Randomly picks one of the amazing photos at http://imgur.com/r/earthporn

earthporn.sh

#!/bin/bash
# Usage: earthporn [+format] [-time] [logfile]
# Dependencies:  bash, wget, mktemp...  and well, date and sleep

imgfile=~/.earthporn

# Help and version functions
help () {
    echo "Randomly picks one of the amazing photos at http://imgur.com/r/earthporn"
    echo "and sets it as the background image."
    echo
    echo "Usage: $0 [+format] [-time] [logfile] [-]"
    echo "       $0 {-h|-?|--help}"
    echo "       $0 {-v|-V|--version}"
    echo
    echo "Format string:"
    echo "    %d      Timestamp"
    echo "    %c/%C   Caption (normal / without '[...]')"
    echo "    %u/%U   URL (page / image)"
    echo "    %f      Local wallpaper file ($imgfile)"
    echo "    %t/%n   Tab / newline"
    echo "    %.      A literal '%'"
    exit 0
}
version () {
    echo "earthporn script v0.1"  # couldn't think of anything better
    exit 0
}

# Function to change/refresh the wallpaper, if needed
environ=''
get_environ () {
    if [ gnome = "$DESKTOP_SESSION" ]; then  # !!TODO!! gnome-fallback
        environ=gnome
        case "$(gnome-session --version)" in
            'gnome-session 2'*) gconftool-2 --type=string --set \
                /desktop/gnome/background/picture_filename "$imgfile" ;;
            'gnome-session 3'*) gsettings set org.gnome.desktop.background \
                picture-uri file://"$imgfile" ;;  # UNTESTED!
        esac
    elif [ kde = "$DESKTOP_SESSION" ]; then
        environ=kde
        : ##!!TODO!!##
    elif [ LXDE = "$XDG_CURRENT_DESKTOP" ]; then
        environ=lxde
    #~ elif [ something_xfce ]; then
        #~ environ=xfce
        #~ : ##!!TODO!!##
    else
        environ='-'
        echo "Please set your wallpaper as $imgfile" >&2
    fi
}
refresh_background () {
    [ -z "$environ" ] && get_environ
    
    case "$environ" in
        gnome) touch "$imgfile" ;;
        #~ kde)   : ;; ##!!TODO!!##
        lxde)  pcmanfm -w "$imgfile" ;;
        #~ xfce)  : ;; ##!!TODO!!##
        *)     echo "New wallpaper available" >&2 ;;
    esac
}


# Parse command line options
time=''
format=''
logfile=''
for arg; do
    case "$arg" in
        -h|--help|'-?')   help ;;
        -v|-V|--version)  version ;;
        -*[!0-9.smhd]*)   echo 'Invalid option `'"$arg'" >&2; exit 1 ;;
        
        -)   format='%U'; imgfile='' ;;
        -*)  time="${arg#-}" ;;
        +*)  format="${arg#+}"; format="${format//\%\%/%.}" ;;
        *)   logfile="$arg" ;;
    esac
done

# Main loop, to be executed multiple times iff there's a -<time> option
while true; do

    images=()
    while read -r line; do
        [[ $line = *'<img alt="" src="'*'" title="'* ]] && images+=("$line")
    done   < <( wget -qO- http://imgur.com/r/earthporn/top/week )
    if [[ ${#images[@]} = 0 ]]; then
        echo 'Download error! (no images found)' >&2
        exit 2
        # !!TODO!! something more elegant if in loop mode
    fi
    image="${images[RANDOM % ${#images[@]}]}"
    
    # Get image URL
    imurl="${image#*src=\"}"
    imurl="${imurl%%\"*}"
    imurl="${imurl/b./.}"
    
    # Download image
    if [ -n "$imgfile" ]; then
        tmpfile="$(mktemp)"
        if wget "$imurl" -q -O "$tmpfile"; then
            mv "$tmpfile" "$imgfile"
            refresh_background
        else
            echo 'Download error! (image download failed)' >&2
            rm "$tmpfile"
            exit 2
            # !!TODO!! something more elegant if in loop mode
        fi
    fi
    
    # Get metadata
    if [ -n "$logfile" -o -n "$format" ]; then
        # Get image page
        pageurl="${imurl%.*}"
        pageurl="http://imgur.com/r/earthporn/${pageurl##*/}"
        
        # Get photo description (title; caption)
        caption="${image#*title=\"}"
        caption="${caption%%<p>*}"
        
        # Get timestamp
        timestamp="$(date +%F,%T 2>/dev/null || echo '????-??-??,??:??:??')"
    fi
    
    # Write to logfile
    [ -n "$logfile" ] && echo "$timestamp	$pageurl	$caption" >> "$logfile"
    
    # Print info
    if [ -n "$format" ]; then
        caption="${caption//\%/%.}"
        caption_stripped="${caption/\[*\]/}"
        
        print="$format"
        print="${print//\%d/$timestamp}"
        print="${print//\%c/$caption}"
        print="${print//\%C/$caption_stripped}"
        print="${print//\%u/$pageurl}"
        print="${print//\%U/$imurl}"
        print="${print//\%f/$imgfile}"
        print="${print//\%t/$'\t'}"
        print="${print//\%n/$'\n'}"
        print="${print//\%./%}"
        
        echo "$print"
    fi
    
    [ -z "$time" ] && exit 0  # if no time specified, do stuff once and exit
    sleep "$time" || exit 1  # time might be wrong.  Better to just exit then.

done