"""
LectureLens — Tests: Video Analyzer
Run with: pytest tests/test_video.py -v
Requires ffprobe on PATH and opencv-python-headless installed.
"""

from __future__ import annotations

from pathlib import Path

import numpy as np
import pytest


# ── Helpers ────────────────────────────────────────────────────────────────────

def make_mp4(path: Path, duration: float = 3.0, width: int = 640, height: int = 480) -> Path:
    """
    Generate a minimal MP4 using ffmpeg (solid colour, silent).
    Requires ffmpeg on PATH.
    """
    import subprocess
    cmd = [
        "ffmpeg", "-y",
        "-f", "lavfi",
        "-i", f"color=c=blue:size={width}x{height}:rate=25:duration={duration}",
        "-f", "lavfi", "-i", "aevalsrc=0:c=mono:s=44100:d={}".format(duration),
        "-c:v", "libx264", "-c:a", "aac",
        "-shortest",
        str(path),
    ]
    result = subprocess.run(cmd, capture_output=True, text=True)
    if result.returncode != 0:
        pytest.skip(f"ffmpeg not available or failed: {result.stderr[:200]}")
    return path


@pytest.fixture(scope="module")
def sample_mp4(tmp_path_factory) -> Path:
    p = tmp_path_factory.mktemp("video") / "sample.mp4"
    return make_mp4(p, duration=4.0)


# ── ffprobe parsing ────────────────────────────────────────────────────────────

def test_get_video_info_returns_dict(sample_mp4):
    from app.analyzers.video_analyzer import get_video_info
    info = get_video_info(sample_mp4)
    assert "stream" in info
    assert "format" in info


def test_parse_resolution(sample_mp4):
    from app.analyzers.video_analyzer import get_video_info, parse_resolution
    info = get_video_info(sample_mp4)
    res = parse_resolution(info)
    assert res == "640x480", f"Unexpected resolution: {res}"


def test_parse_fps(sample_mp4):
    from app.analyzers.video_analyzer import get_video_info, parse_fps
    info = get_video_info(sample_mp4)
    fps = parse_fps(info)
    assert fps is not None
    assert 24 <= fps <= 31, f"Unexpected FPS: {fps}"


# ── Brightness / Sharpness ────────────────────────────────────────────────────

def test_brightness_solid_blue_frame(sample_mp4):
    """A solid blue frame has moderate brightness."""
    from app.analyzers.video_analyzer import get_brightness_and_sharpness
    brightness, sharpness = get_brightness_and_sharpness(sample_mp4, sample_rate_seconds=1)
    assert brightness is not None
    # Blue frame: grayscale ~29 (0.07*R + 0.72*G + 0.21*B, B=255)
    assert 10 <= brightness <= 100, f"Unexpected brightness for solid blue: {brightness}"


def test_sharpness_is_low_for_solid_frame(sample_mp4):
    """A solid-colour frame has near-zero Laplacian variance (no edges)."""
    from app.analyzers.video_analyzer import get_brightness_and_sharpness
    _, sharpness = get_brightness_and_sharpness(sample_mp4, sample_rate_seconds=1)
    assert sharpness is not None
    assert sharpness < 50, f"Expected low sharpness for solid frame, got {sharpness}"


# ── Freeze / Black detection ──────────────────────────────────────────────────

def test_no_freeze_in_solid_video(sample_mp4):
    """A static solid-colour video is NOT flagged as frozen (below threshold duration)."""
    from app.analyzers.video_analyzer import detect_frozen_frames
    segs = detect_frozen_frames(sample_mp4)
    # solid colour = technically frozen; check the structure at least
    assert isinstance(segs, list)


def test_no_black_segments(sample_mp4):
    from app.analyzers.video_analyzer import detect_black_frames
    segs = detect_black_frames(sample_mp4)
    assert isinstance(segs, list)
    # Blue frame should not be flagged as black
    assert len(segs) == 0, f"Unexpected black segments: {segs}"


# ── Alert engine (video) ───────────────────────────────────────────────────────

def test_alert_dark_video():
    from app.schemas import VideoMetrics
    from app.alert_engine import generate_alerts

    metrics = VideoMetrics(avg_brightness=40.0)
    alerts = generate_alerts(metrics, "video", thresholds_path="thresholds.yaml")
    kpis = [a.kpi for a in alerts]
    assert "avg_brightness" in kpis


def test_alert_blurry_video():
    from app.schemas import VideoMetrics
    from app.alert_engine import generate_alerts

    metrics = VideoMetrics(avg_sharpness_laplacian=20.0)
    alerts = generate_alerts(metrics, "video", thresholds_path="thresholds.yaml")
    kpis = [a.kpi for a in alerts]
    assert "avg_sharpness_laplacian" in kpis


def test_no_alerts_for_ideal_video():
    from app.schemas import VideoMetrics
    from app.alert_engine import generate_alerts

    metrics = VideoMetrics(
        avg_brightness=130.0,
        avg_sharpness_laplacian=250.0,
        dropped_frames_ratio=0.0,
        compression_artifact_score=0.1,
    )
    alerts = generate_alerts(metrics, "video", thresholds_path="thresholds.yaml")
    assert len(alerts) == 0, f"Expected no alerts, got: {alerts}"


# ── Score ──────────────────────────────────────────────────────────────────────

def test_video_score_range():
    from app.schemas import VideoMetrics
    from app.alert_engine import compute_video_score

    m = VideoMetrics(
        avg_brightness=130.0,
        avg_sharpness_laplacian=250.0,
        dropped_frames_ratio=0.0,
    )
    score = compute_video_score(m)
    assert 0.0 <= score <= 1.0
    assert score > 0.7


def test_video_score_low_for_bad_metrics():
    from app.schemas import VideoMetrics
    from app.alert_engine import compute_video_score

    m = VideoMetrics(
        avg_brightness=20.0,
        avg_sharpness_laplacian=10.0,
        dropped_frames_ratio=0.15,
    )
    score = compute_video_score(m)
    assert score < 0.5, f"Expected low score for bad metrics, got {score}"