ap

#!/usr/bin/env bash
# @Function
# convert to Absolute Path.
#
# @Usage
#   # print Absolute Path of current directory.
#   $ ./ap
#   # print Absolute Path of arguments.
#   $ ./ap a.txt ../dir1/b.txt
#
# @online-doc https://github.com/oldratlee/useful-scripts/blob/dev-3.x/docs/shell.md#-ap-and-rp
# @author Jerry Lee (oldratlee at gmail dot com)
set -eEuo pipefail

readonly PROG=${0##*/}
readonly PROG_VERSION='3.x-dev'

################################################################################
# util functions
################################################################################

errorMsgPrint() {
  local errorMsg="$PROG: $*"
  # if stdout is a terminal, turn on color output.
  #   '-t' check: is a terminal?
  #   check isatty in bash https://stackoverflow.com/questions/10022323
  if [ -t 1 ]; then
    printf '\e[1;31m%s\e[0m\n' "$errorMsg"
  else
    printf '%s\n' "$errorMsg"
  fi
} >&2

die() {
  local prompt_help=false exit_status=2
  while (($# > 0)); do
    case "$1" in
    -h)
      prompt_help=true
      shift
      ;;
    -s)
      exit_status=$2
      shift 2
      ;;
    *)
      break
      ;;
    esac
  done

  (($# > 0)) && errorMsgPrint "$*"
  $prompt_help && echo "Try '$PROG --help' for more information."

  exit "$exit_status"
} >&2

# `realpath` command exists on Linux and macOS, return resolved physical path
#   - realpath command on macOS do NOT support option `-e`;
#     combined `[ -e $file ]` to check file existence first.
#   - How can I get the behavior of GNU's readlink -f on a Mac?
#     https://stackoverflow.com/questions/1055671
realpath() {
  [ -e "$1" ] && command realpath -- "$1"
}

usage() {
  cat <<EOF
Usage: $PROG [OPTION]... [FILE]...
convert to Absolute Path.

Example:
  $PROG arg1 arg2
  $PROG */*.py

Options:
  -h, --help      display this help and exit
  -V, --version   display version information and exit
EOF

  exit
}

progVersion() {
  printf '%s\n' "$PROG $PROG_VERSION"
  exit
}

################################################################################
# parse options
################################################################################

files=()
while (($# > 0)); do
  case "$1" in
  -h | --help)
    usage
    ;;
  -V | --version)
    progVersion
    ;;
  --)
    shift
    files=(${files[@]:+"${files[@]}"} "$@")
    break
    ;;
  -*)
    die -h "unrecognized option '$1'"
    ;;
  *)
    # if not option, treat all follow files as args
    files=(${files[@]:+"${files[@]}"} "$@")
    break
    ;;
  esac
done

# if files is empty, use "."
readonly files=("${files[@]:-.}")

################################################################################
# biz logic
################################################################################

has_error=false

for f in "${files[@]}"; do
  realpath "$f" || {
    has_error=true
    errorMsgPrint "$f: No such file or directory!"
  }
done

# set exit status
! $has_error