First draft of support for task list - NOT READY FOR MERGE

src/GovUk.Frontend.AspNetCore/HtmlGeneration/ComponentGenerator.TaskList.cs

@@ -0,0 +1,144 @@
+#nullable enable
+
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+
+namespace GovUk.Frontend.AspNetCore.HtmlGeneration
+{
+    public partial class ComponentGenerator
+    {
+        internal const string TaskListElement = "ul";
+        internal const string TaskListTaskElement = "li";
+        internal const string TaskListTaskNameElement = "span";
+        internal const string TaskListHintElement = "span";
+        internal const string TaskListStatusElement = "span";
+
+        public TagBuilder GenerateTaskList(
+            AttributeDictionary? attributes,
+            IEnumerable<TaskListTask> tasks)
+        {
+            Guard.ArgumentNotNull(nameof(tasks), tasks);
+            Guard.ArgumentValid(nameof(tasks), "A task list must contain at least one task", tasks.Any());
+
+            var tagBuilder = new TagBuilder(TaskListElement);
+            if (attributes != null) { tagBuilder.MergeAttributes(attributes); }
+            tagBuilder.MergeCssClass("govuk-task-list");
+
+            var taskNumber = 1;
+            foreach (var task in tasks)
+            {
+                Guard.ArgumentValid(nameof(tasks), "Task name cannot be null or empty", task.Name.Content != null);
+
+                string taskId = GenerateTaskId(attributes, taskNumber, task);
+                var itemTagBuilder = new TagBuilder(TaskListTaskElement);
+                if (task.Attributes != null) { itemTagBuilder.MergeAttributes(task.Attributes); }
+                if (!itemTagBuilder.Attributes.ContainsKey("id")) { itemTagBuilder.MergeAttribute("id", taskId); }
+                itemTagBuilder.MergeCssClass("govuk-task-list__item");
+                tagBuilder.InnerHtml.AppendHtml(itemTagBuilder);
+
+                var taskNameTagBuilder = new TagBuilder(TaskListTaskNameElement);
+                taskNameTagBuilder.MergeAttributes(task.Name.Attributes);
+                taskNameTagBuilder.MergeCssClass("govuk-task-list__task-name-and-hint");
+
+                var statusText = TaskListTaskStatusText(task.Status.Status, task.Status.Content);
+
+                if (!string.IsNullOrEmpty(task.Href) && task.Status.Status != TaskListTaskStatus.NotApplicable && task.Status.Status != TaskListTaskStatus.CannotStartYet)
+                {
+                    var taskLinkTagBuilder = new TagBuilder("a");
+                    taskLinkTagBuilder.MergeAttribute("href", task.Href);
+                    taskLinkTagBuilder.MergeCssClass("govuk-link");
+                    taskLinkTagBuilder.MergeCssClass("govuk-task-list__link");
+                    taskLinkTagBuilder.InnerHtml.AppendHtml(task.Name.Content!);
+                    taskNameTagBuilder.InnerHtml.AppendHtml(taskLinkTagBuilder);
+                    itemTagBuilder.MergeCssClass("govuk-task-list__item--with-link");
+
+                    if (!string.IsNullOrEmpty(statusText))
+                    {
+                        var statusId = task.Status.Attributes.ContainsKey("id") ? task.Status.Attributes["id"] : taskId + "-status";
+                        taskLinkTagBuilder.MergeAttribute("aria-describedby", statusId);
+                    }
+                }
+                else
+                {
+                    var unlinkedTaskTagBuilder = new TagBuilder("span");
+                    unlinkedTaskTagBuilder.MergeCssClass("govuk-task-list__task-no-link");
