#!/bin/sh

# A screen-grab will be saved in $SCREEN_GRAB_DEST_DIR if set, otherwise
# in $HOME/screen_grab/ if it exsts; otherwise $HOME.

default_basename=screen_grab
default_extension=png
date_format=+%F_%H%M%S

chdir_to_destination()
{
        local d
        d=$HOME/$default_basename
        if [ "$SCREEN_GRAB_DEST_DIR" ]
        then cd "$SCREEN_GRAB_DEST_DIR"
        elif [ -d "$d" ]
        then cd "$d"
        else cd
        fi
}

choose_destination()
{
        local stamp basename extension now
        case $# in
                1) ;;
                0) now=$(date "$date_format")
                   DESTINATION=$default_basename.$now.$default_extension
                   return
                   ;;
                *) return 1 ;;
        esac

        case "$1" in
        *.*)
                basename=${1%.*}
                extension=${1##*.}
                ;;
        *)
                basename=$1
                extension=$default_extension
                ;;
        esac
        DESTINATION=$basename.$extension
}

get_out_the_way()
{
        local stamp basename extension destination
        [ -e "$1" ] || return 0

        stamp=$(date -r "$1" "$date_format") || return
        case "$1" in
        *.*)
                basename=${1%.*}
                extension=${1##*.}
                destination=$basename.$stamp.$extension
                ;;
        *)
                destination=$1.$stamp
                ;;
        esac
        [ ! -e "$destination" ] || return
        mv "$1" "$destination"
}

set -e

chdir_to_destination
choose_destination "$@"
get_out_the_way "$DESTINATION"
import "$DESTINATION"
marginate "$DESTINATION"