SideMenuViewController.swift

//
//  SideMenuViewController.swift
//  sieum
//
//  Created by 홍성호 on 2018. 6. 26..
//  Copyright © 2018년 홍성호. All rights reserved.
//

import UIKit
import SnapKit

class SideMenuViewController: UIViewController {

    private lazy var didUpdateViewConstraints: Bool = false
    private var trailingConstraint: Constraint?
    private var trailingMaxOffset: CGFloat {
        return view.frame.width * 0.6
    }
    
    private var tableView: UITableView = {
        let tableView = UITableView()
        return tableView
    }()
    
    private var closeButton: UIButton = {
        let closeButton = UIButton()
        closeButton.backgroundColor = .black
        closeButton.addTarget(self, action: #selector(onCloseButton(_:)), for: .touchUpInside)
        closeButton.alpha = 0.0
        return closeButton
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor = .clear
        view.isOpaque = false
        
        view.addSubview(tableView)
        view.addSubview(closeButton)

        tableView.snp.makeConstraints { make in
            make.top.leading.bottom.equalToSuperview()
            self.trailingConstraint = make.trailing.equalTo(view.snp.leading).constraint
        }
        
        closeButton.snp.makeConstraints { make in
            make.top.trailing.bottom.equalToSuperview()
            make.leading.equalTo(tableView.snp.trailing)
        }
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        show()
    }
    
    @objc func onCloseButton(_ sender: UIButton) {
        hide { [weak self] in
            self?.dismiss(animated: false)
        }
    }
    
    private func show(completion: (() -> Void)? = nil) {
        trailingConstraint?.update(offset: trailingMaxOffset)
        animateLayout(animations: { [weak self] in
            self?.closeButton.alpha = 0.5
        }) { isFinished in
            if isFinished {
                completion?()
            }
        }
    }
    
    private func hide(completion: (() -> Void)? = nil) {
        trailingConstraint?.update(offset: 0)
        animateLayout(animations: { [weak self] in
            self?.closeButton.alpha = 0.0
        }) { isFinished in
            if isFinished {
                completion?()
            }
        }
    }
}

extension UIViewController {
    
    func animateLayout(duration: TimeInterval = 0.3, animations: (() -> Void)? = nil, completion: ((Bool) -> Void)? = nil) {
        
        UIView.animate(withDuration: duration, animations: { [weak self] in
            self?.view.layoutIfNeeded()
            animations?()
            }, completion: { isFinished in
                completion?(isFinished)
        })
    }
}