"""Tests for AnnotatedVideoWriter (src/video_writer.py)."""

import cv2
import numpy as np
import pytest
from src.video_writer import AnnotatedVideoWriter


def test_writer_creates_output_file(tmp_path):
    out = tmp_path / "test_output.mp4"
    writer = AnnotatedVideoWriter(str(out), fps=25.0, frame_size=(640, 480))
    frame = np.zeros((480, 640, 3), dtype=np.uint8)
    writer.write_frame(frame)
    writer.finish()
    assert out.exists()
    assert out.stat().st_size > 0


def test_writer_multiple_frames(tmp_path):
    out = tmp_path / "multi.mp4"
    writer = AnnotatedVideoWriter(str(out), fps=25.0, frame_size=(320, 240))
    for _ in range(10):
        writer.write_frame(np.zeros((240, 320, 3), dtype=np.uint8))
    writer.finish()
    assert out.exists()


def test_writer_close_idempotent(tmp_path):
    out = tmp_path / "idem.mp4"
    writer = AnnotatedVideoWriter(str(out), fps=25.0, frame_size=(320, 240))
    writer.write_frame(np.zeros((240, 320, 3), dtype=np.uint8))
    writer.finish()
    writer.finish()  # second call should not raise
    assert out.exists()


def test_writer_invalid_fps():
    with pytest.raises(ValueError):
        AnnotatedVideoWriter("/tmp/x.mp4", fps=0.0, frame_size=(640, 480))