From c20602596d16e9c9e177b58d11dc8b0a5ce97770 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mikul=C3=A1=C5=A1=20Hobl=C3=ADk?= <mikuhoblik@gmail.com>
Date: Fri, 2 Sep 2022 18:36:44 +0200
Subject: [PATCH] [HxSearchBox] Keyboard navigation #348

---
 .../HxSearchBoxDoc/HxSearchBox_Demo.razor     | 17 ++--
 .../Forms/SearchBox/HxSearchBox.razor         | 26 +++++-
 .../Forms/SearchBox/HxSearchBox.razor.cs      | 84 +++++++++++++++++++
 .../Forms/SearchBox/HxSearchBox.razor.css     |  4 +
 4 files changed, 119 insertions(+), 12 deletions(-)

diff --git a/Havit.Blazor.Components.Web.Bootstrap.Documentation/Pages/Components/HxSearchBoxDoc/HxSearchBox_Demo.razor b/Havit.Blazor.Components.Web.Bootstrap.Documentation/Pages/Components/HxSearchBoxDoc/HxSearchBox_Demo.razor
index c8f9433f9..72958f395 100644
--- a/Havit.Blazor.Components.Web.Bootstrap.Documentation/Pages/Components/HxSearchBoxDoc/HxSearchBox_Demo.razor
+++ b/Havit.Blazor.Components.Web.Bootstrap.Documentation/Pages/Components/HxSearchBoxDoc/HxSearchBox_Demo.razor
@@ -28,11 +28,12 @@
     private string textQuery;
 
     List<SearchBoxItem> Data { get; set; } = new()
-        {
-            new() { Title = "Table", Subtitle = "50 000", Icon = BootstrapIcon.Table },
-            new() { Title = "Mouse", Subtitle = "400", Icon = BootstrapIcon.Mouse },
-            new() { Title = "Door", Subtitle = "1000", Icon = BootstrapIcon.DoorClosed }
-        };
+    {
+        new() { Title = "Table", Subtitle = "50 000", Icon = BootstrapIcon.Table },
+        new() { Title = "Mouse", Subtitle = "400", Icon = BootstrapIcon.Mouse },
+        new() { Title = "Door", Subtitle = "1000", Icon = BootstrapIcon.DoorClosed },
+        new() { Title = "Tasks", Subtitle = "720", Icon = BootstrapIcon.ListTask }
+    };
 
     private void OnItemSelected(SearchBoxItem item)
     {
@@ -49,9 +50,9 @@
         await Task.Delay(400); // imitate slower server API
 
         return new()
-            {
-                Data = Data.Where(i => i.Title.Contains(request.UserInput, StringComparison.OrdinalIgnoreCase))
-            };
+        {
+            Data = Data.Where(i => i.Title.Contains(request.UserInput, StringComparison.OrdinalIgnoreCase))
+        };
     }
 
     class SearchBoxItem
diff --git a/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor b/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor
index fb1060c84..c54f13620 100644
--- a/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor
+++ b/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor
@@ -15,7 +15,7 @@
 
             <div class="position-relative">
                 <form @onsubmit="HandleTextQueryTriggered" @onfocusout="HandleInputBlur">
-                    <HxInputText Value="@TextQuery"
+@*                    <HxInputText Value="@TextQuery"
                                  ValueChanged="HandleTextQueryValueChanged"
                                  ValueExpression="() => this.TextQuery"
                                  InputMode="InputMode.Search"
@@ -29,7 +29,15 @@
                                  InputGroupStartText="@InputGroupStartText"
                                  InputGroupEndText="@InputGroupEndText"
                                  InputGroupStartTemplate="@InputGroupStartTemplate"
-                                 InputGroupEndTemplate="@InputGroupEndTemplate" />
+                                 InputGroupEndTemplate="@InputGroupEndTemplate" />*@
+                    <input
+                        value="@TextQuery"
+                        @oninput="(eventArgs) => HandleTextQueryValueChanged(eventArgs.Value.ToString())"
+                        @onkeydown="UpdateFocusedItem"
+                        inputmode="search"
+                        enabled="@Enabled"
+                        placeholder="@Placeholder"
+                        class="@CssClassHelper.Combine("form-control", InputCssClassEffective)" />
 
                     @if (InputGroupEndText is null && InputGroupEndTemplate is null)
                     {
@@ -66,7 +74,12 @@
                     IconBase icon = ItemIconSelector?.Invoke(item) ?? null;
 
