Python Download Tool: Download Files from FTP, HTTP, and Torrent Links

import transmissionrpc
import argparse
import os
import urllib.request
from concurrent.futures import ThreadPoolExecutor
from tqdm import tqdm


def download_torrent(magnet, filename):
    tc = transmissionrpc.Client('localhost', port=9091)
    tc.add_torrent(magnet, download_dir=os.path.dirname(filename))
    print(f'Download started: {filename}')
    
def download_file(url, filename, num_threads=4):
    response = urllib.request.urlopen(url)
    size = int(response.getheader('Content-Length'))
    chunk_size = int(size / num_threads) + 1

    with open(filename, 'wb') as f:
        with tqdm(total=size, unit='B', unit_scale=True, desc=os.path.basename(filename), ncols=80, position=0) as bar:
            futures = []
            for i in range(num_threads):
                start = i * chunk_size
                end = min(start + chunk_size, size)
                futures.append((start, end, f))

            with ThreadPoolExecutor(max_workers=num_threads) as executor:
                for future in futures:
                    executor.submit(download_range, url, future, bar)

    print(f'Download complete: {filename}')


def download_range(url, future, bar):
    start, end, fileobj = future
    req = urllib.request.Request(url, headers={'Range': f'bytes={start}-{end-1}'})
    with urllib.request.urlopen(req) as response:
        fileobj.seek(start)
        while True:
            chunk = response.read(1024)
            if not chunk:
                break
            fileobj.write(chunk)
            bar.update(len(chunk))


def download_ftp(url, filename, num_threads=4):
    with urllib.request.urlopen(url) as response:
        total_size = response.getheader('Content-Length')
        if total_size:
            total_size = int(total_size.strip())
            with tqdm(total=total_size, unit='B', unit_scale=True, desc=os.path.basename(filename), ncols=80, position=0) as bar:
                with open(filename, 'wb') as f:
                    chunk_size = int(total_size / num_threads) + 1
                    futures = []
                    for i in range(num_threads):
                        start = i * chunk_size
                        end = min(start + chunk_size, total_size)
                        futures.append((start, end, f, bar))

                    with ThreadPoolExecutor(max_workers=num_threads) as executor:
                        for future in futures:
                            executor.submit(download_range_ftp, url, future)
            print(f'Download complete: {filename}')
        else:
            with open(filename, 'wb') as f:
                f.write(response.read())
            print(f'Download complete: {filename}')


def download_range_ftp(url, future):
    start, end, fileobj, bar = future
    req = urllib.request.Request(url)
    req.headers['Range'] = f'bytes={start}-{end-1}'
    with urllib.request.urlopen(req) as response:
        while True:
            chunk = response.read(1024)
            if not chunk:
                break
            fileobj.write(chunk)
            bar.update(len(chunk))


def main():
    parser = argparse.ArgumentParser(description='A command-line tool for downloading files')
    parser.add_argument('-u', '--url', metavar='<URL>', type=str, required=True, help='The download URL')
    parser.add_argument('-o', '--output', metavar='<FILENAME>', type=str, required=True, help='The output filename')
    parser.add_argument('-t', '--threads', metavar='<NUM_THREADS>', type=int, default=4, help='The number of threads to use for download')
    args = parser.parse_args()
    url, filename, num_threads = args.url, args.output, args.threads

    if not os.path.isfile(filename):
        if os.path.isdir(os.path.dirname(filename)):
            if url.startswith('ftp'):
                download_ftp(url, filename, num_threads)
            elif url.startswith('http') or url.startswith('https'):
                download_file(url, filename, num_threads)
            elif url.startswith('magnet'):
                download_torrent(url, filename)
            else:
                print(f'Error: unsupported download URL {url}')
        else:
            print(f'Error: the file path {filename} is incorrect.')
    else:
        ans = input(f'The file {filename} exists, do you want to overwrite it? (Y/N)').upper()
        if ans == 'Y':
            os.remove(filename)
            if url.startswith('ftp'):
                download_ftp(url, filename, num_threads)
            elif url.startswith('http') or url.startswith('https'):
                download_file(url, filename, num_threads)
            elif url.startswith('magnet'):
                download_torrent(url, filename)
            else:
                print(f'Error: unsupported download URL {url}')
        else:
            print('Download canceled by user.')

if __name__ == '__main__':
    main()

This script allows you to download files from different sources like FTP, HTTP, and torrent links using the command line. It utilizes multithreading for faster downloads and displays a progress bar using the tqdm library. You can adjust the number of threads used for downloading by using the -t or --threads flag.

How to use:

1. Make sure you have Python installed on your system.
2. Install the required libraries by running pip install transmissionrpc argparse urllib3 tqdm.
3. Save the script as a .py file (e.g., downloader.py).
4. Run the script from the command line with the following arguments:
   • -u <URL>: The URL of the file to download.
   • -o <FILENAME>: The desired output filename.
   • -t <NUM_THREADS> (optional): The number of threads to use for downloading (default is 4).

Example:

python downloader.py -u https://example.com/file.zip -o downloaded_file.zip -t 8

This will download the file file.zip from https://example.com/file.zip and save it as downloaded_file.zip using 8 threads.

Note:

• For downloading torrent files, you need to have the transmission-daemon running on your system.
• The script assumes the transmission-daemon is running on localhost and port 9091. If your settings are different, update the transmissionrpc.Client settings accordingly.
• You can customize the script by modifying the download functions and error handling to meet your specific needs.