/** Helpers for integration tests: boot a real server, act as browser clients. */
import { mkdtempSync } from 'node:fs';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import type { ServerMessage } from '@bg/shared';
import { loadConfig } from './config';
import { startServer, type StartOptions } from './server';

export const ORIGIN = 'http://localhost:5173';

export function tempDbPath(): string {
  const dir = mkdtempSync(join(process.env.TMPDIR ?? tmpdir(), 'bg-test-'));
  return join(dir, 'app.db');
}

export function boot(dbPath = tempDbPath(), extra: Partial<StartOptions> = {}) {
  const config = loadConfig({ PORT: '0', DB_PATH: dbPath, PUBLIC_ORIGIN: ORIGIN });
  const app = startServer({ config, log: () => {}, staticDir: null, ...extra });
  const base = `http://localhost:${app.server.port}`;
  return { ...app, base, dbPath, config };
}

export async function api(base: string, path: string, init: RequestInit & { cookie?: string } = {}) {
  const headers = new Headers(init.headers);
  headers.set('origin', ORIGIN);
  if (init.cookie) headers.set('cookie', init.cookie);
  if (init.body && !headers.has('content-type')) headers.set('content-type', 'application/json');
  const res = await fetch(base + path, { ...init, headers, redirect: 'manual' });
  const setCookie = res.headers.get('set-cookie');
  let body: any = null;
  try {
    body = await res.clone().json();
  } catch {
    body = await res.text();
  }
  return { res, body, setCookie };
}

export async function guest(base: string, nickname: string): Promise<{ cookie: string; id: string }> {
  const r = await api(base, '/api/auth/guest', { method: 'POST', body: JSON.stringify({ nickname }) });
  if (r.res.status !== 200) throw new Error(`guest failed: ${JSON.stringify(r.body)}`);
  const cookie = r.setCookie!.split(';')[0]!;
  return { cookie, id: r.body.me.id };
}

export class Client {
  ws!: WebSocket;
  messages: ServerMessage[] = [];
  private waiters: { pred: (m: ServerMessage) => boolean; resolve: (m: ServerMessage) => void }[] = [];
  closed: { code: number; reason: string } | null = null;
  cs = 0;

  constructor(
    private base: string,
    public cookie: string,
    public id: string,
  ) {}

  async connect(): Promise<this> {
    this.closed = null;
    const url = this.base.replace('http', 'ws') + '/ws';
    // Bun's WebSocket client accepts custom headers.
    this.ws = new WebSocket(url, { headers: { cookie: this.cookie, origin: ORIGIN } } as unknown as string[]);
    this.ws.onmessage = (e) => {
      const m = JSON.parse(String(e.data)) as ServerMessage;
      this.messages.push(m);
      for (const w of [...this.waiters]) {
        if (w.pred(m)) {
          this.waiters.splice(this.waiters.indexOf(w), 1);
          w.resolve(m);
        }
      }
    };
    this.ws.onclose = (e) => {
      this.closed = { code: e.code, reason: e.reason };
    };
    await this.waitFor((m) => m.t === 'welcome');
    return this;
  }

  send(m: unknown): void {
    this.ws.send(JSON.stringify(m));
  }

  /** Resolves with the first message (already received after `since`, or future) matching pred. */
  waitFor<T extends ServerMessage['t']>(
    pred: (m: ServerMessage) => boolean,
    timeout = 3000,
    since = 0,
  ): Promise<Extract<ServerMessage, { t: T }>> {
    const existing = this.messages.slice(since).find(pred);
    if (existing) return Promise.resolve(existing as any);
    return new Promise((resolve, reject) => {
      const w = { pred, resolve: resolve as (m: ServerMessage) => void };
      this.waiters.push(w);
      setTimeout(() => {
        const i = this.waiters.indexOf(w);
        if (i >= 0) {
          this.waiters.splice(i, 1);
          reject(new Error(`timeout waiting; last: ${JSON.stringify(this.messages.slice(-3))}`));
        }
      }, timeout);
    });
  }

  /** Waits for the next message of type t received after now. */
  next<T extends ServerMessage['t']>(t: T, pred: (m: Extract<ServerMessage, { t: T }>) => boolean = () => true, timeout = 3000) {
    const since = this.messages.length;
    return this.waitFor<T>((m) => m.t === t && pred(m as any), timeout, since);
  }

  lastOf<T extends ServerMessage['t']>(t: T): Extract<ServerMessage, { t: T }> | undefined {
    for (let i = this.messages.length - 1; i >= 0; i--) if (this.messages[i]!.t === t) return this.messages[i] as any;
    return undefined;
  }

  act(a: unknown): number {
    const cs = ++this.cs;
    this.send({ t: 'act', cs, a });
    return cs;
  }

  close(): void {
    this.ws.close();
  }
}

export const sleep = (ms: number) => new Promise((r) => setTimeout(r, ms));