download_mp3.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import argparse
import datetime
import os
import sys
import requests
from urllib.parse import urlparse

def download_file(url: str, filename: str = None):
    """
    Downloads a file from a given URL with a progress bar.

    Args:
        url (str): The URL of the file to download.
        filename (str, optional): The path to save the file to. 
                                  If None, a timestamped filename is generated.
    """
    # --- 1. 确定最终的文件名 ---
    if filename is None:
        try:
            # 尝试从 URL 路径中提取扩展名
            path = urlparse(url).path
            ext = os.path.splitext(path)[1]
            # 如果 URL 类似 "https://.../resource" 没有扩展名，或查询参数中有 .mp3
            if not ext and '.mp3' in url:
                 ext = '.mp3'
            # 如果还是没有，使用 .bin 作为通用二进制文件后缀
            if not ext:
                ext = '.bin'
        except Exception:
            ext = '.mp3' # 最终回退到 .mp3，符合您最初的用例
            
        timestamp = datetime.datetime.now().strftime('%Y-%m-%dT%H-%M-%S')
        output_filename = f"{timestamp}{ext}"
    else:
        output_filename = filename

    # --- 2. 执行下载 ---
    try:
        print(f"URL: {url}")
        print(f"Output: {output_filename}")

        # 使用 stream=True 进行流式下载
        with requests.get(url, stream=True, allow_redirects=True, timeout=30) as r:
            # 检查请求是否成功 (HTTP 状态码 200-299)
            r.raise_for_status()

            # 从响应头获取文件总大小
            total_size = int(r.headers.get('content-length', 0))
            
            # 设置块大小 (8KB)
            chunk_size = 8192
            downloaded_size = 0

            print("Downloading...")
            with open(output_filename, 'wb') as f:
                for chunk in r.iter_content(chunk_size=chunk_size):
                    f.write(chunk)
                    downloaded_size += len(chunk)
                    
                    # --- 3. 绘制进度条 ---
                    if total_size > 0:
                        # 计算进度
                        progress = downloaded_size / total_size
                        bar_length = 40
                        filled_length = int(bar_length * progress)
                        bar = '█' * filled_length + '-' * (bar_length - filled_length)
                        
                        # 已下载和总大小的可读格式 (MB)
                        downloaded_mb = downloaded_size / (1024 * 1024)
                        total_mb = total_size / (1024 * 1024)
                        
                        # 打印到同一行
                        sys.stdout.write(f"\rProgress: [{bar}] {progress:.1%} ({downloaded_mb:.2f}MB / {total_mb:.2f}MB)")
                        sys.stdout.flush()

        # 下载完成，换行
        print("\n" + "="*50)
        print(f"Downloaded '{output_filename}' successfully.")
        print("="*50)

    # --- 4. 错误处理 ---
    except requests.exceptions.HTTPError as e:
        print(f"\nError: HTTP request failed with status code {e.response.status_code}")
        print(f"URL: {e.request.url}")
    except requests.exceptions.RequestException as e:
        print(f"\nError: A network-related error occurred: {e}")
    except KeyboardInterrupt:
        print("\nDownload cancelled by user. Deleting partial file.")
        if os.path.exists(output_filename):
            os.remove(output_filename) # 删除未下载完的片段文件
        sys.exit(1)
    except Exception as e:
        print(f"\nAn unexpected error occurred: {e}")


def main():
    """主函数，处理命令行参数"""
    parser = argparse.ArgumentParser(
        description="A simple script to download a file from a URL with a progress bar.",
        # 让帮助信息中的换行符生效
        formatter_class=argparse.RawTextHelpFormatter 
    )
    parser.add_argument(
        "url",
        metavar="URL",
        type=str,
        help="The URL of the file to download."
    )
    parser.add_argument(
        "-o", "--output",
        metavar="FILENAME",
        type=str,
        default=None,
        help="Optional. The output filename.\nIf not provided, a timestamp-based name will be generated.\n(e.g., 2025-06-19T10-30-00.mp3)"
    )
    
    args = parser.parse_args()
    download_file(args.url, args.output)


if __name__ == "__main__":
    main()