"""Standalone validation harness for build-order step 1: confirm python-mpv
gives frame-accurate seeking before any of the rest of the UI is built.

Steps frame-by-frame across the known flash event in the synthetic test clip
(white flash at t=5.000s, frame 150 @ 30fps) and dumps a screenshot + reported
position/frame-number per step, so the results can be inspected directly
instead of trusted on faith.
"""
import sys
import time
from pathlib import Path

from PyQt6.QtWidgets import QApplication

sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
from player_widget import PlayerWidget

CLIP = str(Path(__file__).resolve().parent.parent / "test_media" / "sync_test_INSYNC.mp4")
OUT_DIR = Path(__file__).resolve().parent.parent / "test_media" / "seek_validation"


def main():
    OUT_DIR.mkdir(exist_ok=True)
    app = QApplication(sys.argv)

    w = PlayerWidget()
    w.resize(640, 480)
    w.show()
    app.processEvents()

    w.load(CLIP)
    app.processEvents()
    print(f"fps reported by mpv: {w.fps()}")

    # Land a few frames before the flash (frame 150 == t=5.000s), then
    # single-step across it.
    w.seek(4.900)
    app.processEvents()
    time.sleep(0.2)
    app.processEvents()

    results = []
    for i in range(8):
        pos = w.get_position()
        frame = w.get_estimated_frame()
        shot = OUT_DIR / f"step_{i:02d}_frame{frame}.png"
        w.screenshot(str(shot))
        results.append((i, pos, frame, shot.name))
        print(f"step {i}: time_pos={pos:.4f}s estimated_frame={frame} -> {shot.name}")
        w.step_frame(1)
        app.processEvents()

    w.shutdown()

    print("\nExpected: flash frame is frame index 150 (t=5.000-5.033s).")
    print("Check the dumped PNGs in test_media/seek_validation/ to confirm")
    print("exactly one frame is white/bright and it lines up with the")
    print("reported frame number close to 150.")


if __name__ == "__main__":
    main()