#########################################################################
# File Name: project.sh
# Author: lixiaogang
# mail: [email protected]
# Created Time: 2017年07月07日 星期五 19時13分07秒
#########################################################################

#!/bin/bash
#  程式設計方面比Windows批處理強大很多，無論是在迴圈、運算
 

# 不適應需要處理大任務的數學操作，尤其是浮點運算，精確運算，或者複雜的算術運

echo
echo -e "\e[1;35m ^_^  Welcome to use  ^_^   \e[0m"
echo -e "\e[1;35m please enter your choice \e[0m"

function add(){     /* 加法功能 */
    echo -ne "\e[1;35m Please enter the first number:  \e[0m" 
    read var1
    echo -en "\e[1;35m Please enter the second number: \e[0m"
 

    read var2
    echo -e "\e[1;35m The two numbers are ${var1} and ${var2}   \e[0m"
    return  $((${var1}+${var2}))  
}

function sub(){     /* 減法功能 */
    echo -ne "\e[1;36m Please enter the first number:  \e[0m"
    read var1
    echo -ne "\e[1;36m Please enter the second number: \e[0m"
    read var2
    echo -e "\e[1;36m The two numbers are ${var1} and ${var2}   \e[0m"
 


    if test ${var1} -gt ${var2}
    then
        return  $((${var1}-${var2}))  
    elif [ ${var1} -le ${var2} ]
        then
            return -$((${var2}-${var1}))
    elif [ ${var1} -eq ${var2}]
    then
        return 0
    else
        echo "^_^ ^_^ ^_^"
    fi
}

function mul(){     /* 乘法功能 */
    echo -ne "\e[1;35m Please enter the first number: \e[0m"
    read var1
    echo -ne "\e[1;35m Please enter the second number:\e[0m"
    read var2
    echo -e "\e[1;36m The two numbers are ${var1} and ${var2} \e[0m"
    return $((${var1}*${var2}))
}


function div(){     /* 除法功能 */
    echo -ne "\e[1;35m Please enter the first number: \e[0m"
    read var1
    echo -ne "\e[1;35m Please enter the second number:\e[0m"
    read var2
    echo -e "\e[1;36m The two numbers are ${var1} and ${var2} \e[0m"
    return $((${var1}/${var2}))
}


function rdwr(){        /* 檔案操作功能 */
    # 0-255 can only be integer  can't return string
    array=("yes" "no")
    echo -ne "\e[1;32m 陣列元素個數有: ${#array[*]}個,分別是:\e[0m"
    for value in ${array[*]}    #等價於 for var in ${array[@]} 
    do
        echo -ne "\e[1;36m  \"$value\"  \e[0m"
    done

    echo
    read input   # Debugging 40 minutes. Oh my god. it's crazy.
    if [ ${input}=${array[0]} ] 
    then
        # yes
        touch lxg.inf
        return 0
    elif [[ ${input}=${array[1]} ]]
    then
        echo -e "\e[1;32m  You chose no \e[0m"
    else
        echo -e "\e[1;32m  Input Error! \e[0m" 
    fi
}


while true  # while command(通常為測試條件)
do

printf "\n%s\n" " 1.calculator 2.rdwr_file"
list="Please enter your operator:   \" + - * / \" "
read val
if [ ${val} -eq 1 ]
then
    #   -n表示echo終端列印不換行 -e使用轉義字元
    echo -n " You choice is: ${val}"
    echo  
    echo -e "\e[1;32m  ${list}  \e[0m"
    fmat="Ubuntu> "
    echo -en "\e[1;31m $fmat \e[0m"
    read operator

    #   case 多分支選擇結構 支援 a|b|c|d)
    case ${operator} in
        +)
            add  
            readonly ret=$?
            echo "sum is: ${ret}"
            echo -e "\e[1;31m Do you want to save the value? \"yes\" or \"no\" \e[0m"
            rdwr
            file=$?  #最後執行的命令的結束程式碼（返回值） 
            if test $file -eq 0
            then
                DATE=`date`
                echo $DATE >> lxg.inf
                echo $ret >> lxg.inf
            fi
            ;;
        -)
            sub
            ret=$?
            echo "sub is: ${ret}"
            echo -e "\e[1;31m Do you want to save the value?  \e[0m"
            rdwr
            file=$?  
            if test $file -eq 0
            then
                DATE=`date`
                echo $DATE >> lxg.inf
                echo $ret >> lxg.inf
            fi
            ;;
        \*)
            mul
            ret=$?
            echo "mul is: ${ret}"
            echo -e "\e[1;31m Do you want to save the value?  \e[0m"
            rdwr
            file=$?  
            if test $file -eq 0
            then
                DATE=`date`
                echo $DATE >> lxg.inf
                echo $ret >> lxg.inf
            fi
            ;;
        /)
            div
            ret=$?
            echo "div is: ${ret}"
            echo -e "\e[1;31m Do you want to save the value?  \e[0m"
            rdwr
            file=$? 
            if test $file -eq 0
            then
                DATE=`date`
                echo $DATE >> lxg.inf
                echo $ret >> lxg.inf
            fi
            ;;
        *)  #若沒有找到匹配模式，*來匹配改值
            echo -e"\e[1;31m input ${operator} error. \e[0m"
            break
            ;;
    esac

elif test ${val} -eq 2
then
    echo -n "You choice is: ${val}"
    #   rdwr
else
    echo -e "\e[1;32m You choice error. \e[0m"
fi

done

echo "Thank you. Bye"