#!/usr/bin/env bash
declare -gA ARGP
declare -gA SHORT

__reset_argparse() {
  declare -gA ARGP
  declare -gA SHORT
}

die() { echo "Error: $*"; exit 1; }

def_arg() {
  test "$3" = bool -o "$3" = value || die "def_arg: type (\$3) must be 'bool' or 'value', received '$3'"
  ARGP["$1,type"]="$3"

  if [ "$3" = bool ]; then
    test -z "$4" || die "def_arg: bool args cannot specify required/default"
    declare -g "$1=0"
  else
    test "$4" = required -o "$4" = default || die "def_arg: \$4 must be 'required' or 'default', received '$4'"
    if [ "$4" = required ]; then
      ARGP["$1,required"]=1
    else
      value="$5"
      declare -g "$1=$value"
    fi
  fi

  if [ -n "$2" ]; then
    SHORT["$2"]="$1"
  fi
}

parse_args() {
  positional=()
  while (( $# > 0 )); do
    next="$1"; shift
    if [[ "$next" == --* ]]; then
      arg=${next#--}
      test -n "${ARGP["$arg,type"]}" || die "unknown arg --$arg"
      if [ "${ARGP["$arg,type"]}" = bool ]; then
        value=1
      elif [ $# -eq 0 ]; then
        die "Missing value for --$arg"
      else
        value="$1"; shift
      fi
      declare -g "$arg=$value"
    elif [[ "$next" == -* ]]; then
      for ((i = 1 ; i < ${#next} ; i++ )); do
        short=${next:$i:1}
        arg=${SHORT["$short"]}
        test -n "$arg" || die "unknown short arg -$short"
        if [ "${ARGP["$arg,type"]}" = bool ]; then
          declare -g "$arg=1"
        else
          value=${next:$(( i+1 ))}
          if [ -z "$value" ]; then
            value="$1"; shift
          fi
          test -n "$value" || die "missing value for -$short"
          declare -g "$arg=$value"
          break
        fi
      done
    else
      positional+=("$next")
    fi
  done

  # check for missing required
  for arg in "${!ARGP[@]}"; do
    arg="${arg%%,*}"
    [ "${ARGP["$arg,required"]}" != 1 ] || [ -n "${!arg}" ] || die "missing argument --$arg"
  done
}