#!/bin/bash
#Csandriel
#08.03.2018

#wallshow

#The script  intended to periodicaly change wallpapers. It sets random
#images from certain directory. It has the ability to change chedule on the fly

#time interval can been set with '-p' key, in such the notations:
#wallshow -p 5min
#wallshow -p 2hours
#wallshow -p 5days
#Called without  any key, the script just does randomly wallpaper change,
#not affecting chedule if it is set.
#Every new invocation of -p key erases the chedule previosly set
#Key -s stops wallshow, leaving current wallpaper remained, and removing chedule.
#Key -d deletes the source file of current wallpaper
#Key -u refreshes the images-list of script

#The command line that performs setting of wallpaper
#supposed dependendency: feh
#Remember QUOTES here:
PERFORM="feh --bg-fill "

#####  TODO:пока что отказывается корректно работать сброс рут-прав, если запущено от рута.
#####  Поэтому в таком виде нужно следить чтобы запускался скрипт из под одного пользователя
#####  Иначе будет существовать столько расписаний смены обоев, сколько пользователей
#####  запускали скрипт
#####
#USER=user
#if launched as root then restart script as user
#if [ $UID -eq 0 ] ; then echo "DROP ROOT & recurse"; echo "$0 $@"; su "$USER" -c "$0 $@"; exit; fi


#the directory where wallpapers are stored:
WS_DIR=/data0/graph/wallpaper

#list of graphic files found in WS_DIR:
WS_FILE=/home/bin/.wallshow.lst
#Generating/Updating of the list
#may be done with '-u' key

#count of lines in wallpapers-list:
WS_FILE_LINES=$(echo $(wc -l $WS_FILE)|sed 's_\([^ ]*\).*_\1_')

#id of the display wich wallshow must be performed for:
DISPLAY_NUM=:0

#gets a random number from  a given range
gfromrange(){
    Max_RAND=32762
            MIN=$1
            MAX=$2
            RANGE=$(($MAX-$MIN))
            r=$(bc -l <<<"($RANGE/$Max_RAND)*$RANDOM+$MIN")
            x=$(echo $r|sed 's_^.*[\.]\(.\).*_\1_')
            r=$(echo $r|sed -e 's/[\.].*//')
            if  [ $x -gt 4 ] ; then  ((r++)) ; fi

            echo $r
    }
    #enumerates graphical files in $WS_DIR, stores the list in $WS_FILE
getlist(){
echo "image list have been updating..........."
    find "$WS_DIR" \
    -iname "*png" -o \
    -iname "*jpg" -o \
    -iname "*gif" -o \
    -iname "*bmp" -o \
    -iname "*jpeg" -o \
    -iname "*tiff" -o \
    -iname "*tif"  \
    >"$WS_FILE"
    echo "done."
    echo "$(wc -l $WS_FILE|sed 's_\([0-9]*\).*_\1_')" files was added
}

selectfile(){
    num=`gfromrange 1 $WS_FILE_LINES`
    echo $(sed -n "$num"p $WS_FILE)
}


settime(){
    #a tricky passage: list at-jobs related to the script
    #and removing it in the same time by pricessing 'at -l' report
    #directly to removing command
    at -qw -l|sed 's_\([0-9]*\).*_atrm \1_'|sh
    #set new shedule
    at <<EOF -qw now+"$PAUSE"
DISPLAY="$DISPLAY_NUM" "$0" -p "$PAUSE"
EOF
}

usage(){
echo "RTFM in the script itself"
}

#main()

while getopts usdp: OPTION
    do  case "$OPTION" in
        u) getlist; exit 0;;
        p) PAUSE="$OPTARG"
            settime
            echo "interval has set to $PAUSE";;
        s)  at -qw -l|sed 's_\([0-9]*\).*_atrm \1_'|sh; exit 0;;
        d)#now we have became severe enough
        #to store our variables in system files:
        WSW=$(sed -n 's/WS_WALLPAPER:\(.*\)/\1/p' ~/.Xresources)
            rm "$WSW"
            echo -e " $WSW\n was deleted";
            exit 0;;

        ?) usage; exit 1;;
    esac
    done

WS_WALLPAPER=$(selectfile)

sed -i '/WS_WALLPAPER/d' ~/.Xresources
echo "WS_WALLPAPER:$WS_WALLPAPER" >> ~/.Xresources

DISPLAY=$DISPLAY_NUM $($PERFORM "$WS_WALLPAPER")
echo -e " WS_WALLPAPER="$WS_WALLPAPER"\n was set"