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

from typing import Optional, Tuple

from common import _unstructured_elements_to_markdown, parse_with_markitdown


def parse_pdf_with_docling(file_path: str) -> Tuple[Optional[str], Optional[str]]:
    """使用 docling 库解析 PDF 文件（不启用 OCR）"""
    try:
        from docling.datamodel.base_models import InputFormat
        from docling.datamodel.pipeline_options import PdfPipelineOptions
        from docling.document_converter import DocumentConverter, PdfFormatOption
    except ImportError:
        return None, "docling 库未安装"

    try:
        converter = DocumentConverter(
            format_options={
                InputFormat.PDF: PdfFormatOption(
                    pipeline_options=PdfPipelineOptions(do_ocr=False)
                )
            }
        )
        result = converter.convert(file_path)
        markdown_content = result.document.export_to_markdown()
        if not markdown_content.strip():
            return None, "文档为空"
        return markdown_content, None
    except Exception as e:
        return None, f"docling 解析失败: {str(e)}"


def parse_pdf_with_docling_ocr(file_path: str) -> Tuple[Optional[str], Optional[str]]:
    """使用 docling 库解析 PDF 文件（启用 OCR）"""
    try:
        from docling.document_converter import DocumentConverter
    except ImportError:
        return None, "docling 库未安装"

    try:
        converter = DocumentConverter()
        result = converter.convert(file_path)
        markdown_content = result.document.export_to_markdown()
        if not markdown_content.strip():
            return None, "文档为空"
        return markdown_content, None
    except Exception as e:
        return None, f"docling OCR 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（fast 策略）"""
    try:
        from unstructured.partition.pdf import partition_pdf
    except ImportError:
        return None, "unstructured 库未安装"

    try:
        elements = partition_pdf(
            filename=file_path,
            infer_table_structure=True,
            strategy="fast",
            languages=["chi_sim"],
        )
        # fast 策略不做版面分析，Title 类型标注不可靠
        content = _unstructured_elements_to_markdown(elements, trust_titles=False)
        if not content.strip():
            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_unstructured_ocr(
    file_path: str,
) -> Tuple[Optional[str], Optional[str]]:
    """使用 unstructured 库解析 PDF 文件（hi_res 策略 + PaddleOCR）"""
    try:
        from unstructured.partition.pdf import partition_pdf
    except ImportError:
        return None, "unstructured 库未安装"

    try:
        from unstructured.partition.utils.constants import OCR_AGENT_PADDLE
    except ImportError:
        return None, "unstructured-paddleocr 库未安装"

    try:
        elements = partition_pdf(
            filename=file_path,
            infer_table_structure=True,
            strategy="hi_res",
            languages=["chi_sim"],
            ocr_agent=OCR_AGENT_PADDLE,
            table_ocr_agent=OCR_AGENT_PADDLE,
        )
        content = _unstructured_elements_to_markdown(elements, trust_titles=True)
        if not content.strip():
            return None, "文档为空"
        return content, None
    except Exception as e:
        return None, f"unstructured OCR 解析失败: {str(e)}"


def parse_pdf_with_markitdown(file_path: str) -> Tuple[Optional[str], Optional[str]]:
    """使用 MarkItDown 库解析 PDF 文件"""
    return parse_with_markitdown(file_path)


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)}"