#!/bin/bash
# Recursively gets into each folder, checks if there is an audio file
# and extracts the cover with ffmpeg

### Helpers

# Check all extensions available
# find . -type f | perl -ne 'print $1 if m/\.([^.\/]+)$/' | sort -u


### Configuration

export MUSIC_PATH="."

### Functions

file_exists()
{
    files=( ./*$1 )
    if [ ${#files[@]} -gt 0 ]; then
        echo ${files[0]}
    fi
}

check_extensions()
{
    EXTENSIONS_SUPPORTED=("MP3" "Mp3" "mp3" "m4a")

    for i in "${EXTENSIONS_SUPPORTED[@]}"
    do
        file_exists "$i"
    done
}

extract_cover()
{
    if [ ! -f "cover.jpg" ]
    then
        shopt -s nullglob # erase not matching result
        val=$(check_extensions)
        #echo "file found" $val "in" $(pwd)
        ffmpeg -i "$val" cover.jpg
    else
        echo "cover.jpg exists in " $(pwd)
    fi
}


### Program

find $MUSIC_PATH -type f -name ".*" -delete # remove hidden files
export -f extract_cover check_extensions file_exists
find $MUSIC_PATH \( -iname \*.MP3 -o -iname \*.Mp3 -o -iname \*.mp3 -o -iname \*.m4a \) -type f -execdir bash -c 'extract_cover "$0"' {} \;