# Standard Imports
import sys
import subprocess
from pathlib import Path
from datetime import datetime

# Local Imports
import config
from helpers.peertube_api import authenticate_to_peertube, upload_to_peertube
from helpers.owncast_api import get_owncast_title, send_owncast_message


def get_recent_segments(directory: Path, n: int):
    """
    Returns a filtered list of the most recent .ts files in a directory.

    Args:
        directory (Path): The directory to search for .ts files.
        n (int): The maximum number of files to return.

    Returns:
        list[str]: A list of absolute paths of the most recent n files.
    """

    files = [f for f in directory.iterdir() if f.is_file()
             and f.suffix.lower() == '.ts']
    files.sort(key=lambda f: f.stat().st_mtime, reverse=False)
    return [str(f.resolve()) for f in files[:n]]


def merge_segments_to_mp4(segments: list[str], output_path: Path, output_filename: str):
    """
    Accepts a list of .ts files and attempts to concatenate them via ffmpeg.

    Args:
        segments (list[str]): A list of absolute paths to .ts filenames.
        output_path (Path): An absolute path of the directory to create the new output file.
        output_filename (str): The filename of the file to be created.

    Returns:
        Path: An asbsolute path to the created file, or None if the process failed.
    """

    output_file = output_path / output_filename
    if output_file.exists():
        print(f'File already exists at: {output_file}. Abandoning.')
        return None

    # concat:/path/to/file1|/path/to/file2|...
    segment_list = 'concat:' + '|'.join([f'{f}' for f in segments])
    command = ['ffmpeg',
               '-protocol_whitelist', 'concat,file',
               '-i', segment_list,
               '-c', 'copy',
               output_file
               ]

    process = subprocess.Popen(
        command, stdin=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
    stdout, stderr = process.communicate()

    if process.returncode != 0:
        print(f'ffmpeg ran into an issue creating {output_file}: {stderr}')
        return None
    return output_file


def delete_clip(filename: str):
    """
    Deletes a named file from the temporary directory

    Args:
        filename (str): The name of the file to be deleted, e.g. file.mp4

    Returns:
        None
    """

    file = config.TEMP_DIRECTORY / filename
    try:
        file.unlink()
    except FileNotFoundError:
        print(f'Error deleting temporary file: {file}; file not found.')
    except Exception as e:
        print(f'Error deleting temporary file: {file}; {e}.')
    return


def generate_and_post_clip(user: str, title: str, timestamp: datetime):
    """
    Invokes clip collection, remux, upload, and notification (chat) routines.

    Args:
        user (str): The name of the chat user that invoked the clip request.
        title (str): The provided (or generated) title of the clip to be uploaded.
        timestamp (datetime): The tz-aware timestamp indicating when clip was made.

    Returns:
        None
    """

    if not (recent_clips := get_recent_segments(config.CLIP_DIRECTORY, config.CLIP_QUANTITY)):
        return
    new_filename = f'{timestamp.strftime("%Y%m%d_%H%M%S_%f")}.mp4'
    new_filepath = merge_segments_to_mp4(
        recent_clips, config.TEMP_DIRECTORY, new_filename)

    if (token := authenticate_to_peertube(config.PT_API_BASE, config.PEERTUBE_USER, config.PEERTUBE_PASS)) is None:
        print(f'Failed to authenticate to PeerTube', file=sys.stderr)
        delete_clip(new_filename)
        return

    stream_title = ''
    if (stream_title := get_owncast_title()):
        stream_title = f'during the "{stream_title}" stream'

    upload_options = {}
    upload_options[
        'description'] = f'🎞️ Clipped by **{user}** {stream_title} on {timestamp.strftime("%Y-%m-%d %H:%M:%S")}'
    upload_options['description'] += f'\n🌐 {config.OWNCAST_HOST}'
    if (video_url := upload_to_peertube(config.PT_API_BASE, token, new_filepath, config.PEERTUBE_CHANNEL_ID, title, **upload_options)) is None:
        print(f'Failed to upload file to PeerTube', file=sys.stderr)
        delete_clip(new_filename)
        return
    delete_clip(new_filename)

    clip_url = f'{config.PEERTUBE_HOST}{video_url}'
    message = f'**{title}**: {clip_url}'
    send_owncast_message(message)

    print(f'Clip created by {user} at {timestamp}: {clip_url}')
    return