feat(panzerfaust): add search support allowing user to find projet by name (#399) (#447)

* fix(buildengine): update glm cmake minimum version to 3.5

* docs: update with some dependencies some might find useful to build the engine

* docs: update setup windows machine section

* feat(panzerfaust): add search support allowing user to find projet by name

* docs: update with some dependencies some might find useful to build the engine

* docs: update setup windows machine section

* feat(panzerfaust): add search support allowing user to find projet by name

* chore: replace naive pattern matching implementation with kmp algorithm

* chore: remove throttle() and make kmp functions static

Author: AmanMenda

Panzerfaust/ViewModels/MainWindowViewModel.cs

@@ -1,5 +1,6 @@
 using DynamicData;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
 using Panzerfaust.Models;
 using ReactiveUI;
 using System;
@@ -18,27 +19,122 @@ namespace Panzerfaust.ViewModels
 {
     internal class MainWindowViewModel : ViewModelBase
     {
-        public ObservableCollection<ProjectViewModel> Projects { get; set; } = new();
+
+        // Field which keep updated with the user inputs in the search bar
+        private string searchText = string.Empty;
+        public string SearchText
+        {
+            get => searchText;
+            set => this.RaiseAndSetIfChanged(ref searchText, value);
+        }
+
+        // Use of DynamicData's SourceList for batch updates later on,
+        // reduces UI refreshes
+        private readonly SourceList<ProjectViewModel> projects = new();
+        public ReadOnlyObservableCollection<ProjectViewModel> FilteredProjects { get; set; }
+
         public ReactiveCommand<Unit, Unit> CreateProjectCommand { get; }
         public Interaction<ProjectWindowViewModel, ProjectViewModel?> NewProjectDialog { get; } = new();
         public Interaction<MessageBoxWindowViewModel, bool> DeleteProjectInteraction { get; } = new();
 
+
         public MainWindowViewModel()
         {
+            var filterPredicate = this.WhenAnyValue(x => x.SearchText)
+                .Select(searchText => CreateFilterPredicate(searchText.Trim()))
+                .DistinctUntilChanged();
+
+            // The connect() method links the project list to the filtered view while
+            // bind() propagates the changes to FilteredProjects on the UI thread.
+            // Subscribe() is required to activate the "pipeline".
+            projects.Connect()
+                .Filter(filterPredicate)
+                .Bind(out var filteredProjects)
+                .Subscribe();
+
+            FilteredProjects = filteredProjects;
+
             RxApp.MainThreadScheduler.Schedule(LoadProjectsAsync);
 
             CreateProjectCommand = ReactiveCommand.CreateFromTask(OnCreateProjectCommand);
 
             MessageBus.Current.Listen<(string, ProjectViewModel)>().Subscribe(OnReceiveMessage);
         }
+        private static int[] BuildKMPTable(string pattern)
+        {
+            int j = 0; // Position in the pattern
+
+            int m = pattern.Length;
+            int[] lps = new int[m]; // longest prefix which is also a suffix
+
+            lps[0] = 0;
+            for (int i = 1; i < m; i++)
+            {
+                while (j > 0 && char.ToLower(pattern[i]) != char.ToLower(pattern[j]))
+                {
+                    j = lps[j - 1];
+                }
+                if (char.ToLower(pattern[i]) == char.ToLower(pattern[j]))
+                {
+                    j++;
+                }
+                lps[i] = j;
+            }
+            return lps;
+        }
+
+        private static bool KMPSearch(string searchText, string pattern)
+        {
+
+            int j;
+            int[] lps;
+            
+            // Edge cases
+            if (string.IsNullOrEmpty(pattern))
+                return true;
+
+            if (string.IsNullOrEmpty(searchText))
+                return false;
+
+            if (pattern.Length > searchText.Length)
+                return false;
+
+            j = 0;
+            lps = BuildKMPTable(pattern);
+
+            for (int i = 0; i < searchText.Length; i++)
+            {
+                while (j > 0 && char.ToLower(searchText[i]) != char.ToLower(pattern[j]))
+                {
+                    j = lps[j - 1];
+                }
+                if (char.ToLower(searchText[i]) == char.ToLower(pattern[j]))
+                {
+                    j++;
+                }
+                if (j == pattern.Length)
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        private Func<ProjectViewModel, bool> CreateFilterPredicate(string searchTerm)
+        {
+            return string.IsNullOrWhiteSpace(searchTerm)
+                ? _ => true
+                : p => KMPSearch(p.Name, searchTerm);
+        }
 
