import os
import requests
import subprocess


def download_and_trim_video(url: str, download_path: str, start_time: float, end_time: float) -> str:
    """
    Downloads a video from the given CDN URL and saves it to download_path.

    Args:
        url (str): The URL of the video.
        download_path (str): Full file path (including filename) to save the video.
        start_time (float): Start time in seconds for trimming.
        end_time (float): End time in seconds for trimming.

    Returns:
        str: The file path of the downloaded and trimmed video.

    Raises:
        requests.RequestException: If the download fails.
        IOError: If the file cannot be written.
        subprocess.CalledProcessError: If ffmpeg trimming fails.
    """
    print(f"Downloading video from {url} to {download_path}")
    try:
        # Ensure directory exists
        os.makedirs(os.path.dirname(download_path), exist_ok=True)

        # Stream the download to avoid loading large files into memory
        response = requests.get(url, stream=True, timeout=60)  # Longer timeout for videos
        response.raise_for_status()  # Check for HTTP errors

        with open(download_path, "wb") as f:
            for chunk in response.iter_content(chunk_size=8192):
                if chunk:  # filter out keep-alive new chunks
                    f.write(chunk)
        print("Video downloaded successfully.", download_path)

        # Trim the video using ffmpeg
        trimmed_path = download_path.replace(".mp4", "_trimmed.mp4")
        duration = end_time - start_time

        # Build ffmpeg command
        command = [
            "ffmpeg",
            "-y",  # Overwrite output file if it exists
            "-i",
            download_path,  # Input file
            "-ss",
            str(start_time),  # Start time
            "-t",
            str(duration),  # Duration
            "-c:v",
            "libx264",  # Video codec
            "-c:a",
            "aac",  # Audio codec
            "-preset",
            "medium",  # Encoding preset
            "-crf",
            "23",  # Constant Rate Factor (quality)
            trimmed_path,  # Output file
        ]

        # Execute ffmpeg command
        subprocess.run(command, check=True, capture_output=True)

        # Remove original downloaded file
        os.remove(download_path)

        return trimmed_path

    except requests.RequestException as e:
        print(f"ERROR: Failed to download video from {url}: {e}")
        raise  # Re-raise
    except IOError as e:
        print(f"ERROR: Failed to write video to {download_path}: {e}")
        raise  # Re-raise
    except subprocess.CalledProcessError as e:
        print(f"ERROR: Failed to trim video: {e}")
        print(f"STDERR: {e.stderr.decode()}")
        raise  # Re-raise