#!/bin/bash

# Updates destop background to one of several continuously updated photos. 
# Maintains a file called $PREFIX(timestamp).jpg in ~/Pictures.
# Allows for an image to be composited via Imagemagick

# A filename prefix that won't conflict with anything already in ~/Pictures
PREFIX='GOES'
# path to identify, mogrify, and composite executables (ImageMagick)
ID='/sw/bin/identify'
MOG='/sw/bin/mogrify'
COMP='/sw/bin/composite'

function help () {
 NM=$(basename $1)
 echo " sets desktop background to a satellite image (with optional overlay)"
 echo
 echo " use: $NM [-c|-f|-i|-m|-v|-w] [overlay file] [composite style]"
 echo "     -c GOES east coast color composite (15 mins)"
 echo "     -f GOES west hemisphere full disk (3 hrs)"
 echo "     -i GOES east coast IR (30 mins)"
 echo "     -m die.net mercator full earth (3 hrs)"
 echo "     -v GOES east coast vis (30 mins)"
 echo "     -w weather.com current weather (?)"
 echo 
 echo "     overlay file:" 
 echo "         requires ImageMagick" 
 echo "         resizes to width of downloaded image"
 echo
 echo "     composite style:"
 echo "         default: multiply"
 echo "         available: clear, src-over, dst-over, src-in, dst-in, src-out,"
 echo "                    dst-out, src-atop, dst-atop, xor, plus, multiply,"
 echo "                    screen, overlay, darken, lighten, color-dodge,"
 echo "                    color-burn, hard-light, soft-light, difference,"
 echo "                    exclusion"
 exit
}

case $1 in
 -b) PIC='http://goes.gsfc.nasa.gov/goescolor/goeseast/hurricane2/color_lrg/latest.jpg';;
 -c) PIC='http://goes.gsfc.nasa.gov/goescolor/goeseast/hurricane2/color_med/latest.jpg';;
 -f) PIC='http://www.goes.noaa.gov/FULLDISK/GEVS.JPG';;
 -i) PIC='http://www.goes.noaa.gov/GIFS/ECIR.JPG';;
 -m) PIC='http://static.die.net/earth/mercator_1600.jpg';;
 -v) PIC='http://www.goes.noaa.gov/GIFS/ECVS.JPG';;
 -w) PIC='http://image.weather.com/images/maps/current/curwx_600x405.jpg';;
 *) help $0;;
esac

# for crontab
[ "$(uname)" == "Darwin" ] && PATH=$PATH:/sw/bin/

NEW="$PREFIX$(date +%s)"
curl -s -m 40 $PIC 2>/dev/null > ~/Pictures/$NEW

[ $? == "0" ] || {
  rm ~/Pictures/$NEW 2>/dev/null
  exit
}

rm ~/Pictures/$PREFIX[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9].jpg 2>/dev/null
mv ~/Pictures/$NEW ~/Pictures/$NEW.jpg

[ $2 ] && {
 W1=$($ID ~/Pictures/$NEW.jpg | awk '{split($3,a,"x"); print a[1]}')
 cp $2 /tmp/$$
 [ "W1" != "$($ID $2 | awk '{split($3,a,"x"); print a[1]}')" ] && $MOG -scale $W1 /tmp/$$
 if [ ! $3 ];then COMPOSITE='multiply'; else COMPOSITE=$3; fi
 $COMP -compose $COMPOSITE -gravity SouthEast /tmp/$$ ~/Pictures/$NEW.jpg ~/Pictures/$NEW.jpg
 rm /tmp/$$
}

[ "`uname`" == "Linux" ] && {
 # resizing stuff
 $MOG -resize 2560 ~/Pictures/$NEW.jpg && $MOG -crop 2560x1024+0+100 ~/Pictures/$NEW.jpg
 #feh --bg-center ~/Pictures/$NEW.jpg
 xsetbg ~/Pictures/$NEW.jpg
}

[ "`uname`" == "Darwin" ] && osascript -e "tell application \"Finder\" to set desktop picture to file \"$NEW.jpg\" in (path to pictures folder)"