#!/bin/sh
#
# Requirements : pngcrush, pngnq
#
# pngnq  quantizes  a  32-bit  RGBA  PNG  image to an 8 bit RGBA palette PNG using the neuquant algorithm.
# Image optimization based on http://developer.yahoo.com/performance/rules.html#opt_images
#
# Usage is recursive and takes as argument a folder or file"
#
#####################################################################
#  DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
#  Version 2, December 2004
#
#  Copyright (C) 2009 curlybracket.net
#  Everyone is permitted to copy and distribute verbatim or modified
#  copies of this license document, and changing it is allowed as long
#  as the name is changed.
#  DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
#  TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
#  0. You just DO WHAT THE FUCK YOU WANT TO.
#####################################################################

# define a logfile
# LOGFILE=$HOME/png-alpha-and-optimize.log
LOGFILE=./png-alpha-and-optimize.log

if [ ! -f '/usr/bin/pngcrush' ] ; then
	    echo "pngcrush is not installed."
		exit
fi

if [ ! -f '/usr/bin/pngnq' ] ; then
	    echo "pngnq is not installed."
		exit
fi

# Put all the PNG files into an array
PNGFILES=`find $1 -name "*.png"`

echo "=== STARTING OPTIMIZATION ==="
# we want a clean log every time we start the script
echo `date` > $LOGFILE
# if you want the same log for all executions of this script
#echo `date` >> $LOGFILE

for i in ${PNGFILES}; do
    echo "=== $i ==="

	# temporary filenames : could've been easier, but whatever.
    tmp_crush="$i.tmp"
    tmp_alpha="$i.tmp_alpha"

    # =========== convert to PNG alpha  ===============
	# this operation will overwrite the existing images !
	# -s : sample ; 1 samples every pixel, 3 gives good results and is default
	# -n : colors
    pngnq -s 1 -n 256 -e '.png.tmp_alpha' -f $i

	# =========== optimize PNG ========================
    pngcrush -q -rem alla -reduce -brute $tmp_alpha $tmp_crush

	# =========== testing filesize ====================
	CURRENTFILESIZE=`ls -l $i | cut -d " " -f 5`
	ALPHAFILESIZE=`ls -l $tmp_alpha | cut -d " " -f 5`
	CRUSHFILESIZE=`ls -l $tmp_crush | cut -d " " -f 5`
	echo "OLD: $CURRENTFILESIZE"
	echo "ALPHA: $ALPHAFILESIZE"
	echo "CRUSH: $CRUSHFILESIZE"
	if [ "$ALPHAFILESIZE" -gt "$CRUSHFILESIZE" ]; then
		echo "`date +%T` Replacing $i by $tmp_crush (with alpha channel)." >> $LOGFILE
		mv $tmp_crush $i
		rm $tmp_alpha
	else
		echo "`date +%T` Replacing $i by $tmp_alpha (uncrushed)." >> $LOGFILE
		mv $tmp_alpha $i
		rm $tmp_crush
	fi;
done
exit 0