Transaction mechanism implemented. UI improved.

QRBee.Core/Client/Client.cs

@@ -205,6 +205,77 @@ namespace QRBee.Core.Client
             }
         }
 
+        /// <returns>Success</returns>
+        /// <exception cref="ApiException">A server side error occurred.</exception>
+        public virtual System.Threading.Tasks.Task InsertTransactionAsync(PaymentRequest body)
+        {
+            return InsertTransactionAsync(body, System.Threading.CancellationToken.None);
+        }
+
+        /// <param name="cancellationToken">A cancellation token that can be used by other objects or threads to receive notice of cancellation.</param>
+        /// <returns>Success</returns>
+        /// <exception cref="ApiException">A server side error occurred.</exception>
+        public virtual async System.Threading.Tasks.Task InsertTransactionAsync(PaymentRequest body, System.Threading.CancellationToken cancellationToken)
+        {
+            var urlBuilder_ = new System.Text.StringBuilder();
+            urlBuilder_.Append(BaseUrl != null ? BaseUrl.TrimEnd('/') : "").Append("/api/QRBee/InsertTransaction");
+
+            var client_ = _httpClient;
+            var disposeClient_ = false;
+            try
+            {
+                using (var request_ = new System.Net.Http.HttpRequestMessage())
+                {
+                    var content_ = new System.Net.Http.StringContent(Newtonsoft.Json.JsonConvert.SerializeObject(body, _settings.Value));
+                    content_.Headers.ContentType = System.Net.Http.Headers.MediaTypeHeaderValue.Parse("application/json");
+                    request_.Content = content_;
+                    request_.Method = new System.Net.Http.HttpMethod("POST");
+
+                    PrepareRequest(client_, request_, urlBuilder_);
+
+                    var url_ = urlBuilder_.ToString();
+                    request_.RequestUri = new System.Uri(url_, System.UriKind.RelativeOrAbsolute);
+
+                    PrepareRequest(client_, request_, url_);
+
+                    var response_ = await client_.SendAsync(request_, System.Net.Http.HttpCompletionOption.ResponseHeadersRead, cancellationToken).ConfigureAwait(false);
+                    var disposeResponse_ = true;
+                    try
+                    {
+                        var headers_ = System.Linq.Enumerable.ToDictionary(response_.Headers, h_ => h_.Key, h_ => h_.Value);
+                        if (response_.Content != null && response_.Content.Headers != null)
+                        {
+                            foreach (var item_ in response_.Content.Headers)
+                                headers_[item_.Key] = item_.Value;
+                        }
+
+                        ProcessResponse(client_, response_);
+
+                        var status_ = (int)response_.StatusCode;
+                        if (status_ == 200)
+                        {
+                            return;
+                        }
+                        else
+                        {
+                            var responseData_ = response_.Content == null ? null : await response_.Content.ReadAsStringAsync().ConfigureAwait(false);
+                            throw new ApiException("The HTTP status code of the response was not expected (" + status_ + ").", status_, responseData_, headers_, null);
+                        }
+                    }
+                    finally
+                    {
+                        if (disposeResponse_)
+                            response_.Dispose();
+                    }
+                }
+            }
+            finally
+            {
+                if (disposeClient_)
+                    client_.Dispose();
+            }
+        }
+
         protected struct ObjectResponseResult<T>
         {
             public ObjectResponseResult(T responseObject, string responseText)

QRBee.Core/Data/ClientToMerchantResponse.cs

@@ -2,7 +2,7 @@
 {
     public record ClientToMerchantResponse
     {
-        public MerchantToClientRequest Request
+        public MerchantToClientRequest MerchantRequest
         {
             get;
             set;
@@ -36,7 +36,7 @@
         /// Convert ClientToMerchantResponse to string to be used as QR Code source (along with client signature)
         /// </summary>
         /// <returns> Converted string</returns>
-        public string AsString() => $"{ClientId}|{TimeStampUTC:O}|{Request.AsString()}";
+        public string AsQRCodeString() => $"{ClientId}|{TimeStampUTC:O}|{MerchantRequest.AsQRCodeString()}";
 
         /// <summary>
         /// Convert from string
@@ -47,14 +47,14 @@
         public static ClientToMerchantResponse FromString(string input)
         {
             var s = input.Split('|');
-            if (s.Length != 3)
+            if (s.Length < 3)
             {
-                throw new ApplicationException("Expected 3 elements");
+                throw new ApplicationException("Expected 3 or more elements");
             }
 
             var res = new ClientToMerchantResponse()
             {
-                Request = MerchantToClientRequest.FromString(string.Join("|", s.Skip(2))),
+                MerchantRequest = MerchantToClientRequest.FromString(string.Join("|", s.Skip(2))),
                 ClientId = s[0],
                 TimeStampUTC = DateTime.ParseExact(s[1], "O", null)
             };

