name="$(ifconfig | awk -F- '$2 ~ /eth/ { print  $1; exit;}')"

log_directory=$HOME/logs/
log_file=${name}-rt.log


while [[ $# -gt 0 ]]; do
  case $1 in
    -c|--cmd)
      RT_COMMAND="$2"
      shift # past argument
      shift # past value
      ;;
    -o|--output)
      OUTPUT_FILE="$2"
      shift # past argument
      shift # past value
      ;;
    -*|--*)
      echo "Unknown option $1"
      exit 1
      ;;
  esac
done

: "${RT_COMMAND:='route -n'}"
: "${OUTPUT_FILE:=${log_directory}${log_file}}"

echo "COMMAND: $RT_COMMAND"
echo "OUTPUT: $OUTPUT_FILE"

echo > "$OUTPUT_FILE"
echo "starting at: $(date +"%T %N")" >> "$OUTPUT_FILE"

function parse_diff () {

    str=$(echo "$1" | sed '1,5d')

    add_line=$(echo "$str" | grep -E '^\+')
    rem_line=$(echo "$str" | grep -E '^-')

    [ -n "$rem_line" ] && log "$(echo "$rem_line" | cut -c 2-)" "del:"
    [ -n "$add_line" ] && log "$(echo "$add_line" | cut -c 2-)" "add:"    
}

function log () {
    while IFS= read -r line; do
        echo "here"
        echo -e "$(date +"%T %N")\t$2\t$line" >> "$OUTPUT_FILE"
    done <<< "$1"
}


curr=$($RT_COMMAND)
atstart="$(echo "$curr" | sed '1,2d')"
log "$atstart" "add:"


while true;
do
    prev="$curr"
    curr=$($RT_COMMAND)

    diff_out=$(diff -u <(echo "$prev") <(echo "$curr"))
    [ $? -eq 0 ] || parse_diff "$diff_out"
    sleep 0.5
    
done