#!/bin/sh

VERSION=1.4.5
RED="$(printf '\033[38;5;9m')"
GREEN="$(printf '\033[38;5;10m')"
YELLOW="$(printf '\033[38;5;11m')"
RESET="$(printf '\033[m')"
set -euf
BN="${0##*/}"
NL='
'
export POSIXLY_CORRECT=1

if [ -n "${NO_COLOR:-}" ]; then
	RED="" GREEN="" YELLOW="" RESET=""
fi

errecho() {
	>&2 echo "$*$RESET"
}

fail() {
	errecho "${RED}error: $BN: $RESET$*"
	exit 1
}

warn() {
	errecho "${YELLOW}warning: $BN: $*"
	if [ -z "$IGNOREWARNINGS" ]; then
		errecho 'you can ignore stopping for warnings in the future with -i'
		errecho 'press enter to continue, or C-c to quit'
		read -r __
	fi
}

_tempdir() {
	set +u
	[ -n "$TMPDIR" ] || \
	{ [ -n "$TEMP" ] && TMPDIR="$TEMP"; } || \
	{ [ -n "$TMP" ] && TMPDIR="$TMP"; } || \
	{ [ -d "/tmp" ] && TMPDIR="/tmp"; } || \
	{ [ -d "/var/tmp" ] && TMPDIR="/var/tmp"; } || \
	{ [ -d "/usr/tmp" ] && TMPDIR="/usr/tmp"; } || \
	TMPDIR="$PWD"
	set -u
}

checkupdate() {
	errecho "you are running version ${GREEN}${VERSION}"
	errecho "until I learn if forgejo has an equivalent for github's latest release download shenanigans just check to see if this version matches the latest release"
	errecho "https://git.unix.dog/yosh/flacconv/releases/latest"
	exit 0
}

metaflac() { command metaflac --no-utf8-convert "$@"; } # don't wanna fuck up any tags from locale shit

convwarn() { errecho "${RED}an error occured while encoding ${RESET}$infile${RED}, skipping and not deleting" && err=1 && DELETE= ; }

_opusenc() {
	opusenc --discard-comments \
		"$@" \
		${pic:+--picture "${pic}"} \
		--bitrate "${BITRATE}k" \
		"$infile" \
		"${infile%.*}.opus"
}

_mp3enc() {
	flac --decode --stdout "$infile" | lame \
		-q 0 \
		${cbr:--V "${VLVL}"} \
		--add-id3v2 \
		--tt "${title#*=}" \
		--ta "${artist#*=}" \
		--tl "${album#*=}" \
		--ty "${year#*=}" \
		--tn "${tracknumber#*=}" \
		--tg "${genre#*=}" \
		--tc "${comment#*=}" \
		--tv "TPE2=${albumartist#*=}" \
		${pic:+--ti "${pic}"} \
		- \
		"${infile%.*}.mp3"
}

process_file() {
	infile="$1"
	bname="${infile##*/}"

	# tagnames will be used for all non-metaflac operations, as it allows for multiline comment shit
	tagnames="$(metaflac --export-tags-to=- "$infile" | grep -E '^[A-Z]+=' | cut -d '=' -f 1 | sort | uniq)"

	# check if flac has a picture, if not, set RMPIC
	metaflac --export-picture-to=- "$infile" 1>/dev/null 2>&1 || RMPIC=1

	# first detect any potential ID3 tags
	head_bytes="$(dd if="$infile" bs=1 count=3 2>/dev/null)"
	if [ "$head_bytes" = "ID3" ]; then
		warn "invalid id3 tags found in $infile, you should get that fixed!"
		# in a previous version this would remove invalid id3 tags automatically
		# I have since realized that this is outside the scope of this script
		# additionally, some people may have tags only in the id3 values, and as
		# such would be lost forever if removed automatically
		# therefore, this script only detects id3 tags and alterts the user
	fi

	# now test if keepkeys or removekeys was used, set exported tags
	if [ -n "$KEEPKEYS" ]; then
		tagnames="$(printf '%s' "$tagnames" | grep -i -E "^$KEEPKEYS")"
	fi
	if [ -n "$REMOVEKEYS" ]; then
		[ "$REMOVEKEYS" = "ALL" ] && REMOVEKEYS=''
		tagnames="$(printf '%s' "$tagnames" | grep -v -i -E "^$REMOVEKEYS")"
	fi