+                    unlinkedTaskTagBuilder.InnerHtml.AppendHtml(task.Name.Content!);
+                    taskNameTagBuilder.InnerHtml.AppendHtml(unlinkedTaskTagBuilder);
+                }
+
+                if (task.Hint.Content != null)
+                {
+                    var hintTagBuilder = new TagBuilder(TaskListHintElement);
+                    hintTagBuilder.MergeAttributes(task.Hint.Attributes);
+                    hintTagBuilder.MergeCssClass("govuk-task-list__task_hint");
+                    hintTagBuilder.InnerHtml.AppendHtml(task.Hint.Content);
+                    taskNameTagBuilder.InnerHtml.AppendHtml(hintTagBuilder);
+                }
+
+                itemTagBuilder.InnerHtml.AppendHtml(taskNameTagBuilder);
+
+                if (!string.IsNullOrEmpty(statusText))
+                {
+                    var statusOuterTagBuilder = new TagBuilder(TaskListStatusElement);
+                    statusOuterTagBuilder.MergeCssClass("govuk-task-list__status-container");
+
+                    var statusInnerTagBuilder = new TagBuilder("span");
+                    statusInnerTagBuilder.MergeAttributes(task.Status.Attributes);
+                    statusInnerTagBuilder.MergeCssClass("govuk-task-list__status");
+                    if (task.Status.Status.HasValue)
+                    {
+                        statusInnerTagBuilder.MergeCssClass(TaskStatusCssClass(task.Status.Status.Value));
+                    }
+                    if (!statusInnerTagBuilder.Attributes.ContainsKey("id")) { statusInnerTagBuilder.MergeAttribute("id", taskId + "-status"); }
+
+                    statusInnerTagBuilder.InnerHtml.AppendHtml(statusText);
+                    statusOuterTagBuilder.InnerHtml.AppendHtml(statusInnerTagBuilder);
+                    itemTagBuilder.InnerHtml.AppendHtml(statusOuterTagBuilder);
+                }
+
+                taskNumber++;
+            }
+
+            return tagBuilder;
+        }
+
+        private string TaskStatusCssClass(TaskListTaskStatus status)
+        {
+            return "govuk-task-list__status-" + Regex.Replace(status.ToString(), "([A-Z])", "-$1").ToLowerInvariant();
+        }
+
+        public static string? TaskListTaskStatusText(TaskListTaskStatus? status, string? customStatus = null)
+        {
+            if (!string.IsNullOrEmpty(customStatus))
+            {
+                return customStatus;
+            }
+            else if (status.HasValue)
+            {
+                var statusText = Regex.Replace(status.ToString()!, "([A-Z])", " $1").ToLowerInvariant().Trim();
+                return statusText.Substring(0, 1).ToUpperInvariant() + statusText.Substring(1);
+            }
+            else return null;
+        }
+
+        private static string GenerateTaskId(AttributeDictionary? attributes, int taskNumber, TaskListTask task)
+        {
+            string taskId = string.Empty;
+            if (task.Attributes != null && task.Attributes.ContainsKey("id"))
+            {
+                taskId = task.Attributes["id"]!;
+            }
+            else
+            {
+                taskId = Regex.Replace(Regex.Replace(task.Name.Content!.Value!, "<.*?>", string.Empty, RegexOptions.IgnoreCase), "[^A-Z0-9- ]", string.Empty, RegexOptions.IgnoreCase).Replace(" ", "-").ToLowerInvariant();
+            }
+            if (string.IsNullOrEmpty(taskId)) { taskId = "task-" + taskNumber; }
+            if (attributes != null && attributes.ContainsKey("id")) { taskId = attributes["id"] + "-" + taskId; }
+
+            return taskId;
+        }
+    }
+}

