# -*- coding: utf-8 -*-

import random
import mimetypes
from datetime import datetime
from typing import List, Dict, Tuple
import aiofiles
from fastapi import UploadFile
from pathlib import Path
from urllib.parse import urljoin  # 添加URL拼接工具导入
from sqlalchemy.orm.writeonly import strategies

from app.config.setting import settings
from app.core.exceptions import CustomException
from app.core.logger import logger

class UploadUtil:
    """
    上传工具类
    """

    @staticmethod
    def generate_random_number() -> str:
        """生成3位数字构成的字符串"""
        return f'{random.randint(1, 999):03}'

    @staticmethod
    def check_file_exists(filepath: Path) -> bool:
        """检查文件是否存在"""
        return filepath.exists()

    @staticmethod
    def check_file_extension(file: UploadFile) -> bool:
        """检查文件后缀是否合法"""
        file_extension = mimetypes.guess_extension(file.content_type)
        return file_extension in settings.ALLOWED_EXTENSIONS if file_extension else False

    @staticmethod
    def check_file_timestamp(filename: str) -> bool:
        """校验文件时间戳是否合法"""
        try:
            name_parts = filename.rsplit('.', 1)[0].split('_')
            timestamp = name_parts[-1].split(settings.UPLOAD_MACHINE)[0]
            datetime.strptime(timestamp, '%Y%m%d%H%M%S')
            return True
        except (ValueError, IndexError):
            return False

    @staticmethod
    def check_file_machine(filename: str) -> bool:
        """校验文件机器码是否合法"""
        try:
            name_without_ext = filename.rsplit('.', 1)[0]
            return len(name_without_ext) >= 4 and name_without_ext[-4] == settings.UPLOAD_MACHINE
        except IndexError:
            return False

    @staticmethod
    def check_file_random_code(filename: str) -> bool:
        """校验文件随机码是否合法"""
        try:
            code = filename.rsplit('.', 1)[0][-3:]
            return code.isdigit() and 1 <= int(code) <= 999
        except IndexError:
            return False

    @staticmethod
    def check_file_size(file: UploadFile) -> bool:
        """校验文件大小是否合法"""
        return file.size <= settings.MAX_FILE_SIZE

    @classmethod
    def generate_file_name(cls, filename: str) -> str:
        """生成文件名称"""
        name, ext = filename.rsplit(".", 1)
        timestamp = datetime.now().strftime("%Y%m%d%H%M%S")
        return f'{name}_{timestamp}{settings.UPLOAD_MACHINE}{cls.generate_random_number()}.{ext}'
    
    @staticmethod
    def generate_file(filepath: Path, chunk_size: int = 8192):
        """根据文件生成二进制数据"""
        with filepath.open('rb') as f:
            while chunk := f.read(chunk_size):
                yield chunk

    @staticmethod
    def delete_file(filepath: Path) -> bool:
        """
        删除文件
        :return: 删除是否成功
        """
        try:
            filepath.unlink(missing_ok=True)
            return True
        except OSError:
            return False
    
    @classmethod
    async def upload_file(cls, file: UploadFile, base_url: str) -> Tuple[str, Path, str]:
        """
        文件上传
        :param file: 上传的文件对象
        :param base_url: 基础URL
        :raises CustomException: 当文件类型不支持或大小超限时抛出
        :return: (文件名, 文件路径, 文件URL)的元组
        """
        # 文件校验
        if not all([cls.check_file_extension(file), cls.check_file_size(file)]):
            raise CustomException(msg='文件类型或大小不合法')
            
        try:
            # 构建完整的目录路径
            dir_path = settings.UPLOAD_FILE_PATH.joinpath(datetime.now().strftime("%Y/%m/%d"))
            dir_path.mkdir(parents=True, exist_ok=True)
            
            # 生成文件名并保存
            filename = cls.generate_file_name(file.filename)
            filepath = str(dir_path.joinpath(filename)).replace('\\', '/')  # 转换为字符串后替换斜杠
            file_url = urljoin(base_url, filepath)
            # filepath.mkdir(parents=True, exist_ok=True)

            # 分块写入文件
            chunk_size = 8 * 1024 * 1024  # 8MB chunks
            async with aiofiles.open(filepath, 'wb') as f:
                while chunk := await file.read(chunk_size):
                    await f.write(chunk)

            # 返回相对路径
            return filename, filepath, file_url
            
        except Exception as e:
            logger.error(f"文件上传失败: {e}")
            raise CustomException(msg='文件上传失败')

    @staticmethod
    def get_file_tree(file_path: str) -> List[Dict]:
        """
        获取文件树结构
        :param file_path: 文件路径
        :return: 文件树列表
        """
        return [item for item in Path(file_path).iterdir()]

    @classmethod
    async def download_file(cls, file_path: str) -> str:
        """
        下载文件,生成新的文件名
        :param file_path: 文件路径
        :return: 文件下载信息
        """
        # 解析文件路径
        filename = cls.generate_file_name(file_path)
        return filename