Concurrent Downloader

import os
import time
import requests
from concurrent.futures import ThreadPoolExecutor, as_completed
from tqdm import tqdm  # For progress bars

# -------------------- Configuration --------------------
URLS = [
    "https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf",
    "https://people.sc.fsu.edu/~jburkardt/data/csv/airtravel.csv",
    "https://www.learningcontainer.com/wp-content/uploads/2020/05/sample-mp4-file.mp4"
]

DOWNLOAD_DIR = "downloads"
MAX_THREADS = 3
RETRY_LIMIT = 3  # Number of times to retry a failed download

# -------------------- Helper Function --------------------
def download_file(url):
    """Download a single file from URL and save it locally with progress."""
    local_filename = os.path.join(DOWNLOAD_DIR, url.split("/")[-1])

    for attempt in range(1, RETRY_LIMIT + 1):
        try:
            response = requests.get(url, stream=True, timeout=15)
            response.raise_for_status()

            total_size = int(response.headers.get("content-length", 0))
            chunk_size = 8192

            # Progress bar setup
            progress = tqdm(
                total=total_size,
                unit="B",
                unit_scale=True,
                desc=f"Downloading {local_filename}",
                leave=False
            )

            with open(local_filename, "wb") as f:
                for chunk in response.iter_content(chunk_size=chunk_size):
                    if chunk:
                        f.write(chunk)
                        progress.update(len(chunk))
            progress.close()

            return f" Download complete: {local_filename}"

        except Exception as e:
            print(f" Attempt {attempt} failed for {url}: {e}")
            if attempt == RETRY_LIMIT:
                return f" Failed to download {url} after {RETRY_LIMIT} attempts."
            time.sleep(2)  # Wait before retrying

# -------------------- Main Program --------------------
def main():
    if not os.path.exists(DOWNLOAD_DIR):
        os.makedirs(DOWNLOAD_DIR)

    start_time = time.time()
    print(f"\n Starting concurrent downloads using {MAX_THREADS} threads...\n")

    with ThreadPoolExecutor(max_workers=MAX_THREADS) as executor:
        future_to_url = {executor.submit(download_file, url): url for url in URLS}

        for future in as_completed(future_to_url):
            print(future.result())

    total_time = time.time() - start_time
    print(f"\n All downloads completed in {total_time:.2f} seconds.\n")

# -------------------- Run --------------------
if __name__ == "__main__":
    main()