#! /bin/bash

set -e
shopt -s extglob

TEMPFILE=image.png TEMPDIR= DIR="$(pwd)"

usage () {
cat <<EOF
This script saves image from cliboard into
a png file which name is sha256sum of that
image.
This script uses xclip and therefore is
valid only for X11 sessions.

Options:
-1          Nothing will work without
            this option. Don't ask why.
-h (--help):        Show this help.
-d (--directory):   Specify target directory.
            Otherwise current is used.
-t (--tempdir):     Set directory for temp file.
EOF
}

create_tempfile () {
    local dirs=("/tmp/$USER" "/tmp/_$USER" "/tmp/__$USER") \
        files=(".image" "._image" ".__image")

    for dir in "${dirs[@]}"
    do
        if [[ -d $dir ]]
        then
            for file in "${files[@]}"
            do
                if [[ ! -a $dir/$file ]]
                then
                    TEMPDIR="$dir"
                    TEMPFILE="$file"
                    return 0
                fi
            done
        else
            mkdir "$dir"
            TEMPDIR="$dir"
            TEMPFILE="${files[0]}"
            return 0
        fi
    done
    [[ -z $TEMPDIR ]] && return 1
}

if [[ -z $1 || $1 = @(-h|--help) ]]
then
    usage
    exit $(( $# ? 0 : 1 ))
fi

while (( $# ))
do
    case $1 in
        -1)
            GO=1
            shift
            ;;
        -d|--directory)
            DIR="$2"
            shift 2
            ;;
        -t|--tempdir)
            TEMPDIR="$2"
            shift 2
            ;;
        *)
            echo "Unknown option '$1'."
            echo
            usage
            exit 1
            ;;
    esac
done

if (( ! GO ))
then
    usage
    exit 1
fi

[[ -z $TEMPDIR ]] &&
if ! create_tempfile
then
    echo "Could not create tempfile, try -t."
    exit 1
fi


for dir in "$DIR" "$TEMPDIR"
do
    if [[ ! -d $dir ]]
    then
        echo "'$dir' is not a directory."
        exit 1
    fi
done

touch "$TEMPDIR/$TEMPFILE"



xclip -t image/png -selection c -o > "$TEMPDIR/$TEMPFILE"
sha256sum - <"$TEMPDIR/$TEMPFILE" | cut -d' ' -f 1 |
    cp "$TEMPDIR/$TEMPFILE" "$DIR/$( cat - ).png"
rm "${TEMPDIR:?}/$TEMPFILE"
rmdir "$TEMPDIR" 2>/dev/null || true