src/GovUk.Frontend.AspNetCore/HtmlGeneration/ComponentGenerator.TaskListSummary.cs

@@ -0,0 +1,53 @@
+#nullable enable
+
+using System;
+using System.Web;
+using Microsoft.AspNetCore.Mvc.Rendering;
+
+namespace GovUk.Frontend.AspNetCore.HtmlGeneration
+{
+    public partial class ComponentGenerator
+    {
+        internal const string TaskListSummaryElement = "div";
+        internal const int TaskListSummaryDefaultHeadingLevel = 2;
+        internal const int TaskListSummaryMinHeadingLevel = 1;
+        internal const int TaskListSummaryMaxHeadingLevel = 6;
+        public const string TaskListSummaryDefaultIncompleteStatus = "Tasks incomplete";
+        public const string TaskListSummaryDefaultCompletedStatus = "Tasks completed";
+        public const string TaskListSummaryDefaultTracker = "You've completed {0} of {1} tasks.";
+
+        public TagBuilder GenerateTaskListSummary(TaskListSummary taskListSummary)
+        {
+            if (taskListSummary.HeadingLevel < TaskListSummaryMinHeadingLevel || taskListSummary.HeadingLevel > TaskListSummaryMaxHeadingLevel)
+            {
+                throw new ArgumentOutOfRangeException(
+                    $"{nameof(taskListSummary.HeadingLevel)} must be between {TaskListSummaryMinHeadingLevel} and {TaskListSummaryMaxHeadingLevel}.",
+                    nameof(taskListSummary.HeadingLevel));
+            }
+
+            Guard.ArgumentNotNullOrEmpty(nameof(taskListSummary.IncompleteStatus), taskListSummary.IncompleteStatus);
+            Guard.ArgumentNotNullOrEmpty(nameof(taskListSummary.CompletedStatus), taskListSummary.CompletedStatus);
+            Guard.ArgumentNotNullOrEmpty(nameof(taskListSummary.Tracker), taskListSummary.Tracker);
+
+            var tagBuilder = new TagBuilder(TaskListSummaryElement);
+            if (taskListSummary.Attributes != null) { tagBuilder.MergeAttributes(taskListSummary.Attributes); }
+            tagBuilder.MergeCssClass("govuk-task-list-summary");
+
+            var statusTagBuilder = new TagBuilder($"h{taskListSummary.HeadingLevel}");
+            statusTagBuilder.MergeCssClass("govuk-heading-s");
+            statusTagBuilder.MergeCssClass("govuk-task-list-summary__heading");
+            statusTagBuilder.InnerHtml.Append(taskListSummary.CompletedTasks == taskListSummary.TotalTasks ? taskListSummary.CompletedStatus : taskListSummary.IncompleteStatus);
+            tagBuilder.InnerHtml.AppendHtml(statusTagBuilder);
+
+            var trackerTagBuilder = new TagBuilder("p");
+            trackerTagBuilder.MergeCssClass("govuk-body");
+            trackerTagBuilder.MergeCssClass("govuk-task-list-summary__tracker");
+            trackerTagBuilder.InnerHtml.AppendHtml(string.Format(HttpUtility.HtmlEncode(taskListSummary.Tracker),
+                "<span class=\"govuk-task-list-summary__completed-tasks\">" + taskListSummary.CompletedTasks + "</span>",
+                "<span class=\"govuk-task-list-summary__total-tasks\">" + taskListSummary.TotalTasks + "</span>"));
+            tagBuilder.InnerHtml.AppendHtml(trackerTagBuilder);
+
+            return tagBuilder;
+        }
+    }
+}

src/GovUk.Frontend.AspNetCore/HtmlGeneration/TaskListSummary.cs

@@ -0,0 +1,15 @@
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+
+namespace GovUk.Frontend.AspNetCore.HtmlGeneration
+{
+    public class TaskListSummary
+    {
+        public AttributeDictionary Attributes { get; set; }
+        public string IncompleteStatus { get; set; }
+        public string CompletedStatus { get; set; }
+        public string Tracker { get; set; }
+        public int TotalTasks { get; set; }
+        public int CompletedTasks { get; set; }
+        public int HeadingLevel { get; set; }
+    }
+}

src/GovUk.Frontend.AspNetCore/HtmlGeneration/TaskListTask.cs

@@ -0,0 +1,14 @@
+using Microsoft.AspNetCore.Html;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+
+namespace GovUk.Frontend.AspNetCore.HtmlGeneration
+{
+    public class TaskListTask
+    {
+        public AttributeDictionary Attributes { get; set; }
+        public (AttributeDictionary Attributes, HtmlString Content) Name { get; init; }
+        public string Href { get; set; }
+        public (AttributeDictionary Attributes, TaskListTaskStatus? Status, string Content) Status { get; internal set; }
+        public (AttributeDictionary Attributes, HtmlString Content) Hint { get; internal set; }
+    }
+}

src/GovUk.Frontend.AspNetCore/IGovUkHtmlGenerator.cs

@@ -159,6 +159,10 @@ TagBuilder GenerateTabs(
 
         TagBuilder GenerateTag(IHtmlContent content, AttributeDictionary attributes);
 
+        TagBuilder GenerateTaskList(AttributeDictionary? attributes, IEnumerable<TaskListTask> tasks);
+
+        TagBuilder GenerateTaskListSummary(TaskListSummary taskListSummary);
+
         TagBuilder GenerateTextArea(
             bool haveError,
             string id,

src/GovUk.Frontend.AspNetCore/TagHelpers/TaskListContext.cs

@@ -0,0 +1,32 @@
+using System.Collections.Generic;
+using GovUk.Frontend.AspNetCore.HtmlGeneration;
+
+namespace GovUk.Frontend.AspNetCore.TagHelpers
+{
+    internal class TaskListContext
+    {
+        private readonly List<TaskListTask> _tasks;
+
+        public TaskListContext()
+        {
+            _tasks = new List<TaskListTask>();
+        }
+
+        public IReadOnlyList<TaskListTask> Tasks => _tasks;
+
+        public void AddTask(TaskListTask task)
+        {
+            Guard.ArgumentNotNull(nameof(task), task);
+
+            _tasks.Add(task);
+        }
+
+        public void ThrowIfIncomplete()
+        {
+            if (Tasks.Count < 1)
+            {
+                throw ExceptionHelper.AChildElementMustBeProvided(TaskListTaskTagHelper.TagName);
+            }
+        }
+    }
+}

