messengerapi/code/MessengerApi/Handlers/Endpoint/SendEndpointHandler.cs

using MessengerApi.Configuration.Model;
using MessengerApi.Contracts.Models.Scoped;
using MessengerApi.Db.Entities;
using MessengerApi.Models.Scoped;

namespace MessengerApi.Handlers.Endpoint
{
    public class SendEndpointHandler
    {
        private readonly MessengerConfiguration configuration;
        private readonly ILogger logger;

        private readonly Timing timing;
        private readonly Identity identity;
        private readonly IUnitOfWork unitOfWork;

        public SendEndpointHandler(
            MessengerConfiguration configuration,
            ILogger logger,
            IUnitOfWork unitOfWork,
            Timing timing,
            Identity identity)
        {
            this.configuration = configuration;
            this.logger = logger;
            this.unitOfWork = unitOfWork;
            this.timing = timing;
            this.identity = identity;
        }

        public Task<Message> SendMessage(
            Guid? toUserId,
            string payload,
            string payloadType,
            int? timeToLiveInSeconds)
        {
            // Authorize.
            var targetRecipientId = toUserId.HasValue
                ? this.identity.UserRoutes.Single(x => x.From.Id == this.identity.User.Id && x.To.Id == toUserId.Value).To.Id
                : this.identity.UserRoutes.Single().To.Id;

            this.logger.Debug($"[{this.timing.Timestamp:s}] User {this.identity.User.Name} is authorized to send message to {targetRecipientId}.");

            // Act.
            var message = new Message
            {
                Id = Guid.NewGuid(),
                CreatedUtc = this.timing.Timestamp,
                FromId = this.identity.User.Id,
                ToId = targetRecipientId,
                Payload = payload,
                PayloadType = payloadType,
                TimeToLiveInSeconds = timeToLiveInSeconds ?? (this.configuration.DefaultMessageTimeToLiveInSeconds)
            };

            this.unitOfWork.Messages.Add(message);
            return Task.FromResult(message);
        }
    }
}