#!/usr/bin/env bash
#
# Optimized script to append directories to PATH.
# For each given directory, it removes all duplicate occurrences from PATH
# and then appends it if the directory exists.
#
# Usage: x-path-append <directory1> [<directory2> ...]
#
# Enable verbose output by setting the environment variable VERBOSE=1.
#
# Author: Ismo Vuorinen <https://github.com/ivuorinen> 2024
# License: MIT

VERBOSE="${VERBOSE:-0}"

# Ensure that at least one directory is provided.
[ "$#" -lt 1 ] && {
  echo "Usage: $0 <directory> [<directory> ...]"
  exit 1
}

for dir in "$@"; do
  # Check if the specified directory exists.
  if [ ! -d "$dir" ]; then
    [ "$VERBOSE" -eq 1 ] && echo "(?) Directory '$dir' does not exist. Skipping."
    continue
  fi

  # Remove all duplicate occurrences of the directory from PATH.
  case ":$PATH:" in
    *":$dir:"*)
      PATH=":${PATH}:"
      PATH="${PATH//:$dir:/:}"
      PATH="${PATH#:}"
      PATH="${PATH%:}"
      [ "$VERBOSE" -eq 1 ] && echo "Removed previous occurrences of '$dir' from PATH."
      ;;
    *) ;;
  esac

  # Append the directory to PATH.
  export PATH="${PATH:+"$PATH:"}$dir"
  [ "$VERBOSE" -eq 1 ] && echo "Appended '$dir' to PATH."
done