Fixing issues as per suggestions from @kevcunnane

src/Microsoft.SqlTools.ServiceLayer/Connection/ConnectionService.cs

@@ -0,0 +1,232 @@
+//
+// 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.Collections.Generic;
+using System.Data.Common;
+using System.Data.SqlClient;
+using System.Threading.Tasks;
+using Microsoft.SqlTools.EditorServices.Utility;
+using Microsoft.SqlTools.ServiceLayer.Connection.Contracts;
+using Microsoft.SqlTools.ServiceLayer.Hosting;
+using Microsoft.SqlTools.ServiceLayer.Hosting.Protocol;
+using Microsoft.SqlTools.ServiceLayer.SqlContext;
+using Microsoft.SqlTools.ServiceLayer.WorkspaceServices;
+
+namespace Microsoft.SqlTools.ServiceLayer.Connection
+{
+    /// <summary>
+    /// Main class for the Connection Management services
+    /// </summary>
+    public class ConnectionService
+    {
+        #region Singleton Instance Implementation
+
+        /// <summary>
+        /// Singleton service instance
+        /// </summary>
+        private static Lazy<ConnectionService> instance 
+            = new Lazy<ConnectionService>(() => new ConnectionService());
+
+        /// <summary>
+        /// Gets the singleton service instance
+        /// </summary>
+        public static ConnectionService Instance
+        {
+            get
+            {
+                return instance.Value;
+            }
+        }
+
+        /// <summary>
+        /// Default constructor is private since it's a singleton class
+        /// </summary>
+        private ConnectionService()
+        {
+        }
+
+        #endregion
+
+        #region Properties
+
+        /// <summary>
+        /// The SQL connection factory object
+        /// </summary>
+        private ISqlConnectionFactory connectionFactory;
+
+        /// <summary>
+        /// The current connection id that was previously used
+        /// </summary>
+        private int maxConnectionId = 0;
+
+        /// <summary>
+        /// Active connections lazy dictionary instance
+        /// </summary>
+        private readonly Lazy<Dictionary<int, DbConnection>> activeConnections
+            = new Lazy<Dictionary<int, DbConnection>>(() 
+                => new Dictionary<int, DbConnection>());
+          
+        /// <summary>
+        /// Callback for onconnection handler
+        /// </summary>
+        /// <param name="sqlConnection"></param>
+        public delegate Task OnConnectionHandler(DbConnection sqlConnection); 
+
+        /// <summary>
+        /// List of onconnection handlers
+        /// </summary>
+        private readonly List<OnConnectionHandler> onConnectionActivities = new List<OnConnectionHandler>(); 
+
+        /// <summary>
+        /// Gets the active connection map
+        /// </summary>
+        public Dictionary<int, DbConnection> ActiveConnections
+        {
+            get
+            {
+                return activeConnections.Value;
+            }
+        }
+
+        /// <summary>
+        /// Gets the SQL connection factory instance
+        /// </summary>
+        public ISqlConnectionFactory ConnectionFactory
+        {
+            get
+            {
+                if (this.connectionFactory == null)
+                {
+                    this.connectionFactory = new SqlConnectionFactory();
+                }
+                return this.connectionFactory;
+            }
+        }
+
+        #endregion
+
+        /// <summary>
+        /// Test constructor that injects dependency interfaces
+        /// </summary>
+        /// <param name="testFactory"></param>
+        public ConnectionService(ISqlConnectionFactory testFactory)
+        {
+            this.connectionFactory = testFactory;
+        }
+
+        #region Public Methods
+
+        /// <summary>
+        /// Open a connection with the specified connection details
+        /// </summary>
+        /// <param name="connectionDetails"></param>
+        public ConnectionResult Connect(ConnectionDetails connectionDetails)
+        {
+            // build the connection string from the input parameters
+            string connectionString = BuildConnectionString(connectionDetails);
+
+            // create a sql connection instance
+            DbConnection connection = this.ConnectionFactory.CreateSqlConnection(connectionString);
+
+            // open the database
+            connection.Open();
+
+            // map the connection id to the connection object for future lookups
+            this.ActiveConnections.Add(++maxConnectionId, connection);
+
+            // invoke callback notifications
+            foreach (var activity in this.onConnectionActivities)
+            {
+                activity(connection);
+            }
+
+            // return the connection result
+            return new ConnectionResult()
+            {
+                ConnectionId = maxConnectionId
+            };
+        }
+
+        public void InitializeService(ServiceHost serviceHost)
+        {
+            // Register request and event handlers with the Service Host
+            serviceHost.SetRequestHandler(ConnectionRequest.Type, HandleConnectRequest);
+
+            // Register the configuration update handler
+            WorkspaceService<SqlToolsSettings>.Instance.RegisterConfigChangeCallback(HandleDidChangeConfigurationNotification);
+        }
+
+        /// <summary> 
+        /// Add a new method to be called when the onconnection request is submitted 
+        /// </summary> 
+        /// <param name="activity"></param> 
+        public void RegisterOnConnectionTask(OnConnectionHandler activity) 
+        { 
+            onConnectionActivities.Add(activity); 
+        }
+
+        #endregion
+
+        #region Request Handlers
+
+        /// <summary>
+        /// Handle new connection requests
+        /// </summary>
+        /// <param name="connectionDetails"></param>
+        /// <param name="requestContext"></param>
+        /// <returns></returns>
+        protected async Task HandleConnectRequest(
+            ConnectionDetails connectionDetails,
+            RequestContext<ConnectionResult> requestContext)
+        {
+            Logger.Write(LogLevel.Verbose, "HandleConnectRequest");
+
+            try
+            {
+                // open connection base on request details
+                ConnectionResult result = ConnectionService.Instance.Connect(connectionDetails);
+                await requestContext.SendResult(result);
+            }
+            catch(Exception ex)
+            {
+                await requestContext.SendError(ex.Message);
+            }
+        }
+
+        #endregion
+
+        #region Handlers for Events from Other Services
+
+        public Task HandleDidChangeConfigurationNotification(
+            SqlToolsSettings newSettings, 
+            SqlToolsSettings oldSettings, 
+            EventContext eventContext)
+        {
+            return Task.FromResult(true);
+        }
+
+        #endregion
+
+        #region Private Helpers
+
+        /// <summary>
+        /// Build a connection string from a connection details instance
+        /// </summary>
+        /// <param name="connectionDetails"></param>
+        private string BuildConnectionString(ConnectionDetails connectionDetails)
+        {
+            SqlConnectionStringBuilder connectionBuilder = new SqlConnectionStringBuilder();
+            connectionBuilder["Data Source"] = connectionDetails.ServerName;
+            connectionBuilder["Integrated Security"] = false;
+            connectionBuilder["User Id"] = connectionDetails.UserName;
+            connectionBuilder["Password"] = connectionDetails.Password;
+            connectionBuilder["Initial Catalog"] = connectionDetails.DatabaseName;
+            return connectionBuilder.ToString();
+        }
+
+        #endregion
+    }
+}