import json
import subprocess
import tempfile

SHORT_CAP = 720
LONG_CAP = 1280

def _probe(video_path: str) -> dict:
    out = subprocess.run(
        ["ffprobe", "-v", "quiet", "-print_format", "json",
         "-show_format", "-show_streams", video_path],
        capture_output=True, text=True, check=True,
    )
    return json.loads(out.stdout)


def get_duration(video_path: str) -> float:
    return float(_probe(video_path)["format"]["duration"])


def get_display_dims(video_path: str) -> tuple[int, int]:
    """Return (width, height) as DISPLAYED — i.e. after rotation metadata is
    applied. Phone portrait clips are often stored landscape + a rotate flag;
    if we ignored it the target size (and detection) would be sideways.
    """
    info = _probe(video_path)
    v = next(s for s in info["streams"] if s["codec_type"] == "video")
    w, h = int(v["width"]), int(v["height"])

    rot = 0
    if "tags" in v and "rotate" in v["tags"]:
        rot = int(v["tags"]["rotate"])
    for sd in v.get("side_data_list", []):
        if "rotation" in sd:
            rot = int(sd["rotation"])
    if abs(rot) % 180 == 90:        # 90 or 270 -> swap
        w, h = h, w
    return w, h


def compute_target_size(w: int, h: int) -> tuple[int, int]:
    """Scale = min(720/short, 1280/long, 1.0); dims forced even; no upscale."""
    short, long = min(w, h), max(w, h)
    s = min(SHORT_CAP / short, LONG_CAP / long, 1.0)
    out_w = max(2, int(round(w * s / 2)) * 2)
    out_h = max(2, int(round(h * s / 2)) * 2)
    return out_w, out_h


def normalize_video(video_path: str) -> tuple[str, int, int]:
    """ffmpeg: autorotate + scale to target + re-encode H.264 (+ keep audio).
    Returns (normalized_path, out_w, out_h). Everything downstream uses this.
    """
    w, h = get_display_dims(video_path)
    out_w, out_h = compute_target_size(w, h)

    # NamedTemporaryFile gives us a safe unique path (mktemp is deprecated /
    # racy); close it and let ffmpeg overwrite via -y.
    tmp = tempfile.NamedTemporaryFile(delete=False, suffix=".mp4")
    out_path = tmp.name
    tmp.close()

    subprocess.run(
        ["ffmpeg", "-y", "-i", video_path,
         "-vf", f"scale={out_w}:{out_h}",
         "-c:v", "libx264", "-preset", "veryfast", "-pix_fmt", "yuv420p",
         "-c:a", "aac", "-movflags", "+faststart", out_path],
        check=True, capture_output=True,
    )
    return out_path, out_w, out_h