Chapter 15 hooks

Author: tib

Chapter 15/myProject/Sources/App/Framework/Hooks/AnyHookFunction.swift

@@ -0,0 +1,21 @@
+//
+//  File.swift
+//  
+//
+//  Created by Tibor Bodecs on 2022. 01. 08..
+//
+
+struct AnyHookFunction: HookFunction {
+
+    private let functionBlock: HookFunctionSignature<Any>
+
+    /// anonymous hooks can be initialized using a function block
+    init(_ functionBlock: @escaping HookFunctionSignature<Any>) {
+        self.functionBlock = functionBlock
+    }
+
+    /// since they are hook functions they can be invoked with a given argument
+    func invoke(_ args: HookArguments) -> Any {
+        functionBlock(args)
+    }
+}

Chapter 15/myProject/Sources/App/Framework/Hooks/Application+Hooks.swift

@@ -0,0 +1,42 @@
+//
+//  File.swift
+//  
+//
+//  Created by Tibor Bodecs on 2022. 01. 08..
+//
+
+import Vapor
+
+extension Application {
+
+    private struct HookStorageKey: StorageKey {
+        typealias Value = HookStorage
+    }
+
+    var hooks: HookStorage {
+        get {
+            if let existing = storage[HookStorageKey.self] {
+                return existing
+            }
+            let new = HookStorage()
+            storage[HookStorageKey.self] = new
+            return new
+        }
+        set {
+            storage[HookStorageKey.self] = newValue
+        }
+    }
+}
+
+extension Application {
+
+    func invoke<ReturnType>(_ name: String, args: HookArguments = [:]) -> ReturnType? {
+        let ctxArgs = args.merging(["app": self]) { (_, new) in new }
+        return hooks.invoke(name, args: ctxArgs)
+    }
+
+    func invokeAll<ReturnType>(_ name: String, args: HookArguments = [:]) -> [ReturnType] {
+        let ctxArgs = args.merging(["app": self]) { (_, new) in new }
+        return hooks.invokeAll(name, args: ctxArgs)
+    }
+}

Chapter 15/myProject/Sources/App/Framework/Hooks/HookFunction.swift

@@ -0,0 +1,14 @@
+//
+//  File.swift
+//  
+//
+//  Created by Tibor Bodecs on 2022. 01. 08..
+//
+
+typealias HookArguments = [String: Any]
+
+protocol HookFunction {
+    func invoke(_: HookArguments) -> Any
+}
+
+typealias HookFunctionSignature<T> = (HookArguments) -> T

Chapter 15/myProject/Sources/App/Framework/Hooks/HookFunctionPointer.swift

@@ -0,0 +1,19 @@
+//
+//  File.swift
+//  
+//
+//  Created by Tibor Bodecs on 2022. 01. 08..
+//
+
+final class HookFunctionPointer<Pointer> {
+
+    var name: String
+    var pointer: Pointer
+    var returnType: Any.Type
+    
+    init(name: String, function: Pointer, returnType: Any.Type) {
+        self.name = name
+        self.pointer = function
+        self.returnType = returnType
+    }
+}

Chapter 15/myProject/Sources/App/Framework/Hooks/HookStorage.swift

@@ -0,0 +1,33 @@
+//
+//  File.swift
+//  
+//
+//  Created by Tibor Bodecs on 2022. 01. 08..
+//
+
+final class HookStorage {
+
+    private var pointers: [HookFunctionPointer<HookFunction>]
+    
+    init() {
+        self.pointers = []
+    }
+
+    func register<ReturnType>(_ name: String, use block: @escaping HookFunctionSignature<ReturnType>) {
+        let function = AnyHookFunction { args -> Any in
+            block(args)
+        }
+        let pointer = HookFunctionPointer<HookFunction>(name: name, function: function, returnType: ReturnType.self)
+        pointers.append(pointer)
+    }
+
+    func invoke<ReturnType>(_ name: String, args: HookArguments = [:]) -> ReturnType? {
+        pointers.first { $0.name == name && $0.returnType == ReturnType.self }?.pointer.invoke(args) as? ReturnType
+    }
+ 
+    func invokeAll<ReturnType>(_ name: String, args: HookArguments = [:]) -> [ReturnType] {
+        let fn = pointers.filter { $0.name == name && $0.returnType == ReturnType.self }
+        return fn.compactMap { $0.pointer.invoke(args) as? ReturnType }
+    }
+}
+

