From dd0be1e9690361e7086901b9f59378e1c74b3fce Mon Sep 17 00:00:00 2001
From: Trevi Awater <t.awater@resoftware.nl>
Date: Tue, 11 Jan 2022 00:22:50 +0100
Subject: [PATCH] Fixed error handling

---
 .../Xamarin.Neo4j/Services/Neo4jService.cs    | 32 ++++++++++++-----
 .../ViewModels/AddConnectionViewModel.cs      | 36 ++++---------------
 2 files changed, 30 insertions(+), 38 deletions(-)

diff --git a/Xamarin.Neo4j/Xamarin.Neo4j/Xamarin.Neo4j/Services/Neo4jService.cs b/Xamarin.Neo4j/Xamarin.Neo4j/Xamarin.Neo4j/Services/Neo4jService.cs
index ea4a0ef..365cbfc 100644
--- a/Xamarin.Neo4j/Xamarin.Neo4j/Xamarin.Neo4j/Services/Neo4jService.cs
+++ b/Xamarin.Neo4j/Xamarin.Neo4j/Xamarin.Neo4j/Services/Neo4jService.cs
@@ -25,25 +25,39 @@ namespace Xamarin.Neo4j.Services
 
         public async Task<bool> EstablishConnection(Neo4jConnectionString connectionString)
         {
-            var boltUri = $"bolt://{connectionString.Host}:{connectionString.Port}";
-
-            var driver = GraphDatabase.Driver(boltUri, AuthTokens.Basic(connectionString.Username, connectionString.Password), builder =>
-            {
-                builder.WithEncryptionLevel(connectionString.Encrypted ? EncryptionLevel.Encrypted : EncryptionLevel.None);
-            });
-
-            GraphClient = new BoltGraphClient(driver);
-
             try
             {
+                var boltUri = $"bolt://{connectionString.Host}:{connectionString.Port}";
+
+                var driver = GraphDatabase.Driver(boltUri,
+                    AuthTokens.Basic(connectionString.Username, connectionString.Password),
+                    builder =>
+                    {
+                        builder.WithEncryptionLevel(connectionString.Encrypted
+                            ? EncryptionLevel.Encrypted
+                            : EncryptionLevel.None);
+                    });
+
+                GraphClient = new BoltGraphClient(driver);
+
                 await GraphClient.ConnectAsync();
             }
 
+            catch (ServiceUnavailableException)
+            {
+                return false;
+            }
+
             catch (AuthenticationException)
             {
                 return false;
             }
 
+            catch (UriFormatException)
+            {
+                return false;
+            }
+
             return true;
         }
 
diff --git a/Xamarin.Neo4j/Xamarin.Neo4j/Xamarin.Neo4j/ViewModels/AddConnectionViewModel.cs b/Xamarin.Neo4j/Xamarin.Neo4j/Xamarin.Neo4j/ViewModels/AddConnectionViewModel.cs
index a75fc29..62758f9 100644
--- a/Xamarin.Neo4j/Xamarin.Neo4j/Xamarin.Neo4j/ViewModels/AddConnectionViewModel.cs
+++ b/Xamarin.Neo4j/Xamarin.Neo4j/Xamarin.Neo4j/ViewModels/AddConnectionViewModel.cs
@@ -43,8 +43,6 @@ namespace Xamarin.Neo4j.ViewModels
 
             Commands.Add("Test", new Command(async () =>
             {
-                if (!ValidateInput()) return;
-
                 var connectionString = BuildConnectionString();
 
                 var couldConnect = await _neo4jService.EstablishConnection(connectionString);
@@ -54,8 +52,6 @@ namespace Xamarin.Neo4j.ViewModels
 
             Commands.Add("Save", new Command(async () =>
             {
-                if (!ValidateInput()) return;
-
                 var connectionString = BuildConnectionString();
 
                 var namePromptResult = await UserDialogs.Instance.PromptAsync("How do you want to name this connection?", "Save Connection", "Save", "Cancel");
@@ -72,11 +68,15 @@ namespace Xamarin.Neo4j.ViewModels
 
             Commands.Add("Connect", new Command(async () =>
             {
-                if (!ValidateInput()) return;
-
                 var connectionString = BuildConnectionString();
 
-                await Navigation.PushAsync(new SessionPage(connectionString));
+                var couldConnect = await _neo4jService.EstablishConnection(connectionString);
+
+                if (couldConnect)
+                    await Navigation.PushAsync(new SessionPage(connectionString));
+
+                else
+                    await UserDialogs.Instance.AlertAsync( "Connection failed.");
             }));
         }
 
@@ -105,28 +105,6 @@ namespace Xamarin.Neo4j.ViewModels
             };
         }
 
-        private bool ValidateInput()
-        {
-            // Username and Password not checked because username- and passwordless connections are allowed
-
-            var ipRegex = new Regex(@"\b((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.|$)){4}\b");
-            var portRegex = new Regex(@"^([0-9]{1,4}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])$");
-
-            if (!ipRegex.IsMatch(Host))
-            {
-                UserDialogs.Instance.AlertAsync("Incorrect host format");
-                return false;
-            }
-
-            if (!portRegex.IsMatch(Port.ToString()))
-            {
-                UserDialogs.Instance.AlertAsync("Incorrect port format");
-                return false;
-            }
-
-            return true;
-        }
-        
         #region Bindable Properties
 
         public bool Encrypted