//
//  BaseScrollView.swift
//  PrivadoVPN
//
//  Created by Lizaveta Malinouskaya on 15.07.21.
//  Copyright © 2021 Privado LLC. All rights reserved.
//

import Foundation
import UIKit

class BaseScrollView: UIScrollView, ReactivelyConstrained {
    
    // MARK: - Properties
    
    var portraitConstraints = [NSLayoutConstraint]()
    var landscapeConstraints = [NSLayoutConstraint]()
    var sharedConstraints = [NSLayoutConstraint]()
    
    let layoutEmitter = Emitter<EmitterLayoutChangeType>()
    
    // MARK: - Init
    
    init() {
        super.init(frame: .zero)
        self.layoutEmitter.addReaction { [weak self] isLandscape -> ShouldContinueReceiveNotifications in
            
            guard let self = self else { return false }
            
            if isLandscape {
                NSLayoutConstraint.deactivate(self.portraitConstraints)
                NSLayoutConstraint.activate(self.landscapeConstraints)
            } else {
                NSLayoutConstraint.deactivate(self.landscapeConstraints)
                NSLayoutConstraint.activate(self.portraitConstraints)
            }
            NSLayoutConstraint.activate(self.sharedConstraints)
            
            return true
        }
        
        self.addKeyboardObserverIfNeeded()
    }
    
    @available(*, unavailable)
    required init?(coder: NSCoder) { nil }
    
    // MARK: - Private
    
    private func addKeyboardObserverIfNeeded() {
        
        guard self is KeyboardListening else { return }
        
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(self.keyboardWillShowObserved),
            name: UIResponder.keyboardWillShowNotification,
            object: nil
        )
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(self.keyboardWillHideObserved),
            name: UIResponder.keyboardWillHideNotification,
            object: nil
        )
    }
    
    @objc
    private func keyboardWillShowObserved(_ notification: Notification) {
        (self as? KeyboardListening)?.keyboardWillShow(notification)
    }
    
    @objc
    private func keyboardWillHideObserved(_ notification: Notification) {
        (self as? KeyboardListening)?.keyboardWillHide(notification)
    }
}