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

# TODO:
# * Reorganize mpd integration into abstract functions

# 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"
[ -z "$XDG_MUSIC_DIR" ] && [ -f "$_xdguserdirs" ] && source "$_xdguserdirs"
_musicdir="${XDG_MUSIC_DIR:-$HOME/Music}"
_ptgdpmusicdir="$_musicdir/${PTGDP_MUSIC_DIR:-PTGDP Songs}"
declare -a _queue

# Helper functions
log() {
	[ -z "$1" ] && return 1 # Message body
	printf "%s: %s\\n" \
		"$_name" \
		"$1"
}
error() {
	[ -z "$1" ] && return 1 # Message body
	# 2: Exit code
	printf "%s: \\e[31m%s\\e[0m\\n" \
		"$_name" \
		"$1"
	[ -n "$2" ] && exit "${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
}
checkforsong() {
	# $1: A song name to validate
	[ -z "$1" ] && return 1
	# Very rudimentary implementation
	# TODO: Make this a lot more thorough, maybe ensure MIME is good
	for file in "$_ptgdpmusicdir/$1"*; do
		if [ -f "$file" ]; then
			_return="$file"
			return 0
		fi
	done
	return 1
}
cachesong() {
	# $1: A song query to download
	# $_return: The relative file path to song from XDG_MUSIC_DIR
	# If in a dry run, $_return is the title of the video, if extracted
	# Note that this will return 100 if the file is cached, so do not assume only 0 is success
	[ -z "$1" ] && return 1
	# Clean up tmpfile
	rm "$_tmpfile"* > /dev/null 2>&1
	sanitize "$1"
	filename="$_ptgdpmusicdir/$_return"
	if [ -z "$_optdryrun" ]; then
		if ! checkforsong "$_return"; then
			# We need to download the song
			youtube-dl \
				--add-metadata \
				--audio-format "best" \
				--geo-bypass \
				--playlist-items 1 \
				-x \
				-o "$_tmpfile.%(ext)s" \
				ytsearch:"$1" \
				> /dev/null 2>&1 &
			if wait $!; then
				for file in "$_tmpfile"*; do
					[ -f "$file" ] && local extension="$file"
					break
				done
				extension="${extension##*/}"
				extension="${extension##*.}"
				filename="$filename.$extension"
				mv "$_tmpfile"* "$filename"
				_return="$filename"
				return 0
			else
				return 1
			fi
		else
			#_return is already an existing cached file, so just die
			return 100
		fi
	else
		output="$(
			youtube-dl \
				--get-title \
				--geo-bypass \
				--playlist-items 1 \
				ytsearch:"$1" 2>&1
		)"
		exitcode="$?"
		if [ $exitcode -gt 0 ]; then
			return 1
		fi
		if ! [ "$output" = "${output#*WARNING}" ]; then
			# Title could not be extracted
			unset _return
		else
			# Title was found
			_return="$output"
		fi
		return 0
	fi
}
queuesong() {
	# $1: A song query to queue
	# returns 0 if successful, 100 if cached, 1 if error
	# Adds a song to $_queue
	[ -z "$1" ] && return 2
	cachesong "$1"
	local errorcode=$?
	if [ -z "$_optdryrun" ]; then
		case $errorcode in
			0)
				# Downloaded
				log "Downloaded song \"$1\""
				;;
			100)
				# Cached
				log "Using cached song \"$1\""
				;;
			*)
				# Failed
				dlfailure+=1
				notify "Could not download song" \
					"youtube-dl did not download a song for \"$1\"" \
					normal dialog-error 3000
				error "Could not download song \"$1\""
				continue
				;;
		esac
		_queue+=("$_return")
	else
		case $errorcode in
			0)
				# Success
				if [ -n "$_return" ]; then
					log "$1 - \"$output\""
				else
					log "$1 parsed, but title could not be extracted"
				fi
				;;
			*)
				# Failure
				error "Could not find song \"$1\""
				;;
		esac
	fi
	return $errorcode
}
execqueue() {
	# Plays all songs in _queue
	mpc update --wait > /dev/null 2>&1
	for file in "${_queue[@]}"; do
		file=${file##$_musicdir/}
		mpc add "$file" > /dev/null 2>&1 || error "Could not add file: \"$file\""
	done
	if [ -n "$_optautoplay" ]; then
		mpc play > /dev/null 2>&1
		unset _optautoplay
	fi
}
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
}
validateline() {
	# $1: A line to check for comments or whitespace
	# Strictly speaking, this removes all whitespace from the line
	# While not *exactly* what I'm looking for, it's sufficient for trimming whitespace lines
	local linenows=${1//[[:space:]]}
	if ! [ "${1#\#}" = "$1" ] || [ -z "$linenows" ]; then
		return 1
	fi
	return 0
}
validateplaylistenv() {
	[ -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 \"$1\"" 51
	if [ -z "$_optdownloadonly" ] && ! mpc status > /dev/null 2>&1; then
		notify "Could not communicate with MPD" \
			"MPD connection was refused. Ensure your configuration is correct and the daemon is currently running." \
			normal dialog-error 3000
		error "Failed to communicate with MPD" 52
	fi
}
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 "$_ptgdpmusicdir" ] && rm "$_ptgdpmusicdir"/* > /dev/null 2>&1
	log "Cache has been emptied"
}
helptext() {
	cat << EOF
Usage: $_name [OPTION]
Use youtube-dl and mpc 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 "PTGDP Songs" for offline use.
  -f <file>		The playlist file to load. The file should be plaintext
			containing a YouTube search query on each line.
			Comments are supported and prepended with #

