import boto3
import subprocess
import os
from django.db.models.signals import post_save
from django.dispatch import receiver
from django.core.files import File
from pathlib import Path
from decouple import config
from .models import Lecture

AWS_STORAGE_BUCKET_NAME = config("AWS_STORAGE_BUCKET_NAME")

s3 = boto3.resource("s3")
bucket = s3.Bucket(AWS_STORAGE_BUCKET_NAME)


@receiver(post_save, sender=Lecture)
def handle_video_upload(sender, instance, created, **kwargs):
    """
    Variables names:
        - file_absolute_path: absolute path of the saved instance
        - file_suffix: file suffix to check if the video is a new
            .mkv video being uploaded, to check if the conversion
            is needed
        - file_absolute_path_m3u8: a string with absolute path to save
            the new .m3u8 file
        - file_name_m3u8: the name of the file with .m3u8 suffix
    """
    file_absolute_path = Path(instance.file.path)
    file_suffix = file_absolute_path.suffix

    if not file_suffix == '.m3u8' and instance.file_type == "V":
        file_absolute_path_m3u8 = file_absolute_path.with_suffix(".m3u8")
        file_name_m3u8 = file_absolute_path_m3u8.name

        # use shell commands to create HLS .m3u8 file
        # and delete the original video file
        subprocess.run([
            "ffmpeg",
            "-i",
            file_absolute_path,
            "-f",
            "hls",
            file_absolute_path_m3u8
        ])
        subprocess.run(["rm", file_absolute_path])

        # update the file with the new .m3u8 file
        with open(file_absolute_path_m3u8, "r") as file_object:
            file_m3u8 = File(name=file_absolute_path_m3u8, file=file_object)
            subprocess.run(["rm", file_absolute_path_m3u8])
            instance.file.save(file_name_m3u8, file_m3u8)