#!/usr/bin/env bash

set -o errexit -o noclobber -o nounset -o pipefail

codec=libmp3lame
extension=mp3
mode=chaptered
authcode=".authcode";
auth="";

if [ -z ${HOME+x} ] && ! [ -z ${USERPROFILE+x} ]; then HOME="$USERPROFILE"; fi
authcodeDirs="${HOME}/ ./"
GREP=$(grep --version | grep -q GNU && echo "grep" || echo "ggrep")

if ! [[ $(type -P "$GREP") ]]; then
    echo "$GREP (GNU grep) is not in your PATH"
    echo "Without it, this script will break."
    echo "On macOS, you may want to try: brew install grep"
    exit 1
fi

if ! [[ $(type -P ffmpeg) ]]; then
    echo "ffmpeg is not in your PATH"
    echo "Without it, this script will break."
    exit 1
fi

function print_manual(){
    echo ""
	echo "Usage: bash AAXtoMP3 [--flac] [--aac] [--opus ] [--single] --auth=AUTHCODE {FILES}"
    echo "	Note that when you enter conflicting parameters, the last one will be the one used."
    echo "	You HAVE to use the equals-sign. You may also use -a=AUTHCODE. But the '=' is mandatory."
    echo "	Everything after the authcode must be a filename to a file which you want to convert"
    echo ""
    echo "		[--flac]: The flac codec is used in the resulting files. Default is MP3"
    echo "		[--aac]: The aac codec is used in the resulting files. Default is MP3"
    echo "		[--opus]: The opus codec is used in the resulting files. Default is MP3"
    echo "		[--single] : Prevents creation of chapters. Results in a single file."
    echo "		--authcode=XXXXXXXX: Your personal autcode. Everything after this parameter will be used as an inputfile!"
    echo "		{FILES}: Files to convert, seperated by spaces."
    echo ""
}


if [ "$#" -eq 0 ]; then
	print_manual
    exit 1
fi


if [[ "$1" = '-h' ]]; then
	print_manual
    exit 1
fi
if [[ "$1" = '--help' ]]; then
	print_manual
    exit 1
fi



ParamArray=()
#the multithreadcontroller adds whitespaces to the params, they are removed here.
for var in "$@"
do
	if ! [[ "$var" = '' ]]
	then
		ParamArray+=("$var")
	fi
done


#Iterate over the parameter to find all entered ones
for var in "${ParamArray[@]}"
do
	
	if [[ "$var" = '--flac' ]]
	then
		codec=flac
		extension=flac
		shift
	fi

	if [[ "$var" == '--aac' ]]
	then
		codec=copy
		extension=m4a
		mode=single
		shift
	fi

	if [[ "$var" = '--opus' ]]
	then
		codec=libopus
		extension=ogg
		shift
	fi
	
	if [[ "$var" == '--single' ]]
	then
		mode=single
		shift
	fi
	
	case "$var" in
		-a=*|--auth=*)
		auth=$(echo $var | cut -d '=' -f 2)
		shift
	esac
done

auth_code="";
for dir in $authcodeDirs; do
	codeFile="${dir}$authcode";

	if [ ! -f "$codeFile" -o ! -s "$codeFile" ]; then
		codeFile=""
		echo "INFO: Sorry, missing or empty \"$codeFile\" found, skipping.";
	fi;
done;

if [ -f "$codeFile" ]; then
	auth_code=`head -1 "$codeFile"`
fi

if [ -z "$auth_code" ]; then
	auth_code="$auth";
fi;

if [ -z "$auth_code" ]; then
	echo "INFO: Sorry, no authcode provided.";
	exit 1;
fi;

debug() {
    echo "$(date "+%F %T%z") ${1}"
}

trap 'rm -r -f "${working_directory}"' EXIT
working_directory=`mktemp -d 2>/dev/null || mktemp -d -t 'mytmpdir'`
metadata_file="${working_directory}/metadata.txt"

