import { tmpdir } from "node:os";
import { describe, expect, it } from "vitest";
import {
  assertDiskSpace,
  defaultMediaJobLimits,
  freeBytes,
  isDiskFull,
  MediaDiskFullError,
  MediaJobLimiter,
} from "./media-jobs.js";

describe("media job limits", () => {
  it("defaults to one GPU job and a bounded number of CPU jobs", () => {
    expect(defaultMediaJobLimits(1)).toEqual({ gpu: 1, cpu: 1 });
    expect(defaultMediaJobLimits(4)).toEqual({ gpu: 1, cpu: 2 });
    expect(defaultMediaJobLimits(64)).toEqual({ gpu: 1, cpu: 2 });
  });

  it("hands out permits up to the limit per class and never waits", () => {
    const limiter = new MediaJobLimiter({ gpu: 1, cpu: 2 });
    const gpu = limiter.tryAcquire("gpu");
    expect(gpu).not.toBeNull();
    expect(limiter.tryAcquire("gpu")).toBeNull();
    const cpu = [limiter.tryAcquire("cpu"), limiter.tryAcquire("cpu")];
    expect(cpu.every(Boolean)).toBe(true);
    expect(limiter.tryAcquire("cpu")).toBeNull();

    gpu?.();
    gpu?.();
    expect(limiter.running("gpu")).toBe(0);
    expect(limiter.tryAcquire("gpu")).not.toBeNull();
    cpu[0]?.();
    expect(limiter.running("cpu")).toBe(1);
  });

  it("rejects limits below one", () => {
    expect(() => new MediaJobLimiter({ gpu: 0, cpu: 1 })).toThrow();
    expect(() => new MediaJobLimiter({ gpu: 1, cpu: 1.5 })).toThrow();
  });
});

describe("disk backpressure", () => {
  it("reports free space and pauses below the reserve", async () => {
    const dir = tmpdir();
    expect(await freeBytes(dir)).toBeGreaterThan(0);
    await expect(assertDiskSpace(dir, 0)).resolves.toBeUndefined();
    await expect(assertDiskSpace(dir, Number.MAX_SAFE_INTEGER)).rejects.toBeInstanceOf(
      MediaDiskFullError,
    );
  });

  it("recognizes a full disk from errno or ffmpeg output", () => {
    expect(isDiskFull(Object.assign(new Error("write"), { code: "ENOSPC" }))).toBe(true);
    expect(isDiskFull(new Error("ffmpeg failed: No space left on device"))).toBe(true);
    expect(isDiskFull(new Error("Invalid data found"))).toBe(false);
    expect(isDiskFull(null)).toBe(false);
  });
});