import { describe, it, expect, beforeEach, afterEach } from 'vitest';
import { createServer, type Server } from 'node:http';
import type { AddressInfo } from 'node:net';
import { mkdtemp, readFile, rm } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import { downloadImage } from '../../src/lib/server/images/image-downloader';

// 1×1 PNG (transparent)
const PNG_BYTES = Buffer.from(
  '89504e470d0a1a0a0000000d49484452000000010000000108060000001f15c489' +
    '0000000d49444154789c6300010000000500010d0a2db40000000049454e44ae426082',
  'hex'
);

let server: Server;
let baseUrl: string;
let dir: string;

beforeEach(async () => {
  server = createServer();
  await new Promise<void>((r) => server.listen(0, '127.0.0.1', r));
  const addr = server.address() as AddressInfo;
  baseUrl = `http://127.0.0.1:${addr.port}`;
  dir = await mkdtemp(join(tmpdir(), 'kochwas-img-'));
});

afterEach(async () => {
  await new Promise<void>((r) => server.close(() => r()));
  await rm(dir, { recursive: true, force: true });
});

describe('downloadImage', () => {
  it('downloads and stores a PNG with sha256 filename', async () => {
    server.on('request', (_req, res) => {
      res.writeHead(200, { 'content-type': 'image/png' });
      res.end(PNG_BYTES);
    });
    const fname = await downloadImage(`${baseUrl}/img.png`, dir);
    expect(fname).not.toBeNull();
    expect(fname!.endsWith('.png')).toBe(true);
    const saved = await readFile(join(dir, fname!));
    expect(saved.equals(PNG_BYTES)).toBe(true);
  });

  it('is idempotent — returns same filename, does not rewrite', async () => {
    server.on('request', (_req, res) => {
      res.writeHead(200, { 'content-type': 'image/png' });
      res.end(PNG_BYTES);
    });
    const first = await downloadImage(`${baseUrl}/img.png`, dir);
    const second = await downloadImage(`${baseUrl}/img.png`, dir);
    expect(second).toBe(first);
  });

  it('returns null on 404', async () => {
    server.on('request', (_req, res) => {
      res.writeHead(404);
      res.end();
    });
    const fname = await downloadImage(`${baseUrl}/missing.png`, dir);
    expect(fname).toBeNull();
  });
});