Create MS.SqlTools.Credentials project (#249)

* Initial credential service files

* Clean-up hostloader

* Update build scripts to build credentials archive

* Move hosting files to new assembly

* Add credentials files to MS.SqlTools.Credentials

* Remove duplicate files

* Update namespace in program.cs

* Fix test build breaks

* Update extensions visibility.

* Remove unused resource strings

* Add xproj files to SLN for appveyor builds

* Fix appveyor build break in test project

* Fix extensibility tests

* Fix various typos in latest iteration

* Add settings for Integration build

* Fix codecoverage.bat to use full pdb for new projects

* Fix bug when packing in folder with native images

* Fix typos in xproj

* Reset XLF to fix build.cmd

src/Microsoft.SqlTools.Hosting/Extensibility/ExtensionServiceProvider.cs

@@ -0,0 +1,205 @@
+//
+// 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;
+using System.Collections.Generic;
+using System.Composition.Convention;
+using System.Composition.Hosting;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.Loader;
+using Microsoft.Extensions.DependencyModel;
+using Microsoft.SqlTools.ServiceLayer.Utility;
+
+namespace Microsoft.SqlTools.ServiceLayer.Extensibility
+{
+    public class ExtensionServiceProvider : RegisteredServiceProvider
+    {
+        private Func<ConventionBuilder, ContainerConfiguration> config;
+
+        public ExtensionServiceProvider(Func<ConventionBuilder, ContainerConfiguration> config)
+        {
+            Validate.IsNotNull(nameof(config), config);
+            this.config = config;
+        }
+
+        public static ExtensionServiceProvider CreateDefaultServiceProvider()
+        {
+            string assemblyPath = typeof(ExtensionStore).GetTypeInfo().Assembly.Location;
+            string directory = Path.GetDirectoryName(assemblyPath);
+            
+            AssemblyLoadContext context = new AssemblyLoader(directory);
+            var assemblyPaths = Directory.GetFiles(directory, "*.dll", SearchOption.TopDirectoryOnly);
+
+            List<Assembly> assemblies = new List<Assembly>();
+            foreach (var path in assemblyPaths)
+            {
+                try
+                {
+                    assemblies.Add(
+                        context.LoadFromAssemblyName(
+                            AssemblyLoadContext.GetAssemblyName(path)));
+                }
+                catch (System.BadImageFormatException)
+                {
+                    // we expect exceptions trying to scan all DLLs since directory contains native libraries
+                }
+            }
+
+            return Create(assemblies);
+        }
+
+        public static ExtensionServiceProvider Create(IEnumerable<Assembly> assemblies)
+        {
+            Validate.IsNotNull(nameof(assemblies), assemblies);
+            return new ExtensionServiceProvider(conventions => new ContainerConfiguration().WithAssemblies(assemblies, conventions));
+        }
+
+        public static ExtensionServiceProvider Create(IEnumerable<Type> types)
+        {
+            Validate.IsNotNull(nameof(types), types);
+            return new ExtensionServiceProvider(conventions => new ContainerConfiguration().WithParts(types, conventions));
+        }
+
+        protected override IEnumerable<T> GetServicesImpl<T>()
+        {
+            EnsureExtensionStoreRegistered<T>();
+            return base.GetServicesImpl<T>();
+        }
+
+        private void EnsureExtensionStoreRegistered<T>()
+        {
+            if (!services.ContainsKey(typeof(T)))
+            {
+                ExtensionStore store = new ExtensionStore(typeof(T), config);
+                base.Register<T>(() => store.GetExports<T>());
+            }
+        }
+    }
+    
+    /// <summary>
+    /// A store for MEF exports of a specific type. Provides basic wrapper functionality around MEF to standarize how
+    /// we lookup types and return to callers.
+    /// </summary>
+    public class ExtensionStore
+    {
+        private CompositionHost host;
+        private IList exports;
+        private Type contractType;
+        
+        /// <summary>
+        /// Initializes the store with a type to lookup exports of, and a function that configures the
+        /// lookup parameters.
+        /// </summary>
+        /// <param name="contractType">Type to use as a base for all extensions being looked up</param>
