#!/usr/bin/env bash

### description ################################################################

# A partial replacement for Debian's "run-parts" tool. Execute files in a
# directory in their lexical order with the specialty of being able to
# use symlinks to create an order without executing the files twice.

### shellcheck #################################################################

# Nothing here.

### dependencies ###############################################################

# Nothing here.

### variables ##################################################################

# Nothing here.

### functions ##################################################################

function main
{
  local mode=$1
  local dir=$2

  local file_pattern

  if [ -d "$dir" ]; then
    # reconstruct to make it proper (e.g. remove superfluous slashes)
    dir=$(dirname "$dir")/$(basename "$dir")
  else
    # split into directory and file
    file_pattern=$(basename "$dir")
    dir=$(dirname "$dir")
  fi

  file_pattern=${file_pattern:-*}   # default pattern is "*"

  local linked_files
  linked_files=$(find "$dir" -type l -exec readlink {} +)

  for file in "$dir"/$file_pattern; do   # requires 'shopt -s nullglob'
    # Only process files that have no symlinks (in that same directory) pointing
    # at them.
    if [[ "$linked_files" != *$(basename "$file")* ]]; then
      case "$mode" in
        list)
          echo "$file"
          ;;
        run)
          $file
          ;;
      esac
    fi
  done
}

### main #######################################################################

set -e

shopt -s nullglob   # in case no files are found

case "$1" in
  list)
    main "list" "$2"
    ;;
  *)
    main "run" "$1"
    ;;
esac