  -c			Clears the cache (which can become quite large)
  -d			Download only; don't queue anything up
			Conflicts with -p
  -D			Dry run; parse out all songs, downloaded or not, and
			print out the resolved names. Useful for testing, as
			YouTube searches can sometimes be finicky.
  -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.
  -R <directory|file>	As above, but also parse out the selected playlist and
			present a listing of individual songs. The argument can
			be a file in this mode

  -h			Print this help text

Environment Variables

In addition to XDG-spec variables (XDG_CACHE_HOME, user-dirs.dirs, etc.), ptgdp
also respects an additional variable:

  PTGDP_MUSIC_DIR	The subdirectory in XDG_MUSIC_DIR to save music to

Copyright (c) 2019 rehashedsalt@cock.li
Licensed under the MIT license
EOF
}
rofimenu() {
	validatedeps rofi || error "$_return is not currently installed" 1
	if ! [ -d "$_optrofi" ]; then
		if [ -z "$_optrofisong" ]; then
			error "Could not open directory \"$_optrofi\"" 2
		else
			[ -f "$_optrofi" ] || error "Could not open file \"$_optrofi\"" 2
		fi
	fi
	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 \"$_optrofi\"." \
			normal dialog-error 5000
		error "No playlists found" 61
	fi
	prompt="$_name list"
	[ -n "$_optautplay" ] && prompt="$prompt ap"
	choice="$(rofi -dmenu -i -p "$prompt" <<< "$playlists" 2>/dev/null)"
	[ -z "$choice" ] && error "User aborted at selection" 62
	if [ -z "$_optrofisong" ]; then
		playlist "$_optrofi"/"$choice".gdp
	else
		rofiplaysong "$_optrofi"/"$choice".gdp
	fi
	return 0
}
rofiplaysong() {
	validateplaylistenv "$1" || return $?
	local songs=""
	while read line; do
		validateline "$line" || continue
		if [ -z "$songs" ]; then
			songs="$line"
		else
			songs="$songs"$'\n'"$line"
		fi
	done < "$1"
	IFS=$'\n'
	prompt="$_name song"
	[ -n "$_optautplay" ] && prompt="$prompt ap"
	choice="$(rofi -dmenu -i -p "$prompt" <<< "$songs" 2>/dev/null)"
	if [ -z "$choice" ]; then
		# Assume user is looking for another list
		# Kick him back to the main menu
		rofimenu
	fi
	log "User picked: $choice"
	queuesong "$choice"
	[ "$?" = "1" ] && return 62
	execqueue
	return 0
}
playlist() {
	validateplaylistenv "$1" || return $?
	[ -z "$_optdryrun" ] && local -a queue # An array of songs to later enqueue into mpd
	local -i dlexist=0
	local -i dlsuccess=0
	local -i dlfailure=0
	local -i maxlines=0
	while read line; do
		validateline "$line" || continue
		maxlines+=1
	done < "$1"
	log "Enqueued playlist \"$1\" with $maxlines songs"
	while read line; do
		[ -z "$line" ] && continue
		validateline "$line" || continue
		rm "$_tmpfile"* > /dev/null 2>&1
		# Do the do
		queuesong "$line"
		# What did we do?
		local errorcode=$?
		case $errorcode in
			0)
				dlsuccess+=1
				;;
			100)
				dlexist+=1
				;;
			*)
				dlfailure+=1
				;;
		esac
	done < <(if [ -n "$_optshuffle" ]; then shuf "$1"; else cat "$1"; fi)
	if [ "$dlexist" = "0" ] && [ "$dlsuccess" = "0" ] && [ -z "$_optdryrun" ]; then
		notify "Failed to download playlist" \
			"The playlist in its entirety could not be downloaded. 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
	elif [ -z "$_optdryrun" ]; then
		if [ -z "$_optdownloadonly" ]; then
			notify "Finished downloading playlist" \
				"The playlist has been downloaded and will be added to mpd shortly"
			log "Finished downloading: $dlexist cached, $dlsuccess downloaded, $dlfailure failed"
			execqueue
		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
	else
		log "Finished dry run: $dlsuccess succeeded, $dlfailure failed"
	fi
}

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

	# Actual program stuff
	while getopts ":cdDf:pr:R:sh" opt; do
		case $opt in
			c)
				clearcache
				exit $?
				;;
			d)
				_optdownloadonly=1
				;;
			D)
				_optdryrun=1
				;;
			f)
				_optfile="$OPTARG"
				;;
			p)
				_optautoplay=1
				;;
			r)
				_optrofi="$OPTARG"
				;;
			R)
				_optrofi="$OPTARG"
				_optrofisong=1
				;;
			s)
				_optshuffle=1
				;;
			h)
				helptext
				exit $?
				;;
			:)
				error "Option requires argument: -$OPTARG" 2
				;;
			*)
				error "Invalid option: -$OPTARG" 2
				;;
		esac
	done
	[ -z "$_optdownloadonly" ] && [ -z "$_optdryrun" ] && validatedeps mpc || error "$_return is required outside of dry- and download-only runs"
	[ -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 "$@"