	# export pic if we're keeping it
	if [ -z "$RMPIC" ]; then
		pic="$TMPDIR/${bname%.*}_IMG"
		metaflac --export-picture-to="$pic" "$infile"
	fi

	# time to encode
	if [ "$TYPE" = "opus" ]; then
		VLVL=
		# build opus comment chain, can't "import" tags like with flac
		set --
		[ -n "$tagnames" ] && while read -r name; do
			tag="$(metaflac --show-tag="$name" "$infile")"
			# need a while loop here to handle tags with multiple values
			while [ "$tag" != "${tag#*$name=}" ]; do # check if we're on last one
				tag="${tag#*$name=}" # trim prefix
				set -- "$@" "--comment" "$name=${tag%%$NL$name=*}" # set to val without suffix*
			done
		done <<-EOF
			$tagnames
		EOF
		if [ -n "$VERBOSE" ]; then
			_opusenc "$@" || convwarn
		else
			_opusenc "$@" 1>/dev/null 2>&1 || convwarn
		fi

		# remove encoding metadata
		[ -n "$RMENCTAG" ] && opustags -d ENCODER -d ENCODER_OPTIONS -i "${infile%.*}.opus"
	else
		album="$(metaflac --show-tag=album "$infile")"
		artist="$(metaflac --show-tag=artist "$infile")"
		albumartist="$(metaflac --show-tag=albumartist "$infile")"
		title="$(metaflac --show-tag=title "$infile")"
		year="$(metaflac --show-tag=date "$infile")"
		genre="$(metaflac --show-tag=genre "$infile")"
		tracknumber="$(metaflac --show-tag=tracknumber "$infile")"
		comment="$(metaflac --show-tag=comment "$infile")"

		[ -z "$VLVL" ] && cbr="-b $BITRATE --cbr"
		if [ -n "$VERBOSE" ]; then
			_mp3enc || convwarn
		else
			_mp3enc 1>/dev/null 2>&1 || convwarn
		fi
	fi

	[ -n "${pic:-}" ] && rm -f "$pic"
	[ -n "$DELETE" ] && rm -f "$infile"
	[ -z "${err:-}" ] && errecho "$infile ${GREEN}successfully converted to ${RESET}$TYPE${GREEN} with bitrate/quality ${RESET}${VLVL:+V}${VLVL:-${BITRATE}k}"
}

usage() {
	cat >&2 <<-EOF
		flacconv $VERSION
		usage: $BN [-huvVipe3] [-b BITRATE] [-l LEVEL] [-k KEYS] [-r KEYS] [-j THREADS] [--] [DIRECTORY...]

		$BN recursively converts directories of flac files to opus/mp3
		DIRECTORY can be specified multiple times. if omitted, the current directory is used
		by default, this script outputs opus with variable bitrate 128k
		${RED}IF ENCODING TO MP3, -k AND -r WILL NOT WORK.${RESET} the only metadata that will be kept is the following:
		  ${YELLOW}TITLE, ARTIST, ALBUM, ALBUMARTIST, DATE, GENRE, TRACKNUMBER, COMMENT, and the cover picture${RESET}
		(blame id3. just use opus)

