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

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


def probe(path):
    cap = cv2.VideoCapture(str(path))
    assert cap.isOpened(), f"cannot reopen {path}"
    info = (
        int(cap.get(cv2.CAP_PROP_FRAME_COUNT)),
        int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)),
        int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)),
    )
    cap.release()
    return info


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))


def test_max_height_downscale(tmp_path):
    out = tmp_path / "down.mp4"
    writer = AnnotatedVideoWriter(
        str(out), fps=25.0, frame_size=(640, 480), max_height=240
    )
    assert writer.written_size == (320, 240)
    for _ in range(3):
        writer.write_frame(np.zeros((480, 640, 3), dtype=np.uint8))
    writer.finish()
    assert out.exists() and out.stat().st_size > 0
    count, w, h = probe(out)
    assert count == 3
    assert (w, h) == writer.written_size


def test_no_max_height_keeps_native_size(tmp_path):
    out = tmp_path / "native.mp4"
    writer = AnnotatedVideoWriter(str(out), fps=25.0, frame_size=(640, 480))
    assert writer.written_size == (640, 480)
    writer.write_frame(np.zeros((480, 640, 3), dtype=np.uint8))
    writer.finish()
    assert probe(out)[1:] == (640, 480)


def test_even_dimensions_after_downscale(tmp_path):
    out = tmp_path / "even.mp4"
    writer = AnnotatedVideoWriter(
        str(out), fps=25.0, frame_size=(641, 481), max_height=240
    )
    tw, th = writer.written_size
    assert tw % 2 == 0 and th % 2 == 0
    assert th <= 240
    writer.write_frame(np.zeros((481, 641, 3), dtype=np.uint8))
    writer.finish()
    assert probe(out)[1:] == writer.written_size


def test_auto_codec_records_backend(tmp_path):
    out = tmp_path / "auto.mp4"
    writer = AnnotatedVideoWriter(str(out), fps=25.0, frame_size=(640, 480))
    assert isinstance(writer.backend, str)
    assert writer.backend
    writer.write_frame(np.zeros((480, 640, 3), dtype=np.uint8))
    writer.finish()


def test_explicit_codec_forces_fourcc(tmp_path):
    out = tmp_path / "explicit.mp4"
    writer = AnnotatedVideoWriter(
        str(out), fps=25.0, frame_size=(640, 480), codec="mp4v"
    )
    assert writer.backend == "mp4v"
    writer.write_frame(np.zeros((480, 640, 3), dtype=np.uint8))
    writer.finish()
    assert out.exists() and out.stat().st_size > 0