Get Azure functions operation (#1228)

* add GetAzureFunctions

* add tests

* cleanup

* check for quotes

* address other comments

* add logging and let error result get sent

* rename file

src/Microsoft.SqlTools.ServiceLayer/AzureFunctions/GetAzureFunctionsOperation.cs

@@ -0,0 +1,76 @@
+//
+// 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.IO;
+using System.Linq;
+using System.Collections.Generic;
+using System.Diagnostics;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.SqlTools.ServiceLayer.AzureFunctions.Contracts;
+using Microsoft.SqlTools.Utility;
+using Microsoft.CodeAnalysis.CSharp;
+
+namespace Microsoft.SqlTools.ServiceLayer.AzureFunctions
+{
+    /// <summary>
+    /// Class to represent getting the Azure Functions in a file
+    /// </summary>
+    class GetAzureFunctionsOperation
+    {
+        const string functionAttributeText = "FunctionName";
+
+        public GetAzureFunctionsParams Parameters { get; }
+
+        public GetAzureFunctionsOperation(GetAzureFunctionsParams parameters)
+        {
+            Validate.IsNotNull("parameters", parameters);
+            this.Parameters = parameters;
+        }
+
+        /// <summary>
+        /// Gets the names of all the azure functions in a file
+        /// </summary>
+        /// <returns>the result of trying to get the names of all the Azure functions in a file</returns>
+        public GetAzureFunctionsResult GetAzureFunctions()
+        {
+            try
+            {
+                string text = File.ReadAllText(Parameters.filePath);
+
+                SyntaxTree tree = CSharpSyntaxTree.ParseText(text);
+                CompilationUnitSyntax root = tree.GetCompilationUnitRoot();
+
+                // Look for Azure Functions in the file
+                // Get all method declarations
+                IEnumerable<MethodDeclarationSyntax> methodDeclarations = root.DescendantNodes().OfType<MethodDeclarationSyntax>();
+
+                // get all the method declarations with the FunctionName attribute
+                IEnumerable<MethodDeclarationSyntax> methodsWithFunctionAttributes = methodDeclarations.Where(md => md.AttributeLists.Count > 0).Where(md => md.AttributeLists.Where(a => a.Attributes.Where(attr => attr.Name.ToString().Contains(functionAttributeText)).Count() == 1).Count() == 1);
+
+                // Get FunctionName attributes
+                IEnumerable<AttributeSyntax> functionNameAttributes = methodsWithFunctionAttributes.Select(md => md.AttributeLists.Select(a => a.Attributes.Where(attr => attr.Name.ToString().Contains(functionAttributeText)).First()).First());
+
+                // Get the function names in the FunctionName attributes
+                IEnumerable<AttributeArgumentSyntax> nameArgs = functionNameAttributes.Select(a => a.ArgumentList.Arguments.First());
+
+                // Remove quotes from around the names
+                string[] aFNames = nameArgs.Select(ab => ab.ToString().Trim('\"')).ToArray();
+
+                return new GetAzureFunctionsResult()
+                {
+                    Success = true,
+                    azureFunctions = aFNames
+                };
+            }
+            catch (Exception ex)
+            {
+                Logger.Write(TraceEventType.Information, $"Failed to get Azure functions. Error: {ex.Message}");
+                throw ex;
+            }
+        }
+    }
+}