//
//  ViewController.swift
//  RxGesture
//
//  Created by Marin Todorov on 03/22/2016.
//  Copyright (c) 2016 Marin Todorov. All rights reserved.
//

import UIKit

import RxSwift
import RxGesture

class Step {
    enum Action { case previous, next }
    typealias InitialState = (alpha: CGFloat, color: UIColor, transform: CGAffineTransform)
    let title: String
    let code: String
    let initialState: InitialState
    let install: (UIView, UILabel, @escaping () -> Void, DisposeBag) -> Void

    init(title: String, code: String, initialState: InitialState, install: @escaping (UIView, UILabel, @escaping () -> Void, DisposeBag) -> Void) {
        self.title = title
        self.code = code
        self.initialState = initialState
        self.install = install
    }
}

class ViewController: UIViewController {

    @IBOutlet private var myView: UIView!
    @IBOutlet private var myViewText: UILabel!
    @IBOutlet private var info: UILabel!
    @IBOutlet private var code: UITextView!

    private let nextStepObserver = PublishSubject<Step.Action>()
    private let bag = DisposeBag()
    private var stepBag = DisposeBag()

    override func viewDidLoad() {
        super.viewDidLoad()

        navigationController?.navigationBar.shadowImage = UIImage()
        let steps: [Step] = [
            tapStep,
            doubleTapStep,
            swipeDownStep,
            swipeHorizontallyStep,
            longPressStep,
            touchDownStep,
            forceTouchStep,
            panStep,
            pinchStep,
            rotateStep,
            transformStep
        ]

        func newIndex(for index: Int, action: Step.Action) -> Int {
            switch action {
            case .previous:
                return (steps.count + index - 1) % steps.count
            case .next:
                return (steps.count + index + 1) % steps.count
            }
        }

        nextStepObserver
            .scan(0, accumulator: newIndex)
            .startWith(0)
            .map { (steps[$0], $0) }
            .subscribe(onNext: { [unowned self] step, index in
                self.updateStep(step, at: index)
            })
            .disposed(by: bag)
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        guard let superview = myView.superview, let window = view.window else {
            return
        }
        window.addSubview(myView)
        myView.centerXAnchor.constraint(equalTo: superview.centerXAnchor).isActive = true
        myView.centerYAnchor.constraint(equalTo: superview.centerYAnchor).isActive = true
    }

    @IBAction func previousStep(_ sender: Any) {
        nextStepObserver.onNext(.previous)
    }

    @IBAction func nextStep(_ sender: Any) {
        nextStepObserver.onNext(.next)
    }

    func updateStep(_ step: Step, at index: Int) {
        stepBag = DisposeBag()

        info.text = "\(index + 1). " + step.title
        code.text = step.code
        
        myViewText.text = nil
        myViewText.numberOfLines = 1
        
        UIView.animate(withDuration: 0.5, delay: 0, options: .beginFromCurrentState) {
            self.myView.alpha = step.initialState.alpha
            self.myView.backgroundColor = step.initialState.color
            self.myView.transform = step.initialState.transform
        }
        
        step.install(myView, myViewText, { [nextStepObserver] in nextStepObserver.onNext(.next) }, stepBag)

        print("active gestures: \(myView.gestureRecognizers?.count ?? 0)")
    }

    lazy var tapStep: Step = Step(
        title: "Tap the red square",
        code: """
        view.rx
            .tapGesture()
            .when(.recognized)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)
        """,
        initialState: (1.0, .red, .identity),
        install: { view, _, nextStep, stepBag in
            view.rx
                .tapGesture()
                .when(.recognized)
                .subscribe(onNext: { _ in
                    nextStep()
                })
                .disposed(by: stepBag)
    })

    lazy var doubleTapStep: Step = Step(
        title: "Double tap the green square",
        code: """
        view.rx
            .tapGesture() { gesture, _ in
                gesture.numberOfTapsRequired = 2
            }
            .when(.recognized)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)
        """,
        initialState: (1.0, .green, .identity),
        install: { view, _, nextStep, stepBag in
            view.rx
                .tapGesture { gesture, _ in
                    gesture.numberOfTapsRequired = 2
                }
                .when(.recognized)
                .subscribe(onNext: { _ in
                    nextStep()
                })
                .disposed(by: stepBag)
    })

