#!/bin/bash
#
#		 	 Cronrss
#		    Old style RSS feed
#
# http://freaknet.org/alpt/src/utils/cronrss
# 
# It verifies if the web page pointed by a given URL has changed.
# If it has, cronrss will send a notice email to you.
# The URL list is kept in the ~/.cronrss/url text file (one URL per line).
#
# It is very useful to use URLs which point to rss feeds.
#
# *** Usage:
# 
# 1) Put all the URLs you want to check in the ~/.cronrss/url text file (one
#    URL per line).
# 
# 2) Run cronrss
#
#	   cronrss [-d [seconds]]
#
# If the `-d' option is specified, it will check periodically the URLs. 
# You can specify its frequency in seconds (default is 1800s = 30min)
#
#	   cronrss update
#
# Each time you modify the url_list, you have to run `cronrss update`
#
# *** Examples: 
#
# 	 echo http://www.hackaday.org >> ~/.cronrss/url
#	 cronrss update
#	 cronrss -d
#	 # From this point on, whenever hackday.org changes you will get an email
# 	 # which shows you the text differences
# 	 # Since hackaday has a rss feed it is better to use this URL instead:
# 	 # http://www.hackaday.com/rss.xml
#
# *** Links:
#
#	This webservice maybe useful:
#		http://page2rss.com/
#
# PS: the idea of Cronrss was initially published on Idiki:
# http://idiki.dyne.org/wiki/Cronrss
#
#
# AlpT (@freaknet.org)
#


#
#
## Configure here
#

dir=`echo ~/.cronrss`	# cronrss stuff is saved in this directory
dump="$dir/dump"	# dumps of the web pages
url_list="$dir/url"	# url list file

mail_to="`whoami`"	# this is the email address where the notice is sent
#mail_to="foo@bar.org`"
mail_subject="Cronrss digest"  

#
##
#
#

check_it() {
	local notice

	if [ "$1" == "no_notice" ]
	then
		notice=0
	else
		notice=1
	fi

	if [ ! -d $dump ]
	then
		mkdir -p $dump/
	fi

	for i in `cat $url_list`
	do
		md5=`echo "$i" | md5sum | cut -d ' ' -f 1`

		rm -f $dump/old-$md5  		    	&> /dev/null
		mv -f $dump/new-$md5 $dump/old-$md5 	&> /dev/null
		links -dump "$i" > $dump/new-$md5

		if [ "$?" != "0" ] || [ ! -f $dump/old-$md5 ] || [ ! -f $dump/new-$md5 ]
		then
			continue
		fi

		diff -q $dump/old-$md5 $dump/new-$md5 	&> /dev/null
		if [ "$?" == 1 ] && [ "$notice" == "1" ]
		then
			local t
			t=`tempfile`

			echo "$i changed" 		      > $t
			echo "" 			      >> $t
			diff -u $dump/old-$md5 $dump/new-$md5 >> $t

			cat $t | mail -s "$mail_subject" $mail_to

			rm $t
		fi
	done
}

if test "$1" = "help" -o "$1" = "-h" -o "$1" = "--help"
then
	echo "Usage:"
	echo "        cronrss [-d [seconds]]"
	echo "        cronrss update"
	echo ""
	echo " If the \"-d\" option is specified, it will check periodically the URLs."
	echo " You can specify its frequency in seconds (default is 1800s = 30min)"
	echo ""
	echo " Each time you modify the url_list, you have to run \"cronrss update\""
	exit 1
fi

if [ "$1" == "-d" ]
then
	seconds=1800
	if [ ! -z "$2" ]
	then
		seconds=$2
	fi

	while true
	do
		check_it
		sleep $seconds
	done
elif [ "$1" == "update" ]
then
	
	check_it no_notice
else
	check_it
fi