function month_change ()
    {
        if ( $('select#category').length > 0 )
        {
            catergory_load ();
        }
        
        if ( $('select#age_group').length > 0 )
        {
            age_groups_load ();
        }
        
        if ( $('select#province').length > 0 )
        {
            province_load ();
        }    
    }
    
    function category_changed ()
	{
        if ( $('select#category').length > 0 )
        {
            sub_category_load ();
        }        
        
        if ( $('select#age_group').length > 0 )
        {
            age_groups_load ();
        }
        
        if ( $('select#province').length > 0 )
        {
            province_load ();
        }
        
        if ( $('select#author').length > 0 )
        {
            author_load ();
        }
	}

    function sub_category_changed ()
    {
        if ( $('select#age_group').length > 0 )
        {
            age_groups_load ();
        }
        
        if ( $('select#province').length > 0 )
        {
            province_load ();
        }
        
        if ( $('select#author').length > 0 )
        {
            author_load ();
        }   
    }
    
    function age_group_changed ()
    {
        if ( $('select#province').length > 0 )
        {
            province_load ();
        }
        
        if ( $('select#author').length > 0 )
        {
            author_load ();
        }   
    }
    
    function province_changed ()
	{
		region_load ();
	}
    
    function catergory_load()
    {
        disable ( $('select#category') );
        disable ( $('select#sub_category') );
		$('select#category').val ( "" );
		$('select#sub_category').val ( "" );

		//if ( $('select#month' ).val () != "" )
		//{		
			var url = "/main/filter_categories";
            var params;
            if ( $('select#month' ).length > 0 )
            {	
                params = 'month=' + $('select#month' ).val();
            }
            
			$.ajax (
				{
					type: "POST",
					url: url,
					data: params,
					complete: function ( xml, msg )
					{
					},
					success: function ( data )
					{
						$('select#category').html ( data );
						$('select#category').val ( "" );
						enable ( $('select#category') );
					}
				}
			);					
		//}     
    }    
    
    function sub_category_load()
    {
        disable ( $('select#sub_category') );
		$('select#sub_category').val ( "" );

		if ( $('select#category' ).val () != "" )
		{		
			var url = "/main/filter_sub_categories";
            var params;
            if ( $('select#category' ).length > 0 )
            {	
                params = 'category_id=' + $('select#category' ).val();
            }
            if ( $('select#month' ).length > 0 )
            {	
                params += '&month=' + $('select#month' ).val();
            }
            
			$.ajax (
				{
					type: "POST",
					url: url,
					data: params,
					complete: function ( xml, msg )
					{
					},
					success: function ( data )
					{
						$('select#sub_category').html ( data );
						$('select#sub_category').val ( "" );
						enable ( $('select#sub_category') );
					}
				}
			);					
		}     
    }    
    
    function age_groups_load ()
    {
        disable ( $('select#age_group') );
		$('select#age_group').val ( "" );

        var url = "/main/filter_age_groups";
        var params;
        if ( $('select#category' ).length > 0 )
        {	
            params = 'category_id=' + $('select#category' ).val();
        }
        if ( $('select#sub_category').length > 0 )
        {
            params += '&sub_category_id=' + $('select#sub_category').val();
        }
        if ( $('select#month' ).length > 0 )
        {	
            params += '&month=' + $('select#month' ).val();
        }
            
        $.ajax (
            {
                type: "POST",
                url: url,
                data: params,
                complete: function ( xml, msg )
                {
                },
                success: function ( data )
                {
                    $('select#age_group').html ( data );
                    $('select#age_group').val ( "" );
                    enable ( $('select#age_group') );
                }
            }
        );					
    }
    

    function province_load ()
    {
        disable ( $('select#province') );
        disable ( $('select#region') );
		$('select#province').val ( "" );
		$('select#region').val ( "" );

        var url = "/main/filter_provinces";
        var params;
        if ( $('select#category' ).length > 0 )
        {	
            params = 'category_id=' + $('select#category' ).val();
        }
        if ( $('select#sub_category').length > 0 )
        {
            params += '&sub_category_id=' + $('select#sub_category').val();
        }
        if ( $('select#age_group').length > 0 )
        {
            params += '&age_group_id=' + $('select#age_group').val();
        }
        if ( $('select#month' ).length > 0 )
        {	
            params += '&month=' + $('select#month' ).val();
        }
            
        $.ajax (
            {
                type: "POST",
                url: url,
                data: params,
                complete: function ( xml, msg )
                {
                },
                success: function ( data )
                {
                    $('select#province').html ( data );
                    $('select#province').val ( "" );
                    enable ( $('select#province') );
                }
            }
        );					
    }
    
    function region_load ()
    {
        disable ( $('select#region') );
		$('select#region').val ( "" );

		if ( $('select#province' ).val () != "" )
		{		
			var url = "/main/filter_regions";
			var params;
            if ( $('select#category' ).length > 0 )
            {	
                params = 'category_id=' + $('select#category' ).val();
            }
            if ( $('select#sub_category').length > 0 )
            {
                params += '&sub_category_id=' + $('select#sub_category').val();
            }
            if ( $('select#age_group').length > 0 )
            {
                params += '&age_group_id=' + $('select#age_group').val();
            }            
            if ( $('select#province').length > 0 )
            {
                params += '&province_id=' + $('select#province').val();
            }            
            if ( $('select#month' ).length > 0 )
            {	
                params += '&month=' + $('select#month' ).val();
            }
            
			$.ajax (
				{
					type: "POST",
					url: url,
					data: params,
					complete: function ( xml, msg )
					{
					},
					success: function ( data )
					{
						$('select#region').html ( data );
						$('select#region').val ( "" );
						enable ( $('select#region') );
					}
				}
			);					
		}
    }
    
    function author_load ()
    {
        disable ( $('select#author') );
		$('select#author').val ( "" );

        var url = "/main/filter_authors";
        var params;
        if ( $('select#category' ).length > 0 )
        {	
            params = 'category_id=' + $('select#category' ).val();
        }
        if ( $('select#sub_category').length > 0 )
        {
            params += '&sub_category_id=' + $('select#sub_category').val();
        }
        if ( $('select#age_group').length > 0 )
        {
            params += '&age_group_id=' + $('select#age_group').val();
        }
        
        $.ajax (
            {
                type: "POST",
                url: url,
                data: params,
                complete: function ( xml, msg )
                {
                },
                success: function ( data )
                {
                    $('select#author').html ( data );
                    $('select#author').val ( "" );
                    enable ( $('select#author') );
                }
            }
        );					
    }
    
    
    $(document).ready ( function () 
        {
            $('input#keywords').click ( function ()
                {
                    if ( $('input#keywords').val() == 'Insleutel sleutelwoorde »' )
                    {    
                        $('input#keywords').val ('');
                    }
                }
                ).blur ( function ()
                    {
                        if ( $('input#keywords').val() == '' )
                        {
                            $('input#keywords').val('Insleutel sleutelwoorde »');
                        }
                    });
                    
            disable ( $('select#sub_category') );
            disable ( $('select#region') );
            
            $('select#month').change ( function () { month_change(); } );
            $('select#category').change ( function () { category_changed(); } );
            $('select#sub_category').change ( function () { sub_category_changed(); } );
            $('select#age_group').change ( function () { age_group_changed(); } );
            $('select#province').change ( function () { province_changed(); } );
        });