#!/bin/bash
#Author: Kyle Agronick
#Email: agronick@gmail.com
 
#Usage: wallpaper_slideshow.sh [FOLDER] [MINUTES]...
#display a new one every [MINUTES] minutes. This script is 
#best used when invoked from an autostart folder. Run with
# --help to display help information.

line()
{
	printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' =
}

if [[  $@ == **help** ]] || [[  $@ == **-h** ]]; then  
line
cat << EOF
Usage: $0  [FOLDER] [MINUTES]

Loads a random background image every [MINUTES]
from FOLDER].  Defaults to 2 minutes. Default 
images are the Elementary OS stock background 
images.
 
OPTIONS:
   --bootonly   To load one image and exit
   --makecmd    Make the command to paste into 
   --wait       Sleep [MINUTES] minutes before changing to the first image
   --nologin    Do not changed the picture on the login screen 
   --log	    Write information to the terminal as well as syslog
   --help	    Show this help and exit
EOF
line
exit
fi
 
IS_NUM='^[0-9]+\.?[0-9]*$'  
FOLDER=$1
MINS=2 
DO_LOG=false;
if [[  $@ == **log** ]]; then  
    DO_LOG=true; 
fi
     
 

if [[  $@ == **makecmd** ]]; then   
	CMD="Copy and paste this command: " 
	CMD+="$(readlink -f "$0")"

	cmds=($1 $2 $3 $4 $5) 
	for i in "${cmds[@]}"; do
		if [[  $i != **makecmd** ]]; then
		CMD+=" $i "
		fi 
	done

	echo -e "\n"
	line
	echo "$CMD"
	line
	echo -e "\n"
	exit;
fi

FOLDER='/usr/share/backgrounds';
if [[ -d $1 ]];
    then FOLDER=$1
fi

if [[ $1 =~ $IS_NUM ]];
    then MINS=$1 
elif [[ $2 =~ $IS_NUM ]];
    then MINS=$2 
fi

if  $DO_LOG ; then  
	exec 1> >(logger -s -t "$(basename "$0")") 2>&1 
	echo "Starting slideshow at a $MINS minute(s) interval with images from $FOLDER"
fi
 
IFS=$'\n'

cd "$FOLDER"

if [[  $@ == **wait** ]]; then  
	sleep "$MINS""m"
fi

function do_exit()
{ 
    if   $DO_LOG ; then  
		echo "Exiting..."
		pkill logger -s -t "$(basename "$0")"
	fi 
	exit;
}
trap do_exit EXIT TERM

HAS_DBUS=$(command -v qdbus)
if [[  $@ == **nologin** ]]; then 
    if  $DO_LOG ; then
        echo "Disabling login screen change."
    fi 
    HAS_DBUS=""
fi
ERRORCOUNT=0

sleep 3
while true; do
	FILES=$(find ./ -iregex '.*\.\(tga\|jpg\|gif\|png\|jpeg\)$' | shuf)
	 
	if [ -z "$FILES" ]; then
	    echo "There does not appear to be any image files in $FOLDER"
	    exit
	fi

	for item in $FILES
	do  

	   item=$(readlink -f "$item")  
	   OUTPUT=$(gsettings set org.gnome.desktop.background picture-uri "$item" 2>&1) 
     
       if [ ${#OUTPUT} -gt 3 ]; then
            ((ERRORCOUNT++))  
            if [  $((ERRORCOUNT * MINS))  -gt 10 ]; then
                do_exit
            fi 
       else     
           ERRORCOUNT=0
           if $DO_LOG ; then
		   		echo "Set background image to $item"
           fi
	       if [ ${#HAS_DBUS} -gt 5 ]; then  
	         $(qdbus --system org.freedesktop.Accounts /org/freedesktop/Accounts/User$UID org.freedesktop.Accounts.User.SetBackgroundFile "$item")
	       fi
       fi 
        
	   if [[  $@ == **bootonly** ]]; then 
		do_exit
	   fi 
	   sleep "$MINS""m"

	done
done