input

#!/bin/bash

# Copyright (C) 2015 Benjamin Abendroth
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

################################################################################
# Inputfunctions ###############################################################
################################################################################

read_default () {
  # Usage: read_default <variable> <prompt>
  # Options:
  #   -e echo value instead of setting it to var

  local REPLY="" DEFAULT="" ECHO=0 

  [[ "$1" = "-e" ]] && ECHO=1 && shift

  DEFAULT="${!1}"

  read -p "$2[$DEFAULT]: "

  if [[ $ECHO -eq 1 ]]; then
    echo "${REPLY:-$DEFAULT}"
  else
    declare -g "$1"="${REPLY:-$DEFAULT}"
  fi
}

readyesno () {
  # Usage: readyesno <prompt>
  # Options:
  #   -n use no as default
  #   -y use yes as default
  #   -e echo 0 or 1 instead of returning an exit code
  #   -v <var> assign 0 or 1 to var instead of ''

  # make getopts variables private
  local OPTIND OPTARG OPTERR OPTION
  local -l ANSWER= DEFAULT=" " #lowercase
  local ECHO=0 VAR=

  while getopts :nyev: OPTION ; do
    case "$OPTION" in
      n) DEFAULT="n" ;;
      y) DEFAULT="y" ;;
      e) ECHO=1 ;;
      v) VAR="$OPTARG" ;;
      \?) echo "Unknown option \"-$OPTARG\"" >&2
          return 2;;
      :)  echo "Option \"-$OPTARG\" needs an argument." >&2
          return 2;;
      *)  echo printf "Internal error..." >&2
          return 2;;
    esac
  done

  shift $(( OPTIND - 1 ))

  YES_NO=`echo "[y/n]: " | tr "$DEFAULT" "${DEFAULT^^}"`

  while [[ -z "$ANSWER" ]] ; do
    read -p "$1$YES_NO" -n 1 ANSWER

    if [[ -z "$ANSWER" ]] && [[ -n "$DEFAULT" ]] ; then
      ANSWER="$DEFAULT"
    else # enter was not pressed, print a newline!
      printf "\n"
    fi

    case "$ANSWER" in
      n|y) break ;;
      *) ANSWER= ;;
    esac
  done

  if [[ -n "$VAR" ]] ; then
    case "$ANSWER" in
      y) declare -g "$VAR"=1 ;;
      n) declare -g "$VAR"=0 ;;
    esac
  elif [[ $ECHO -eq 1 ]]; then
    case "$ANSWER" in
      y) echo 1 ;;
      n) echo 0 ;;
    esac
  else
    case "$ANSWER" in
      y) return 0 ;;
      n) return 1 ;;
    esac
  fi
}