"""PDF 文件阅读器，支持多种解析方法（OCR 优先）。"""

import os
from typing import List, Optional, Tuple

from readers.base import BaseReader
from utils import is_valid_pdf

from . import docling_ocr
from . import unstructured_ocr
from . import docling
from . import unstructured
from . import markitdown
from . import pypdf


PARSERS = [
    ("docling OCR", docling_ocr.parse),
    ("unstructured OCR", unstructured_ocr.parse),
    ("docling", docling.parse),
    ("unstructured", unstructured.parse),
    ("MarkItDown", markitdown.parse),
    ("pypdf", pypdf.parse),
]


class PdfReader(BaseReader):
    """PDF 文件阅读器"""

    def supports(self, file_path: str) -> bool:
        return file_path.lower().endswith('.pdf')

    def parse(self, file_path: str) -> Tuple[Optional[str], List[str]]:
        failures = []

        # 检查文件是否存在
        if not os.path.exists(file_path):
            return None, ["文件不存在"]

        # 验证文件格式
        if not is_valid_pdf(file_path):
            return None, ["不是有效的 PDF 文件"]

        content = None

        for parser_name, parser_func in PARSERS:
            try:
                content, error = parser_func(file_path)
                if content is not None:
                    return content, failures
                else:
                    failures.append(f"- {parser_name}: {error}")
            except Exception as e:
                failures.append(f"- {parser_name}: [意外异常] {type(e).__name__}: {str(e)}")

        return None, failures