public delegate Task PromptAsyncDelegate()

in CSharp/Library/Microsoft.Bot.Builder/FormFlow/IPrompt.cs [186:323]
111 lines of code
18 McCabe index (conditional complexity)

    public delegate Task<FormPrompt> PromptAsyncDelegate<T>(IDialogContext context, FormPrompt prompt, T state, IField<T> field)
        where T : class;

    public static partial class Extensions
    {
        /// <summary>
        /// Generate a hero card from a FormPrompt.
        /// </summary>
        /// <param name="prompt">Prompt definition.</param>
        /// <returns>Either an empty list if no buttons or a list with one hero card.</returns>
        public static IList<Attachment> GenerateHeroCard(this FormPrompt prompt)
        {
            var actions = new List<CardAction>();
            foreach (var button in prompt.Buttons)
            {
                actions.Add(new CardAction(ActionTypes.ImBack, button.Description, button.Image, button.Message ?? button.Description));
            }

            var attachments = new List<Attachment>();
            if (actions.Count > 0)
            {
                var description = prompt.Description;
                // Facebook requires a title https://github.com/Microsoft/BotBuilder/issues/1678
                attachments.Add(new HeroCard(text: prompt.Prompt, title: description.Title ?? string.Empty, subtitle: description.SubTitle,
                    buttons: actions,
                    images: prompt.Description?.Image == null ? null : new List<CardImage>() { new CardImage() { Url = description.Image } })
                    .ToAttachment());
            }
            return attachments;
        }

        /// <summary>
        /// Generate a list of hero cards from a prompt definition.
        /// </summary>
        /// <param name="prompt">Prompt definition.</param>
        /// <returns>List of hero cards.</returns>
        public static IList<Attachment> GenerateHeroCards(this FormPrompt prompt)
        {
            var attachments = new List<Attachment>();
            var description = prompt.Description;
            foreach (var button in prompt.Buttons)
            {
                string image = button.Image ?? description.Image;
                attachments.Add(new HeroCard(
                    title: button.Title ?? description.Title ?? string.Empty,
                    subtitle: button.SubTitle ?? description.SubTitle,
                    text: prompt.Prompt,
                    images: (image == null ? null : (new List<CardImage>() { new CardImage() { Url = image } })),
                    buttons: new List<CardAction>() { new CardAction(ActionTypes.ImBack, button.Description, null, button.Message ?? button.Description) })
                    .ToAttachment());
            }
            return attachments;
        }

        /// <summary>
        /// Given a prompt definition generate messages to send back.
        /// </summary>
        /// <param name="prompt">Prompt definition.</param>
        /// <param name="preamble">Simple text message with all except last line of prompt to allow markdown in prompts.</param>
        /// <param name="promptMessage">Message with prompt definition including cards.</param>
        /// <returns>True if preamble should be sent.</returns>
        public static bool GenerateMessages(this FormPrompt prompt, IMessageActivity preamble, IMessageActivity promptMessage)
        {
            var promptCopy = (FormPrompt) prompt.Clone();
            bool hasPreamble = false;
            if (promptCopy.Buttons?.Count > 0 || promptCopy.Description?.Image != null)
            {
                // If we are generating cards we do not support markdown so create a separate message
                // for all lines except the last one.  
                var lines = promptCopy.Prompt.Split(new string[] { Environment.NewLine }, StringSplitOptions.None);
                if (lines.Length > 1)
                {
                    var builder = new StringBuilder();
                    for (var i = 0; i < lines.Length - 1; ++i)
                    {
                        if (i > 0)
                        {
                            builder.AppendLine();
                        }
                        builder.Append(lines[i]);
                    }
                    preamble.Text = builder.ToString();
                    promptCopy.Prompt = lines.Last();
                    hasPreamble = true;
                }
                if (promptCopy.Buttons?.Count > 0)
                {
                    var style = promptCopy.Style;
                    if (style == ChoiceStyleOptions.Auto)
                    {
                        foreach (var button in promptCopy.Buttons)
                        {
                            // Images require carousel
                            if (button.Image != null)
                            {
                                style = ChoiceStyleOptions.Carousel;
                                break;
                            }
                        }
                    }
                    if (style == ChoiceStyleOptions.Carousel)
                    {
                        promptMessage.AttachmentLayout = AttachmentLayoutTypes.Carousel;
                        promptMessage.Attachments = promptCopy.GenerateHeroCards();
                    }
                    else
                    {
                        promptMessage.AttachmentLayout = AttachmentLayoutTypes.List;
                        promptMessage.Attachments = promptCopy.GenerateHeroCard();
                    }
                }
                else if (promptCopy.Description?.Image != null)
                {
                    promptMessage.AttachmentLayout = AttachmentLayoutTypes.List;
                    var card = new HeroCard() { Title = promptCopy.Prompt, Images = new List<CardImage> { new CardImage(promptCopy.Description.Image) } };
                    promptMessage.Attachments = new List<Attachment> { card.ToAttachment() };
                }
            }
            else
            {
                promptMessage.Text = promptCopy.Prompt;
            }
            return hasPreamble;
        }

        internal static void AddRange<T>(this ICollection<T> collection, IEnumerable<T> enumerable)
        {
            foreach (var cur in enumerable)
            {
                collection.Add(cur);
            }
        }

        internal static IList<T> Clone<T>(this IList<T> listToClone) where T : ICloneable
        {
            return listToClone.Select(item => (T)item.Clone()).ToList();
        }
    }