// The editor's page and bundle from F (editorFiles.ts, precompress.ts):
// which file a path names and which it never names, what goes out packed,
// how long a browser keeps it, and that F's own routes stay F's.

import { randomBytes } from 'node:crypto';
import { mkdirSync, mkdtempSync, readdirSync, readFileSync, writeFileSync } from 'node:fs';
import { createServer, request as httpRequest, type IncomingHttpHeaders, type Server } from 'node:http';
import type { AddressInfo } from 'node:net';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import { brotliDecompressSync, gunzipSync } from 'node:zlib';
import { afterAll, beforeAll, describe, expect, it } from 'vitest';
import { accepts, ASSET_CACHE, editorFiles, fileOf, PAGE_CACHE, PostgresSessions, PostgresStore, precompress } from '../src/index.js';
import { testDatabase, type TestDatabase } from './database.js';
import { startTestServer } from './harness.js';

const PAGE = '<!doctype html><title>Filius</title>';
const SCRIPT = `export const devices = [${Array.from({ length: 400 }, (_, index) => `'device ${index}'`).join(', ')}];\n`;

/** A built editor as Vite lays it, beside a file it must never hand out. */
function builtEditor(): string {
  const outside = mkdtempSync(join(tmpdir(), 'filius-editor-files-'));
  writeFileSync(join(outside, 'secret.txt'), 'not for the browser');
  const folder = join(outside, 'editor');
  mkdirSync(join(folder, 'assets'), { recursive: true });
  writeFileSync(join(folder, 'index.html'), PAGE);
  writeFileSync(join(folder, 'assets.json'), '{}');
  writeFileSync(join(folder, 'assets', 'index-AbC123.js'), SCRIPT);
  writeFileSync(join(folder, 'assets', 'index-AbC123.js.br'), 'packed with brotli');
  writeFileSync(join(folder, 'assets', 'index-AbC123.js.gz'), 'packed with gzip');
  writeFileSync(join(folder, 'assets', 'router-Xy9.png'), Buffer.from([0x89, 0x50, 0x4e, 0x47]));
  writeFileSync(join(folder, 'assets', 'Netz-Ab1.fls'), 'PK');
  writeFileSync(join(folder, 'assets', 'style-Q1.css'), 'a{color:red}');
  writeFileSync(join(folder, 'assets', 'style-Q1.css.gz'), 'packed with gzip only');
  return folder;
}

interface Answer {
  readonly status: number;
  readonly headers: IncomingHttpHeaders;
  readonly body: Buffer;
}

/** A request as it leaves a browser, the body as it arrives (not unpacked). */
function ask(base: string, path: string, headers: Record<string, string> = {}, method = 'GET'): Promise<Answer> {
  return new Promise((resolve, reject) => {
    const sent = httpRequest(`${base}${path}`, { method, headers }, (response) => {
      const parts: Buffer[] = [];
      response.on('data', (part: Buffer) => parts.push(part));
      response.on('end', () => resolve({ status: response.statusCode ?? 0, headers: response.headers, body: Buffer.concat(parts) }));
    });
    sent.on('error', reject);
    sent.end();
  });
}

describe('fileOf', () => {
  const root = '/srv/editor';

  it('names the page for the root and a file below for its path', () => {
    expect(fileOf(root, '/')).toBe('/srv/editor/index.html');
    expect(fileOf(root, '/index.html')).toBe('/srv/editor/index.html');
    expect(fileOf(root, '/assets/index-AbC123.js')).toBe('/srv/editor/assets/index-AbC123.js');
    expect(fileOf(root, '/assets/Gro%C3%9Fes%20Netz.fls')).toBe('/srv/editor/assets/Großes Netz.fls');
  });

  it('resolves a way round inside the folder to where it leads', () => {
    expect(fileOf(root, '/assets/../index.html')).toBe('/srv/editor/index.html');
    expect(fileOf(root, '/./assets//index-AbC123.js')).toBe('/srv/editor/assets/index-AbC123.js');
  });

  it.each([['/..'], ['/../secret.txt'], ['/%2e%2e/secret.txt'], ['/assets/..%2f..%2fsecret.txt'], ['/assets/../../editor-old/index.html'], ['/%E0%A4%A']])('names nothing for %s', (path) => {
    expect(fileOf(root, path)).toBeUndefined();
  });
});

