#!/bin/bash
# split2components.sh

################################################################################
# split2components.sh - Script for splitting video files into components
################################################################################
# This script processes video files, extracts video streams to MKV format,
# extracts subtitles to SRT format, and converts audio streams to separate FLAC files.
# It supports various video file formats like MP4, MKV, AVI, FLV, and MOV.
# The script requires ffmpeg and pv to be installed on the system.
#
# Usage: ./split2components.sh <target_path>
# - <target_path>: The path where the files will be processed and components stored.
#
# Dependencies:
# - ffmpeg: A multimedia processing tool (https://ffmpeg.org/)
# - pv: A terminal-based tool for processing data (https://www.ivarch.com/programs/pv.shtml)
#
# Note: Make sure to install the required dependencies before using this script.
################################################################################

# Check if ffmpeg and pv are installed
if ! command -v ffmpeg &> /dev/null || ! command -v pv &> /dev/null
then
    echo "Error: ffmpeg or pv is not installed. Please install them first."
    exit
fi

# Check if a target path is provided
if [ "$#" -eq 0 ]
then
    echo "Error: Please provide the target path where the files will be processed."
    exit
fi

target_path="$1"

# Check if the target path exists
if [ ! -d "$target_path" ]
then
    echo "Error: The specified target path does not exist."
    exit
fi

# Create the required directories
mkdir -p "$target_path/mkv" "$target_path/flac" "$target_path/srt"

# Create a temporary directory for subtitle files
temp_dir="temp_subs"
mkdir -p "$temp_dir" || { echo "Error creating $temp_dir"; exit 1; }

# Loop through all supported video file formats in the specified directory
find "$target_path" -type f \( -iname \*.mp4 -o -iname \*.mkv -o -iname \*.avi -o -iname \*.flv -o -iname \*.mov \) -print0 | while IFS= read -r -d '' video_file
do
    # Check if there is a suitable video file
    if [ -e "$video_file" ]
    then
        # Extract the filename without extension
        filename_no_ext=$(basename -- "$video_file" | cut -f 1 -d '.')
        new_video_file="$target_path/mkv/$filename_no_ext.mkv"
        srt_subtitle_file="$target_path/srt/$filename_no_ext.srt"

        # Convert video to MKV format
        ffmpeg -fflags +genpts -i "$video_file" -c:v copy -pix_fmt yuv420p -an -sn -fflags +genpts -avoid_negative_ts make_zero "$new_video_file" -y < /dev/null

        # Extract subtitles to SRT format (if available)
        subtitle_file="$temp_dir/$filename_no_ext.srt"
        ffmpeg -i "$video_file" -map 0:s:0 "$subtitle_file"

        # Convert subtitles to SRT format if available
        if [ -e "$subtitle_file" ]
        then
            mv "$subtitle_file" "$srt_subtitle_file"
        fi

        # Loop through all audio streams and convert them to separate FLAC files
        audio_stream_index=0
        while true
        do
            flac_audio_file="$target_path/flac/${filename_no_ext}_audio$audio_stream_index.flac"
            if ! ffmpeg -i "$video_file" -map 0:a:"$audio_stream_index" -c:a flac -y "$flac_audio_file" < /dev/null
            then
                break
            fi
            echo "Audio Stream $audio_stream_index converted."
            ((audio_stream_index++))
        done

        echo "Processing of $filename_no_ext completed."
    fi
done

# Delete temporary directory
rm -r "$temp_dir"