"""Shared utilities."""
import os

VIDEO_EXTENSIONS = {
    ".mp4", ".mkv", ".avi", ".mov", ".wmv", ".flv", ".webm",
    ".m4v", ".mpg", ".mpeg", ".ts", ".m2ts", ".3gp",
}


def fmt_size(n: int | float) -> str:
    if n < 0:
        return "—"
    for unit in ("B", "KB", "MB", "GB", "TB"):
        if n < 1024:
            return f"{n:.1f} {unit}"
        n /= 1024
    return f"{n:.1f} PB"


def fmt_eta(seconds: float) -> str:
    if seconds <= 0 or seconds != seconds:
        return "—"
    seconds = int(seconds)
    h, r = divmod(seconds, 3600)
    m, s = divmod(r, 60)
    if h:
        return f"{h}h {m}m"
    if m:
        return f"{m}m {s}s"
    return f"{s}s"


def is_video(path: str) -> bool:
    return os.path.splitext(path)[1].lower() in VIDEO_EXTENSIONS


def find_first_video(directory: str) -> str:
    for root, _, files in os.walk(directory):
        for f in files:
            if is_video(f):
                return os.path.join(root, f)
    return ""


def ffmpeg_ok() -> bool:
    import shutil
    return shutil.which("ffmpeg") is not None