+        /// <param name="configure">Function that returns the configuration to be used</param>
+        public ExtensionStore(Type contractType, Func<ConventionBuilder, ContainerConfiguration> configure)
+        {
+            Validate.IsNotNull(nameof(contractType), contractType);
+            Validate.IsNotNull(nameof(configure), configure);
+            this.contractType = contractType;
+            ConventionBuilder builder = GetExportBuilder();
+            ContainerConfiguration config = configure(builder);
+            host = config.CreateContainer();
+        }
+
+        /// <summary>
+        /// Loads extensions from the current assembly
+        /// </summary>
+        /// <returns>ExtensionStore</returns>
+        public static ExtensionStore CreateDefaultLoader<T>()
+        {
+            return CreateAssemblyStore<T>(typeof(ExtensionStore).GetTypeInfo().Assembly);
+        }
+        
+        public static ExtensionStore CreateAssemblyStore<T>(Assembly assembly)
+        {
+            Validate.IsNotNull(nameof(assembly), assembly);
+            return new ExtensionStore(typeof(T), (conventions) =>
+                new ContainerConfiguration().WithAssembly(assembly, conventions));
+        }
+
+        public static ExtensionStore CreateStoreForCurrentDirectory<T>()
+        {
+            string assemblyPath = typeof(ExtensionStore).GetTypeInfo().Assembly.Location;
+            string directory = Path.GetDirectoryName(assemblyPath);
+            return new ExtensionStore(typeof(T), (conventions) => 
+                new ContainerConfiguration().WithAssembliesInPath(directory, conventions));
+        }
+
+        public IEnumerable<T> GetExports<T>()
+        {
+            if (exports == null)
+            {
+                exports = host.GetExports(contractType).ToList();
+            }
+            return exports.Cast<T>();
+        }
+        
+        private ConventionBuilder GetExportBuilder()
+        {
+            // Define exports as matching a parent type, export as that parent type
+            var builder = new ConventionBuilder();
+            builder.ForTypesDerivedFrom(contractType).Export(exportConventionBuilder  => exportConventionBuilder.AsContractType(contractType));
+            return builder;
+        }
+    }
+    
+    public static class ContainerConfigurationExtensions
+    {
+        public static ContainerConfiguration WithAssembliesInPath(this ContainerConfiguration configuration, string path, SearchOption searchOption = SearchOption.TopDirectoryOnly)
+        {
+            return WithAssembliesInPath(configuration, path, null, searchOption);
+        }
+
+        public static ContainerConfiguration WithAssembliesInPath(this ContainerConfiguration configuration, string path, AttributedModelProvider conventions, SearchOption searchOption = SearchOption.TopDirectoryOnly)
+        {
+            AssemblyLoadContext context = new AssemblyLoader(path);
+            var assemblyNames = Directory
+                .GetFiles(path, "*.dll", searchOption)
+                .Select(AssemblyLoadContext.GetAssemblyName);
+
+            var assemblies = assemblyNames
+                .Select(context.LoadFromAssemblyName)
+                .ToList();
+
+            configuration = configuration.WithAssemblies(assemblies, conventions);
+
+            return configuration;
+        }
+    }
+
+    public class AssemblyLoader : AssemblyLoadContext
+    {
+        private string folderPath;
+
+        public AssemblyLoader(string folderPath)
+        {
+            this.folderPath = folderPath;
+        }
+
+        protected override Assembly Load(AssemblyName assemblyName)
+        {
+            var deps = DependencyContext.Default;
+            var res = deps.CompileLibraries.Where(d => d.Name.Equals(assemblyName.Name)).ToList();
+            if (res.Count > 0)
+            {
+                return Assembly.Load(new AssemblyName(res.First().Name));
+            }
+            else
+            {
+                var apiApplicationFileInfo = new FileInfo($"{folderPath}{Path.DirectorySeparatorChar}{assemblyName.Name}.dll");
+                if (File.Exists(apiApplicationFileInfo.FullName))
+                {
+                    var asl = new AssemblyLoader(apiApplicationFileInfo.DirectoryName);
+                    return asl.LoadFromAssemblyPath(apiApplicationFileInfo.FullName);
+                }
+            }
+            return Assembly.Load(assemblyName);
+        }
+    }
+}

