#!/bin/bash

## Files and Data
PREV_TOTAL=0
PREV_IDLE=0
cpuFile="/tmp/.cpu_usage"

## Get CPU usage
get_cpu() {
	if [[ -f "${cpuFile}" ]]; then
		fileCont=$(cat "${cpuFile}")
		PREV_TOTAL=$(echo "${fileCont}" | head -n 1)
		PREV_IDLE=$(echo "${fileCont}" | tail -n 1)
	fi

	CPU=(`cat /proc/stat | grep '^cpu '`) # Get the total CPU statistics.
	unset CPU[0]                          # Discard the "cpu" prefix.
	IDLE=${CPU[4]}                        # Get the idle CPU time.

	# Calculate the total CPU time.
	TOTAL=0

	for VALUE in "${CPU[@]:0:4}"; do
		let "TOTAL=$TOTAL+$VALUE"
	done

	if [[ "${PREV_TOTAL}" != "" ]] && [[ "${PREV_IDLE}" != "" ]]; then
		# Calculate the CPU usage since we last checked.
		let "DIFF_IDLE=$IDLE-$PREV_IDLE"
		let "DIFF_TOTAL=$TOTAL-$PREV_TOTAL"
		let "DIFF_USAGE=(1000*($DIFF_TOTAL-$DIFF_IDLE)/$DIFF_TOTAL+5)/10"
		echo "${DIFF_USAGE}"
	else
		echo "?"
	fi

	# Remember the total and idle CPU times for the next check.
	echo "${TOTAL}" > "${cpuFile}"
	echo "${IDLE}" >> "${cpuFile}"
}

## Get Used memory
get_mem() {
	printf "%.0f\n" $(free -m | grep Mem | awk '{print ($3/$2)*100}')
}


## Get Disk Usage
get_disk() {
	df -h / | awk '{print $5}' | tail -n1 | sed 's/%//g'
}

## Execute accordingly
if [[ "$1" == "--cpu" ]]; then
	get_cpu
elif [[ "$1" == "--mem" ]]; then
	get_mem

fi
