"""Tesseract 本地 OCR 实现。"""
from __future__ import annotations

import asyncio
from pathlib import Path
from typing import Optional

from .base import OCRProvider


class TesseractOCR(OCRProvider):
    """通过 pytesseract 调用本地 tesseract。

    需提前安装 tesseract-ocr 及中文语言包。
    """

    name = "tesseract"

    def __init__(self, lang: str = "chi_sim+eng", cmd: Optional[str] = None) -> None:
        self.lang = lang
        self.cmd = cmd

    async def recognize(self, image_path: Path) -> str:
        """异步包装：避免阻塞事件循环。"""
        return await asyncio.to_thread(self._sync_recognize, image_path)

    def _sync_recognize(self, image_path: Path) -> str:
        try:
            import pytesseract
            from PIL import Image
        except ImportError as exc:  # pragma: no cover
            raise RuntimeError("未安装 pytesseract / Pillow") from exc

        if self.cmd:
            pytesseract.pytesseract.tesseract_cmd = self.cmd

        with Image.open(image_path) as img:
            text = pytesseract.image_to_string(img, lang=self.lang)
        return text.strip()