"""
文档解析服务
从 PDF/Word/Excel 文档中提取纯文本
"""
import os
import tempfile
from typing import Optional

import httpx


class DocumentParser:
    """从文档中提取纯文本"""

    @staticmethod
    async def download_and_parse(document_url: str, document_name: str) -> str:
        """
        下载文档并解析为纯文本

        Args:
            document_url: 文档 URL (TOS)
            document_name: 原始文件名（用于判断格式）

        Returns:
            提取的纯文本
        """
        # 下载到临时文件
        tmp_path: Optional[str] = None
        try:
            async with httpx.AsyncClient(timeout=60.0) as client:
                resp = await client.get(document_url)
                resp.raise_for_status()

            ext = document_name.rsplit(".", 1)[-1].lower() if "." in document_name else ""
            with tempfile.NamedTemporaryFile(delete=False, suffix=f".{ext}") as tmp:
                tmp.write(resp.content)
                tmp_path = tmp.name

            return DocumentParser.parse_file(tmp_path, document_name)
        finally:
            if tmp_path and os.path.exists(tmp_path):
                os.unlink(tmp_path)

    @staticmethod
    def parse_file(file_path: str, file_name: str) -> str:
        """
        根据扩展名选择解析器，返回纯文本

        Args:
            file_path: 本地文件路径
            file_name: 原始文件名

        Returns:
            提取的纯文本
        """
        ext = file_name.rsplit(".", 1)[-1].lower() if "." in file_name else ""

        if ext == "pdf":
            return DocumentParser._parse_pdf(file_path)
        elif ext in ("doc", "docx"):
            return DocumentParser._parse_docx(file_path)
        elif ext in ("xls", "xlsx"):
            return DocumentParser._parse_xlsx(file_path)
        elif ext == "txt":
            return DocumentParser._parse_txt(file_path)
        else:
            raise ValueError(f"不支持的文件格式: {ext}")

    @staticmethod
    def _parse_pdf(path: str) -> str:
        """pdfplumber 提取 PDF 文本"""
        import pdfplumber

        texts = []
        with pdfplumber.open(path) as pdf:
            for page in pdf.pages:
                text = page.extract_text()
                if text:
                    texts.append(text)
        return "\n".join(texts)

    @staticmethod
    def _parse_docx(path: str) -> str:
        """python-docx 提取 Word 文本"""
        from docx import Document

        doc = Document(path)
        texts = []
        for para in doc.paragraphs:
            if para.text.strip():
                texts.append(para.text)
        # 也提取表格内容
        for table in doc.tables:
            for row in table.rows:
                row_text = "\t".join(cell.text.strip() for cell in row.cells if cell.text.strip())
                if row_text:
                    texts.append(row_text)
        return "\n".join(texts)

    @staticmethod
    def _parse_xlsx(path: str) -> str:
        """openpyxl 提取 Excel 文本（所有 sheet 拼接）"""
        from openpyxl import load_workbook

        wb = load_workbook(path, read_only=True, data_only=True)
        texts = []
        for sheet in wb.worksheets:
            for row in sheet.iter_rows(values_only=True):
                row_text = "\t".join(str(cell) for cell in row if cell is not None)
                if row_text.strip():
                    texts.append(row_text)
        wb.close()
        return "\n".join(texts)

    @staticmethod
    def _parse_txt(path: str) -> str:
        """纯文本文件"""
        with open(path, "r", encoding="utf-8") as f:
            return f.read()