#!/usr/bin/env python3
"""PDF 文件解析模块，提供三种解析方法。"""

from typing import Optional, Tuple


def parse_pdf_with_markitdown(file_path: str) -> Tuple[Optional[str], Optional[str]]:
    """使用 MarkItDown 库解析 PDF 文件"""
    try:
        from markitdown import MarkItDown

        md = MarkItDown()
        result = md.convert(file_path)
        if not result.text_content.strip():
            return None, "文档为空"
        return result.text_content, None
    except ImportError:
        return None, "MarkItDown 库未安装"
    except Exception as e:
        return None, f"MarkItDown 解析失败: {str(e)}"


def parse_pdf_with_unstructured(file_path: str) -> Tuple[Optional[str], Optional[str]]:
    """使用 unstructured 库解析 PDF 文件"""
    try:
        from unstructured.partition.pdf import partition_pdf
    except ImportError:
        return None, "unstructured 库未安装"

    try:
        elements = partition_pdf(
            filename=file_path,
            strategy="fast",
            infer_table_structure=True,
            extract_images_in_pdf=False,
        )

        md_lines = []
        for element in elements:
            if hasattr(element, "text") and element.text and element.text.strip():
                text = element.text.strip()
                md_lines.append(text)
                md_lines.append("")

        content = "\n".join(md_lines).strip()
        if not content:
            return None, "文档为空"
        return content, None
    except Exception as e:
        return None, f"unstructured 解析失败: {str(e)}"


def parse_pdf_with_pypdf(file_path: str) -> Tuple[Optional[str], Optional[str]]:
    """使用 pypdf 库解析 PDF 文件"""
    try:
        from pypdf import PdfReader
    except ImportError:
        return None, "pypdf 库未安装"

    try:
        reader = PdfReader(file_path)
        md_content = []

        for page in reader.pages:
            text = page.extract_text(extraction_mode="plain")
            if text and text.strip():
                md_content.append(text.strip())
                md_content.append("")

        content = "\n".join(md_content).strip()
        if not content:
            return None, "文档为空"
        return content, None
    except Exception as e:
        return None, f"pypdf 解析失败: {str(e)}"