import { mkdtemp, rm, stat, writeFile } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import { dirname, join } from 'node:path';
import type { FastifyBaseLogger } from 'fastify';
import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';

vi.mock('../src/services/ytDlpRunner.js', async (importOriginal) => {
	const actual = await importOriginal<typeof import('../src/services/ytDlpRunner.js')>();
	return { ...actual, runYtDlp: vi.fn() };
});

import { QueueService } from '../src/services/QueueService.js';
import type { DownloadMode } from '../src/services/downloadPlan.js';
import { YtDlpError, runYtDlp } from '../src/services/ytDlpRunner.js';

const noopLogger = { info: () => {}, error: () => {} } as unknown as FastifyBaseLogger;
const url = 'https://www.youtube.com/watch?v=dQw4w9WgXcQ';
const videoMode: DownloadMode = {
	kind: 'video',
	options: { subtitles: false, embedThumbnail: false },
};

/** Extrait le dossier de sortie passé à yt-dlp via `-o` (voir downloadPlan.ts). */
function extractOutputDir(args: readonly string[]): string {
	const oIndex = args.indexOf('-o');
	const template = args[oIndex + 1] ?? '';
	const withoutPrefix = template.replace(/^thumbnail:/, '');
	return withoutPrefix.slice(0, withoutPrefix.lastIndexOf('/'));
}

/** Attend qu'une condition devienne vraie, en pollant (pas de timers factices ici : vraie I/O fichier en jeu). */
async function waitFor(predicate: () => boolean, timeoutMs = 2000): Promise<void> {
	const start = Date.now();
	while (!predicate()) {
		if (Date.now() - start > timeoutMs) {
			throw new Error('waitFor: timeout');
		}
		await new Promise((resolve) => setTimeout(resolve, 10));
	}
}

let baseDir: string;

beforeEach(async () => {
	baseDir = await mkdtemp(join(tmpdir(), 'ytdl-queue-test-'));
	vi.mocked(runYtDlp).mockReset();
});

afterEach(async () => {
	await rm(baseDir, { recursive: true, force: true });
});

describe('QueueService', () => {
	it('exécute un élément jusqu’à complétion et retrouve le fichier produit', async () => {
		vi.mocked(runYtDlp).mockImplementation(async (args, options) => {
			options?.onStdoutLine?.('[download]  50.0% of 10.00MiB');
			await writeFile(join(extractOutputDir(args), 'My Video.mp4'), 'fake');
			return '';
		});

		const service = new QueueService(noopLogger, baseDir, 2);
		const item = service.enqueue(url, videoMode);

		await waitFor(() => service.get(item.id)?.status === 'completed');

		const final = service.get(item.id);
		expect(final?.fileName).toBe('My Video.mp4');
		expect(final?.progress).toBe(100);
		expect(final?.error).toBeNull();
	});

	it('respecte la concurrence maximale configurée', async () => {
		let concurrentCount = 0;
		let maxObservedConcurrent = 0;
		const releaseFns: Array<() => void> = [];

		vi.mocked(runYtDlp).mockImplementation(async (args) => {
			concurrentCount += 1;
			maxObservedConcurrent = Math.max(maxObservedConcurrent, concurrentCount);
			await new Promise<void>((resolve) => releaseFns.push(resolve));
			concurrentCount -= 1;
			await writeFile(join(extractOutputDir(args), 'v.mp4'), 'x');
			return '';
		});

		const service = new QueueService(noopLogger, baseDir, 2);
		const first = service.enqueue(url, videoMode);
		const second = service.enqueue(url, videoMode);
		const third = service.enqueue(url, videoMode);
		const items = [first, second, third];

		await waitFor(() => releaseFns.length === 2);
		expect(maxObservedConcurrent).toBe(2);
		expect(service.get(third.id)?.status).toBe('pending');

		releaseFns[0]?.();
		await waitFor(() => releaseFns.length === 3);
		releaseFns[1]?.();
		releaseFns[2]?.();

