#!/bin/bash


usage() { echo "Usage: $0 [-n <filename>] [-t <unix timestamp in seconds>] [-d <description>] [-O <output directory>]" 1>&2; exit 1; }

while getopts ":n:t:O:d:" o; do
    case "${o}" in
        n) 
            n="${OPTARG}"
           [ -f "${n}" ]    || ( echo "Bad filename $n" && usage )
           ;;
        t) 
            t=${OPTARG}
           [[ ${t} =~ ^[0-9]+$ ]] || ( echo "Bad time $t" && usage )
           ;;
        O) 
            O="${OPTARG}" 
        ;;
        d) d="${OPTARG}" 
        ;;
        *) usage
        ;;
    esac
done        

if [ -z "$1" ]; then
    usage
    exit 1
fi
formatted_date=$(date -d @${t} '+%Y:%m:%d %H:%M:%S')

exiftool -Artist="Messenger" -Description="$d" -CreateDate="$formatted_date" -DateTimeOriginal="$formatted_date" "$n" -o "$O"