describe('accepts', () => {
  it.each([
    ['gzip, deflate, br, zstd', 'br', true],
    ['gzip, deflate, br, zstd', 'gzip', true],
    ['gzip;q=0.5, br;q=1.0', 'br', true],
    ['BR', 'br', true],
    ['gzip, br;q=0', 'br', false],
    ['br; q=0.000', 'br', false],
    ['br;q=0.01', 'br', true],
    ['gzip', 'br', false],
    ['', 'gzip', false],
    ['xbr, brx', 'br', false],
  ])('%j takes %s: %s', (header, name, taken) => {
    expect(accepts(header, name)).toBe(taken);
  });
});

describe('editorFiles', () => {
  let server: Server;
  let base: string;

  beforeAll(async () => {
    const files = editorFiles(builtEditor());
    server = createServer((request, response) => {
      void files(request, response, new URL(request.url ?? '/', 'http://filius').pathname).then((answered) => {
        if (!answered) response.writeHead(404).end();
      });
    });
    await new Promise<void>((resolve) => server.listen(0, '127.0.0.1', resolve));
    base = `http://127.0.0.1:${(server.address() as AddressInfo).port}`;
  });

  afterAll(() => new Promise<void>((resolve) => server.close(() => resolve())));

  it('hands out the page, asked for again at every opening', async () => {
    for (const path of ['/', '/?project=1b4e28ba-2fa1-41d2-883f-0016d3cca427', '/index.html']) {
      const answer = await ask(base, path);
      expect(answer.status).toBe(200);
      expect(answer.body.toString()).toBe(PAGE);
      expect(answer.headers['content-type']).toBe('text/html; charset=utf-8');
      expect(answer.headers['cache-control']).toBe(PAGE_CACHE);
      expect(answer.headers['x-content-type-options']).toBe('nosniff');
    }
  });

  it('keeps a file of the bundle a year: its name changes with its content', async () => {
    const answer = await ask(base, '/assets/router-Xy9.png');
    expect(answer.headers['cache-control']).toBe(ASSET_CACHE);
    expect(answer.headers['content-type']).toBe('image/png');
    expect(answer.headers['content-length']).toBe('4');
  });

  it('keeps only what lies in assets/ a year, not a neighbour of a like name', async () => {
    expect((await ask(base, '/assets.json')).headers['cache-control']).toBe(PAGE_CACHE);
  });

  it('names what it does not know a series of bytes', async () => {
    expect((await ask(base, '/assets/Netz-Ab1.fls')).headers['content-type']).toBe('application/octet-stream');
  });

  it('sends the packed file the browser takes, the better first', async () => {
    const brotli = await ask(base, '/assets/index-AbC123.js', { 'accept-encoding': 'gzip, deflate, br, zstd' });
    expect([brotli.headers['content-encoding'], brotli.body.toString()]).toEqual(['br', 'packed with brotli']);
    expect(brotli.headers['content-length']).toBe(String('packed with brotli'.length));
    expect(brotli.headers['content-type']).toBe('text/javascript; charset=utf-8');
    expect(brotli.headers.vary).toBe('Accept-Encoding');
    const gzip = await ask(base, '/assets/index-AbC123.js', { 'accept-encoding': 'gzip, br;q=0' });
    expect([gzip.headers['content-encoding'], gzip.body.toString()]).toEqual(['gzip', 'packed with gzip']);
    const plain = await ask(base, '/assets/index-AbC123.js');
    expect([plain.headers['content-encoding'], plain.body.toString()]).toEqual([undefined, SCRIPT]);
  });

  it('sends the next packed file the browser takes when the better one is missing', async () => {
    const answer = await ask(base, '/assets/style-Q1.css', { 'accept-encoding': 'br, gzip' });
    expect([answer.headers['content-encoding'], answer.body.toString()]).toEqual(['gzip', 'packed with gzip only']);
  });

  it('sends a file without a packed one as it is, whatever the browser takes', async () => {
    const answer = await ask(base, '/index.html', { 'accept-encoding': 'br, gzip' });
    expect([answer.headers['content-encoding'], answer.body.toString()]).toEqual([undefined, PAGE]);
  });

  it('answers HEAD with the headers alone', async () => {
    const answer = await ask(base, '/', {}, 'HEAD');
    expect(answer.status).toBe(200);
    expect(answer.headers['content-length']).toBe(String(PAGE.length));
    expect(answer.body.length).toBe(0);
  });

  it.each([
    ['GET', '/../secret.txt'],
    ['GET', '/%2e%2e/secret.txt'],
    ['GET', '/..%5csecret.txt'],
    ['GET', '/index.html%00'],
    ['GET', '/assets'],
    ['GET', '/assets/'],
    ['GET', '/missing.js'],
    ['POST', '/'],
    ['DELETE', '/index.html'],
  ])('leaves %s %s to the caller', async (method, path) => {
    expect((await ask(base, path, {}, method)).status).toBe(404);
  });
});

