import { describe, expect, it } from 'vitest';
import { RedditRequestCoordinator } from '../src/reddit/request-coordinator.js';

describe('RedditRequestCoordinator', () => {
  it('paces requests and applies a shared cooldown to the next queued request', async () => {
    let now = 0;
    const sleeps: number[] = [];
    const coordinator = new RedditRequestCoordinator(6_500, {
      now: () => now,
      sleep: async (ms) => { sleeps.push(ms); now += ms; },
    });

    await coordinator.schedule(async () => undefined);
    coordinator.extendCooldown(30_000);
    await coordinator.schedule(async () => undefined);

    expect(sleeps).toEqual([31_000]);
  });

  it('serializes concurrent requests through one process-wide queue', async () => {
    const order: string[] = [];
    let releaseFirst!: () => void;
    const firstFinished = new Promise<void>((resolve) => { releaseFirst = resolve; });
    const coordinator = new RedditRequestCoordinator(0);

    const first = coordinator.schedule(async () => {
      order.push('first:start');
      await firstFinished;
      order.push('first:end');
    });
    const second = coordinator.schedule(async () => { order.push('second'); });

    await Promise.resolve();
    expect(order).toEqual(['first:start']);
    releaseFirst();
    await Promise.all([first, second]);
    expect(order).toEqual(['first:start', 'first:end', 'second']);
  });

  it('does not release a queued request before a failing request records its cooldown', async () => {
    let now = 0;
    const sleeps: number[] = [];
    const coordinator = new RedditRequestCoordinator(0, {
      now: () => now,
      sleep: async (ms) => { sleeps.push(ms); now += ms; },
    });

    const first = coordinator.schedule(async () => {
      coordinator.extendCooldown(15_000);
      throw new Error('429');
    });
    const second = coordinator.schedule(async () => undefined);

    await expect(first).rejects.toThrow('429');
    await second;
    expect(sleeps).toEqual([16_000]);
  });

  it('paces a queued request after a failed attempt without an explicit cooldown', async () => {
    let now = 0;
    const sleeps: number[] = [];
    const coordinator = new RedditRequestCoordinator(6_500, {
      now: () => now,
      sleep: async (ms) => { sleeps.push(ms); now += ms; },
    });

    await expect(coordinator.schedule(async () => { throw new Error('403'); })).rejects.toThrow('403');
    await coordinator.schedule(async () => undefined);

    expect(sleeps).toEqual([6_500]);
  });
});