//
//  GradientButton.swift
//  DreamJay
//
//  Created by Mateusz Nadolski on 24/02/2017.
//  Copyright © 2017 Tooploox. All rights reserved.
//

import UIKit

class GradientButton: Button {

    let buttonSize: CGFloat
    let fillSize: CGFloat

    private let fillView = ViewsFactory.gradientView(withColors: [UIColor.basic1, UIColor.basic9])
    private let innerBackgroundView = ViewsFactory.gradientView(
        withColors: [UIColor.basic1.withAlphaComponent(0.05), UIColor.basic9.withAlphaComponent(0.05)]
    )
    private let outerBackgroundView = ViewsFactory.gradientView(
        withColors: [UIColor.basic1.withAlphaComponent(0.03), UIColor.basic9.withAlphaComponent(0.03)]
    )

    init(buttonSize: CGFloat, fillSize: CGFloat) {
        self.buttonSize = buttonSize
        self.fillSize = fillSize
        super.init(frame: .zero)
        addSubviews()
        setupConstraints()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    private func addSubviews() {
        addSubview(outerBackgroundView)
        addSubview(innerBackgroundView)
        addSubview(fillView)
    }

    private func setupConstraints() {
        let constraints = Array([
            constraintsForFillView(),
            constraintsForInnerBackgroundView(),
            constraintsForOuterBackgroundView()
        ].joined())
        NSLayoutConstraint.activate(constraints)
    }

    private func constraintsForFillView() -> [NSLayoutConstraint] {
        return [
            fillView.widthAnchor.constraint(equalToConstant: fillSize),
            fillView.heightAnchor.constraint(equalToConstant: fillSize),
            fillView.centerXAnchor.constraint(equalTo: centerXAnchor),
            fillView.centerYAnchor.constraint(equalTo: centerYAnchor)
        ]
    }

    private func constraintsForInnerBackgroundView() -> [NSLayoutConstraint] {
        let size = (buttonSize - fillSize) / 2.0 + fillSize
        return [
            innerBackgroundView.widthAnchor.constraint(equalToConstant: size),
            innerBackgroundView.heightAnchor.constraint(equalToConstant: size),
            innerBackgroundView.centerXAnchor.constraint(equalTo: centerXAnchor),
            innerBackgroundView.centerYAnchor.constraint(equalTo: centerYAnchor)
        ]
    }

    private func constraintsForOuterBackgroundView() -> [NSLayoutConstraint] {
        return [
            outerBackgroundView.widthAnchor.constraint(equalToConstant: buttonSize),
            outerBackgroundView.heightAnchor.constraint(equalToConstant: buttonSize),
            outerBackgroundView.centerXAnchor.constraint(equalTo: centerXAnchor),
            outerBackgroundView.centerYAnchor.constraint(equalTo: centerYAnchor)
        ]
    }
}