#!/bin/bash

while getopts "H:C:m:w:c:h" OPT; do
        case $OPT in
                "H") host=$OPTARG;;
                "C") community=$OPTARG;;
                "m") mode=$OPTARG;;
                "w") warning=$OPTARG;;
                "c") critical=$OPTARG;;
                "h")
                        echo "Syntax:  $0 -H <host address> -C <snmp community> -m <mode> -w <pct used warning> -c <pct used critical>"
                        exit 3
                ;;
        esac
done

function bytesToHuman(){
    b=${1:-0}; d=''; s=0; S=(Bytes {K,M,G,T,E,P,Y,Z}iB)
    while ((b > 1024)); do
        d="$(printf ".%02d" $((b % 1024 * 100 / 1024)))"
        b=$((b / 1024))
        let s++
    done
    echo "$b$d ${S[$s]}"
}

check_cpu (){
        idle_oid=".1.3.6.1.4.1.2021.11.11.0"
        user_oid=".1.3.6.1.4.1.2021.11.9.0"
        system_oid=".1.3.6.1.4.1.2021.11.10.0"

        output=$(snmpget -t 50 -v 2c -c $community $host $idle_oid $user_oid $system_oid)

        cpu_idle=$(echo "$output" |awk 'FNR==1 {print $4}')
        cpu_used=$((100-cpu_idle))
        cpu_user=$(echo "$output" |awk 'FNR==2 {print $4}')
        cpu_system=$(echo "$output" |awk 'FNR==3 {print $4}')

        if [[ $cpu_used -ge $critical ]]; then
                status=2
                message="Critical -"
        else if [[ $cpu_used -ge $warning ]]; then
                status=1
                message="Warning -"
        else
                status=0
                message="OK -"
        fi
        fi

        echo "CPU $message Usage: $cpu_used% | cpu=$cpu_used%;$warning;$critical user=$cpu_user% system=$cpu_system% idle=$cpu_idle%"
        exit $status
}


check_memory (){
        swap_total_oid=".1.3.6.1.4.1.2021.4.3.0"
        swap_free_oid=".1.3.6.1.4.1.2021.4.4.0"
        memory_total_oid=".1.3.6.1.4.1.2021.4.5.0"
        memory_free_oid=".1.3.6.1.4.1.2021.4.11.0"

        output=$(snmpget -t 50 -v 2c -c $community $host $swap_total_oid $swap_free_oid $memory_total_oid $memory_free_oid)

        swap_total=$(echo "$output" |awk 'FNR==1 {print $4}')
        swap_free=$(echo "$output" |awk 'FNR==2 {print $4}')
        memory_total=$(echo "$output" |awk 'FNR==3 {print $4}')
        memory_free=$(echo "$output" |awk 'FNR==4 {print $4}')
        swap_free_pct=$(echo "scale=0; $swap_free*100/$swap_total" | bc)
        memory_free_pct=$(echo "scale=0; $memory_free*100/$memory_total" | bc)

        swap_used=$((100-$swap_free_pct))
        memory_used=$((100-$memory_free_pct))

        memory_warning=$(echo $warning |cut -d ',' -f 1)
        swap_warning=$(echo $warning |cut -d ',' -f 2)

        memory_critical=$(echo $critical |cut -d ',' -f 1)
        swap_critical=$(echo $critical |cut -d ',' -f 2)

        if [[ $memory_used -ge $memory_critical ]] || [[ $swap_used -ge $swap_critical ]]; then
                status=2
                message="Critical -"
        else if [[ $memory_used -ge $memory_warning ]] || [[ $swap_used -ge $swap_warning ]]; then
                status=1
                message="Warning -"
        else
                status=0
                message="OK -"
        fi
        fi

        echo "MEMORY $message Usage: $memory_used% (Swap: $swap_used%) | memory=$memory_used%;$memory_warning;$memory_critical swap=$swap_used%;$swap_warning;$swap_critical"
        exit $status
}

check_load (){
        load1_oid=".1.3.6.1.4.1.2021.10.1.3.1"
        load5_oid=".1.3.6.1.4.1.2021.10.1.3.2"
        load15_oid=".1.3.6.1.4.1.2021.10.1.3.3"

        output=$(snmpget -t 50 -v 2c -c $community $host $load1_oid $load5_oid $load15_oid)

        load1_long=$(echo "$output" |awk 'FNR==1 {print $4}'|sed -e 's/^"//'  -e 's/"$//')
        load5_long=$(echo "$output" |awk 'FNR==2 {print $4}'|sed -e 's/^"//'  -e 's/"$//')
        load15_long=$(echo "$output" |awk 'FNR==3 {print $4}'|sed -e 's/^"//'  -e 's/"$//')

        load1=$(echo $load1_long|cut -d '.' -f 1)
        load5=$(echo $load5_long|cut -d '.' -f 1)
        load15=$(echo $load15_long|cut -d '.' -f 1)

        if [[ $load1 -ge $critical ]] || [[ $load5 -ge $critical ]] || [[ $load15 -ge $critical ]]; then
                status=2
                message="Critical -"
        else if [[ $load1 -ge $warning ]] || [[ $load5 -ge $warning ]] || [[ $load15 -ge $warning ]]; then
                status=1
                message="Warning -"
        else
                status=0
                message="OK -"
        fi
        fi

        echo "LOAD AVERAGE $message $load1_long,$load5_long,$load15_long | load1=$load1_long;$warning;$critical load5=$load5_long;$warning;$critical load15=$load15_long;$warning;$critical"
        exit $status
}

check_disk (){
        used_pct_oid=".1.3.6.1.4.1.2021.9.1.9.1"
        disk_total_oid=".1.3.6.1.4.1.2021.9.1.6.1"
        disk_free_oid=".1.3.6.1.4.1.2021.9.1.7.1"

        output=$(snmpget -t 50 -v 2c -c $community $host $used_pct_oid $disk_total_oid $disk_free_oid)

        used_pct=$(echo "$output" |awk 'FNR==1 {print $4}')
        total_kbytes=$(echo "$output" |awk 'FNR==2 {print $4}')
        free_kbytes=$(echo "$output" |awk 'FNR==3 {print $4}')
        total_bytes=$((1024*$total_kbytes))
        free_bytes=$((1024*$free_kbytes))
        total=$(bytesToHuman $total_bytes)
        free=$(bytesToHuman $free_bytes)


        if [[ $used_pct -ge $critical ]]; then
                status=2
                message="Critical -"
        else if [[ $used_pct -ge $warning ]]; then
                status=1
                message="Warning -"
        else
                status=0
                message="OK -"
        fi
        fi

        echo "DISK USAGE $message Usage: $used_pct% (Total: $total - Free: $free) | used_pct=$used_pct%;$warning;$critical total=$total_bytes free=$free_bytes"
        exit $status
}

case $mode in
        "cpu") check_cpu;;
        "memory") check_memory;;
        "load") check_load;;
        "disk") check_disk;;
        "*")
                echo "Available modes: cpu memory disk load"
                exit 3
        ;;
esac