#!/bin/bash
# Wunderbackground script for OS X.
# Copyright 2005 Perette Barella.
# Public domain.
# There is no warranty for this software.  Use at your own risk.
#
# This script converts cached files from the Wunderground screensaver
# into jpeg files by stripping of the headers Wunderground puts there.
# It then places them in the Library/Cache directory, where you can
# point the file selector for desktop backgrounds and get random
# backgrounds new each day... or whenever your screensaver runs.
#
# Dependencies: ImageMagick
#
# To install this:
# Create a folder called "bin" in your home directory, and put
# this file in it named "wunderbackground-osx"
# Open a terminal window (Applications->Utilities->Terminal), and type:
# chmod u+x bin/wunderbackground-osx
# crontab -e
# Go
# 18 5 * * * ~/bin/wunderbackground-osx <escape>ZZ
# bin/wunderbackground-osx
# Watch your capitalization.  Add <returns> after each line, and
# press the escape/esc key for <escape>, don't type it in.
# You are done!  The background images will be updated at 5:18 every morning.

# Use ImageMagick from Fink
PATH="/sw/bin:$PATH"

# The desktop random displayer can stretch an image, but distorts it
# if it isn't in proportion to the screen.  It can fill the screen,
# but then only displays a portion of an image.  There is no "Make it
# as big as possible without distorting it" option.  Do it ourselves.
IMAGEWIDTH=1024
IMAGEHEIGHT=768

BADSCREENSAVER="$HOME/Library/Preferences/Screentime prefs/cache"
SCREENSAVER="$HOME/Library/Caches/Screentime"
IMAGECACHE="$HOME/Library/Caches/Wunderground/Images"
KEEPDAYS=5



######################################################################
# Function:	resize_jpeg
# Purpose:	Resize a jpeg (making a thumbnail) and write out the new file.
# Arguments:	$1 - the file to resize.
# Returns:	0 on success, non-0 on error
# Author:	Perette Barella
#---------------------------------------------------------------------
function resize_jpeg
{
	typeset file="$1" SIZE x y dirname adjwidth adjheight adjust

	[ $IMAGEWIDTH -eq 0 -o $IMAGEHEIGHT -eq 0 ] && return 0
	dirname=$(dirname "$file")
	typeset resized="$dirname/$$.temp.jpeg"
	set $(identify -format "%w %h" "$file") || exit 1
	x="$1"
	y="$2"

	# calculate the adjustment for width and height as a per thousand.
	let adjwidth="(IMAGEWIDTH * 1000) / $x"
	let adjheight="(IMAGEHEIGHT * 1000) / $y"

	typeset adjust=$adjwidth
	[ $adjheight -lt $adjwidth ] && let adjust=$adjheight
	let newwidth="(x * adjust) / 1000"
	let newheight="(y * adjust) / 1000"

	if convert -quality 95 -geometry ${newwidth}x${newheight} "$file" "$resized"
	then
		mv "$resized" "$file"
	else
		rm "$resized"
	fi
	return $?
}
##### End of function resize_jpeg #####

function clean_older
{
	typeset minimum="$1" directory="$2"
	typeset days=1 file

	[ $(find "$2" -type f -print | wc -l) -le $minimum ] && return 1

	# See how far into past we need to go to keep enough files to
	# meet minimum.
	while [ $(find "$2" -type f -mtime -$days -print | wc -l) -lt $minimum ]
	do
		let days=days+1
	done

	find "$2" -type f -mtime +$days -print |
	while read file
	do
		rm "$file"
	done
	return 0
}

# If the damned cache file is in the preferences directory, move it
# into the cache directory where it should be.  A change request
# has been submitted to the ScreenTime folks.
if [ ! -d "$SCREENSAVER" ]
then
	mkdir "$SCREENSAVER" || exit 1
	# Move the cached files
	if ! mv "$BADSCREENSAVER/"* "$SCREENSAVER"
	then
		rmdir "$SCREENSAVER"
		exit 2
	fi
	# Remove the old cache directory, and link to the corrected one.
	rm -rf "$BADSCREENSAVER"
	ln -s "$SCREENSAVER" "$BADSCREENSAVER"
fi

# Now create the new cache directory, clear it out, and convert files into it.
mkdir -p "$IMAGECACHE" || exit 1

# For some reason, the screensaver doesn't clear it's cache directory
# (Maybe it's confused by moving the files, or maybe it's just stupid.)
# Clean up older crap in the screensaver cache when it's old.
clean_older 40 "$SCREENSAVER"

for file in "$SCREENSAVER"/*/*_ok
do
	# Copy the file, stripping off the header
	destfile="$IMAGECACHE/$(basename "$file").jpeg"
	[ -f "$destfile" ] && continue
	tail +4 "$file" > "$destfile"

	# Make sure it's a jpeg file
	jpeg=false
	[ $(file "$destfile" | grep -c JPEG) -gt 0 ] && jpeg=true
	if $jpeg
	then
		resize_jpeg "$destfile"
	else
		rm "$destfile"
	fi
done

clean_older 40 "$IMAGECACHE"

exit 0