Removed the Type Registry

Author: fabianfett

Sources/AWSLambdaEvents/Cloudwatch.swift

@@ -17,13 +17,23 @@ import struct Foundation.Date
 /// EventBridge has the same payloads/notification types as CloudWatch
 typealias EventBridge = Cloudwatch
 
+public protocol CloudwatchDetail: Decodable {
+    static var name: String { get }
+}
+
+public extension CloudwatchDetail {
+    var detailType: String {
+        Self.name
+    }
+}
+
 public enum Cloudwatch {
     /// CloudWatch.Event is the outer structure of an event sent via CloudWatch Events.
     ///
     /// **NOTE**: For examples of events that come via CloudWatch Events, see
     /// https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/EventTypes.html
     /// https://docs.aws.amazon.com/eventbridge/latest/userguide/event-types.html
-    public struct Event<Detail: Decodable>: Decodable {
+    public struct Event<Detail: CloudwatchDetail>: Decodable {
         public let id: String
         public let source: String
         public let accountId: String
@@ -39,6 +49,7 @@ public enum Cloudwatch {
             case time
             case region
             case resources
+            case detailType = "detail-type"
             case detail
         }
 
@@ -51,61 +62,28 @@ public enum Cloudwatch {
             self.time = (try container.decode(ISO8601Coding.self, forKey: .time)).wrappedValue
             self.region = try container.decode(AWSRegion.self, forKey: .region)
             self.resources = try container.decode([String].self, forKey: .resources)
-            self.detail = (try DetailCoding(from: decoder)).guts
-        }
 
-        private struct DetailCoding {
-            public let guts: Detail
-
-            internal enum CodingKeys: String, CodingKey {
-                case detailType = "detail-type"
-                case detail
+            let detailType = try container.decode(String.self, forKey: .detailType)
+            guard detailType == Detail.name else {
+                throw PayloadTypeMismatch(name: detailType, type: Detail.self)
             }
 
-            public init(from decoder: Decoder) throws {
-                let container = try decoder.container(keyedBy: CodingKeys.self)
-                let detailType = try container.decode(String.self, forKey: .detailType)
-                let detailFactory: (Decoder) throws -> Decodable
-                switch detailType {
-                case ScheduledEvent.name:
-                    detailFactory = Empty.init
-                case EC2.InstanceStateChangeNotificationEvent.name:
-                    detailFactory = EC2.InstanceStateChangeNotification.init
-                case EC2.SpotInstanceInterruptionNoticeEvent.name:
-                    detailFactory = EC2.SpotInstanceInterruptionNotice.init
-                default:
-                    guard let factory = Cloudwatch.detailPayloadRegistry[detailType] else {
-                        throw UnknownPayload(name: detailType)
-                    }
-                    detailFactory = factory
-                }
-                let detailsDecoder = try container.superDecoder(forKey: .detail)
-                guard let detail = try detailFactory(detailsDecoder) as? Detail else {
-                    throw PayloadTypeMismatch(name: detailType, type: Detail.self)
-                }
-                self.guts = detail
-            }
+            self.detail = try container.decode(Detail.self, forKey: .detail)
         }
     }
 
-    // MARK: - Detail Payload Registry
-
-    // FIXME: make thread safe
-    private static var detailPayloadRegistry = [String: (Decoder) throws -> Decodable]()
-
-    public static func registerDetailPayload<T: Decodable>(label: String, type: T.Type) {
-        detailPayloadRegistry[label] = type.init
-    }
-
     // MARK: - Common Event Types
 
-    public typealias ScheduledEvent = Event<Empty>
-
-    public struct Empty: Decodable {}
+    public typealias ScheduledEvent = Event<Scheduled>
+    public struct Scheduled: CloudwatchDetail {
+        public static let name = "Scheduled Event"
+    }
 
     public enum EC2 {
         public typealias InstanceStateChangeNotificationEvent = Event<InstanceStateChangeNotification>
-        public struct InstanceStateChangeNotification: Decodable {
+        public struct InstanceStateChangeNotification: CloudwatchDetail {
+            public static let name = "EC2 Instance State-change Notification"
+
             public enum State: String, Codable {
                 case running
                 case shuttingDown = "shutting-down"
@@ -124,7 +102,9 @@ public enum Cloudwatch {
         }
 
         public typealias SpotInstanceInterruptionNoticeEvent = Event<SpotInstanceInterruptionNotice>
-        public struct SpotInstanceInterruptionNotice: Decodable {
+        public struct SpotInstanceInterruptionNotice: CloudwatchDetail {
+            public static let name = "EC2 Spot Instance Interruption Warning"
+
             public enum Action: String, Codable {
                 case hibernate
                 case stop
@@ -150,15 +130,3 @@ public enum Cloudwatch {
         let type: Any
     }
 }
-
-extension Cloudwatch.ScheduledEvent {
-    static var name: String { "Scheduled Event" }
-}
-
-extension Cloudwatch.EC2.InstanceStateChangeNotificationEvent {
-    static var name: String { "EC2 Instance State-change Notification" }
-}
-
-extension Cloudwatch.EC2.SpotInstanceInterruptionNoticeEvent {
-    static var name: String { "EC2 Spot Instance Interruption Warning" }
-}