describe('precompress', () => {
  it('lays a smaller .br and .gz beside each compressible file, below too, and nothing else', async () => {
    const folder = mkdtempSync(join(tmpdir(), 'filius-precompress-'));
    mkdirSync(join(folder, 'assets'));
    writeFileSync(join(folder, 'index.html'), `<!doctype html>${'<p>Filius</p>'.repeat(50)}`);
    writeFileSync(join(folder, 'assets', 'index.js'), SCRIPT);
    writeFileSync(join(folder, 'assets', 'tiny.css'), 'a{}');
    // A picture would pack well here; it is left alone for its kind, not its size.
    writeFileSync(join(folder, 'assets', 'router.png'), SCRIPT);
    writeFileSync(join(folder, 'assets', 'packed.js'), randomBytes(4096));
    expect(await precompress(folder)).toBe(4);
    expect(readdirSync(folder).sort()).toEqual(['assets', 'index.html', 'index.html.br', 'index.html.gz']);
    expect(readdirSync(join(folder, 'assets')).sort()).toEqual(['index.js', 'index.js.br', 'index.js.gz', 'packed.js', 'router.png', 'tiny.css']);
    const script = join(folder, 'assets', 'index.js');
    expect(brotliDecompressSync(readFileSync(`${script}.br`)).toString()).toBe(SCRIPT);
    expect(gunzipSync(readFileSync(`${script}.gz`)).toString()).toBe(SCRIPT);
    expect(readFileSync(`${script}.br`).length).toBeLessThan(readFileSync(`${script}.gz`).length);
    // A second run packs the same files again, not the packed ones.
    expect(await precompress(folder)).toBe(4);
    expect(readdirSync(join(folder, 'assets'))).toHaveLength(6);
  });
});

describe('the editor on server F', () => {
  let database: TestDatabase;
  let store: PostgresStore;
  let sessions: PostgresSessions;

  beforeAll(async () => {
    database = await testDatabase();
    store = PostgresStore.connect(database.url);
    sessions = new PostgresSessions(store.pool);
    await store.migrate();
    await sessions.migrate();
  }, 60_000);

  afterAll(async () => {
    await store?.close();
    await database?.stop();
  });

  it("comes from F's host, and F's own routes stay F's", async () => {
    const folder = builtEditor();
    writeFileSync(join(folder, 'healthz'), 'a file named like a route');
    mkdirSync(join(folder, 'svc'));
    writeFileSync(join(folder, 'svc', 'sessions'), 'a file named like a route');
    const server = await startTestServer(store, sessions, { editor: editorFiles(folder) });
    try {
      expect((await ask(server.base, '/')).body.toString()).toBe(PAGE);
      const health = await ask(server.base, '/healthz');
      expect(JSON.parse(health.body.toString())).toMatchObject({ status: 'ok' });
      expect((await ask(server.base, '/svc/sessions')).status).toBe(403);
      expect(JSON.parse((await ask(server.base, '/missing.js')).body.toString())).toEqual({ error: 'notFound' });
    } finally {
      await server.close();
    }
  });

  it('lets a browser go that leaves mid-file, without counting it a failure', async () => {
    const folder = builtEditor();
    writeFileSync(join(folder, 'assets', 'large-Zz1.js'), randomBytes(16 * 1024 * 1024));
    const server = await startTestServer(store, sessions, { editor: editorFiles(folder) });
    try {
      await new Promise<void>((resolve) => {
        const sent = httpRequest(`${server.base}/assets/large-Zz1.js`, (response) => response.once('data', () => sent.destroy()));
        sent.on('close', () => resolve());
        sent.on('error', () => undefined);
        sent.end();
      });
      await new Promise((resolve) => setTimeout(resolve, 200));
      expect(server.log.lines.filter((line) => line.event === 'http.failed')).toEqual([]);
      expect((await ask(server.base, '/')).body.toString()).toBe(PAGE);
    } finally {
      await server.close();
    }
  });

  it('answers only its own routes without an editor', async () => {
    const server = await startTestServer(store, sessions);
    try {
      const answer = await ask(server.base, '/');
      expect([answer.status, JSON.parse(answer.body.toString())]).toEqual([404, { error: 'notFound' }]);
    } finally {
      await server.close();
    }
  });
});