src/Microsoft.SqlTools.Hosting/Extensibility/IComposableService.cs

@@ -0,0 +1,22 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+
+namespace Microsoft.SqlTools.ServiceLayer.Extensibility
+{
+    /// <summary>
+    /// A Service that expects to lookup other services. Using this interface on an exported service
+    /// will ensure the <see cref="SetServiceProvider(IMultiServiceProvider)"/> method is called during
+    /// service initialization
+    /// </summary>
+    public interface IComposableService
+    {
+        /// <summary>
+        /// Supports settings the service provider being used to initialize the service.
+        /// This is useful to look up other services and use them in your own service.
+        /// </summary>
+        void SetServiceProvider(IMultiServiceProvider provider);
+    }
+}

src/Microsoft.SqlTools.Hosting/Extensibility/IEnumerableExt.cs

@@ -0,0 +1,18 @@
+//
+// 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;
+
+namespace Microsoft.SqlTools.ServiceLayer.Extensibility
+{
+
+    internal static class IEnumerableExt
+    {
+        public static IEnumerable<T> SingleItemAsEnumerable<T>(this T item)
+        {
+            yield return item;
+        }
+    }
+}

src/Microsoft.SqlTools.Hosting/Extensibility/IMultiServiceProvider.cs

@@ -0,0 +1,104 @@
+//
+// 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.Linq;
+using Microsoft.SqlTools.ServiceLayer.Utility;
+
+namespace Microsoft.SqlTools.ServiceLayer.Extensibility
+{
+    public interface IMultiServiceProvider
+    {
+        /// <summary>
+        /// Gets a service of a specific type. It is expected that only 1 instance of this type will be
+        /// available
+        /// </summary>
+        /// <typeparam name="T">Type of service to be found</typeparam>
+        /// <returns>Instance of T or null if not found</returns>
+        /// <exception cref="InvalidOperationException">The input sequence contains more than one element.-or-The input sequence is empty.</exception>
+        T GetService<T>();
+
+        /// <summary>
+        /// Gets a service of a specific type. The first service matching the specified filter will be returned
+        /// available
+        /// </summary>
+        /// <typeparam name="T">Type of service to be found</typeparam>
+        /// <param name="filter">Filter to use in </param>
+        /// <returns>Instance of T or null if not found</returns>
+        /// <exception cref="InvalidOperationException">The input sequence contains more than one element.-or-The input sequence is empty.</exception>
+        T GetService<T>(Predicate<T> filter);
+
+        /// <summary>
+        /// Gets multiple services of a given type
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <returns>An enumerable of matching services</returns>
+        IEnumerable<T> GetServices<T>();
+
+        /// <summary>
+        /// Gets multiple services of a given type, where they match a filter
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <param name="filter"></param>
+        /// <returns></returns>
+        IEnumerable<T> GetServices<T>(Predicate<T> filter);
+    }
+    
+    
+    public abstract class ServiceProviderBase : IMultiServiceProvider
+    {
+
+        public T GetService<T>()
+        {
+            return GetServices<T>().SingleOrDefault();
+        }
+
+        public T GetService<T>(Predicate<T> filter)
+        {
+            Validate.IsNotNull(nameof(filter), filter);
+            return GetServices<T>().Where(t => filter(t)).SingleOrDefault();
+        }
+
+        public IEnumerable<T> GetServices<T>(Predicate<T> filter)
+        {
+            Validate.IsNotNull(nameof(filter), filter);
+            return GetServices<T>().Where(t => filter(t));
+        }
+
+        public virtual IEnumerable<T> GetServices<T>()
+        {
+            var services = GetServicesImpl<T>();
+            if (services == null)
+            {
+                return Enumerable.Empty<T>();
+            }
+
+            return services.Select(t =>
+            {
+                InitComposableService(t);
+                return t;
+            });
+        }
+
+        private void InitComposableService<T>(T t)
+        {
+            IComposableService c = t as IComposableService;
+            if (c != null)
+            {
+                c.SetServiceProvider(this);
+            }
+        }
+        
+        /// <summary>
+        /// Gets all services using the build in implementation
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <returns></returns>
+        protected abstract IEnumerable<T> GetServicesImpl<T>();
+
+    }
+
+}

