FeedCenter/Application/MainWindow/CategoryList.cs

using FeedCenter.Properties;
using System;
using System.Linq;
using System.Windows;
using System.Windows.Controls;

namespace FeedCenter
{
    public partial class MainWindow
    {
        private void DisplayCategory()
        {
            CategoryLabel.Text = string.Format(Properties.Resources.CategoryFilterHeader, _currentCategory == null ? Properties.Resources.AllCategory : _currentCategory.Name);
        }

        private void HandleCategoryButtonClick(object sender, RoutedEventArgs e)
        {
            // Create a new context menu
            var contextMenu = new ContextMenu();

            // Create the "all" menu item
            var menuItem = new MenuItem
            {
                Header = Properties.Resources.AllCategory,
                Tag = null,

                // Set the current item to bold
                FontWeight = _currentCategory == null ? FontWeights.Bold : FontWeights.Normal
            };

            // Handle the click
            menuItem.Click += HandleCategoryMenuItemClick;

            // Add the item to the list
            contextMenu.Items.Add(menuItem);

            // Loop over each feed
            foreach (var category in _database.Categories.OrderBy(category => category.Name))
            {
                // Create a menu item
                menuItem = new MenuItem
                {
                    Header = category.Name,
                    Tag = category,

                    // Set the current item to bold
                    FontWeight = category.Id == _currentCategory?.Id ? FontWeights.Bold : FontWeights.Normal
                };

                // Handle the click
                menuItem.Click += HandleCategoryMenuItemClick;

                // Add the item to the list
                contextMenu.Items.Add(menuItem);
            }

            // Set the context menu placement to this button
            contextMenu.PlacementTarget = this;

            // Open the context menu
            contextMenu.IsOpen = true;
        }

        private void HandleCategoryMenuItemClick(object sender, RoutedEventArgs e)
        {
            // Get the menu item clicked
            var menuItem = (MenuItem) sender;

            // Get the category from the menu item tab
            var category = (Category) menuItem.Tag;

            // If the category changed then reset the current feed to the first in the category
            if (_currentCategory?.Id != category?.Id)
            {
                _currentFeed = category == null ? _database.Feeds.FirstOrDefault() : category.Feeds.FirstOrDefault();
            }

            // Set the current category
            _currentCategory = category;

            // Get the current feed list to match the category
            _feedList = _currentCategory == null ? _database.Feeds : _database.Feeds.Where(feed => feed.CategoryId == _currentCategory.Id);

            // Refresh the feed index
            _feedIndex = -1;

            // Get the first feed
            NextFeed();

            // Update the feed timestamp
            _lastFeedDisplay = DateTime.Now;

            // Update the display
            DisplayCategory();
            DisplayFeed();

            Settings.Default.LastCategoryID = _currentCategory?.Id.ToString() ?? string.Empty;
        }
    }
}