save_metadata() {
    local media_file
    media_file="$1"
    ffprobe -i "$media_file" 2> "$metadata_file"
}

get_metadata_value() {
    local key
    key="$1"
    normalize_whitespace "$($GREP --max-count=1 --only-matching "${key} *: .*" "$metadata_file" | cut -d : -f 2- | sed -e 's#/##g;s/ (Unabridged)//' | tr -s '[:blank:]' ' ')"
}

get_bitrate() {
    get_metadata_value bitrate | $GREP --only-matching '[0-9]\+'
}

normalize_whitespace() {
    echo $*
}

alreadys_skipped_to_auth=0
for path in "${ParamArray[@]}"
do
	if (( $alreadys_skipped_to_auth == 0 ))
	then
		case "$path" in -a=*|--auth=*)
			alreadys_skipped_to_auth=1;
			continue ;
		esac
		continue ;
	fi

	if (( $alreadys_skipped_to_auth == 1 ))
	then
		debug "Decoding ${path} with auth code ${auth_code}..."
	
		save_metadata "${path}"
		genre=$(get_metadata_value genre)
		artist=$(get_metadata_value artist)
		title=$(get_metadata_value title | sed 's/'\:'/'\ -'/g' | xargs -0)
		output_directory="$(dirname "${path}")/${genre}/${artist}/${title}"
		mkdir -p "${output_directory}"
		full_file_path="${output_directory}/${title}.${extension}"
	
		</dev/null ffmpeg -loglevel error -stats -activation_bytes "${auth_code}" -i "${path}" -vn -codec:a "${codec}" -ab "$(get_bitrate)k" -map_metadata -1 -metadata title="${title}" -metadata artist="${artist}" -metadata album_artist="$(get_metadata_value album_artist)" -metadata album="$(get_metadata_value album)" -metadata date="$(get_metadata_value date)" -metadata track="1/1" -metadata genre="${genre}" -metadata copyright="$(get_metadata_value copyright)" "${full_file_path}"
	
		debug "Created ${full_file_path}."
	
		cover_path="${output_directory}/cover.jpg"
		debug "Extracting cover into ${cover_path}..."
		</dev/null ffmpeg -loglevel error -activation_bytes "${auth_code}" -i "${path}" -an -codec:v copy "${cover_path}"
	
		if [ "${mode}" == "chaptered" ]; then
			chaptercount=$($GREP -Pc "Chapter.*start.*end" $metadata_file)
			debug "Extracting ${chaptercount} chapter files from ${full_file_path}..."
	
			chapternum=1
			while read -r -u9 first _ _ start _ end
			do
				if [[ "${first}" = "Chapter" ]]
				then
					read -r -u9 _
					read -r -u9 _ _ chapter
					chapter_title="${title} - $(printf %0${#chaptercount}d $chapternum) ${chapter}"
					chapter_file="${output_directory}/${chapter_title}.${extension}"
	
					# the ID3 tags must only be specified for *.mp3 files,
					# the other container formats come with their own
					# tagging mechanisms.
					id3_version_param=""
					if test "${extension}" = "mp3"; then
					id3_version_param="-id3v2_version 3"
					fi
	
					</dev/null ffmpeg -loglevel error -stats -i "${full_file_path}" -i "${cover_path}" -ss "${start%?}" -to "${end}" -map 0:0 -map 1:0 -acodec copy ${id3_version_param} \
						-metadata:s:v title="Album cover" -metadata:s:v comment="Cover (Front)" -metadata track="${chapternum}" -metadata title="${chapter_title}" \
						"${chapter_file}"
					chapternum=$((chapternum + 1 ))
				fi
			done 9< "$metadata_file"
			rm "${full_file_path}"
			debug "Done creating chapters. Chaptered files contained in ${output_directory}."
		fi
	
		debug "Done."
		rm "${metadata_file}"
	fi
done