"""文件类型检测模块，用于验证和检测输入文件类型。"""

import os
import zipfile
from typing import List, Optional


def _is_valid_ooxml(file_path: str, required_files: List[str]) -> bool:
    """验证 OOXML 格式文件（DOCX/PPTX/XLSX）"""
    try:
        with zipfile.ZipFile(file_path, "r") as zip_file:
            names = set(zip_file.namelist())
            return all(r in names for r in required_files)
    except (zipfile.BadZipFile, zipfile.LargeZipFile):
        return False


_DOCX_REQUIRED = ["[Content_Types].xml", "_rels/.rels", "word/document.xml"]
_PPTX_REQUIRED = ["[Content_Types].xml", "_rels/.rels", "ppt/presentation.xml"]
_XLSX_REQUIRED = ["[Content_Types].xml", "_rels/.rels", "xl/workbook.xml"]


def is_valid_docx(file_path: str) -> bool:
    """验证文件是否为有效的 DOCX 格式"""
    return _is_valid_ooxml(file_path, _DOCX_REQUIRED)


def is_valid_pptx(file_path: str) -> bool:
    """验证文件是否为有效的 PPTX 格式"""
    return _is_valid_ooxml(file_path, _PPTX_REQUIRED)


def is_valid_xlsx(file_path: str) -> bool:
    """验证文件是否为有效的 XLSX 格式"""
    return _is_valid_ooxml(file_path, _XLSX_REQUIRED)


def is_valid_pdf(file_path: str) -> bool:
    """验证文件是否为有效的 PDF 格式"""
    try:
        with open(file_path, "rb") as f:
            header = f.read(4)
            return header == b"%PDF"
    except (IOError, OSError):
        return False


def is_html_file(file_path: str) -> bool:
    """判断文件是否为 HTML 文件（仅检查扩展名）"""
    ext = file_path.lower()
    return ext.endswith(".html") or ext.endswith(".htm")


def is_url(input_str: str) -> bool:
    """判断输入是否为 URL"""
    return input_str.startswith("http://") or input_str.startswith("https://")


_FILE_TYPE_VALIDATORS = {
    ".docx": is_valid_docx,
    ".pptx": is_valid_pptx,
    ".xlsx": is_valid_xlsx,
    ".pdf": is_valid_pdf,
}


def detect_file_type(file_path: str) -> Optional[str]:
    """检测文件类型，返回 'docx'、'pptx'、'xlsx' 或 'pdf'"""
    ext = os.path.splitext(file_path)[1].lower()
    validator = _FILE_TYPE_VALIDATORS.get(ext)
    if validator and validator(file_path):
        return ext.lstrip(".")
    return None