Tests/AWSLambdaEventsTests/CloudwatchTests.swift

@@ -34,7 +34,7 @@ class CloudwatchTests: XCTestCase {
     }
 
     func testScheduledEventFromJSON() {
-        let payload = CloudwatchTests.eventPayload(type: Cloudwatch.ScheduledEvent.name, details: "{}")
+        let payload = CloudwatchTests.eventPayload(type: Cloudwatch.Scheduled.name, details: "{}")
         let data = payload.data(using: .utf8)!
         var maybeEvent: Cloudwatch.ScheduledEvent?
         XCTAssertNoThrow(maybeEvent = try JSONDecoder().decode(Cloudwatch.ScheduledEvent.self, from: data))
@@ -52,7 +52,7 @@ class CloudwatchTests: XCTestCase {
     }
 
     func testEC2InstanceStateChangeNotificationEventFromJSON() {
-        let payload = CloudwatchTests.eventPayload(type: Cloudwatch.EC2.InstanceStateChangeNotificationEvent.name,
+        let payload = CloudwatchTests.eventPayload(type: Cloudwatch.EC2.InstanceStateChangeNotification.name,
                                                    details: "{ \"instance-id\": \"0\", \"state\": \"stopping\" }")
         let data = payload.data(using: .utf8)!
         var maybeEvent: Cloudwatch.EC2.InstanceStateChangeNotificationEvent?
@@ -73,7 +73,7 @@ class CloudwatchTests: XCTestCase {
     }
 
     func testEC2SpotInstanceInterruptionNoticeEventFromJSON() {
-        let payload = CloudwatchTests.eventPayload(type: Cloudwatch.EC2.SpotInstanceInterruptionNoticeEvent.name,
+        let payload = CloudwatchTests.eventPayload(type: Cloudwatch.EC2.SpotInstanceInterruptionNotice.name,
                                                    details: "{ \"instance-id\": \"0\", \"instance-action\": \"terminate\" }")
         let data = payload.data(using: .utf8)!
         var maybeEvent: Cloudwatch.EC2.SpotInstanceInterruptionNoticeEvent?
@@ -94,13 +94,13 @@ class CloudwatchTests: XCTestCase {
     }
 
     func testCustomEventFromJSON() {
-        struct Custom: Decodable {
+        struct Custom: CloudwatchDetail {
+            public static let name = "Custom"
+
             let name: String
         }
 
-        Cloudwatch.registerDetailPayload(label: "Custom", type: Custom.self)
-
-        let payload = CloudwatchTests.eventPayload(type: "Custom", details: "{ \"name\": \"foo\" }")
+        let payload = CloudwatchTests.eventPayload(type: Custom.name, details: "{ \"name\": \"foo\" }")
         let data = payload.data(using: .utf8)!
         var maybeEvent: Cloudwatch.Event<Custom>?
         XCTAssertNoThrow(maybeEvent = try JSONDecoder().decode(Cloudwatch.Event<Custom>.self, from: data))
@@ -122,16 +122,16 @@ class CloudwatchTests: XCTestCase {
         let payload = CloudwatchTests.eventPayload(type: UUID().uuidString, details: "{}")
         let data = payload.data(using: .utf8)!
         XCTAssertThrowsError(try JSONDecoder().decode(Cloudwatch.ScheduledEvent.self, from: data)) { error in
-            XCTAssert(error is Cloudwatch.UnknownPayload, "expected UnknownPayload but recieved \(error)")
+            XCTAssert(error is Cloudwatch.PayloadTypeMismatch, "expected PayloadTypeMismatch but received \(error)")
         }
     }
 
     func testTypeMismatch() {
-        let payload = CloudwatchTests.eventPayload(type: Cloudwatch.EC2.InstanceStateChangeNotificationEvent.name,
+        let payload = CloudwatchTests.eventPayload(type: Cloudwatch.EC2.InstanceStateChangeNotification.name,
                                                    details: "{ \"instance-id\": \"0\", \"state\": \"stopping\" }")
         let data = payload.data(using: .utf8)!
         XCTAssertThrowsError(try JSONDecoder().decode(Cloudwatch.ScheduledEvent.self, from: data)) { error in
-            XCTAssert(error is Cloudwatch.PayloadTypeMismatch, "expected PayloadTypeMismatch but recieved \(error)")
+            XCTAssert(error is Cloudwatch.PayloadTypeMismatch, "expected PayloadTypeMismatch but received \(error)")
         }
     }
 }