import shutil
import subprocess

import pytest

from app.remux import remux_to_mp4

needs_ffmpeg = pytest.mark.skipif(shutil.which("ffmpeg") is None, reason="ffmpeg not installed")


def make_mkv(path):
    subprocess.run(
        ["ffmpeg", "-v", "error", "-y",
         "-f", "lavfi", "-i", "testsrc=size=320x240:rate=30",
         "-f", "lavfi", "-i", "sine=frequency=440",
         "-t", "1", "-c:v", "libx264", "-c:a", "aac", str(path)],
        check=True,
    )


@needs_ffmpeg
def test_remux_good_mkv(tmp_path):
    src, dst = tmp_path / "in.mkv", tmp_path / "out.mp4"
    make_mkv(src)
    assert remux_to_mp4(src, dst) is True
    assert dst.read_bytes()[4:8] == b"ftyp"


def test_remux_garbage_returns_false(tmp_path):
    src, dst = tmp_path / "in.mkv", tmp_path / "out.mp4"
    src.write_bytes(b"not a video at all")
    assert remux_to_mp4(src, dst) is False
    assert not dst.exists()


def test_remux_missing_ffmpeg_returns_false(tmp_path, monkeypatch):
    monkeypatch.setenv("PATH", "")
    src, dst = tmp_path / "in.mkv", tmp_path / "out.mp4"
    src.write_bytes(b"x")
    assert remux_to_mp4(src, dst) is False