//  Copyright © 2018 Keith Harrison. All rights reserved.
//
//  Redistribution and use in source and binary forms, with or without
//  modification, are permitted provided that the following conditions are met:
//
//  1. Redistributions of source code must retain the above copyright
//  notice, this list of conditions and the following disclaimer.
//
//  2. Redistributions in binary form must reproduce the above copyright
//  notice, this list of conditions and the following disclaimer in the
//  documentation and/or other materials provided with the distribution.
//
//  3. Neither the name of the copyright holder nor the names of its
//  contributors may be used to endorse or promote products derived from
//  this software without specific prior written permission.
//
//  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
//  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
//  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
//  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
//  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
//  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
//  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
//  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
//  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
//  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
//  POSSIBILITY OF SUCH DAMAGE.

import UIKit

final class ViewController: UIViewController {

    private let backgroundView: UIView = {
        let view = UIView()
        view.translatesAutoresizingMaskIntoConstraints = false
        view.backgroundColor = .green
        return view
    }()

    override func viewDidLoad() {
        super.viewDidLoad()
        setupView()
    }

    private func setupView() {
        view.backgroundColor = .yellow
        view.addSubview(backgroundView)

        let optionalWidth = backgroundView.widthAnchor.constraint(equalTo: view.widthAnchor)
        optionalWidth.priority = .defaultHigh

        NSLayoutConstraint.activate([
            // center the background view in the root view
            backgroundView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            backgroundView.centerYAnchor.constraint(equalTo: view.centerYAnchor),

            // Aspect ratio 1:1 - makes the background view square
            backgroundView.widthAnchor.constraint(equalTo: backgroundView.heightAnchor),

            // width and height can grow up to the size of the root view
            backgroundView.widthAnchor.constraint(lessThanOrEqualTo: view.widthAnchor),
            backgroundView.heightAnchor.constraint(lessThanOrEqualTo: view.heightAnchor),

            // Pull the width as close as possible to the width
            // of the root view (without violating other required constraints)
            optionalWidth
            ])
    }
}
