#!/bin/bash
# Author: 
#   Philip Newborough <corenominal@corenominal.org>
# Copyright:
#   © 2008 Philip Newborough <corenominal@corenominal.org>
# License:
#   This program is free software; you can redistribute it and/or
#   modify it under the terms of the GNU Lesser General Public
#   License as published by the Free Software Foundation; either
#   version 2.1 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
#   Lesser General Public License for more details.
#
#   You should have received a copy of the GNU Lesser General Public
#   License along with this library; if not, write to the Free Software
#   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#
#   On Debian systems, the complete text of the GNU Lesser General Public
#   License V2.1 can be found in the file `/usr/share/common-licenses/LGPL-2.1'.
#-------------------------------------------------------------------------------   
# Display help
if [ "$1" = "" ] || [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
    echo "Usage:"
    echo "  rotate-wallpaper --path DIRECTORY"
    echo ""
    echo "    -h, --help"
    echo "          Shows this message and exits."
    echo "    -p, --path"
    echo "          Set path to directory containing images."
    echo ""
    exit    
fi
if [ "$1" = "-p" ] || [ "$1" = "--path" ];then
    if [ ! "$2" = "" ];then
        # Set the path to your wallpaper directory
        WALLPAPERS=$2
        # Sanity check. Does wallpaper directory exist
        if [ ! -d $WALLPAPERS ]; then
            echo "Oops! Specified directory does not exist."
            echo ""
            rotate-wallpaper --help
            exit 1
        fi
        # the sanity check for files at all is unecessary because of this next part
        # Sanity check. Is wallpapers directory empty of images?
        # + Build query
        QUERY=""
        if [ "$(ls $WALLPAPERS/*.jpg 2> /dev/null)" ]; then
            QUERY="$QUERY$WALLPAPERS/*.jpg "
        fi
        if [ "$(ls $WALLPAPERS/*.JPG 2> /dev/null)" ]; then
            QUERY="$QUERY$WALLPAPERS/*.JPG "
        fi
        if [ "$(ls -l $WALLPAPERS/*.PNG 2> /dev/null)" ]; then
            QUERY="$QUERY$WALLPAPERS/*.PNG "
        fi
        if [ "$(ls -l $WALLPAPERS/*.png 2> /dev/null)" ]; then
            QUERY="$QUERY$WALLPAPERS/*.png "
        fi
        if [ "$QUERY" = "" ];then
            echo "Oops! No images found within specified directory."
            echo ""
            rotate-wallpaper --help
            exit 1
        fi
        # Sanity check. Does config directory exist?
        if [ ! -d ~/.config/rotate-wallpaper ]; then
            mkdir ~/.config/rotate-wallpaper
        fi
        # Sanity check. Does config file exist?
        if [ ! -f ~/.config/rotate-wallpaper/count ]; then
            touch ~/.config/rotate-wallpaper/count
            echo "0" > ~/.config/rotate-wallpaper/count
        fi
        # Count number of wallpapers
        NO_OF_WALLPAPERS=0
        for file in $QUERY; do
            if [ ! -d "$file" ];then
                NO_OF_WALLPAPERS=$(( NO_OF_WALLPAPERS+1 ))
            fi
        done
        # Read in number of last wallpaper displayed, or start from 1
        PREVIOUS_WALLPAPER="$(cat ~/.config/rotate-wallpaper/count)"
        NEW_WALLPAPER=$(( PREVIOUS_WALLPAPER+1 ))
        # Do we need to loop back to 1?
        if [ $NEW_WALLPAPER -gt $NO_OF_WALLPAPERS ];then
            NEW_WALLPAPER=1
        fi
        # Set wallpaper
        CNT=1
        for file in $QUERY; do
            if [ $CNT = $NEW_WALLPAPER ]; then
                if [ ! -d "$file" ];then
                    FILE_TYPE=$(file -i "$file")
                    if [ "$FILE_TYPE" = "$file: image/png" ] || \
                    [ "$FILE_TYPE" = "$file: image/jpeg" ];then
                        nitrogen --set-scaled "$file"
                    fi
                fi
            fi
            CNT=$(( CNT+1 ))
        done
        # Save count and exit
        echo "$NEW_WALLPAPER" > ~/.config/rotate-wallpaper/count
        exit
    else
        # Show error if no directory given
        echo "Oops! Image directory not specified."
        echo ""
        rotate-wallpaper --help
        exit 1
    fi
fi
# If all else fails
echo "Oops! Invalid command. Have a clue..."
rotate-wallpaper --help
exit 1