Cleaned up connection management code

src/Microsoft.SqlTools.ServiceLayer/LanguageServices/IntellisenseCache.cs

@@ -0,0 +1,119 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.Collections.Generic;
+using System.Data;
+using System.Data.Common;
+using System.Threading.Tasks;
+using Microsoft.SqlTools.ServiceLayer.Connection;
+using Microsoft.SqlTools.ServiceLayer.Connection.Contracts;
+using Microsoft.SqlTools.ServiceLayer.LanguageServices.Contracts;
+using Microsoft.SqlTools.ServiceLayer.Workspace.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
+{
+
+    internal class IntellisenseCache
+    {
+        // connection used to query for intellisense info
+        private DbConnection connection;
+
+        // number of documents (URI's) that are using the cache for the same database
+        // the autocomplete service uses this to remove unreferenced caches
+        public int ReferenceCount { get; set; }
+
+        public IntellisenseCache(ISqlConnectionFactory connectionFactory, ConnectionDetails connectionDetails)
+        {
+            ReferenceCount = 0;
+            DatabaseInfo = connectionDetails.Clone();
+
+            // TODO error handling on this. Intellisense should catch or else the service should handle
+            connection = connectionFactory.CreateSqlConnection(ConnectionService.BuildConnectionString(connectionDetails));
+            connection.Open();
+        }
+
+        /// <summary>
+        /// Used to identify a database for which this cache is used
+        /// </summary>
+        public ConnectionSummary DatabaseInfo
+        {
+            get;
+            private set;
+        }
+        /// <summary>
+        /// Gets the current autocomplete candidate list
+        /// </summary>
+        public IEnumerable<string> AutoCompleteList { get; private set; }
+
+        public async Task UpdateCache()
+        {
+            DbCommand command = connection.CreateCommand();
+            command.CommandText = "SELECT name FROM sys.tables";
+            command.CommandTimeout = 15;
+            command.CommandType = CommandType.Text;
+            var reader = await command.ExecuteReaderAsync();
+
+            List<string> results = new List<string>();
+            while (await reader.ReadAsync())
+            {
+                results.Add(reader[0].ToString());
+            }
+
+            AutoCompleteList = results;
+            await Task.FromResult(0);
+        }
+
+        public List<CompletionItem> GetAutoCompleteItems(TextDocumentPosition textDocumentPosition)
+        {
+            List<CompletionItem> completions = new List<CompletionItem>();
+
+            int i = 0;
+
+            // Take a reference to the list at a point in time in case we update and replace the list
+            var suggestions = AutoCompleteList;
+            // the completion list will be null is user not connected to server
+            if (this.AutoCompleteList != null)
+            {
+
+                foreach (var autoCompleteItem in suggestions)
+                {
+                    // convert the completion item candidates into CompletionItems
+                    completions.Add(new CompletionItem()
+                    {
+                        Label = autoCompleteItem,
+                        Kind = CompletionItemKind.Keyword,
+                        Detail = autoCompleteItem + " details",
+                        Documentation = autoCompleteItem + " documentation",
+                        TextEdit = new TextEdit
+                        {
+                            NewText = autoCompleteItem,
+                            Range = new Range
+                            {
+                                Start = new Position
+                                {
+                                    Line = textDocumentPosition.Position.Line,
+                                    Character = textDocumentPosition.Position.Character
+                                },
+                                End = new Position
+                                {
+                                    Line = textDocumentPosition.Position.Line,
+                                    Character = textDocumentPosition.Position.Character + 5
+                                }
+                            }
+                        }
+                    });
+
+                    // only show 50 items
+                    if (++i == 50)
+                    {
+                        break;
+                    }
+                }
+            }
+
+            return completions;
+        }
+    }
+}