Part 4: Designing the API.

Package.swift

@@ -9,7 +9,12 @@ let package = Package(
         .macOS(.v15)
     ],
     dependencies: [
-        .package(url: "https://github.com/swift-server-community/dynamo-db-tables", from: "0.1.0")
+        .package(url: "https://github.com/swift-server-community/dynamo-db-tables", from: "0.1.0"),
+        .package(url: "https://github.com/apple/swift-openapi-generator", from: "1.6.0"),
+        .package(url: "https://github.com/apple/swift-openapi-runtime", from: "1.7.0"),
+        .package(url: "https://github.com/swift-server/swift-openapi-hummingbird", from: "2.0.1"),
+        .package(url: "https://github.com/hummingbird-project/hummingbird", from: "2.0.0"),
+        .package(url: "https://github.com/tachyonics/smockable", from: "1.0.0-alpha.1"),
     ],
     targets: [
         .target(
@@ -22,9 +27,38 @@ let package = Package(
                 .product(name: "DynamoDBTables", package: "dynamo-db-tables"),
             ]
         ),
+        .target(
+            name: "TaskAPI",
+            dependencies: [
+                .product(name: "OpenAPIRuntime", package: "swift-openapi-runtime")
+            ],
+            plugins: [
+                .plugin(name: "OpenAPIGenerator", package: "swift-openapi-generator")
+            ]
+        ),
+        .target(
+            name: "TaskClusterApp",
+            dependencies: [
+                "TaskAPI",
+                "TaskClusterModel",
+                .product(name: "Hummingbird", package: "hummingbird"),
+                .product(name: "OpenAPIRuntime", package: "swift-openapi-runtime"),
+                .product(name: "OpenAPIHummingbird", package: "swift-openapi-hummingbird"),
+            ]
+        ),
         .executableTarget(
             name: "task-cluster"
         ),
+        .testTarget(
+            name: "TaskClusterTests",
+            dependencies: [
+                "TaskClusterApp",
+                "TaskClusterModel",
+                .product(name: "Smockable", package: "smockable"),
+                .product(name: "Hummingbird", package: "hummingbird"),
+                .product(name: "HummingbirdTesting", package: "hummingbird"),
+            ]
+        ),
         .testTarget(
             name: "TaskClusterDynamoDBModelTests",
             dependencies: [

Sources/TaskAPI/TaskAPI.swift

@@ -0,0 +1 @@
+// Placeholder to silence SPM "no source files" warning.

Sources/TaskAPI/openapi-generator-config.yaml

@@ -0,0 +1,7 @@
+generate:
+  - types
+  - server
+accessModifier: package
+filter:
+  tags:
+    - Tasks

Sources/TaskAPI/openapi.yaml

@@ -0,0 +1 @@
+../../openapi.yaml

Sources/TaskClusterApp/Application+build.swift

@@ -0,0 +1,25 @@
+import Hummingbird
+import Logging
+import OpenAPIHummingbird  // swiftlint:disable:this unused_import
+import TaskClusterModel
+
+package func buildApplication<Repository: TaskRepository>(
+    repository: Repository,
+    configuration: ApplicationConfiguration,
+    logger: Logger
+) throws -> some ApplicationProtocol {
+    let router = Router(context: BasicRequestContext.self)
+
+    router.addMiddleware {
+        LogRequestsMiddleware(.info)
+    }
+
+    router.get("/health") { _, _ in
+        HTTPResponse.Status.ok
+    }
+
+    let controller = TaskController(repository: repository)
+    try controller.registerHandlers(on: router)
+
+    return Application(router: router, configuration: configuration, logger: logger)
+}

Sources/TaskClusterApp/TaskController.swift

@@ -0,0 +1,100 @@
+import Foundation
+import TaskAPI
+import TaskClusterModel
+
+package struct TaskController<Repository: TaskRepository>: APIProtocol {
+    var repository: Repository
+
+    package func createTask(_ input: Operations.createTask.Input) async throws -> Operations.createTask.Output {
+        let body =
+            switch input.body {
+            case .json(let value): value
+            }
+
+        guard (1...10).contains(body.priority) else {
+            return .badRequest(.init())
+        }
+
+        let task = TaskItem(
+            title: body.title,
+            description: body.description,
+            priority: body.priority,
+            dueBy: body.dueBy
+        )
+
+        let created = try await repository.create(task: task)
+        return .created(.init(body: .json(created.toResponse())))
+    }
+
+    package func getTask(_ input: Operations.getTask.Input) async throws -> Operations.getTask.Output {
+        guard let taskId = UUID(uuidString: input.path.taskId) else {
+            return .notFound(.init())
+        }
+
+        guard let task = try await repository.get(taskId: taskId) else {
+            return .notFound(.init())
+        }
+
+        return .ok(.init(body: .json(task.toResponse())))
+    }
+
+    package func updateTaskPriority(
+        _ input: Operations.updateTaskPriority.Input
+    ) async throws -> Operations.updateTaskPriority.Output {
+        let body =
+            switch input.body {
+            case .json(let value): value
+            }
+
+        guard (1...10).contains(body.priority) else {
+            return .badRequest(.init())
+        }
+
+        guard let taskId = UUID(uuidString: input.path.taskId) else {
+            return .notFound(.init())
+        }
+
+        guard var task = try await repository.get(taskId: taskId) else {
+            return .notFound(.init())
+        }
+
+        task.priority = body.priority
+        task.updatedAt = Date()
+        let updated = try await repository.update(task: task)
+        return .ok(.init(body: .json(updated.toResponse())))
+    }
+
+    package func cancelTask(_ input: Operations.cancelTask.Input) async throws -> Operations.cancelTask.Output {
+        guard let taskId = UUID(uuidString: input.path.taskId) else {
+            return .notFound(.init())
+        }
+
+        guard var task = try await repository.get(taskId: taskId) else {
+            return .notFound(.init())
+        }
+
+        guard task.status == .pending || task.status == .running else {
+            return .conflict(.init())
+        }
+
+        task.status = .cancelled
+        task.updatedAt = Date()
+        let updated = try await repository.update(task: task)
+        return .ok(.init(body: .json(updated.toResponse())))
+    }
+}
+
+extension TaskItem {
+    package func toResponse() -> Components.Schemas.TaskItem {
+        .init(
+            taskId: taskId.uuidString,
+            title: title,
+            description: description,
+            priority: priority,
+            dueBy: dueBy,
+            status: .init(rawValue: status.rawValue)!,
+            createdAt: createdAt,
+            updatedAt: updatedAt
+        )
+    }
+}

Tests/TaskClusterTests/MockTaskRepository.swift

@@ -0,0 +1,11 @@
+import Foundation
+import Smockable
+
+@testable import TaskClusterModel
+
+@Smock
+protocol TestTaskRepository: TaskRepository {
+    func create(task: TaskItem) async throws -> TaskItem
+    func get(taskId: UUID) async throws -> TaskItem?
+    func update(task: TaskItem) async throws -> TaskItem
+}