#!/usr/bin/perl

use CGI;
use strict;
use Fcntl;

my $cgi = new CGI;
my $date_dir = 'dates/';

# Check month, date & time params
###############################
unless($cgi->param('month') =~ /\w+/ && $cgi->param('date') =~ /\d{2}/ && $cgi->param('time') =~ /\d{1,2}/){
     die "Invalid parameters!\n";
}


my $date_file = $date_dir . $cgi->param('month') . $cgi->param('date');
my $file_identifier = '### CALENDAR.PL DATE FILE ' . $cgi->param('month') . $cgi->param('date');


my $new_entry;
my $redirect = 'showDate.pl?month=' . $cgi->param('month') . '&date=' . $cgi->param('date');

# If we just added an entry write it and bounce back
#######################################################
if($cgi->param('action') eq 'Add new entry'){

	sysopen(DATE_FILE,$date_file, O_RDWR | O_CREAT,0666) || 
		die "Cannot open $date_file: $!\n";
	flock(DATE_FILE,2);
	
	my @old_entries = <DATE_FILE>;

        # Check to see if requested date file is valid
        ################################################
        unless(splice(@old_entries,0,1) eq  $file_identifier){
             die "Not a valid date file!\n";
        }


	seek(DATE_FILE, 0, 0);
	truncate(DATE_FILE, 0);
	
	$new_entry = $cgi->param('time') . ":" . $cgi->param('entry');
	push(@old_entries,$new_entry);
	print DATE_FILE $file_identifier	
	foreach(@old_entries){
		unless(/^\s$/){
			print DATE_FILE $_ . "\n";
		}
	}
	close(DATE_FILE);
	
	print $cgi->redirect($redirect);
}

# Remove an entry
###############################
elsif($cgi->param('action') eq 'rem'){
	sysopen(DATE_FILE,$date_file,O_RDWR) || 
		die "Cannot open $date_file: $!\n";
	flock(DATE_FILE,2);

	my(@old_entries,@new_entries);
        @old_entries = <DATE_FILE>;
        
        # Check to see if requested date file is valid
        ################################################
        unless(splice(@old_entries,0,1) eq  $file_identifier){
             die "Not a valid date file!\n";
        }
       
	my $time = $cgi->param('time');
	while(@old_entries){
		unless(/^$time:.+/){
			push(@new_entries,$_);
		}
	}

	seek(DATE_FILE, 0, 0);
	truncate(DATE_FILE, 0);
        print DATE_FILE $file_identifier;
	foreach(@new_entries){
		unless(/^\s$/){
			print DATE_FILE $_ . "\n";
		}
	}
	close(DATE_FILE);
	
	print $cgi->redirect($redirect);
}

# The form to add an entry
#################################
else{
	print $cgi->header(),
		$cgi->start_html(
			-title=>'Add entry',
			-BGCOLOR=>'#ffffff',
			);

	print $cgi->h2(
		$cgi->param('month'),'-',
		$cgi->param('date'),'-2000 at',
		$cgi->param('time'),':00',
		);

	
	print $cgi->start_form(
		-action=>'alterDate.pl',
		-method=>'post',
	);
	
	print $cgi->p,
		"Enter text:",
		$cgi->br,
		$cgi->textfield(
			-name=>'entry',
			-size=>'40',
		),
		$cgi->p,
		$cgi->submit(
			-value=>'Add new entry',
			-name=>'action',
		),
		'<input type="hidden" name="time" value="' . $cgi->param('time') . '">',
		'<input type="hidden" name="month" value="' . $cgi->param('month') . '">',
		'<input type="hidden" name="date" value="' . $cgi->param('date') . '">';

	print $cgi->end_form();
	print $cgi->end_html();
}