         private void OnReceiveMessage((string, ProjectViewModel) message)
         {
             var (action, data) = message;
 
             if (action == Message.DeleteAction)
             { 
-                Projects.Remove(data);
+                projects.Remove(data);
             }
         }
 
@@ -49,7 +145,7 @@ private async Task OnCreateProjectCommand()
             if (result != null)
             {
                 result.SetRemovalInteraction(DeleteProjectInteraction);
-                Projects.Add(result);
+                projects.Add(result);
             }
         }
 
@@ -58,8 +154,14 @@ private async void LoadProjectsAsync()
             var projectService = App.Current?.ServiceProvider?.GetService<Service.IProjectService>();
             if (projectService == null) return;
 
-            var projects = await projectService.LoadProjectsAsync();
-            Projects.AddRange(projects.Select(project => new ProjectViewModel(project, DeleteProjectInteraction)));
+            var loadedProjects = await projectService.LoadProjectsAsync();
+
+            projects.Edit(innerList =>
+            {
+                innerList.AddRange(
+                    loadedProjects.Select(project => new ProjectViewModel(project, DeleteProjectInteraction))
+                );
+            });
         }
     }
 }

Panzerfaust/Views/MainWindow.axaml

@@ -46,15 +46,15 @@
         <TextBlock Grid.Row="0" Text="Projects" Margin="30, 30, 0, 0" FontSize="25"/>
         <StackPanel Orientation="Vertical" Grid.Row="1" VerticalAlignment="Stretch" HorizontalAlignment="Stretch">
           <Button Content="New project" HorizontalAlignment="Right" Background="Green" Margin="0, 20, 5, 20" FontSize="15" CornerRadius="6" Command="{Binding CreateProjectCommand}"/>
-          <TextBox Watermark="Search..." BorderBrush="Transparent" BorderThickness="0" Foreground="White" MinWidth="200" Width="210" HorizontalAlignment="Right" Margin="0, 5, 5, 5" CornerRadius="6"/>
+          <TextBox Text="{Binding SearchText, UpdateSourceTrigger=PropertyChanged}" Watermark="Search..." BorderBrush="Transparent" BorderThickness="0" Foreground="White" MinWidth="200" Width="210" HorizontalAlignment="Right" Margin="0, 5, 5, 5" CornerRadius="6"/>
           <ProgressBar Foreground="WhiteSmoke" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"/>
           <DataGrid VerticalAlignment="Stretch" HorizontalAlignment="Stretch"
                     IsReadOnly="True"
                     CanUserReorderColumns="False"
                     CanUserSortColumns="False" 
                     VerticalScrollBarVisibility="Auto"
                     CanUserResizeColumns="False" 
-                    BorderThickness="0" BorderBrush="Gray" ItemsSource="{Binding Projects}" SelectionMode="Single">
+                    BorderThickness="0" BorderBrush="Gray" ItemsSource="{Binding FilteredProjects}" SelectionMode="Single">
             <DataGrid.Columns>
               <DataGridTextColumn Header="NAME" Width="*" MinWidth="256" Binding="{Binding Name, Mode=OneWay}"/>
               <DataGridTextColumn Header="PATH" Width="*" MinWidth="256" Binding="{Binding Path, Mode=OneWay}"/>