    lazy var swipeDownStep: Step = Step(
        title: "Swipe the blue square down",
        code: """
        view.rx
            .swipeGesture(.down)
            .when(.recognized)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)
        """,
        initialState: (1.0, .blue, .identity),
        install: { view, _, nextStep, stepBag in
            view.rx
                .swipeGesture(.down)
                .when(.recognized)
                .subscribe(onNext: { _ in
                    nextStep()
                })
                .disposed(by: stepBag)
    })

    lazy var swipeHorizontallyStep: Step = Step(
        title: "Swipe horizontally the blue square (e.g. left or right)",
        code: """
        view.rx
            .swipeGesture(.left, .right)
            .when(.recognized)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)
        """,
        initialState: (1.0, .blue, CGAffineTransform(scaleX: 1.0, y: 2.0)),
        install: { view, _, nextStep, stepBag in
            view.rx
                .swipeGesture(.left, .right)
                .when(.recognized)
                .subscribe(onNext: { _ in
                    nextStep()
                })
                .disposed(by: stepBag)
    })

    lazy var longPressStep: Step = Step(
        title: "Do a long press",
        code: """
        view.rx
            .longPressGesture()
            .when(.began)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)
        """,
        initialState: (1.0, .blue, CGAffineTransform(scaleX: 2.0, y: 2.0)),
        install: { view, _, nextStep, stepBag in
            view.rx
                .longPressGesture()
                .when(.began)
                .subscribe(onNext: { _ in
                    nextStep()
                })
                .disposed(by: stepBag)
    })

    lazy var touchDownStep: Step = Step(
        title: "Touch down the view",
        code: """
        view.rx
            .touchDownGesture()
            .when(.began)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)
        """,
        initialState: (1.0, .green, .identity),
        install: { view, _, nextStep, stepBag in
            view.rx
                .touchDownGesture()
                .when(.began)
                .subscribe(onNext: { _ in
                    nextStep()
                })
                .disposed(by: stepBag)
    })

    @available(iOS 9.0, *)
    lazy var forceTouchStep: Step = Step(
        title: "Force Touch the view",
        code: """
        let forceTouch = view.rx
            .forceTouchGesture()
            .share(replay: 1)

        forceTouch
            .asForce()
            .subscribe(onNext: { force in
                // Do something
            })
            .disposed(by: stepBag)

        forceTouch
            .when(.ended)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: stepBag)
        """,
        initialState: (0.25, .red, .identity),
        install: { view, label, nextStep, stepBag in
            let forceTouch = view.rx
                .forceTouchGesture()
                .share(replay: 1)

            forceTouch
                .when(.possible, .began, .changed)
                .subscribe(onNext: { [unowned view] touch in
                    let max =  touch.maximumPossibleForce
                    let percent = max > 0 ? touch.force / max : 0
                    view.alpha = percent > 0.75 ? 1.0 : 0.25 + (0.5 * percent)
                    label.text = String(format: "%.0f%%", percent * 100)
                })
                .disposed(by: stepBag)

            forceTouch
                .when(.ended)
                .subscribe(onNext: { _ in
                    nextStep()
                })
                .disposed(by: stepBag)

            self.makeImpact(on: forceTouch, stepBag: stepBag)
    })

    lazy var panStep: Step = Step(
        title: "Drag the square to a different location",
        code: """
        let panGesture = view.rx
            .panGesture()
            .share(replay: 1)

        panGesture
            .when(.changed)
            .asTranslation()
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)

        panGesture
            .when(.ended)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)
        """,
        initialState: (1.0, .blue, .identity),
        install: { view, label, nextStep, stepBag in
            let panGesture = view.rx
                .panGesture()
                .share(replay: 1)

