#! /bin/bash
#
# ptgdp - Play the Goddamned Playlist
# Copyright (C) 2019 Vintage Salt <rehashedsalt@cock.li>
#
# Distributed under terms of the MIT license.
#

# TODO:
# * Provide integration with other players, like mpd
# * Add a quick way to append to a playlist

# Variables
_name="$(basename -- "$0")"
_tmpdir="${XDG_CACHE_HOME:-$HOME/.cache}/$_name"
_tmpfile="$_tmpdir/tmpfile-$(cat /dev/urandom | tr -cd 'a-f0-9' | head -c 12)"
_xdguserdirs="${XDG_CONFIG_HOME:-$HOME/.config}/user-dirs.dirs"
[ -f "$_xdguserdirs" ] && source "$_xdguserdirs"
_musicdir="${XDG_DATA_HOME:-$HOME/.local/share}/$_name"
_musiclink="${XDG_MUSIC_DIR:-$HOME/Music}/PTGDP Songs"

# Helper functions
log() {
	[ -z "$1" ] && return 1 # Message body
	printf "%s: %s\\n" \
		"$_name" \
		"$1"
}
error() {
	[ -z "$1" ] && return 1 # Message body
	[ -z "$2" ] && return 2 # Exit code
	log "$1"
	exit "${2:-1}"
}
notify() {
	[ -z "$_optrofi" ] && return 0
	[ -z "$1" ] && return 1 # Title
	[ -z "$2" ] && return 2 # Body
	local urg="${3:-normal}" # Urgency
	local icon="${4:-dialog-information}" # Icon
	local timeout="${5:-3000}" # Timeout in milliseconds
	notify-send \
		-a "$_name" \
		-i "$icon" \
		-u "$urg" \
		-t "$timeout" \
		"$1" \
		"$2" > /dev/null 2>&1
}
validatedeps() {
	# $@: Dependencies to validate
	for prog in "$@"; do
		if ! command -v "$prog" > /dev/null 2>&1; then
			_return="$prog"
			return 1
		fi
	done
	return 0
}
sanitize() {
	[ -z "$1" ] && return 1 # String to strip special chars from
	_return="${1//[^ a-zA-Z0-9\[\]|()_-]/}"
}

# Traps
trapexit() {
	kill $(jobs -p) > /dev/null 2>&1
	[ -n "$_tmpdir" ] && rm "$_tmpfile"* > /dev/null 2>&1
}

# Critical functions
clearcache() {
	[ -n "$_musicdir" ] && rm "$_musicdir"/* > /dev/null 2>&1
	log "Cache has been emptied"
}
helptext() {
	cat << EOF
Usage: $_name [OPTION]
Use youtube-dl and audacious to queue up a playlist given a file of only search
queries. The first result found is the one that will be downloaded. Downloaded
files are cached in your Music folder under "JPTGDP Songs" for offline use.
  -f <file>		The playlist file to load. The file should be plaintext
			containing a YouTube search query on each line

  -c			Clears the cache (which can become quite large)
  -d			Download only; don't queue anything up
			Conflicts with -p
  -p			Play the playlist after it is enqueued.
			Conflicts with -d
  -s			Shuffle the playlist

  -r <directory>	Start up rofi, if installed, and present a listing of
			all .gdp files in the given directory. If notify-send
			is installed, this will also send notifications
			pertaining to playlist status.

