#!/bin/bash
DATE_FORMAT=${DATE_FORMAT:-+%s} # +%s = epoch, -Iseconds = iso8601
CYCLE=${CYCLE:-60s}
OUTPUT_FILE=${OUTPUT_FILE:-ping.csv}
PING_COUNT=${PING_COUNT:-10}
# directories are set relative from the scripts path
script_path=$(cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd)
OUTPUT_PATH=${OUTPUT_PATH:-"$script_path/../data"}
SERVER_FILE=${SERVER_FILE:-"$script_path/../servers.env"}

# helper functions
function log()
{
    local time=$(date +%F_%T)
    local prefix="LOG"
    case $1 in
        ERR | ERROR)
            prefix="ERR"
            shift
            ;;
        INF | INFO)
            prefix="INF"
            shift
            ;;
        WAR | WARNING)
            prefix="WAR"
            shift
            ;;
    esac
    local func=$1; shift
    # remove any \n 
    #local text=$(echo "$@"| tr '\n' '#' | sed 's|#|\\n |g')
    case "$log_file" in
        "")
            echo "[$time]:[$prefix]:[$0][$func]: $@" 2>&1
            ;;
        *)
            echo "[$time]:[$prefix]:[$0][$func]: $@" >> $log_file
            ;;
    esac
}
function sleep_wait()
{
    # waiting on sleep to be able to handle SIGTERM
    sleep $1 &
    wait $!
}

function exit_handler()
{
    echo "stopping pinger"
    exit
}

trap "exit_handler" SIGINT
trap "exit_handler" SIGTERM

# main functions

# this function assumes the following ping output format:
## valid server
# --- 192.168.0.1 ping statistics ---
# 10 packets transmitted, 10 received, 0% packet loss, time 1806ms
# rtt min/avg/max/mdev = 0.278/0.361/1.010/0.216 ms
## valid server 100% package loss
# --- 10.0.0.2 ping statistics ---
# 10 packets transmitted, 0 received, 100% packet loss, time 1861ms
# [empty line]
## invalid server
# [no output]
function ping_server()
{
    local server="$1"
    local packet_loss=""

    ifs_old=$IFS
    IFS=$'\n'
    ping_output=( $(ping $server -c$PING_COUNT -i0.2 -q 2>/dev/null| tail -n2) )
    IFS=$ifs_old
    
    packet_loss=$(echo "${ping_output[0]}" | grep -Eo "[.[:digit:]]{1,10}%")    
    satistic="$(echo "${ping_output[1]}" | cut -d' ' -f4 | sed -E 's/\//,/g')"

    # Name or service not known
    if [ "${#packet_loss}" -eq 0 ]; then 
        packet_loss="-1"
    fi

    # 100% package loss
    if [ "${#satistic}" -eq 0 ]; then 
        satistic="-1,-1,-1,-1"
    fi

    echo "$(date $DATE_FORMAT),$server,$packet_loss,$satistic"
}

function load_server_file()
{
    local result=""
    if [ -f "$SERVER_FILE" ]; then
        local server_file="$(cat $SERVER_FILE)"
        for server in ${server_file[@]}; do
            result="$result $(echo "$server" | cut -f1 -d":")"
        done
    fi
    echo "$result"
}

main()
{
    log INFO main DO NOT PING SERVERS YOU DO NOT HAVE PERMISSION TO DO SO!
    # Environment SERVERS > arguments $@ > file $SERVER_FILE
    local servers=( ${SERVERS:-${@:-$(load_server_file)}} )
    local output_file="$OUTPUT_PATH/$OUTPUT_FILE"
    log main "writing to $output_file"
    while true; do
        if [ ! -d $OUTPUT_PATH ]; then
            mkdir -p $OUTPUT_PATH
        fi
        if [ ! -f $output_file ]; then
            echo "Epoch,Server,PacketLoss,Min,Average,Max,Deviation" > $output_file
        fi
        log main "pinging ${servers[@]}"
        for server in "${servers[@]}"; do
            # run in subshell to catch SIGTERM
            ping_server "$server" >> $output_file &
            wait $!
        done
        log main "sleeping $CYCLE"
        sleep_wait $CYCLE
    done
}

main "$@"