Feature/reliable connection (#44)

* Initial commit of reliable connection port

* Made ReliableSqlConnection inherit from DbConnection instead of IDbConnection

* Cleanup

* Fixed autocomplete service to use reliable connection

* Fix copyright headers

* Renamed ConnectResponse.Server to ServerInfo

* Removed unused using

* Addressing code review feedback

src/Microsoft.SqlTools.ServiceLayer/Connection/ReliableConnection/DbConnectionWrapper.cs

@@ -0,0 +1,113 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using System.Data;
+using System.Data.SqlClient;
+using Microsoft.SqlTools.EditorServices.Utility;
+
+namespace Microsoft.SqlTools.ServiceLayer.Connection.ReliableConnection
+{
+    /// <summary>
+    /// Wraps <see cref="IDbConnection"/> objects that could be a <see cref="SqlConnection"/> or
+    /// a <see cref="ReliableSqlConnection"/>, providing common methods across both.
+    /// </summary>
+    internal sealed class DbConnectionWrapper
+    {
+        private readonly IDbConnection _connection;
+        private readonly bool _isReliableConnection;
+
+        public DbConnectionWrapper(IDbConnection connection)
+        {
+            Validate.IsNotNull(nameof(connection), connection);
+            if (connection is ReliableSqlConnection)
+            {
+                _isReliableConnection = true;
+            }
+            else if (!(connection is SqlConnection))
+            {
+                throw new InvalidOperationException(Resources.InvalidConnectionType);
+            }
+            
+            _connection = connection;
+        }
+
+        public static bool IsSupportedConnection(IDbConnection connection)
+        {
+            return connection is ReliableSqlConnection
+                || connection is SqlConnection;
+        }
+
+        public event SqlInfoMessageEventHandler InfoMessage
+        {
+            add
+            {
+                SqlConnection conn = GetAsSqlConnection();
+                conn.InfoMessage += value;
+            }
+            remove
+            {
+                SqlConnection conn = GetAsSqlConnection();
+                conn.InfoMessage -= value;
+            }
+        }
+
+        public string DataSource
+        {
+            get
+            {
+                if (_isReliableConnection)
+                {
+                    return ((ReliableSqlConnection) _connection).DataSource;
+                }
+                return ((SqlConnection)_connection).DataSource; 
+            }
+        }
+
+        public string ServerVersion
+        {
+            get
+            {
+                if (_isReliableConnection)
+                {
+                    return ((ReliableSqlConnection)_connection).ServerVersion;
+                }
+                return ((SqlConnection)_connection).ServerVersion; 
+            }
+        }
+
+        /// <summary>
+        /// Gets this as a SqlConnection by casting (if we know it is actually a SqlConnection)
+        /// or by getting the underlying connection (if it's a ReliableSqlConnection)
+        /// </summary>
+        public SqlConnection GetAsSqlConnection()
+        {
+            if (_isReliableConnection)
+            {
+                return ((ReliableSqlConnection) _connection).GetUnderlyingConnection();
+            }
+            return (SqlConnection) _connection;
+        }
+
+        /*
+        TODO - IClonable does not exist in .NET Core.
+        /// <summary>
+        /// Clones the connection and ensures it's opened. 
+        /// If it's a SqlConnection it will clone it,
+        /// and for ReliableSqlConnection it will clone the underling connection.
+        /// The reason the entire ReliableSqlConnection is not cloned is that it includes
+        /// several callbacks and we don't want to try and handle deciding how to clone these
+        /// yet.
+        /// </summary>
+        public SqlConnection CloneAndOpenConnection()
+        {
+            SqlConnection conn = GetAsSqlConnection();
+            SqlConnection clonedConn = ((ICloneable) conn).Clone() as SqlConnection;
+            clonedConn.Open();
+            return clonedConn;
+        }
+        */
+    }
+}