		 -h           show script help
		 -u           check for updates
		 -v           verbose output ${YELLOW}(messy with multithreading)${RESET}
		 -V           very verbose output ${RED}(VERY messy, use only for debugging and with like, -j 1)${RESET}
		 -i           ignore script-stopping warnings
		 -d           delete original flac files after transcoding
		 -3           switch output filetype to mp3
		 -b <BITRATE> output bitrate in kbits (default 128)
		              this value is variable for opus & CBR for mp3
		 -l <LEVEL>   mp3 only: use specified mp3 variable quality (0-9). integer only
		              ${YELLOW}OVERRIDES -b${RESET}
		 -k <KEYS>    keep specified flac metadata KEYS in output file
		              keys can be checked with metaflac --export-tags-to=- FILE
		              option argument is a ${YELLOW}PIPE-separated${RESET} list of keys to keep, case-insensitive
		              (i.e. -k "artist|title|albumartist|album|date")
		              ${YELLOW}if both -k and -r are not present, all keys are kept.${RESET}
		 -r <KEYS>    remove specified flac metadata KEYS in output file
		              option argument is of the same format as -k
		              ${YELLOW}if set to "ALL" (with capitalization), all keys are removed${RESET}
		 -p           remove embedded picture in output files
		 -e           remove the "encoder" tag that automatically gets applied with opusenc
		              (requires opustags)
		 -j <THREADS> use the specified amount of threads for parallel processing
		              if omitted, CPU core count will be used
	EOF
}

VERBOSE=
REALLYVERBOSE=
DELETE=
VLVL=
RMPIC=
RMENCTAG=
KEEPKEYS=
REMOVEKEYS=
IGNOREWARNINGS=
TYPE=opus
BITRATE=128
THREADS="$(nproc 2>/dev/null || sysctl -n hw.ncpu 2>/dev/null || getconf _NPROCESSORS_ONLN 2>/dev/null)" # hopefully portable enough to not be an issue
[ $? -ne 0 ] && warn 'unable to find number of cores! defaulting to 1 thread unless otherwise specified...' && THREADS=1
_tempdir # set temp dir

while getopts :huvVid3peb:l:k:r:j: OPT; do
	case "$OPT" in
		h) usage && exit 0 ;;
		u) checkupdate ;;
		v) VERBOSE=1 ;;
		V) VERBOSE=1; REALLYVERBOSE=1 ;;
		i) IGNOREWARNINGS=1 ;;
		d) DELETE=1 ;;
		3) TYPE=mp3 ;;
		p) RMPIC=1 ;;
		e) RMENCTAG=1 ;;
		b) BITRATE="$OPTARG" ;;
		l) VLVL="$OPTARG" ;;
		k) KEEPKEYS="$OPTARG" ;;
		r) REMOVEKEYS="$OPTARG" ;;
		j) THREADS="$OPTARG" ;;
		*) fail "unknown option: -$OPTARG. run $BN -h to see all options" ;;
	esac
done
shift "$((OPTIND - 1))"

[ -n "$REALLYVERBOSE" ] && set -x
command -v metaflac 1>/dev/null 2>&1 || fail 'flac tools are not installed! (metaflac)'
if [ "$TYPE" = "opus" ]; then command -v opusenc 1>/dev/null 2>&1 || fail 'opus-tools is not installed! (opusenc)'
else command -v lame 1>/dev/null 2>&1 || fail 'lame is not installed! (lame)'
fi
[ -n "$RMENCTAG" ] && { command -v opustags 1>/dev/null 2>&1 || fail 'opustags is not installed! this is required for -e (opustags)' ; }

# this script assumes you aren't using newlines in path names
# I do not want to change it to account for this
# you should never put newlines in paths
# it is a very bad idea for many programs
FLACFILES="$(find "$@" -type f -name "*.[fF][lL][aA][cC]")"
[ -z "$FLACFILES" ] && fail 'no flac files found!'

# make a fifo/fd for parallel stuff
mk_parallel_fd() {
	fifo_para="$(mktemp -u "$TMPDIR/flacconvXXXX")"
	mkfifo "$fifo_para"
	exec 9<>"$fifo_para"
	rm -f "$fifo_para"
	while [ "$THREADS" -gt 0 ]; do
		printf "\n" >&9 # start with THREADS amount of lines in fd 9 for later
		THREADS="$((THREADS - 1))"
	done
}

# read each line from fd 9, launch new program for each line
# print a line after program finished such that another one can take its place
run_in_parallel() {
	cmd="$1"
	shift
	read -r __ <&9
	{
		"$cmd" "$@"
		printf '\n' >&9
	} &
}

errecho "${YELLOW}using ${RESET}$THREADS${YELLOW} threads"
mk_parallel_fd
while read -r file; do
	run_in_parallel process_file "$file" 
done <<-EOF
	$FLACFILES
EOF

wait