ReduxExperiment.swift

ReduxExperiment.swift

import UIKit

public final class ModuleController<State, Update, Message, Task> {
    private var state: State
    private var reducer: (inout State, Message) -> ([Update], [Task])
    private var worker: (ModuleController, Task) -> Void
    private var presenter: (Update) -> Void
    
    public init(state: State,
                reducer: @escaping (inout State, Message) -> ([Update], [Task]),
                worker: @escaping (ModuleController, Task) -> Void,
                presenter: @escaping (Update) -> Void) {
        self.state = state
        self.reducer = reducer
        self.worker = worker
        self.presenter = presenter
    }
    
    public func handle(_ message: Message) {
        let (updates, tasks) = reducer(&state, message)
        updates.forEach(presenter)
        tasks.forEach { worker(self, $0) }
    }
}

public enum Dashboard {
    public typealias Controller = ModuleController<State, Update, Message, Task>
    public typealias Item = String
    
    public struct State {
        public var title: String
        public var items: [Item]
    }
    
    public enum Message {
        case load
        case showDetail(Item)
        case handleButton
        case present(UIViewController)
    }
    
    public enum Update {
        case title(String)
        case items([Item])
        case present(UIViewController)
    }
    
    public enum Task {
        case navigate
        case storeItem(Item)
    }
    
    public final class ViewController: UIViewController {
        
        var buttonTapAction: (()->Void)? = nil
        func set(title: String) {}
        
        func setListDataSource(_ dataSource: [String]) {}
        
        public override func loadView() {
            super.loadView()
            view.backgroundColor = .white
            let button = UIButton.init(frame: CGRect.init(x: 50, y: 50, width: 200, height: 80))
            button.setTitle("BUTTON", for: .normal)
            button.setTitleColor(.blue, for: .normal)
            button.addTarget(self, action: #selector(buttonTap), for: .touchUpInside)
            view.addSubview(button)
        }
        
        @objc
        func buttonTap() {
            buttonTapAction?()
        }
    }
    
    static func reducer(state: inout State, message: Message) -> ([Update], [Task]) {
        switch message {
        case .load:
            return ([], [])
        case let .showDetail(item):
            state.items.append(item)
            return ([.items(state.items)], [])
        case .handleButton:
            return ([], [.navigate])
        case let .present(vc):
            return ([.present(vc)], [])
        }
    }
    
    static func buildController(_ context: Void = (), state: State = State(title: "Title", items: [])) -> (UIViewController, Controller) {
        let viewController: ViewController = .init()
        let controller: Controller
            = .init(state: state,
                    reducer: reducer,
                    worker: { (controller, task) in
                        switch task {
                        case .navigate:
                            let (vc, detail) = Detail.buildController(controller, state: "TEST")
                            controller.handle(.present(vc))
                            
                        case let .storeItem(item):
                            break
                        }
                    },
                    presenter: { update in
                        switch update {
                        case let .title(string):
                            viewController.set(title: string)
                        case let .items(list):
                            viewController.setListDataSource(list)
                        case let .present(vc):
                            viewController.present(vc, animated: true, completion: nil)
                        }
            })
        viewController.buttonTapAction = { [weak controller] in controller?.handle(.handleButton) ; print("TAP") }
        return (viewController, controller)
    }
}

public enum Detail {
    public typealias Controller = ModuleController<State, Update, Message, Task>

    public typealias State = String

    public enum Message {
        case back
        case delete(String)
    }

    public typealias Update = String

    public enum Task {
        case navigateBack
        case delete(String)
    }

    public final class ViewController: UIViewController {
        func set(label: String) {}
    }

    static func reducer(state: inout State, message: Message) -> ([Update], [Task]) {
        switch message {
        case .back:
            return ([], [.navigateBack])
        case let .delete(item):
            return ([], [.delete(item), .navigateBack])
        }
    }

    static func buildController<Parent>(_ context: Parent, state: State) -> (UIViewController, Controller) {
        let viewController: ViewController = .init()
        let controller: Controller
            = .init(state: "state",
                    reducer: reducer,
                    worker: { (_, task) in
                        switch task {
                        case .navigateBack:
                            break
                        case .delete:
                            break
                        }
                    },
                    presenter: { update in
                        viewController.set(label: update)
            })
        return (viewController, controller)
    }
}

public final class DashboardViewController: UIViewController {
    func set(title: String) {}
    
    func setListDataSource(_ dataSource: [String]) {}
}

extension UIViewController {
    func push(viewController: UIViewController) {}
    
    func present(viewController: UIViewController) {}
}

let (vc, dashboard) = Dashboard.buildController()

import PlaygroundSupport

PlaygroundPage.current.liveView = vc