QRBee.Core/Data/MerchantToClientRequest.cs

@@ -4,7 +4,13 @@ namespace QRBee.Core.Data
 {
     public record MerchantToClientRequest
     {
-        public string TransactionId
+        public string MerchantId
+        {
+            get;
+            set;
+        }
+
+        public string MerchantTransactionId
         {
             get;
             set;
@@ -38,7 +44,7 @@ namespace QRBee.Core.Data
         /// Convert MerchantToClientRequest to string to be used as QR Code source (along with merchant signature)
         /// </summary>
         /// <returns>String conversion</returns>
-        public string AsString() => $"{TransactionId}|{Name}|{Amount.ToString("0.00", CultureInfo.InvariantCulture)}|{TimeStampUTC:O}";
+        public string AsQRCodeString() => $"{MerchantTransactionId}|{MerchantId}|{Name}|{Amount.ToString("0.00", CultureInfo.InvariantCulture)}|{TimeStampUTC:O}";
 
         /// <summary>
         /// Convert from string
@@ -49,17 +55,18 @@ namespace QRBee.Core.Data
         public static MerchantToClientRequest FromString(string input)
         {
             var s = input.Split('|');
-            if (s.Length != 4)
+            if (s.Length != 5)
             {
-                throw new ApplicationException("Expected 4 elements");
+                throw new ApplicationException("Expected 5 elements");
             }
 
             var res = new MerchantToClientRequest
             {
-                TransactionId = s[0],
+                MerchantId = s[0],
-                Name = s[1],
+                MerchantTransactionId = s[1],
-                Amount = Convert.ToDecimal(s[2], CultureInfo.InvariantCulture),
+                Name = s[2],
-                TimeStampUTC = DateTime.ParseExact(s[3],"O",null)
+                Amount = Convert.ToDecimal(s[3], CultureInfo.InvariantCulture),
+                TimeStampUTC = DateTime.ParseExact(s[4],"O",null)
             };
 
 

QRBee.Core/Data/PaymentRequest.cs

@@ -3,7 +3,7 @@
     public record PaymentRequest
     {
 
-        public ClientToMerchantResponse Request
+        public ClientToMerchantResponse ClientResponse
         {
             get;
             set;
@@ -13,7 +13,18 @@
         /// Convert PaymentRequest to string
         /// </summary>
         /// <returns>Converted string</returns>
-        public string AsString() => Request.AsString();
+        public string AsString() => ClientResponse.AsQRCodeString();
 
+        public static PaymentRequest FromString(string input)
+        {
+            if (string.IsNullOrWhiteSpace(input))
+            {
+                throw new ApplicationException("The input is wrong!");
+            }
+
+            //doesn't work
+            var response = ClientToMerchantResponse.FromString(input);
+            return new PaymentRequest(){ClientResponse = response};
+        }
     }
 }

QRBee/QRBee/ViewModels/ClientPageViewModel.cs

@@ -37,13 +37,13 @@ namespace QRBee.ViewModels
             {
                 var scanner = DependencyService.Get<IQRScanner>();
                 var result = await scanner.ScanQR();
-                if (result != null)
+                if (result == null) 
-                {
+                    return;
+
                 _merchantToClientRequest = MerchantToClientRequest.FromString(result);
                 Amount = $"{_merchantToClientRequest.Amount:N2}";
                 IsVisible = true;
             }
-            }
             catch (Exception)
             {
                 await Application.Current.MainPage.DisplayAlert("Error","Wrong QR code scanned","Ok");
@@ -99,19 +99,20 @@ namespace QRBee.ViewModels
         public async void OnGenerateQrClicked(object obj)
         {
 
-            bool answer = await _clientPage.DisplayAlert("Confirmation", "Would you like to accept the offer?", "Yes", "No");
+            var answer = await _clientPage.DisplayAlert("Confirmation", "Would you like to accept the offer?", "Yes", "No");
-            if (answer)
+            if (!answer) 
-            {
+                return;
+
             var response = new ClientToMerchantResponse
             {
+                //TODO get client id from database
                 ClientId = Guid.NewGuid().ToString("D"),
                 TimeStampUTC = DateTime.UtcNow,
-                    Request = _merchantToClientRequest
+                MerchantRequest = _merchantToClientRequest
                     
