feat(core): add configuration builder implementation

Amplify/Core/Configuration/AmplifyConfiguration+Builder.swift

@@ -0,0 +1,92 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import Foundation
+
+extension AmplifyConfiguration {
+    @resultBuilder
+    public struct Builder {
+        public static func buildBlock(_ plugins: Plugin...) -> [Plugin] {
+            plugins
+        }
+
+        public static func buildOptional(_ plugins: [Plugin]?) -> [Plugin] {
+            plugins ?? []
+        }
+    }
+}
+
+extension Amplify {
+
+    /// Configures Amplify with the specified configuration.
+    ///
+    /// This method must be invoked after registering plugins, and before using any Amplify category. It must not be
+    /// invoked more than once.
+    ///
+    /// **Lifecycle**
+    ///
+    /// Internally, Amplify configures the Hub and Logging categories first, so they are available to plugins in the
+    /// remaining categories during the configuration phase. Plugins for the Hub and Logging categories must not
+    /// assume that any other categories are available.
+    ///
+    /// After Amplify has configured all of its categories, it will dispatch a `HubPayload.EventName.Amplify.configured`
+    /// event to each Amplify Hub channel. After this point, plugins may invoke calls on other Amplify categories.
+    ///
+    ///     do {
+    ///         try Amplify.configure {
+    ///             AWSCognitoAuthPlugin()
+    ///             AWSLocationGeoPlugin()
+    ///             AWSPinpointAnalyticsPlugin()
+    ///
+    ///             let models = AmplifyModels()
+    ///             AWSDataStorePlugin(modelRegistration: models)
+    ///         }
+    ///         print("🎉 Amplify successfully configured")
+    ///     } catch {
+    ///         print("🙀 Something went wrong configuring Amplify - error: \(error)"
+    ///     }
+    ///
+    /// - Parameter builder: The AmplifyConfiguration for specified Categories
+    public static func configure(@AmplifyConfiguration.Builder builder: () -> [Plugin]) throws {
+        let plugins = builder()
+        try plugins.forEach { plugin in
+            try add(plugin: plugin)
+        }
+        try Amplify.configure()
+    }
+
+    // This was added as an internal overload of the existing public generic API.
+    // This could replace the existing generic API in the future.
+    internal static func add(plugin: Plugin) throws {
+        log.debug("Adding plugin: \(plugin))")
+        switch plugin {
+        case let plugin as AnalyticsCategoryPlugin:
+            try Analytics.add(plugin: plugin)
+        case let plugin as APICategoryPlugin:
+            try API.add(plugin: plugin)
+        case let plugin as AuthCategoryPlugin:
+            try Auth.add(plugin: plugin)
+        case let plugin as DataStoreCategoryPlugin:
+            try DataStore.add(plugin: plugin)
+        case let plugin as GeoCategoryPlugin:
+            try Geo.add(plugin: plugin)
+        case let plugin as HubCategoryPlugin:
+            try Hub.add(plugin: plugin)
+        case let plugin as LoggingCategoryPlugin:
+            try Logging.add(plugin: plugin)
+        case let plugin as PredictionsCategoryPlugin:
+            try Predictions.add(plugin: plugin)
+        case let plugin as StorageCategoryPlugin:
+            try Storage.add(plugin: plugin)
+        default:
+            throw PluginError.pluginConfigurationError(
+                "Plugin category does not exist.",
+                "Verify that the library version is correct and supports the plugin's category."
+            )
+        }
+    }
+}