v3_2_prompt.sh

#!/bin/sh

TMP_DIR=".tmp"
PROMPT_DIR="prompt"
mkdir -p $TMP_DIR
mkdir -p $TMP_DIR/$PROMPT_DIR

promptUserEntry(){
    local _outputVar=$1
    local _inputPrompt=$2
    local _reuseCacheValuePrompt=$3
    local _reuseCacheValueMessage=$4
    local _validInputMessage=$5
    local _invalidInputMessage=$6

    local _promptCacheFilename="$TMP_DIR/$PROMPT_DIR/$_outputVar"
    local _reuseCacheDecision=""
    local _userPrompt=""

    if [ -e $_promptCacheFilename ]; then
        _userPrompt=`cat $_promptCacheFilename`
        echo "$_reuseCacheValueMessage \"$_userPrompt\""
        
        while true; do
            read -p "$_reuseCacheValuePrompt " _reuseCacheDecision
            case $_reuseCacheDecision in
                Y|y ) echo ""; eval $_outputVar="'$_userPrompt'"; return 0;;
                N|n ) break;;
                * ) echo $_invalidInputMessage;;
            esac
        done
    fi

    while true; do
        read -p "$_inputPrompt " _userPrompt
        case $_userPrompt in
            "") echo $_invalidInputMessage;;
            * ) echo $_userPrompt > $_promptCacheFilename; break;;
        esac
    done
    echo "$_validInputMessage \"$_userPrompt\"\n"

    eval $_outputVar="'$_userPrompt'"
}

promptUserEntry \
    'gcpProjectID' \
    'Please input your Google Cloud Platform Project ID:' \
    'Use the same project id? (Y/n)' \
    'You previously inputted GCP Project ID as' \
    'You inputted GCP Project ID as' \
    'Please input a valid value.'

# Pretend this this doing something productive for GCP
echo "Running some GCP commands for \"$gcpProjectID\"\n"
sleep 2

promptUserEntry \
    'awsProjectID' \
    'Please input your AWS Project ID:' \
    'Use the same project id? (Y/n)' \
    'You previously inputted AWS Project ID as' \
    'You inputted AWS Project ID as ' \
    'Please input a valid value.'

# Pretend this this doing something productive for AWS
echo "Running some AWS commands for \"$awsProjectID\"\n"
sleep 2