             };
             // TODO Create merchant signature.
-                QrCode = response.AsString();
+            QrCode = response.AsQRCodeString();
-            }
 
 
         }

QRBee/QRBee/ViewModels/MerchantPageViewModel.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Linq;
+using System.Net.Http;
 using QRBee.Core.Data;
 using QRBee.Services;
 using Xamarin.Forms;
@@ -29,17 +30,43 @@ namespace QRBee.ViewModels
             {
                 var scanner = DependencyService.Get<IQRScanner>();
                 var result = await scanner.ScanQR();
-                if (result != null)
+                if (result == null) 
-                {
+                    return;
 
+                var client = new HttpClient(GetInsecureHandler());
+                var localSettings = DependencyService.Resolve<ILocalSettings>();
+
+                var service = new Core.Client.Client(localSettings.QRBeeApiUrl, client);
+                var paymentRequest = PaymentRequest.FromString(result);
+
+                //QrCode = null;
+                IsVisible = false;
+
+                await service.InsertTransactionAsync(paymentRequest);
+
+                await Application.Current.MainPage.DisplayAlert("Success", "The transaction completed successfully ", "Ok");
             }
-            }
+            catch (Exception e)
-            catch (Exception ex)
             {
-                throw;
+                //TODO: delete exception message in error message
+                await Application.Current.MainPage.DisplayAlert("Error", $"The Backend isn't working: {e.Message}", "Ok");
             }
         }
 
+        // This method must be in a class in a platform project, even if
+        // the HttpClient object is constructed in a shared project.
+        public HttpClientHandler GetInsecureHandler()
+        {
+            var handler = new HttpClientHandler();
+            handler.ServerCertificateCustomValidationCallback = (message, cert, chain, errors) =>
+            {
+                if (cert.Issuer.Equals("CN=localhost"))
+                    return true;
+                return errors == System.Net.Security.SslPolicyErrors.None;
+            };
+            return handler;
+        }
+
         public string Name { get; }
 
         public decimal Amount
@@ -98,13 +125,15 @@ namespace QRBee.ViewModels
             {
                 var trans = new MerchantToClientRequest
                 {
-                    TransactionId = Guid.NewGuid().ToString("D"),
+                    //TODO get merchant id from database
+                    MerchantId = Guid.NewGuid().ToString("D"),
+                    MerchantTransactionId = Guid.NewGuid().ToString("D"),
                     Name = Name,
                     Amount = Amount,
                     TimeStampUTC = DateTime.UtcNow
                 };
                 // TODO Create merchant signature.
-                QrCode = trans.AsString();
+                QrCode = trans.AsQRCodeString();
                 IsVisible = true;
             }
 

QRBee/QRBee/ViewModels/RegisterViewModel.cs

@@ -94,7 +94,8 @@ namespace QRBee.ViewModels
 
         private async void OnRegisterClicked(object obj)
         {
-            using var client = new HttpClient(GetInsecureHandler());
+            //TODO when to dispose the client?
+            var client = new HttpClient(GetInsecureHandler());
             var localSettings = DependencyService.Resolve<ILocalSettings>();
 
             var service = new Core.Client.Client(localSettings.QRBeeApiUrl,client);

QRBee/QRBee/Views/MerchantPage.xaml

@@ -27,7 +27,8 @@
                     BarcodeFormat="QR_CODE"
                     BarcodeValue="{Binding QrCode}"
                     HorizontalOptions="FillAndExpand"
-                    VerticalOptions="FillAndExpand">
+                    VerticalOptions="FillAndExpand"
+                    IsVisible="{Binding IsVisible}">
                     <forms:ZXingBarcodeImageView.BarcodeOptions>
                         <common:EncodingOptions Width="300" Height="300" />
                     </forms:ZXingBarcodeImageView.BarcodeOptions>

QRBeeApi/Controllers/QRBeeController.cs

@@ -34,5 +34,12 @@ namespace QRBee.Api.Controllers
             _logger.LogInformation($"Trying to update user {value.Name}");
             return _service.Update(clientId,value);
         }
+
+        [HttpPost("InsertTransaction")]
+        public Task InsertTransaction([FromBody] PaymentRequest value)
+        {
+            _logger.LogInformation($"Trying to insert new transaction {value.ClientResponse.MerchantRequest.MerchantTransactionId}");
+            return _service.InsertTransaction(value);
+        }
     }
 }

QRBeeApi/Services/Database/IStorage.cs

@@ -9,7 +9,6 @@
         /// Insert userInfo into database
         /// </summary>
         /// <param name="info"> Information to be inserted</param>
-        /// <returns></returns>
         Task<string> PutUserInfo(UserInfo info);
 
