#!/bin/dash

# anondcim
# forked from http://code.sotun.de/git/anondcim/
#
# copyright 2012-2014 Jan Huwald, Felix Kästner (fpunktk)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

err() {
    echo "$*" >&2
}

die() {
    err "$*"
    exit 1
}

rand() {
    # random number between 0 and $1 - 1
    # read from urandom, sh interpretes numbers with leading 0 wrong, so prepend $1 which doesn't change the result
    echo $(( $1$(tr -dc "0-9" < /dev/urandom | head -c $((${#1} + 2))) % $1 ))
}

type convert >/dev/null 2>&1 || die "ImageMagick (convert, identify) is not installed"
type jhead 1>/dev/null 2>&1 || type exiftool 1>/dev/null 2>&1 || die "jhead or exiftool has to be installed"

# set default values
file_prefix=""
dst_size="1920"
dst_dir="--same--"
jpg_quality="75"

[ $# -gt 0 ] || die "Usage: $0 [-p image_file_prefix] [-s destination_size (absolute or percentage, default: $dst_size)] [-d destination_directory] [-q destination_jpg_quality (default: $jpg_quality)] imagefile(s)"

while getopts ':p:s:d:q:' OPTION
do
    case $OPTION in
        "p")
            file_prefix="${OPTARG}_"
        ;;
        "s")
            dst_size="$OPTARG"
        ;;
        "d")
            dst_dir="${OPTARG%/}/" # enforce a trailing "/"
            [ -d "$dst_dir" ] || die "destination directory \"$dst_dir\" does not exist"
        ;;
        "q")
            jpg_quality="$OPTARG"
        ;;
        *)
            err "not recognised: OPTION=$OPTION, OPTARG=$OPTARG"
        ;;
    esac
done
shift $(($OPTIND - 1))

cur=1
total=$#
addend=1

for fn in "$@"
do
    [ -f "$fn" ] || { err "source \"$fn\" does not exist and is skipped"; continue; }
    #
    if [ "$dst_dir" = "--same--" ]
    then
        # use the directory of the source file
        dst="$(dirname "$fn")/"
    else
        dst="$dst_dir"
    fi
    #
    # always use a padded number as destination filename suffix
    dst_jpg="$dst$file_prefix$(echo -n "0000000000$cur" | tail -c ${#total}).jpg"
    while [ -e "$dst_jpg" ] && [ $addend -lt 1000 ]
    do
        dst_jpg="$dst$file_prefix$(echo -n "0000000000$(($cur + $addend))" | tail -c ${#total}).jpg"
        addend=$((addend + 1))
    done
    [ -e "$dst_jpg" ] && { err "destination \"$dst_jpg\" for source \"$fn\" already exists, anonymization is skipped"; continue; }
    #
    echo "anonymizing \"$fn\" to \"$dst_jpg\" ($cur/$total)"
    #
    read w h << EOF
$(identify -format '%w %h' "$fn")
EOF
    #
    # resize and distort
    if [ $w -ge 100 ] && [ $h -ge 100 ]
    then
        if [ $w -ge 1000 ]; then dw=$(($w / 100)); else dw=10; fi
        if [ $h -ge 1000 ]; then dh=$(($h / 100)); else dh=10; fi
        #
        w=$(($w - 1))
        h=$(($h - 1))
        #
        convert "$fn" \
            -colorspace RGB \
            -distort Perspective "$(rand $dw) $(rand $dh) 0 0, $(($w - $(rand $dw))) $(rand $dh) $w 0, $(rand $dw) $(($h - $(rand $dh))) 0 $h, $(($w - $(rand $dw))) $(($h - $(rand $dh))) $w $h" \
            -filter gaussian -define filter:support=5 -define filter:sigma=0.5 \
            -attenuate 2 +noise Uniform \
            -resize "$dst_size" \
            -colorspace sRGB \
            -quality "$jpg_quality" \
            "$dst_jpg"
    else
        err "image is too small to be distorted and will just be filtered and resized"
        convert "$fn" \
            -colorspace RGB \
            -filter gaussian -define filter:support=5 -define filter:sigma=0.5 \
            -attenuate 2 +noise Uniform \
            -resize "$dst_size" \
            -colorspace sRGB \
            -quality "$jpg_quality" \
            "$dst_jpg"
    fi
    #
    # remove metadata
    if [ -x "$(which jhead)" ]
    then
        jhead -purejpg -q "$dst_jpg" || err "removing meta-data with jhead failed"
    fi
    if [ -x "$(which exiftool)" ]
    then
        exiftool -quiet -overwrite_original -all= "$dst_jpg" || err "removing meta-data with exiftool failed"
    fi
    #
    cur=$(($cur + 1))
done