#!/bin/bash

if [ $# -ne 2 ]; then
        echo Usage:
        echo "  $(basename $0) <datetime begin> <datetime end>"
        echo Example:
        echo "  $(basename $0) '2012-08-12 15:34:59' '2012-08-13 01:23:45'"
        echo "  $(basename $0) '2012-08-12 15:34:59' 2012-08-13"
        echo "  $(basename $0) '2012-08-11 now"
        echo
        exit 1
fi

START="$1"
STOP="$2"

START_TS=$(date +'%s' -d "$START")
STOP_TS=$(date +'%s' -d "$STOP")

if [[ $STOP_TS -lt $START_TS ]]; then
        echo "$(basename $0): min > max" >&2
        exit 9
fi

ORE=$((($STOP_TS - $START_TS) / 3600 ))
MIN=$(((($STOP_TS - $START_TS) / 60 ) % 60))
SEC=$((($STOP_TS - $START_TS) % 60 ))

if [[ $ORE -gt 24 ]]; then
        GIORNI=$(( $ORE / 24 ))
        ORE_RIMANENTI=$(( $ORE % 24 ))
        if [[ $GIORNI -gt 1 ]];then
                DURATA="$GIORNI days $ORE_RIMANENTI:$MIN:$SEC"
        else
                DURATA="$GIORNI day $ORE_RIMANENTI:$MIN:$SEC"
        fi
else
        DURATA="$ORE:$MIN:$SEC"
fi

echo ""
echo "Begin    : $(date +'%d-%m-%Y %H:%M:%S' -d@$START_TS)"
echo "End      : $(date +'%d-%m-%Y %H:%M:%S' -d@$STOP_TS)"
echo ""
echo "Duration : $DURATA ($(echo $ORE:$MIN:$SEC) hours) ($(($STOP_TS - $START_TS)) seconds)"
echo ""

# vim: ts=2 sw=2 background=dark