/*
 Copyright 2020 New Vector Ltd
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 
 http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

import Foundation

final class CloseButton: UIButton, Themable {
    
    // MARK: - Constants
    
    private enum CircleBackgroundConstants {
        static let height: CGFloat = 30.0
        static let highlightedAlha: CGFloat = 0.5
        static let normalAlha: CGFloat = 1.0
    }
    
    // MARK: - Properties
    
    // MARK: Private
    
    private var theme: Theme?
    
    private var circleBackgroundView: UIView!
    
    // MARK: Public
    
    override var isHighlighted: Bool {
        didSet {
            self.circleBackgroundView.alpha = self.isHighlighted ? CircleBackgroundConstants.highlightedAlha : CircleBackgroundConstants.normalAlha
        }
    }
    
    // MARK: - Life cycle
    
    init() {
        super.init(frame: .zero)
        setup()
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setup()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setup()
    }
    
    private func setup() {
        self.backgroundColor = UIColor.clear
        self.setImage(Asset.Images.closeButton.image, for: .normal)
        self.setupCircleView()
        
        self.update(theme: ThemeService.shared().theme)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        self.sendSubviewToBack(self.circleBackgroundView)
        self.circleBackgroundView.layer.cornerRadius = self.circleBackgroundView.bounds.height/2
    }
    
    // MARK: - Private
    
    private func setupCircleView() {
        
        //  sanity check
        if circleBackgroundView != nil {
            //  already set up
            return
        }
        
        let rect = CGRect(x: 0, y: 0, width: CircleBackgroundConstants.height, height: CircleBackgroundConstants.height)
        let view = UIView(frame: rect)
        view.translatesAutoresizingMaskIntoConstraints = false
        view.isUserInteractionEnabled = false
        view.layer.masksToBounds = true
        
        self.addSubview(view)
        
        NSLayoutConstraint.activate([
            view.heightAnchor.constraint(equalToConstant: CircleBackgroundConstants.height),
            view.widthAnchor.constraint(equalTo: view.heightAnchor, multiplier: 1.0),
            view.centerXAnchor.constraint(equalTo: self.centerXAnchor),
            view.centerYAnchor.constraint(equalTo: self.centerYAnchor)
            ])
        
        self.sendSubviewToBack(view)
        
        self.circleBackgroundView = view
    }
    
    // MARK: - Themable
    
    func update(theme: Theme) {
        self.theme = theme
        
        self.circleBackgroundView.backgroundColor = theme.headerTextSecondaryColor
    }
}