mpc wrapper with a bit of interactivity

mpc.sh

#!/bin/sh

# This script interacts with the `mpc` (Music Player Client) to manage playlists in MPD (Music Player Daemon).
# It allows the user to perform operations such as:
# - Viewing the current playlist with enumerated items.
# - Selecting, loading, or replacing playlists interactively.
# - Clearing the current playlist and loading a new one.
# Usage:
# - Run the script with no arguments to execute `mpc` commands.
# - Use specific arguments like 'playlist', 'iload', or 'replace' to invoke specialized functions.

# Enable exit on errors and on using unset variables
set -e -u

# Find the path to the `mpc` command using `which`
mpc=$(which mpc)

# If `mpc` is not found, exit the script with an error message
if [ -z "$mpc" ]; then
    echo "Error: mpc not found. Please install it and try again."
    exit 1
fi

# If no arguments are passed to the script, just execute the mpc command with the given arguments.
if [ $# -lt 1 ]; then
	"$mpc" "$@"  # Executes the mpc command with the passed arguments
	exit $?       # Exit with the status code of the mpc command
fi

# Function to select a playlist interactively with fzf (fuzzy finder)
select_playlist() {
	# If no search terms are provided, simply list the playlists and let the user choose.
	if [ $# -eq 0 ]; then
		"$mpc" lsplaylists | fzf  # Lists playlists and lets the user pick with fzf
	else
		# If search terms are provided, filter the playlists based on the search terms
		terms="$@"  # Capture the passed search terms
		"$mpc" lsplaylists | fzf -q "$terms"  # Filter playlists using fzf
	fi
}

# Function to list the current playlist with enumerated items
enumerated_playlist() {
	# Get the playlist from mpc and enumerate each item
	"$mpc" playlist | {  # Start a block to process the output of `mpc playlist`
		i=1  # Initialize the counter for the enumeration
		# Read each line (song) from the playlist
		while read line; do
			# Print the index and the song name (line)
			printf "%d\t%s\n" $i "$line"
			i=$((i+1))  # Increment the index for the next song
		done
	}
}

# Case statement to handle different command-line arguments
case "$1" in
	# If the first argument is 'playlist', call the enumerated_playlist function
	playlist)
		enumerated_playlist  # List the playlist with enumeration
		;;
	
	# If the first argument is 'iload', load a selected playlist interactively
	iload)
		shift  # Remove the 'iload' argument and shift the rest
		# Use the select_playlist function to select a playlist
		playlist=$(select_playlist "$@") || exit 0  # If selection fails, exit the script
		# If no playlist was selected (empty string), exit with code 0
		test -z "$playlist" || exit 0
		"$mpc" load "$playlist"  # Load the selected playlist into mpc
		;;

	# If the first argument is 'ireplace' or 'irep', replace the current playlist with a new one interactively
	ireplace|irep)
		shift  # Remove the 'ireplace' or 'irep' argument
		# Select a playlist to replace the current one
		playlist=$(select_playlist "$@") || exit 0  # Exit if no playlist is selected
		# If no playlist was selected, exit with code 0
		test -z "$playlist" || exit 0
		"$mpc" clear  # Clear the current playlist
		"$mpc" load "$playlist"  # Load the new playlist
		"$mpc" play 1  # Start playing the first song in the new playlist
		;;

	# If the first argument is 'replace' or 'reload', clear the current playlist and load a new one
	replace|reload)
		shift  # Remove the 'replace' or 'reload' argument
		"$mpc" clear && "$mpc" load "$@"  # Clear current playlist and load the new one
		;;
	
	# Default case: If no specific case matches, run mpc with the provided arguments
	*)
		"$mpc" "$@"  # Execute mpc with the given arguments
		;;
esac

Here’s a detailed breakdown of the improvements made to the original script{done using chatGPT}:

1. Dynamic Detection of mpc Path

• Original: The script had a hard-coded path for mpc (/usr/bin/mpc).
• Improvement: The path to mpc is now dynamically determined using which mpc. This allows the script to find mpc regardless of where it's installed on the system.

  mpc=$(which mpc)

• Reason: This improves flexibility, ensuring the script works even if mpc is installed in a non-standard location.

2. Error Handling for Missing mpc Command

• Original: There was no check to ensure that mpc was available.
• Improvement: Added a check to ensure mpc is found. If mpc is not available, the script prints an error message and exits.

  if [ -z "$mpc" ]; then
      echo "Error: mpc not found. Please install it and try again."
      exit 1
  fi

• Reason: This prevents the script from running into errors if mpc isn't installed or not available in the PATH. It provides a clear error message to guide the user.

3. Improved Readability of mpc Path Handling

• Original: The mpc path was hardcoded into the script.
• Improvement: Replaced the hardcoded mpc=/usr/bin/mpc with a more flexible approach using which.
• Reason: This enhances the script's portability and ease of maintenance, as it automatically detects where mpc is installed.

4. Clarified Comments

• Original: The script had some comments, but they were sparse and not as detailed.
• Improvement: Added comprehensive header and inline comments to explain the purpose of each section and key commands.
  • Header comments at the top explain the overall functionality of the script.
  • Inline comments describe specific logic, such as what each block or command does.
• Reason: This improves the readability and maintainability of the script, making it easier for others (or yourself) to understand the logic in the future.

5. General Code Structure

• Original: The original structure was mostly fine, but there were minor improvements made to consistency.
• Improvement: Cleaned up function names (e.g., select_playlist() for clarity) and ensured all sections of the code were properly aligned and structured.
  • The select_playlist function is used for playlist selection, with a clearer name.
• Reason: Better naming and structure improve the script's clarity and maintainability.

6. No Functional Logic Change

• The logic of how the script works (selecting playlists, replacing playlists, loading them, etc.) remains the same. The improvements are focused on robustness, flexibility, and readability rather than altering functionality.

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Summary of Improvements:

• Dynamic mpc path detection: Ensures flexibility in locating mpc.
• Error handling: Provides user feedback if mpc is not found.
• Improved readability: More detailed comments and clearer structure for better understanding.