Simple mpd bookmarks

gistfile1.txt

#!/usr/bin/env bash

# -----------------------------------------------------------------------------
# Script: mpc_state_manager.sh
# Description: 
#   This script manages saving and loading the current track and playback state 
#   of the MPD (Music Player Daemon) client `mpc` to/from a file. It provides
#   two main operations:
#   1. Saving the current track and its state (playing/paused) into a file.
#   2. Loading a previously saved track and state, and resuming playback.
#
# Usage: 
#   $0 [-s <savefile>] [-l <loadfile>]
#     -s <savefile>  : Save current track and state to the specified file.
#     -l <loadfile>  : Load the track and state from the specified file and 
#                      resume playback.
#
# Dependencies:
#   - `mpc` must be installed and available in the system's $PATH.
# -----------------------------------------------------------------------------

# Function to check if all required dependencies are installed and accessible
function DEPENDENCY_CHECKS {
	# Loop through each provided dependency name
	for dep in "$@"; do
		# Check if the dependency is in the $PATH using `hash`
		if ! hash "$dep" 2>/dev/null 1>&2; then 
			# If not found, print error and exit with non-zero status
			echo "$dep not found in \$PATH. Abort." && exit 1
		fi
	done
}
# Perform the dependency check for the 'mpc' command
DEPENDENCY_CHECKS mpc

# Define the default MPD connection options
MPC_OPTS="--port 6601"
readonly MPC_OPTS  # Mark MPC_OPTS as readonly to prevent accidental modification

# Function to display the usage information and exit
function USAGE() {
	# Print usage message to STDERR and exit with status code 1
	echo "Usage: $0 [-l <loadfile>] [-s <savefile>]" 1>&2 && exit 1
}

# Function to save the current track and playback state to a file
function save() {
	# Get the current MPD status, including the track and playback state
	OUT=$(mpc status ${MPC_OPTS} --format '%file%')
	TRACK=$(echo "$OUT" | head -n 1)  # Extract the first line (track name)
	STATE=$(echo "$OUT" | head -n 2 | tail -1 | awk '{print $3}' | awk -F"/" '{print $1}')  # Extract the playback state

	# Write the track and state to the specified file
	echo "$TRACK;$STATE" > "$1"
}

# Function to load the track and state from a specified file
function load() {
	# Check if the file is readable, and exit with error if not
	[ ! -r "$1" ] && echo "Not readable: $1. abort" && exit 1
	# Read the contents of the file into a variable
	LOAD=$(cat "$1")

	# Split the file content into track and state using a semicolon delimiter
	TRACK=$(echo "$LOAD" | awk -F";" '{print $1}')
	STATE=$(echo "$LOAD" | awk -F";" '{print $2}')

	# Insert the track into the playlist, start playing it, skip to the next track, 
	# and seek to the saved position
	mpc ${MPC_OPTS} insert "$TRACK" && mpc ${MPC_OPTS} play && mpc ${MPC_OPTS} next && mpc ${MPC_OPTS} seek "$STATE"
}

# Command-line argument parsing
while getopts 's:l:' OPTION; do
	case "$OPTION" in
		# Handle the '-s' option for saving the current state
		s)
			savefile="$OPTARG"  # Store the savefile path
			readonly savefile  # Make savefile readonly to prevent accidental modification
			save "$savefile"  # Call the save function with the provided file
			;;
		# Handle the '-l' option for loading a saved state
		l)
			loadfile="$OPTARG"  # Store the loadfile path
			readonly loadfile  # Make loadfile readonly to prevent accidental modification
			load "$loadfile"  # Call the load function with the provided file
			;;
		# If an invalid option is provided, show usage information
		?)
			USAGE
			;;
		# If no valid options are provided, show usage information
		*)
			USAGE
			;;
	esac
done

# Ensure that at least one option ('-s' or '-l') is provided
[ "$OPTIND" -eq 1 ] && USAGE && exit 1

# Shift processed options (optional cleanup)
shift "$(($OPTIND - 1))"