            panGesture
                .when(.possible, .began, .changed)
                .asTranslation()
                .subscribe(onNext: { translation, _ in
                    label.text = String(format: "(%.2f, %.2f)", translation.x, translation.y)
                    view.transform = CGAffineTransform(translationX: translation.x, y: translation.y)
                })
                .disposed(by: stepBag)

            panGesture
                .when(.ended)
                .subscribe(onNext: { _ in
                    nextStep()
                })
               .disposed(by: stepBag)
    })

    lazy var rotateStep: Step = Step(
        title: "Rotate the square",
        code: """
        let rotationGesture = view.rx
            .rotationGesture()
            .share(replay: 1)

        rotationGesture
            .when(.changed)
            .asRotation()
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)

        rotationGesture
            .when(.ended)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)
        """,
        initialState: (1.0, .blue, .identity),
        install: { view, label, nextStep, stepBag in
            let rotationGesture = view.rx
                .rotationGesture()
                .share(replay: 1)

            rotationGesture
                .when(.possible, .began, .changed)
                .asRotation()
                .subscribe(onNext: { rotation, _ in
                    label.text = String(format: "%.fº", rotation * 180 / .pi)
                    view.transform = CGAffineTransform(rotationAngle: rotation)
                })
                .disposed(by: stepBag)

            rotationGesture
                .when(.ended)
                .subscribe(onNext: { _ in
                    nextStep()
                })
                .disposed(by: stepBag)
    })

    lazy var pinchStep: Step = Step(
        title: "Pinch the square",
        code: """
        let pinchGesture = view.rx.pinchGesture().share(replay: 1)

        pinchGesture
            .when(.changed)
            .asScale()
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)

        pinchGesture
            .when(.ended)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)
        """,
        initialState: (1.0, .blue, .identity),
        install: { view, label, nextStep, stepBag in
            let pinchGesture = view.rx
                .pinchGesture()
                .share(replay: 1)

            pinchGesture
                .when(.possible, .began, .changed)
                .asScale()
                .subscribe(onNext: { scale, _ in
                    label.text = String(format: "x%.2f", scale)
                    view.transform = CGAffineTransform(scaleX: scale, y: scale)
                })
                .disposed(by: stepBag)

            pinchGesture
                .when(.ended)
                .subscribe(onNext: { _ in
                    nextStep()
                })
                .disposed(by: stepBag)
    })

    lazy var transformStep: Step = Step(
        title: "Transform the square",
        code: """
        let transformGestures = view.rx.transformGestures().share(replay: 1)

        transformGestures
            .when(.changed)
            .asTransform()
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)

        transformGestures
            .when(.ended)
            .subscribe(onNext: { _ in
                // Do something
            })
            .disposed(by: disposeBag)
        """,
        initialState: (1.0, .blue, .identity),
        install: { view, label, nextStep, stepBag in
            let transformGestures = view.rx
                .transformGestures()
                .share(replay: 1)

            transformGestures
                .when(.possible, .began, .changed)
                .asTransform()
                .subscribe(onNext: { transform, _ in
                    label.numberOfLines = 3
                    label.text = String(format: "[%.2f, %.2f,\n%.2f, %.2f,\n%.2f, %.2f]", transform.a, transform.b, transform.c, transform.d, transform.tx, transform.ty)
                    view.transform = transform
                })
                .disposed(by: stepBag)

            transformGestures
                .when(.ended)
                .subscribe(onNext: { _ in
                    nextStep()
                })
                .disposed(by: stepBag)
    })

    private func makeImpact(on forceTouch: Observable<ForceTouchGestureRecognizer>, stepBag: DisposeBag) {
        // It looks like #available(iOS 10.0, *) is ignored in the lazy var declaration ¯\_(ツ)_/¯

        guard #available(iOS 10.0, *) else { return }
        forceTouch
            .map { ($0.force / $0.maximumPossibleForce) > 0.75 ? UIImpactFeedbackGenerator.FeedbackStyle.medium : .light }
            .distinctUntilChanged()
            .skip(1)
            .subscribe(onNext: { style in
                UIImpactFeedbackGenerator(style: style).impactOccurred()
            })
            .disposed(by: stepBag)
    }
}