#!/usr/bin/perl

#   program:    iCalDoubleRemover.perl
#   author:     Patrick.Stein@jinx.de
#
#   purpose:    remove duplicate entries from iCal's and give them a new unique id
#
#   usage:      just call it and it will figure out the same entries in one calendar
#   
#
#   a ical File looks like 
#
#   HEADER
#   VEVENTS
#   FOOTER

#   Vevents look like
#   BEGIN:VEVENT
#   DTSTART;TZID=Europe/Berlin:20020912T180000
#   DTEND;TZID=Europe/Berlin:20020912T211500
#   SUMMARY:Snookern
#   UID:ECB5EBB6-A038-11D8-A92C-000A95A733C0
#   SEQUENCE:3
#   DTSTAMP:20040408T084610Z
#   END:VEVENT


use strict;
use Digest::MD5 qw( md5_hex );

###
#	read in the commandline /config file options
###

use Getopt::Long;
use Config::IniFiles;

my %commandlineoption;
{
	my %default		= 	(
								'configurationfilename'					=>	['config.ini','string'],
								'createbackup'                           =>	[1,'flag'],
								'backupextension'                       =>	['icaldoubleremoverbackup','string'],
								'icaldirectory'                         =>	[$ENV{HOME}.'/Library/Calendars','string'],
								'help'									=>	[0,'option'],
								'debug'									=>	[0,'flag'],
						);

	my %optionconverter = ('string' => '=s', 'number' =>,'=i', 'flag'=>'','option'=>'', );
	my @ARGVCOPY = @ARGV;
	GetOptions(	\%commandlineoption, map($_.$optionconverter{${$default{$_}}[-1]},keys %default)  );
	@ARGV = @ARGVCOPY;
	my $configfilename = (defined($commandlineoption{'configurationfilename'})?$commandlineoption{'configurationfilename'}:${$default{'configurationfilename'}}[0]);

	my $configurationObject = new Config::IniFiles( -file => $configfilename ) if -e $configfilename;
	
	my $packagename = __PACKAGE__;
	$packagename = $0 if __PACKAGE__ eq 'main';
	%commandlineoption = map { $_ => (defined($commandlineoption{$_})?$commandlineoption{$_}
												:(($configurationObject && defined($configurationObject->val($packagename,$_)))?$configurationObject->val($packagename,$_)
												:(($configurationObject && defined($configurationObject->val('GLOBAL',$_)))?$configurationObject->val('GLOBAL',$_):${$default{$_}}[0])) 
									)
							} keys(%default);
	if( $commandlineoption{help} )
	{
		warn "[$packagename] options are :\n",join("\t\n",map(sprintf("--%-30s default: %s%s",$_.' ('.${$default{$_}}[-1].')',${$default{$_}}[0],($commandlineoption{$_} ne ${$default{$_}}[0]?sprintf("\n%-32s current: %s",'',$commandlineoption{$_}):'')),sort keys %default))."\n";
		exit if __PACKAGE__ eq 'main' ;
	}
}


####
# main program starts here
#
#   find out all calendar files and work through them
#
#

print STDERR "Finding calendar files in $commandlineoption{icaldirectory}\n";

if(open(FINDPIPE,'find '.$commandlineoption{icaldirectory}.' -type f -name *.ics |') )
{
    WORKONFILES: while( my $filename=<FINDPIPE> )
    {
        chomp($filename);
        print STDERR "Working on file $filename\n";
        workoncalenderfile($filename,($commandlineoption{createbackup}?$commandlineoption{backupextension}:undef));
    }
    close(FINDPIPE);
}
else
{
    die "Couldn't open find command due to $!";
}

print "Work done.";
exit;


sub workoncalenderfile
{
    my($originalfilename,$backupextension)=@_;


    my $intermediatefilename = $originalfilename.'.icaldoubleremoverintermediatefile';
    
    if( ! open(ORIGINALCALENDARFILE,'<'.$originalfilename) )
    {
        die "Can't open Calender $originalfilename due to $!\n";
    } 
    if( ! open(NEWCALENDARFILE,'>'.$intermediatefilename) )
    {
        die "Can't open intemediate Calender $intermediatefilename due to $!\n";
    }
    
    my $state = 0;
    my @currentevent;
    my %knownevents;

    while(<ORIGINALCALENDARFILE>)
    {
        chop;
        
        if( 0 == $state )
        {
            if( /^BEGIN:VEVENT\s*$/ )
            {
                $state = 1;
                @currentevent=($_);
            }
            elsif( /^END:VEVENT\s*$/ )
            {
                die "Found end of VEVENT even though not inside event in line $.";
            }
            else
            {
                print NEWCALENDARFILE $_."\n";       # do nothing
            }
        }
        elsif( 1 == $state )
        {
            if( /^BEGIN:VEVENT\s*$/ )
            {
                die "Found BEGIN of VEVENT even though inside event in line $.";
            }
            elsif( /^END:VEVENT\s*$/ )
            {
                push(@currentevent,$_);
                $state = 0;

                my $currentcardstrippedstring;
                my $currentcardstrippedmd5;
                
                foreach my $line (sort @currentevent)
                {
                    $currentcardstrippedstring.=$line if $line !~ /^(UID|DTSTAMP|DESCRIPTION\:AddressBook\s*UID):/;
                }
                $currentcardstrippedmd5 = md5_hex($currentcardstrippedstring);
                
				
                if( exists( $knownevents{$currentcardstrippedmd5} ) )
                {
                    # event already known;
                    print STDERR "Event already known - wont print:\n";
                    print STDERR "Currentevent:\n".join("\n",@currentevent)."\n";
                    print STDERR "Knownevent:\n".join("\n",@{$knownevents{$currentcardstrippedmd5}})."\n";
                }
                else
                {
                    $knownevents{$currentcardstrippedmd5} = \@currentevent;
                    print NEWCALENDARFILE join("\n",@currentevent)."\n";
                }
            }
            else
            {
                push(@currentevent,$_);
            }
        }
    }
    
    close(ORIGINALCALENDARFILE);
    close(NEWCALENDARFILE);
    
    if( $backupextension )
    {
        die "Can't create backup file $originalfilename.$backupextension due to $!" if !rename($originalfilename,$originalfilename.'.'.$backupextension);
    }
    die "Can't move intermediate ($intermediatefilename) to original ($originalfilename) file due to $!" if !rename($intermediatefilename,$originalfilename); 
    
}