"""字幕引擎：根据 stdout 关键词打时间戳，生成 SRT 字幕文件。"""
from __future__ import annotations

import time
from dataclasses import dataclass
from pathlib import Path
from typing import List, Tuple


@dataclass
class _Entry:
    start: float   # 距录制开始的秒数
    text: str
    duration: float = 5.0  # 每条字幕默认显示 5 秒


class SubtitleEngine:
    def __init__(self, script: List[Tuple[str, str]], default_duration: float = 5.0):
        """
        script: [(关键词, 字幕文案), ...]
        关键词大小写不敏感，每个关键词只触发一次。
        """
        self._script = script
        self._default_duration = default_duration
        self._entries: List[_Entry] = []
        self._matched: set[str] = set()
        self._t0: float = 0.0

    def set_start_time(self, t: float) -> None:
        self._t0 = t

    def process_line(self, line: str) -> None:
        lower = line.lower()
        for keyword, text in self._script:
            if keyword in self._matched:
                continue
            if keyword.lower() in lower:
                elapsed = time.time() - self._t0
                self._entries.append(_Entry(start=elapsed, text=text, duration=self._default_duration))
                self._matched.add(keyword)

    def generate_srt(self, output_path: str) -> None:
        def _fmt(s: float) -> str:
            h = int(s // 3600)
            m = int((s % 3600) // 60)
            sec = int(s % 60)
            ms = int((s % 1) * 1000)
            return f"{h:02d}:{m:02d}:{sec:02d},{ms:03d}"

        Path(output_path).parent.mkdir(parents=True, exist_ok=True)
        with open(output_path, "w", encoding="utf-8") as f:
            for i, e in enumerate(self._entries, 1):
                f.write(f"{i}\n")
                f.write(f"{_fmt(e.start)} --> {_fmt(e.start + e.duration)}\n")
                f.write(f"{e.text}\n\n")