import csv
from pathlib import Path
from typing import Any

import openpyxl
import pandas as pd


class FileParserService:
    """文件解析服务"""

    @staticmethod
    def parse_excel(file_path: str | Path) -> dict[str, Any]:
        """
        解析 Excel 文件
        
        Args:
            file_path: 文件路径
            
        Returns:
            解析结果：headers, sample_rows, total_rows
        """
        file_path = Path(file_path)
        
        # 使用 openpyxl 解析 .xlsx
        if file_path.suffix.lower() == ".xlsx":
            wb = openpyxl.load_workbook(file_path, read_only=True, data_only=True)
            ws = wb.active
            
            # 获取表头（第一行）
            headers = [cell.value for cell in ws[1]]
            
            # 获取样例数据（前5行，不含表头）
            sample_rows = []
            for row_idx, row in enumerate(ws.iter_rows(min_row=2, max_row=6, values_only=True), start=2):
                row_data = dict(zip(headers, row))
                sample_rows.append(row_data)
            
            # 获取总行数
            total_rows = ws.max_row - 1  # 减去表头行
            
            wb.close()
            
            return {
                "headers": headers,
                "sample_rows": sample_rows,
                "total_rows": total_rows,
            }
        
        # 使用 pandas 解析其他格式
        else:
            df = pd.read_excel(file_path)
            
            return {
                "headers": df.columns.tolist(),
                "sample_rows": df.head(5).to_dict(orient="records"),
                "total_rows": len(df),
            }

    @staticmethod
    def parse_csv(file_path: str | Path) -> dict[str, Any]:
        """
        解析 CSV 文件
        
        Args:
            file_path: 文件路径
            
        Returns:
            解析结果
        """
        file_path = Path(file_path)
        
        # 自动检测编码
        encodings = ["utf-8", "gbk", "gb2312", "utf-8-sig"]
        df = None
        
        for encoding in encodings:
            try:
                df = pd.read_csv(file_path, encoding=encoding)
                break
            except (UnicodeDecodeError, Exception):
                continue
        
        if df is None:
            raise ValueError("无法解析CSV文件，编码格式不支持")
        
        return {
            "headers": df.columns.tolist(),
            "sample_rows": df.head(5).to_dict(orient="records"),
            "total_rows": len(df),
        }

    @staticmethod
    def detect_file_type(file_content: bytes) -> str:
        """
        检测文件类型
        
        Args:
            file_content: 文件内容
            
        Returns:
            文件类型
        """
        # 简单的文件类型检测
        if file_content[:2] == b"PK":
            return "xlsx"
        elif file_content[:8] == b"\xd0\xcf\x11\xe0\xa1\xb1\x1a\xe1":
            return "xls"
        else:
            return "csv"


# 单例实例
file_parser_service = FileParserService()