#!/bin/bash

SWAPPATH=/
SWAPNAME="swapfile"
TOTALRAM=$(free -m | gawk  '/Mem:/{print $2}')
SWAPPINESS="10"
SYSCTLCONF="/etc/sysctl.conf"
VERSION="0.1.0"
BUILDDATE="2018-06-05"

# Colors
RED='\033[0;31m'
LRED="\033[1;31m"
BLUE="\033[0;34m"
LBLUE="\033[1;34m"
GREEN="\033[0;32m"
LGREEN="\033[1;32m"
YELLOW="\033[1;33m"
CYAN="\033[0;36m"
LCYAN="\033[1;36m"
PURPLE="\033[0;35m"
LPURPLE="\033[1;35m"
BWHITE="\e[1m"
NC='\033[0m' # No Color

if [ ! -f /usr/bin/gawk ];then
    echo -e "\nPlease install 'gawk' with your package manager\n"
    exit 0
fi
function autoSwap(){
        echo -e "\n${LGREEN}----------------------------------------------------------------${NC}"
        echo -e "\n${LCYAN}Total Physical RAM is: ${TOTALRAM} MB\n${NC}"
        echo -e "${LPURPLE}Creating a ${TOTALRAM} MB file in:${SWAPPATH}..\n${NC}"
        echo -e "${YELLOW}Enter to Accept | Ctrl+c to cancel\n${NC}"
        echo -e "${LGREEN}------------------------------------------------------------------${NC}"
        read

        echo -e "${LCYAN}\nCreating file in ${SWAPPATH}...\n${NC}"
        sudo fallocate -l ${TOTALRAM}M ${SWAPPATH}${SWAPNAME}
        ls -lh ${SWAPPATH}${SWAPNAME}

        sleep 1

        echo -e "\n${LCYAN}Setting permission of ${SWAPPATH}${SWAPNAME} to 600...\n${NC}"
        sudo chmod 600 ${SWAPPATH}${SWAPNAME}
        ls -lh ${SWAPPATH}${SWAPNAME}

        sleep 1
        
        echo -e -n "\n${YELLOW}Do you want to mark ${SWAPPATH}${SWAPNAME} as swap?(Y/n): ${NC}"
        read markswap

        if [ "${markswap}" = "n" ];then
            exit 0
        fi

        echo -e "\n${LCYAN}Marking ${SWAPPATH}${SWAPNAME} as swap...\n\n${NC}"
        sudo mkswap ${SWAPPATH}${SWAPNAME}

        echo -e -n "\n${YELLOW}Do you want to add swapfile to fstab?(Y/n): ${NC}"
        read addfstab

        if [ "${addfstab}" = "n" ];then
            exit 0
        fi

        echo -e "\n${LCYAN}Creating backup of /etc/fstab ...\n${NC}"
        sudo cp /etc/fstab /etc/fstab.bak

        echo -e "${LCYAN}Adding ${SWAPPATH}${SWAPNAME} to /etc/fstab ..\n${NC}"
        echo "${SWAPPATH}${SWAPNAME} none swap sw 0 0" | sudo tee -a /etc/fstab
}

function swappiness(){
    echo -e -n "\n${YELLOW}Enter a number for swappiness (0-100)[default=10]: ${NC}"
    read setSwappiness

    if [ -z "${setSwappiness}" ];then
        echo -e "\n${LCYAN}Setting default (10)\n${NC}"
        echo "vm.swappiness=${SWAPPINESS}" | sudo tee -a /etc/sysctl.conf
    

    elif [[ ! "${setSwappiness}" =~ ^-?[0-9]+$ ]];then
        echo -e "\n${LRED}${setSwappiness} is not a number\n${NC}"
        exit 0
    
    elif [ "${setSwappiness}" -lt "0" ];then
        echo -e "\n${LRED}Please input a number greater than 0 or less than 100\n${NC}"
        exit 0
    
    elif [ "${setSwappiness}" -gt "100" ];then
        echo -e -n "\n${LRED}Please input a number greater than 0 or less than 100\n${NC}"
        exit 0

    else
        echo "vm.swappiness=${setSwappiness}" | sudo tee -a ${SYSCTLCONF}
        SWAPPINESSSET=$(cat ${SYSCTLCONF} | grep vm.swappiness=${setSwappiness})
        if [ ${SWAPPINESSSET} = "vm.swappiness=${setSwappiness}" ] ;then
            echo -e "${LGREEN}Swappiness value set successfully!\n${NC}"
        else
            echo -e "${LRED}Swappiness not set sucessfully...\n${NC}"
        fi
    fi
}

function help(){
    echo -e "\nUsage: $0 [-a] [--auto] [-s] [--swappiness]\n\n"
    echo -e "-a | --auto        Automatically create and size swapfile based on physical memory\n"
    echo -e "-s | --swappiness  Set the swappiness value to minimize swap usage\n\n"
}

function version(){
    echo -e "Version ${VERSION}, built: ${BUILDDATE}\n"
}

case "${1}" in

    -a|--auto)
        autoSwap
    ;;

    -v|version|--version)
        version
    ;;

    -s|--swappiness)
        swappiness
    ;;

    *)
        help
    ;;
esac