//
//  RadioBaseButton.swift
//  PrivadoVPN
//
//  Created by Murad Shabanov on 29.07.2021.
//  Copyright © 2021 Privado LLC. All rights reserved.
//

import Foundation
import Cocoa

// MARK: - RadioBaseButton

public class RadioBaseButton: NSButton {
    
    /// Oberver frame change to update style
    private var sizeChangeObserver: NSKeyValueObservation?
    
    /// Allow delection for button useful in Check bok stype
    internal var allowDeselection: Bool {
        return false
    }
    
    /// Keep the track of Selection and deselction
    @objc dynamic public var isOn = false {
        didSet {
            if self.isOn != oldValue {
                self.updateSelectionState()
                self.callDelegate()
            }
        }
    }
    
    required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.setup()
    }
    
    public override init(frame: CGRect) {
        super.init(frame: frame)
        self.setup()
    }
    
    public convenience init?(type buttonType: NSButton.ButtonType) {
        return nil
    }
    
    /// Setup intial things required
    internal func setup() {
        // Add action here
        self.addObserverSizeChange()
        self.setupLayer()
    }
    
    public override func mouseDown(with event: NSEvent) {
        super.mouseDown(with: event)
        guard isEnabled else { return }
        self.selectionAction()
    }
    
    /// Action handler of button for internal use
    ///
    /// - Parameter sender: RadioButton
    @objc internal func selectionAction() {
        // If toggle enable, change selection state
        if self.allowDeselection {
            self.isOn = !self.isOn
        } else if !isOn {
            self.isOn = true
        }
    }
    
    /// Update selection stage as button selected for deselected
    public func updateSelectionState() {
        if self.isOn {
            self.updateActiveLayer()
        } else {
            self.updateInactiveLayer()
        }
    }
    
    /// Setup layer that will for Radio button
    /// This method can be called mutliple times
    /// Do the stuff by overriding, then call super class method
    internal func setupLayer() {
        self.updateSelectionState()
    }
    
    /// Update active layer as button is selected
    internal func updateActiveLayer() { }
    
    /// Update inative later as button is deselected
    internal func updateInactiveLayer() { }
    
    /// call delegate as button selection state changes
    internal func callDelegate() { }
    
}

// MARK:- frame change handler
extension RadioBaseButton {
    
    private func addObserverSizeChange() {
        self.sizeChangeObserver = observe(\RadioBaseButton.frame, changeHandler: self.sizeChangeObseveHandler)
    }
    
    private func sizeChangeObseveHandler(_ object: RadioBaseButton, _ change: NSKeyValueObservedChange<CGRect>) {
        self.setupLayer()
    }
    
}