Chapter 15/myProject/Sources/App/Framework/Hooks/Request+Hooks.swift

@@ -0,0 +1,21 @@
+//
+//  File.swift
+//  
+//
+//  Created by Tibor Bodecs on 2022. 01. 08..
+//
+
+import Vapor
+
+extension Request {
+
+    func invoke<ReturnType>(_ name: String, args: HookArguments = [:]) -> ReturnType? {
+        let ctxArgs = args.merging(["req": self]) { (_, new) in new }
+        return application.invoke(name, args: ctxArgs)
+    }
+
+    func invokeAll<ReturnType>(_ name: String, args: HookArguments = [:]) -> [ReturnType] {
+        let ctxArgs = args.merging(["req": self]) { (_, new) in new }
+        return application.invokeAll(name, args: ctxArgs)
+    }
+}

Chapter 15/myProject/Sources/App/Framework/ModuleInterface.swift

@@ -12,10 +12,12 @@ public protocol ModuleInterface {
     static var identifier: String { get }
 
     func boot(_ app: Application) throws
+    func setUp(_ app: Application) throws
 }
 
 public extension ModuleInterface {
     func boot(_ app: Application) throws {}
+    func setUp(_ app: Application) throws {}
 
     static var identifier: String { String(describing: self).dropLast(6).lowercased() }
 

Chapter 15/myProject/Sources/App/Modules/Admin/AdminModule.swift

@@ -13,5 +13,11 @@ struct AdminModule: ModuleInterface {
 
     func boot(_ app: Application) throws {
         try router.boot(routes: app.routes)
+        
+        app.hooks.register("admin-routes", use: router.adminRoutesHook)
+    }
+    
+    func setUp(_ app: Application) throws {
+        try router.setUpRoutesHooks(app: app)
     }
 }

Chapter 15/myProject/Sources/App/Modules/Admin/AdminRouter.swift

@@ -11,9 +11,19 @@ struct AdminRouter: RouteCollection {
 
     let controller = AdminFrontendController()
 
-    func boot(routes: RoutesBuilder) throws {
-        routes
+    func boot(routes: RoutesBuilder) throws {}
+
+    func setUpRoutesHooks(app: Application) throws {
+        let adminRoutes = app.routes
             .grouped(AuthenticatedUser.redirectMiddleware(path: "/sign-in/"))
-            .get("admin", use: controller.dashboardView)
+            .grouped("admin")
+
+        let _: [Void] = app.invokeAll("admin-routes", args: ["routes": adminRoutes])
+    }
+    
+    func adminRoutesHook(_ args: HookArguments) -> Void {
+        let routes = args["routes"] as! RoutesBuilder
+
+        routes.get(use: controller.dashboardView)
     }
 }

Chapter 15/myProject/Sources/App/Modules/Admin/Templates/Html/AdminDashboardTemplate.swift

@@ -25,20 +25,12 @@ struct AdminDashboardTemplate: TemplateRepresentable {
                     H1(context.title)
                     P(context.message)
                 }
-                
-                Nav {
-                    H2("Blog")
-                    Ul {
-                        Li {
-                            A("Posts")
-                                .href("/admin/blog/posts/")
-                        }
-                        Li {
-                            A("Categories")
-                                .href("/admin/blog/categories/")
-                        }
-                    }
+          
+                Div {
+                    let widgets: [TemplateRepresentable] = req.invokeAll("admin-widget")
+                    widgets.map { $0.render(req) }    
                 }
+                .class("widgets")
             }
             .id("dashboard")
             .class("container")