MessagesController.cs

namespace CreateNewConversationBot
{
    using System;
    using System.Net;
    using System.Net.Http;
    using System.Threading;
    using System.Threading.Tasks;
    using System.Web.Http;
    using Autofac;
    using Microsoft.Bot.Builder.Dialogs;
    using Microsoft.Bot.Builder.Dialogs.Internals;
    using Microsoft.Bot.Builder.Internals.Fibers;
    using Microsoft.Bot.Connector;
    using Microsoft.Rest;

    [BotAuthentication]
    public class MessagesController : ApiController
    {
        private readonly ILifetimeScope scope;

        public MessagesController(ILifetimeScope scope)
        {
            SetField.NotNull(out this.scope, nameof(scope), scope);
        }

        /// <summary>
        /// POST: api/Messages
        /// Receive a message from a user and reply to it
        /// </summary>
        public async Task<HttpResponseMessage> Post([FromBody]Activity activity, CancellationToken token)
        {
            if (activity.Type == ActivityTypes.Message)
            {
                using (var scope = DialogModule.BeginLifetimeScope(this.scope, activity))
                {
                    ConnectorClient client = new ConnectorClient(new Uri(activity.ServiceUrl));

                    ResourceResponse conversation;

                    try
                    {
                        conversation = await client.Conversations.CreateDirectConversationAsync(activity.Recipient, activity.From);
                    }
                    catch (HttpOperationException ex)
                    {
                        var reply = activity.CreateReply();
                        reply.Text = ex.Message;

                        await client.Conversations.SendToConversationAsync(reply);

                        return new HttpResponseMessage(HttpStatusCode.Accepted);
                    }

                    var cookie = scope.Resolve<ResumptionCookie>();
                    cookie.Address = new Address(cookie.Address.BotId, cookie.Address.ChannelId, cookie.Address.UserId, conversation.Id, cookie.Address.ServiceUrl);

                    var postToBot = scope.Resolve<IPostToBot>();
                    await postToBot.PostAsync(activity, token);
                }
            }
            else
            {
                this.HandleSystemMessage(activity);
            }

            return new HttpResponseMessage(HttpStatusCode.Accepted);
        }

        private Activity HandleSystemMessage(Activity message)
        {
            if (message.Type == ActivityTypes.DeleteUserData)
            {
                // Implement user deletion here
                // If we handle user deletion, return a real message
            }
            else if (message.Type == ActivityTypes.ConversationUpdate)
            {
                // Handle conversation state changes, like members being added and removed
                // Use Activity.MembersAdded and Activity.MembersRemoved and Activity.Action for info
                // Not available in all channels
            }
            else if (message.Type == ActivityTypes.ContactRelationUpdate)
            {
                // Handle add/remove from contact lists
                // Activity.From + Activity.Action represent what happened
            }
            else if (message.Type == ActivityTypes.Typing)
            {
                // Handle knowing tha the user is typing
            }
            else if (message.Type == ActivityTypes.Ping)
            {
            }

            return null;
        }
    }
}