         /// <summary>
@@ -19,7 +18,17 @@
         /// <returns>User information</returns>
         Task<UserInfo> GetUserInfo(string email);
 
+        /// <summary>
+        /// Update user record
+        /// </summary>
+        /// <param name="info">New user record</param>
+        /// <returns></returns>
         Task UpdateUser(UserInfo info);
 
+        /// <summary>
+        /// Insert transactionInfo into database
+        /// </summary>
+        /// <param name="info">Information to be inserted</param>
+        Task PutTransactionInfo(TransactionInfo info);
     }
 }

QRBeeApi/Services/Database/Storage.cs

@@ -68,5 +68,37 @@ namespace QRBee.Api.Services.Database
             await collection.ReplaceOneAsync($"{{ _id: \"{info.Id}\" }}",info, new ReplaceOptions(){IsUpsert = false});
         }
 
+        public async Task PutTransactionInfo(TransactionInfo info)
+        {
+            var collection = _database.GetCollection<TransactionInfo>("Transactions");
+
+            var transaction = await TryGetTransactionInfo(info.Id);
+
+            if (transaction == null)
+            {
+                await collection.InsertOneAsync(info);
+                _logger.LogInformation($"Inserted new transaction with ID: {info.Id}");
+                return;
+            }
+
+            _logger.LogInformation($"Found transaction with ClientId: {info.Id}");
+        }
+
+        /// <summary>
+        /// Try to find if the Transaction already exists in the database
+        /// </summary>
+        /// <param name="id">parameter by which to find TransactionInfo</param>
+        /// <returns>null if transaction doesn't exist or TransactionInfo</returns>
+        private async Task<TransactionInfo?> TryGetTransactionInfo(string id)
+        {
+            var collection = _database.GetCollection<TransactionInfo>("Transactions");
+            using var cursor = await collection.FindAsync($"{{ Id: \"{id}\" }}");
+            if (!await cursor.MoveNextAsync())
+            {
+                return null;
+            }
+
+            return cursor.Current.FirstOrDefault();
+        }
     }
 }

QRBeeApi/Services/Database/TransactionInfo.cs

@@ -0,0 +1,38 @@
+using MongoDB.Bson;
+using MongoDB.Bson.Serialization.Attributes;
+using QRBee.Core.Data;
+
+namespace QRBee.Api.Services.Database
+{
+    public record TransactionInfo
+    {
+        
+#pragma warning disable CS8618
+        public TransactionInfo()
+#pragma warning restore CS8618
+        {
+
+        }
+
+        public TransactionInfo(PaymentRequest request, DateTime serverTimeStamp)
+        {
+            //TODO This is a side effect. The original request will be modified.
+            request.ClientResponse.EncryptedClientCardData = null;
+
+            ServerTimeStamp = serverTimeStamp;
+            Request = request;
+            Id = $"{request.ClientResponse.MerchantRequest.MerchantId}-{request.ClientResponse.MerchantRequest.MerchantTransactionId}";
+        }
+
+        /// <summary>
+        /// Never use directly. Use <see cref="TransactionId"/> instead.
+        /// </summary>
+        [BsonId] public string Id { get; set; }
+
+        [BsonIgnore] public string? TransactionId => Id;
+        public DateTime ServerTimeStamp { get; set; }
+
+        public PaymentRequest Request { get; set; }
+
+    }
+}

QRBeeApi/Services/IQRBeeAPI.cs

@@ -23,5 +23,11 @@ namespace QRBee.Api.Services
         /// <param name="value">Update request</param>
         Task Update(string clientId, RegistrationRequest value);
 
+        /// <summary>
+        /// Handles InsertTransaction request
+        /// </summary>
+        /// <param name="value">Payment request</param>
+        Task InsertTransaction(PaymentRequest value);
+
     }
 }

QRBeeApi/Services/QRBeeAPI.cs

@@ -39,6 +39,12 @@ namespace QRBee.Api.Services
             return _storage.UpdateUser(info);
         }
 
+        public Task InsertTransaction(PaymentRequest value)
+        {
+            var info = Convert(value);
+            return _storage.PutTransactionInfo(info);
+        }
+
         private static void Validate(RegistrationRequest request)
         {
             if (request == null)
@@ -77,5 +83,10 @@ namespace QRBee.Api.Services
             return new UserInfo(request.Name, request.Email, request.DateOfBirth);
         }
 
+        private static TransactionInfo Convert(PaymentRequest request)
+        {
+            return new TransactionInfo(request, DateTime.UtcNow);
+        }
+
     }
 }