src/Microsoft.SqlTools.Hosting/Extensibility/RegisteredServiceProvider.cs

@@ -0,0 +1,111 @@
+//
+// 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;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Reflection;
+using Microsoft.SqlTools.Hosting;
+using Microsoft.SqlTools.ServiceLayer.Utility;
+
+namespace Microsoft.SqlTools.ServiceLayer.Extensibility
+{
+
+    /// <summary>
+    /// A service provider implementation that allows registering of specific services
+    /// </summary>
+    public class RegisteredServiceProvider : ServiceProviderBase
+    {
+        public delegate IEnumerable ServiceLookup();
+
+        protected Dictionary<Type, ServiceLookup> services = new Dictionary<Type, ServiceLookup>();
+
+        /// <summary>
+        /// Registers a singular service to be returned during lookup
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <returns>this provider, to simplify fluent declarations</returns>
+        /// <exception cref="ArgumentNullException">If service is null</exception>
+        /// <exception cref="InvalidOperationException">If an existing service is already registered</exception>
+        public RegisteredServiceProvider RegisterSingleService<T>(T service)
+        {
+            Validate.IsNotNull(nameof(service), service);
+            ThrowIfAlreadyRegistered<T>();
+            services.Add(typeof(T), () => service.SingleItemAsEnumerable());
+            return this;
+        }
+
+        /// <summary>
+        /// Registers a singular service to be returned during lookup
+        /// </summary>
+        /// <param name="type">
+        /// Type or interface this service should be registed as. Any <see cref="IMultiServiceProvider.GetServices{T}"/> request
+        /// for that type will return this service
+        /// </param>
+        /// <param name="service">service object to be added</param>
+        /// <returns>this provider, to simplify fluent declarations</returns>
+        /// <exception cref="ArgumentNullException">If service is null</exception>
+        /// <exception cref="InvalidOperationException">If an existing service is already registered</exception>
+        public RegisteredServiceProvider RegisterSingleService(Type type, object service)
+        {
+            Validate.IsNotNull(nameof(type), type);
+            Validate.IsNotNull(nameof(service), service);
+            ThrowIfAlreadyRegistered(type);
+            ThrowIfIncompatible(type, service);
+            services.Add(type, () => service.SingleItemAsEnumerable());
+            return this;
+        }
+
+        /// <summary>
+        /// Registers a function that can look up multiple services
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <returns>this provider, to simplify fluent declarations</returns>
+        /// <exception cref="ArgumentNullException">If <paramref name="serviceLookup"/> is null</exception>
+        /// <exception cref="InvalidOperationException">If an existing service is already registered</exception>
+        public RegisteredServiceProvider Register<T>(Func<IEnumerable<T>> serviceLookup)
+        {
+            Validate.IsNotNull(nameof(serviceLookup), serviceLookup);
+            ThrowIfAlreadyRegistered<T>();
+            services.Add(typeof(T), () => serviceLookup());
+            return this;
+        }
+
+        private void ThrowIfAlreadyRegistered<T>()
+        {
+            ThrowIfAlreadyRegistered(typeof(T));
+        }
+
+        private void ThrowIfAlreadyRegistered(Type type)
+        {
+            if (services.ContainsKey(type))
+            {
+                throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, SR.ServiceAlreadyRegistered, type.Name));
+            }
+
+        }
+
+        private void ThrowIfIncompatible(Type type, object service)
+        {
+            if (!type.IsInstanceOfType(service))
+            {
+                throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, SR.ServiceNotOfExpectedType, service.GetType().Name, type.Name));
+            }
+
+        }
+
+        protected override IEnumerable<T> GetServicesImpl<T>()
+        {
+            ServiceLookup serviceLookup;
+            if (services.TryGetValue(typeof(T), out serviceLookup))
+            {
+                return serviceLookup().Cast<T>();
+            }
+            return Enumerable.Empty<T>();
+        }
+    }
+}