
  }
  async join() {
    const r = await jsonReq("POST", `${this.serverUrl}/api/session/${this.sid}/join`, {
      jar: this.jar,
      body: { student_id: this.studentId, name: this.name },
    });
    if (!r.ok) throw new Error(`student join failed: ${r.status} ${JSON.stringify(r.data)}`);
    return r;
  }
  connect() {
    return new Promise((resolve, reject) => {
      const wsUrl = this.serverUrl.replace(/^http/, "ws") + `/ws/student/${this.sid}`;
      const headers = { Cookie: this.jar.header() };
      this.ws = new WebSocket(wsUrl, { headers });
      this.ws.on("open", () => resolve());
      this.ws.on("message", buf => {
        let msg;
        try { msg = JSON.parse(buf.toString()); } catch { return; }
        this.messages.push({ ts: nowMs(), msg });
        this.lastMsgByType[msg.type] = msg;
        this.events.dispatchEvent(new CustomEvent("msg", { detail: msg }));
      });
      this.ws.on("close", (code, reason) => {
        this.closed = true;
        this.events.dispatchEvent(new CustomEvent("close", { detail: { code, reason: reason.toString() } }));
      });
      this.ws.on("error", err => reject(err));
    });
  }
  // Wait until a NEW message of the given type arrives (does not use cache).
  // Use lastMsgByType[type] to inspect cached values without waiting.
  waitFor(type, { timeoutMs = 5000, useCache = false } = {}) {
    return new Promise((resolve, reject) => {
      if (useCache && this.lastMsgByType[type]) return resolve(this.lastMsgByType[type]);
      const handler = ev => {
        if (ev.detail?.type === type) {
          this.events.removeEventListener("msg", handler);
          clearTimeout(timer);
          resolve(ev.detail);
        }
      };
      const timer = setTimeout(() => {
        this.events.removeEventListener("msg", handler);
        reject(new Error(`timed out waiting for WS type=${type} after ${timeoutMs}ms`));
      }, timeoutMs);
      this.events.addEventListener("msg", handler);
    });
  }
  send(obj) {
    if (this.ws?.readyState === WebSocket.OPEN) this.ws.send(JSON.stringify(obj));
  }
  submit(qIdx, answer) {
    this.send({ type: "submit", question_idx: qIdx, answer });
  }
  disconnect() {
    if (this.ws && !this.closed) {
      try { this.ws.terminate(); } catch {}
    }
  }
  async reconnect() {
    this.closed = false;
    this.lastMsgByType = {};
    await this.connect();
  }
}

// Admin WS wrapper.
export class Admin {
  constructor(serverUrl, sid, jar) {
    this.serverUrl = serverUrl;
    this.sid = sid;
    this.jar = jar;
    this.ws = null;
    this.messages = [];
    this.events = new EventTarget();
  }
  connect() {
    return new Promise((resolve, reject) => {
      const wsUrl = this.serverUrl.replace(/^http/, "ws") + `/ws/instructor/${this.sid}`;
      this.ws = new WebSocket(wsUrl, { headers: { Cookie: this.jar.header() } });
      this.ws.on("open", () => resolve());
      this.ws.on("message", buf => {
        let msg;
        try { msg = JSON.parse(buf.toString()); } catch { return; }
        this.messages.push({ ts: nowMs(), msg });
        this.events.dispatchEvent(new CustomEvent("msg", { detail: msg }));
      });
      this.ws.on("error", err => reject(err));
    });
  }
  open(qIdx, timeLimit = 60) { this.ws.send(JSON.stringify({ type: "open_question", question_idx: qIdx, time_limit: timeLimit })); }
  close() { this.ws.send(JSON.stringify({ type: "close_question" })); }
  next() { this.ws.send(JSON.stringify({ type: "next" })); }
  end() { this.ws.send(JSON.stringify({ type: "end_session" })); }
  waitFor(type, { timeoutMs = 5000 } = {}) {
    return new Promise((resolve, reject) => {
      const handler = ev => {
        if (ev.detail?.type === type) {
          this.events.removeEventListener("msg", handler);
          clearTimeout(timer);
          resolve(ev.detail);
        }
      };
      const timer = setTimeout(() => {
        this.events.removeEventListener("msg", handler);
        reject(new Error(`admin timed out waiting for type=${type} after ${timeoutMs}ms`));
      }, timeoutMs);
      this.events.addEventListener("msg", handler);
    });
  }
  disconnect() { try { this.ws?.terminate(); } catch {} }
}

// A small fixed pool used for stress runs.
export const STRESS_POOL = {
  title: "Stress Pool",
  score_fn: "linear_decay",
  time_limit_default: 10,
  questions: [
    { id: "s1", text: "2+2?", options: { A: "3", B: "4", C: "5", D: "6" }, correct: "B", explanation: "" },
    { id: "s2", text: "Capital of France?", options: { A: "Berlin", B: "Madrid", C: "Paris", D: "Rome" }, correct: "C", explanation: "" },
    { id: "s3", text: "Fastest sort?", options: { A: "Bubble", B: "Quick", C: "Insertion", D: "Selection" }, correct: "B", explanation: "" },
    { id: "s4", text: "HTTP code for not found?", options: { A: "200", B: "301", C: "404", D: "500" }, correct: "C", explanation: "" },
    { id: "s5", text: "Speed of light (m/s)?", options: { A: "3e8", B: "3e6", C: "1.5e8", D: "9.8" }, correct: "A", explanation: "" },
  ],
};

export { sleep };