"""字幕生成：SRT / WebVTT。"""


def _ts(seconds):
    """秒 → SRT 时间戳 HH:MM:SS,mmm"""
    ms = int(round(seconds * 1000))
    h, ms = divmod(ms, 3600000)
    m, ms = divmod(ms, 60000)
    s, ms = divmod(ms, 1000)
    return f"{h:02d}:{m:02d}:{s:02d},{ms:03d}"


def to_srt(segments):
    lines = []
    for i, seg in enumerate(segments, 1):
        lines.append(str(i))
        lines.append(f"{_ts(seg['start'])} --> {_ts(seg['end'])}")
        lines.append(seg["text"])
        lines.append("")
    return "\n".join(lines)


def to_vtt(segments):
    lines = ["WEBVTT", ""]
    for i, seg in enumerate(segments, 1):
        lines.append(str(i))
        lines.append(f"{_ts(seg['start']).replace(',', '.')} --> "
                     f"{_ts(seg['end']).replace(',', '.')}")
        lines.append(seg["text"])
        lines.append("")
    return "\n".join(lines)