src/GovUk.Frontend.AspNetCore/TagHelpers/TaskListSummaryTagHelper.cs

@@ -0,0 +1,113 @@
+using System;
+using System.Threading.Tasks;
+using GovUk.Frontend.AspNetCore.HtmlGeneration;
+using Microsoft.AspNetCore.Mvc.TagHelpers;
+using Microsoft.AspNetCore.Razor.TagHelpers;
+
+namespace GovUk.Frontend.AspNetCore.TagHelpers
+{
+    /// <summary>
+    /// Generates a GOV.UK task list summary component.
+    /// </summary>
+    [HtmlTargetElement(TagName)]
+    [OutputElementHint(ComponentGenerator.TaskListSummaryElement)]
+    public class TaskListSummaryTagHelper : TagHelper
+    {
+        internal const string TagName = "govuk-task-list-summary";
+
+        private readonly IGovUkHtmlGenerator _htmlGenerator;
+        private int _headingLevel = ComponentGenerator.TaskListSummaryDefaultHeadingLevel;
+
+        /// <summary>
+        /// The heading to display when the task list is incomplete.
+        /// </summary>
+        [HtmlAttributeName("incomplete-status")]
+        public string IncompleteStatus { get; set; } = ComponentGenerator.TaskListSummaryDefaultIncompleteStatus;
+
+        /// <summary>
+        /// The heading to display when the task list is completed.
+        /// </summary>
+        [HtmlAttributeName("completed-status")]
+        public string CompletedStatus { get; set; } = ComponentGenerator.TaskListSummaryDefaultCompletedStatus;
+
+        /// <summary>
+        /// Text that displays how many tasks are completed. {0} is replaced with the number of completed tasks, and {1} is replaced with the total number of tasks.
+        /// </summary>
+        [HtmlAttributeName("tracker")]
+        public string Tracker { get; set; } = ComponentGenerator.TaskListSummaryDefaultTracker;
+
+        /// <summary>
+        /// The total number of tasks in the task list that must be completed.
+        /// </summary>
+        [HtmlAttributeName("total-tasks")]
+        public int TotalTasks { get; set; } = 0;
+
+        /// <summary>
+        /// The number of tasks in the task list that have been completed so far.
+        /// </summary>
+        [HtmlAttributeName("completed-tasks")]
+        public int CompletedTasks { get; set; } = 0;
+
+
+        /// <summary>
+        /// The heading level.
+        /// </summary>
+        /// <remarks>
+        /// Must be between <c>1</c> and <c>6</c> (inclusive). The default is <c>2</c>.
+        /// </remarks>
+        [HtmlAttributeName("heading-level")]
+        public int HeadingLevel
+        {
+            get => _headingLevel;
+            set
+            {
+                if (value < ComponentGenerator.TaskListSummaryMinHeadingLevel ||
+                    value > ComponentGenerator.TaskListSummaryMaxHeadingLevel)
+                {
+                    throw new ArgumentOutOfRangeException(
+                        nameof(value),
+                        $"{nameof(HeadingLevel)} must be between {ComponentGenerator.TaskListSummaryMinHeadingLevel} and {ComponentGenerator.TaskListSummaryMaxHeadingLevel}.");
+                }
+
+                _headingLevel = value;
+            }
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="TaskListSummaryTagHelper"/>.
+        /// </summary>
+        public TaskListSummaryTagHelper()
+            : this(htmlGenerator: null)
+        {
+        }
+
+        internal TaskListSummaryTagHelper(IGovUkHtmlGenerator htmlGenerator)
+        {
+            _htmlGenerator = htmlGenerator ?? new ComponentGenerator();
+        }
+
+        /// <inheritdoc/>
+        public override Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
+        {
+            var tagBuilder = _htmlGenerator.GenerateTaskListSummary(new TaskListSummary
+            {
+                Attributes = output.Attributes.ToAttributeDictionary(),
+                HeadingLevel = HeadingLevel,
+                IncompleteStatus = IncompleteStatus,
+                CompletedStatus = CompletedStatus,
+                Tracker = Tracker,
+                TotalTasks = TotalTasks,
+                CompletedTasks = CompletedTasks
+            });
+
+            output.TagName = tagBuilder.TagName;
+            output.TagMode = TagMode.StartTagAndEndTag;
+
+            output.Attributes.Clear();
+            output.MergeAttributes(tagBuilder);
+            output.Content.SetHtmlContent(tagBuilder.InnerHtml);
+
+            return Task.CompletedTask;
+        }
+    }
+}