#!/bin/bash

users_raw=$(w -hs)
declare -a users
declare -a user_sessions
uindex=0

# Aggregate current session data
while read -r line; do
    uip=$(echo "$line" | egrep -o "([0-9]+.){3}[0-9]+" | sed "s/./_/g")
    u=$(echo "$line" | egrep -o "^[^ "$'t'"]+")
    u="$u@$uip"
    add=1
    for user in "${users[@]}"; do
        if [ "$user" == "$u" ]; then
            add=0
            break
        fi
        ((uindex++))
    done

    if [ "$add" -eq 1 ]; then
        users["${#users[@]}"]="$u"
    fi

    if [ "$uindex" -eq "${#user_sessions[@]}" ]; then
        user_sessions["$uindex"]=1
    else
        ((user_sessions["$uindex"]++))
    fi
done <<< "$users_raw"

# Output config info
if [ "$1" = "config" ]; then

    echo 'graph_title User Sessions'
    echo 'graph_vlabel Sessions'
    echo 'graph_category system'
    echo 'graph_info This graph shows the number of sessions for each user per 5 minutes.'

    # This creates a unique field for each user/ip combo
    for u in "${users[@]}"; do
        uclean="$(echo -n $u | sed "s/_/./g")"
        echo "$u.label $uclean"
        echo "$u.info The number of sessions for user@ip $u."
    done

    exit 0
fi

# Finally, output the actual instantaneous value
uindex=0
for u in "${users[@]}"; do
    echo "$u.value ${user_sessions[$uindex]}"
    ((uindex++))
done