		await waitFor(() => items.every((item) => service.get(item.id)?.status === 'completed'));
		expect(maxObservedConcurrent).toBeLessThanOrEqual(2);
	});

	it('marque un élément en échec et nettoie son dossier de sortie quand yt-dlp échoue', async () => {
		vi.mocked(runYtDlp).mockRejectedValue(new YtDlpError(1, 'network unreachable'));

		const service = new QueueService(noopLogger, baseDir, 2);
		const item = service.enqueue(url, videoMode);

		await waitFor(() => service.get(item.id)?.status === 'failed');

		expect(service.get(item.id)?.error).toContain('network unreachable');
		await expect(stat(join(baseDir, item.id))).rejects.toThrow();
	});

	it('annule un élément encore en attente sans jamais appeler yt-dlp pour lui', async () => {
		vi.mocked(runYtDlp).mockImplementation(() => new Promise(() => {})); // occupe le seul slot indéfiniment

		const service = new QueueService(noopLogger, baseDir, 1);
		service.enqueue(url, videoMode);
		const second = service.enqueue(url, videoMode);

		expect(service.get(second.id)?.status).toBe('pending');
		expect(service.cancel(second.id)).toBe(true);
		expect(service.get(second.id)?.status).toBe('cancelled');

		// Le premier élément appelle yt-dlp de façon asynchrone (après son
		// `mkdir`) : on attend cet appel plutôt que de supposer qu'il a déjà
		// eu lieu au moment où enqueue() rend la main.
		await waitFor(() => vi.mocked(runYtDlp).mock.calls.length === 1);
	});

	it("annule un élément en cours en déclenchant son signal d'annulation", async () => {
		vi.mocked(runYtDlp).mockImplementation(
			(_args, options) =>
				new Promise((_resolve, reject) => {
					const rejectAborted = () => {
						const error = new Error('aborted');
						error.name = 'AbortError';
						reject(error);
					};
					// Le signal peut déjà être annulé si cancel() a été appelé avant
					// que ce mock ne soit invoqué (après le `mkdir` de runItem) : un
					// listener "abort" posé après coup ne se déclencherait jamais.
					if (options?.signal?.aborted) {
						rejectAborted();
						return;
					}
					options?.signal?.addEventListener('abort', rejectAborted);
				}),
		);

		const service = new QueueService(noopLogger, baseDir, 1);
		const item = service.enqueue(url, videoMode);

		await waitFor(() => vi.mocked(runYtDlp).mock.calls.length === 1);
		expect(service.cancel(item.id)).toBe(true);
		await waitFor(() => service.get(item.id)?.status === 'cancelled');
	});

	it('consumeCompletedFile retourne null pour un élément inconnu ou non terminé', () => {
		vi.mocked(runYtDlp).mockImplementation(() => new Promise(() => {}));

		const service = new QueueService(noopLogger, baseDir, 1);
		const item = service.enqueue(url, videoMode);

		expect(service.consumeCompletedFile('inconnu')).toBeNull();
		expect(service.consumeCompletedFile(item.id)).toBeNull(); // encore en cours
	});

	it('consumeCompletedFile expose le fichier puis onSent nettoie le dossier', async () => {
		vi.mocked(runYtDlp).mockImplementation(async (args) => {
			await writeFile(join(extractOutputDir(args), 'My Video.mp4'), 'fake');
			return '';
		});

		const service = new QueueService(noopLogger, baseDir, 1);
		const item = service.enqueue(url, videoMode);
		await waitFor(() => service.get(item.id)?.status === 'completed');

		const result = service.consumeCompletedFile(item.id);
		if (!result) {
			throw new Error('expected consumeCompletedFile to return a result');
		}
		expect(result.fileName).toBe('My Video.mp4');
		expect(result.path).toBe(join(baseDir, item.id, 'My Video.mp4'));

		await result.onSent();
		await expect(stat(dirname(result.path))).rejects.toThrow();
	});
});