                     <li class="overflow-hidden">
-                        <button type="button" tabindex="0" class="@CssClassHelper.Combine("dropdown-item", ItemCssClassEffective)" @onclick="() => HandleItemSelected(item)">
+                        <button
+                            type="button"
+                            tabindex="0"
+                            class="@CssClassHelper.Combine("dropdown-item", HasItemFocus(item) ? "hx-dropdown-item-focused" : null, ItemCssClassEffective)"
+                            @onclick="() => HandleItemSelected(item)">
+                            
                             @if (ItemTemplate is null)
                             {
                                 <HxSearchBoxItem Title="@title" Subtitle="@subtitle" Icon="@icon" />
@@ -91,7 +104,12 @@
             @if (AllowTextQuery && (TextQuery is not null) && (TextQuery.Length >= MinimumLengthEffective))
             {
                 <li class="overflow-hidden">
-                    <button type="button" tabindex="0" class="@CssClassHelper.Combine("dropdown-item", ItemCssClassEffective)" @onclick="HandleTextQueryTriggered">
+                    <button
+                        type="button"
+                        tabindex="0"
+                        class="@CssClassHelper.Combine("dropdown-item", HasFreeTextItemFocus() ? "hx-dropdown-item-focused" : null, ItemCssClassEffective)"
+                        @onclick="HandleTextQueryTriggered">
+
                         @if (TextQueryItemTemplate is null)
                         {
                             <HxSearchBoxItem Title="@TextQuery" Icon="@SearchIconEffective" />
diff --git a/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor.cs b/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor.cs
index 901134e66..787728381 100644
--- a/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor.cs
+++ b/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor.cs
@@ -11,6 +11,12 @@ namespace Havit.Blazor.Components.Web.Bootstrap;
 /// <typeparam name="TItem"></typeparam>
 public partial class HxSearchBox<TItem> : IAsyncDisposable
 {
+	protected const string ArrowUpKeyCode = "ArrowUp";
+	protected const string ArrowDownKeyCode = "ArrowDown";
+
+	protected const string EnterKeyCode = "Enter";
+	protected const string NumpadEnterKeyCode = "NumpadEnter";
+
 	/// <summary>
 	/// Returns application-wide defaults for the component.
 	/// Enables overriding defaults in descandants (use separate set of defaults).
@@ -204,6 +210,7 @@ public partial class HxSearchBox<TItem> : IAsyncDisposable
 	private string dropdownToggleElementId = "hx" + Guid.NewGuid().ToString("N");
 	private string dropdownId = "hx" + Guid.NewGuid().ToString("N");
 	private List<TItem> searchResults = new();
+	private int focusedItemIndex = -1;
 	private HxDropdownToggleElement dropdownToggle;
 	private bool dropdownMenuActive = false;
 	private bool initialized = false;
@@ -274,6 +281,8 @@ protected async Task UpdateSuggestionsAsync()
 		}
 
 		dataProviderInProgress = false;
+
+		focusedItemIndex = default;
 		searchResults = result?.Data.ToList();
 
 		textQueryHasBeenBelowMinimumLength = false;
@@ -282,6 +291,25 @@ protected async Task UpdateSuggestionsAsync()
 		StateHasChanged();
 	}
 
+	protected bool HasItemFocus(TItem item)
+	{
+		TItem focusedItem = GetItemByIndex(focusedItemIndex);
+
+		if ((focusedItem is not null) && (!focusedItem.Equals(default)))
+		{
+			return item.Equals(focusedItem);
+		}
+		else
+		{
+			return false;
+		}
+	}
+
+	protected bool HasFreeTextItemFocus()
+	{
+		return focusedItemIndex == GetFreeTextItemIndex();
+	}
+
 	protected async Task HandleTextQueryValueChanged(string newTextQuery)
 	{
 		this.TextQuery = newTextQuery;
@@ -318,6 +346,62 @@ protected async Task HandleTextQueryValueChanged(string newTextQuery)
 		await InvokeTextQueryChangedAsync(newTextQuery);
 	}
 
+	private async Task UpdateFocusedItem(KeyboardEventArgs keyboardEventArgs)
+	{
+		// Confirm selection on the focused item if an item is focused and the enter key is pressed.
+		TItem focusedItem = GetItemByIndex(focusedItemIndex);
+		if (keyboardEventArgs.Code == EnterKeyCode || keyboardEventArgs.Code == NumpadEnterKeyCode)
+		{
+			if ((focusedItem is not null) && (!focusedItem.Equals(default)))
+			{
+				await HandleItemSelected(focusedItem);
+			}
+			else if (focusedItemIndex == GetFreeTextItemIndex())
+			{
+				await HandleTextQueryTriggered();
+			}
+		}
+
+		// Move focus up or down.
+		if (keyboardEventArgs.Code == ArrowUpKeyCode)
+		{
+			int previousItemIndex = focusedItemIndex - 1;
+			if (previousItemIndex >= -1) // If the index is -1, no item is focused.
+			{
+				focusedItemIndex = previousItemIndex;
+			}
+		}
+		else if (keyboardEventArgs.Code == ArrowDownKeyCode)
+		{
+			int nextItemIndex = focusedItemIndex + 1;
+			if (nextItemIndex < searchResults.Count)
+			{
+				focusedItemIndex = nextItemIndex;
+			}
+			else
+			{
+				focusedItemIndex = GetFreeTextItemIndex(); // Select the item that's used to confirm the freetext.
+			}
+		}
+	}
+
+	private TItem GetItemByIndex(int index)
+	{
+		if (index >= 0 && index < searchResults.Count)
+		{
+			return searchResults[index];
+		}
+		else
+		{
+			return default;
+		}
+	}
+
+	protected int GetFreeTextItemIndex()
+	{
+		return searchResults.Count;
+	}
+
 	private async void HandleTimerElapsed(object sender, System.Timers.ElapsedEventArgs e)
 	{
 		// when a time interval reached, update suggestions
diff --git a/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor.css b/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor.css
index 968c52300..d313ddbff 100644
--- a/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor.css
+++ b/Havit.Blazor.Components.Web.Bootstrap/Forms/SearchBox/HxSearchBox.razor.css
@@ -24,3 +24,7 @@
 .dropdown-item:not(:active) ::deep .hx-search-box-item-subtitle {
     color: var(--hx-search-box-item-subtitle-color);
 }
+
+::deep .hx-dropdown-item-focused {
+    background-color: var(--hx-autosuggest-item-highlighted-background-color);
+}