  -h			Print this help text

Copyright (c) 2019 rehashedsalt@cock.li
Licensed under the MIT license
EOF
}
rofimenu() {
	validatedeps rofi || error "$_return is not currently installed" 1
	[ -d "$_optrofi" ] || error "Could not open directory \"$_optrofi\"" 2
	files=$(find "$_optrofi" -type f -name \*.gdp)
	if [ -n "$files" ]; then
		# Strip file suffixes for a cleaner menu
		playlists=""
		while read file; do
			filebase="$(basename -- "$file")"
			filebase="${filebase%.gdp}"
			[ -n "$playlists" ] && playlists+=$'\n'
			playlists+="$filebase"
		done <<< "$files"
	else
		notify "No playlists found" \
			"No playlists could be found in directory \"$_optrofi\"." \
			normal dialog-error 5000
		error "No playlists found" 61
	fi
	choice="$(rofi -dmenu -i -p "$_name" <<< "$playlists" 2>/dev/null)"
	[ -z "$choice" ] && error "User aborted at selection" 62
	playlist "$_optrofi"/"$choice".gdp
	return 0
}
playlist() {
	[ -z "$1" ] && return 1
	[ -e "$1" ] || error "Playlist \"$1\" does not exist" 50
	[ -f "$1" ] || error "Playlist \"$1\" is not a file" 50
	[ -r "$1" ] || error "Cannot read playlist \"$1\"" 51
	if ! [ -f "$_musicdir/.symlink" ]; then
		if ln -s "$_musicdir" "$_musiclink" > /dev/null 2>&1; then
			log "Made symlink to music directory"
			touch "$_musicdir/.symlink"
		else
			log "Failed to make symlink to music directory"
			log "Music can be found at \"$_musicdir\""
		fi
	fi
	local -i dlexist=0
	local -i dlsuccess=0
	local -i dlfailure=0
	while read line; do
		[ -z "$line" ] && continue
		rm "$_tmpfile"* > /dev/null 2>&1
		sanitize "$line"
		filename="$_musicdir/$_return"
		if ! [ -f "$filename" ]; then
			log "Finding a song for \"$line\""
			youtube-dl \
				--add-metadata \
				--audio-format "best" \
				--geo-bypass \
				--playlist-items 1 \
				-x \
				-o "$_tmpfile.%(ext)s" \
				ytsearch:"$line" \
				> /dev/null 2>&1 &
			if wait $!; then
				dlsuccess+=1
				mv "$_tmpfile"* "$filename"
			else
				dlfailure+=1
				notify "Could not download song" \
					"youtube-dl did not download a song for \"$line\", either because it is out of date or because it could not find a video to rip from" \
					normal dialog-error 3000
				log "Could not download song \"$line\""
				continue
			fi
		else
			dlexist+=1
		fi
		[ -z "$_optdownloadonly" ] && audacious -e "$filename"
		if [ -n "$_optautoplay" ]; then
			audacious -p
			unset _optautoplay
		fi
	done < <(if [ -n "$_optshuffle" ]; then shuf "$1"; else cat "$1"; fi)
	if [ "$dlexist" = "0" ] && [ "$dlsuccess" = "0" ]; then
		notify "Failed to enqueue playlist" \
			"The playlist could not be enqueued. Ensure that youtube-dl is up to date, you have a valid internet connection, and your search queries pull up results" \
			normal dialog-error 10000
	else
		if [ -z "$_optdownloadonly" ]; then
			notify "Finished building queue" \
				"The playlist queue has been built in Audacious"
			log "Finished building queue: $dlexist cached, $dlsuccess downloaded, $dlfailure failed"
		else
			notify "Finished precaching" \
				"Your songs have been cached and are ready for offline playback"
			log "Finished downloading: $dlexist cached, $dlsuccess downloaded, $dlfailure failed"
		fi
	fi
}

# Main
main() {
	# Boostrapping and setup
	validatedeps youtube-dl basename || error "Critical dependency $_return was not met" 1
	mkdir -p "$_tmpdir"
	mkdir -p "$_musicdir"
	trap trapexit EXIT

	# Actual program stuff
	while getopts ":cdf:pr:sh" opt; do
		case $opt in
			c)
				clearcache
				exit $?
				;;
			d)
				_optdownloadonly=1
				;;
			f)
				_optfile="$OPTARG"
				;;
			p)
				_optautoplay=1
				;;
			r)
				_optrofi="$OPTARG"
				;;
			s)
				_optshuffle=1
				;;
			h)
				helptext
				exit $?
				;;
			:)
				error "Option requires argument: -$OPTARG" 2
				;;
			*)
				error "Invalid option: -$OPTARG" 2
				;;
		esac
	done
	[ -n "$_optfile" ] && [ -n "$_optrofi" ] && error "Flags -f and -r conflict" 2
	[ -n "$_optdownloadonly" ] && [ -n "$_optautoplay" ] && error "Flags -d and -p conflict" 2
	if [ -n "$_optrofi" ]; then rofimenu; exit $?; fi
	if [ -n "$_optfile" ]; then playlist "$_optfile"; exit $?; fi
	error "Nothing to do" 0
}

main "$@"