mvm_core_ui/MVMCoreUI/Containers/Container.swift

//
//  Container.swift
//  MVMCoreUI
//
//  Created by Scott Pfeil on 12/11/19.
//  Copyright © 2019 Verizon Wireless. All rights reserved.
//

import UIKit

protocol ContainerModelProtocol {
    var horizontalAlignment: UIStackView.Alignment { get set }
    var verticalAlignment: UIStackView.Alignment { get set }
}

class ContainerHelper: NSObject {
    var leftConstraint: NSLayoutConstraint?
    var topConstraint: NSLayoutConstraint?
    var bottomConstraint: NSLayoutConstraint?
    var rightConstraint: NSLayoutConstraint?
    
    var alignCenterHorizontalConstraint: NSLayoutConstraint?
    var alignCenterLeftConstraint: NSLayoutConstraint?
    var alignCenterRightConstraint: NSLayoutConstraint?
    
    var alignCenterVerticalConstraint: NSLayoutConstraint?
    var alignCenterTopConstraint: NSLayoutConstraint?
    var alignCenterBottomConstraint: NSLayoutConstraint?

    var leftLowConstraint: NSLayoutConstraint?
    var topLowConstraint: NSLayoutConstraint?
    var bottomLowConstraint: NSLayoutConstraint?
    var rightLowConstraint: NSLayoutConstraint?
    
    func constrainView(_ view: UIView) {
        guard let margins = view.superview?.layoutMarginsGuide else { return }
        leftConstraint = view.leftAnchor.constraint(equalTo: margins.leftAnchor)
        leftConstraint?.isActive = true
        
        topConstraint = view.topAnchor.constraint(equalTo: margins.topAnchor)
        topConstraint?.isActive = true
        
        rightConstraint = margins.rightAnchor.constraint(equalTo: view.rightAnchor)
        rightConstraint?.isActive = true
        
        bottomConstraint = margins.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        bottomConstraint?.isActive = true
        
        alignCenterHorizontalConstraint = view.centerXAnchor.constraint(equalTo: margins.centerXAnchor)
        alignCenterLeftConstraint = view.leftAnchor.constraint(greaterThanOrEqualTo: margins.leftAnchor)
        alignCenterRightConstraint = margins.rightAnchor.constraint(greaterThanOrEqualTo: view.rightAnchor)

        alignCenterVerticalConstraint = view.centerYAnchor.constraint(equalTo: margins.centerYAnchor)
        alignCenterTopConstraint = view.topAnchor.constraint(greaterThanOrEqualTo: margins.topAnchor)
        alignCenterBottomConstraint = margins.bottomAnchor.constraint(greaterThanOrEqualTo: view.bottomAnchor)
        
        leftLowConstraint = view.leftAnchor.constraint(equalTo: margins.leftAnchor)
        leftLowConstraint?.priority = UILayoutPriority(rawValue: 200)
        leftLowConstraint?.isActive = true
        
        topLowConstraint = view.topAnchor.constraint(equalTo: margins.topAnchor)
        topLowConstraint?.priority = UILayoutPriority(rawValue: 200)
        topLowConstraint?.isActive = true
        
        rightLowConstraint = margins.rightAnchor.constraint(equalTo: view.rightAnchor)
        rightLowConstraint?.priority = UILayoutPriority(rawValue: 200)
        rightLowConstraint?.isActive = true
        
        bottomLowConstraint = margins.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        bottomLowConstraint?.priority = UILayoutPriority(rawValue: 200)
        bottomLowConstraint?.isActive = true
        
        setAccessibility(view)
    }
    
    func setAccessibility(_ view: UIView) {
        guard let superView = view.superview else { return }
        superView.isAccessibilityElement = false
        if let elements = view.accessibilityElements {
            superView.accessibilityElements = elements
        } else {
            superView.accessibilityElements = [view]
        }
    }
    
    func alignHorizontal(_ alignment: UIStackView.Alignment) {
        switch alignment {
        case .center:
            alignCenterHorizontalConstraint?.isActive = true
            alignCenterLeftConstraint?.isActive = true
            alignCenterRightConstraint?.isActive = true
            leftConstraint?.isActive = false
            rightConstraint?.isActive = false
        case .leading:
            alignCenterHorizontalConstraint?.isActive = false
            alignCenterLeftConstraint?.isActive = false
            alignCenterRightConstraint?.isActive = true
            leftConstraint?.isActive = true
            rightConstraint?.isActive = false
        case .trailing:
            alignCenterHorizontalConstraint?.isActive = false
            alignCenterLeftConstraint?.isActive = true
            alignCenterRightConstraint?.isActive = false
            leftConstraint?.isActive = false
            rightConstraint?.isActive = true
        case .fill:
            alignCenterHorizontalConstraint?.isActive = false
            alignCenterLeftConstraint?.isActive = false
            alignCenterRightConstraint?.isActive = false
            leftConstraint?.isActive = true
            rightConstraint?.isActive = true
        default: break
        }
    }
 
    func alignVertical(_ alignment: UIStackView.Alignment) {
        switch alignment {
        case .center:
            alignCenterVerticalConstraint?.isActive = true
            alignCenterTopConstraint?.isActive = true
            alignCenterBottomConstraint?.isActive = true
            topConstraint?.isActive = false
            bottomConstraint?.isActive = false
        case .leading:
            alignCenterVerticalConstraint?.isActive = false
            alignCenterTopConstraint?.isActive = false
            alignCenterBottomConstraint?.isActive = true
            topConstraint?.isActive = true
            bottomConstraint?.isActive = false
        case .trailing:
            alignCenterVerticalConstraint?.isActive = false
            alignCenterTopConstraint?.isActive = true
            alignCenterBottomConstraint?.isActive = false
            topConstraint?.isActive = false
            bottomConstraint?.isActive = true
        case .fill:
            alignCenterVerticalConstraint?.isActive = false
            alignCenterTopConstraint?.isActive = false
            alignCenterBottomConstraint?.isActive = false
            topConstraint?.isActive = true
            bottomConstraint?.isActive = true
        default: break
        }
    }
    
    func set(with model: ContainerModelProtocol) {
        alignHorizontal(model.horizontalAlignment)
        alignVertical(model.verticalAlignment)
    }
    
    static func getAlignment(for string: String) -> UIStackView.Alignment? {
        switch string {
        case "leading":
            return .leading
        case "trailing":
            return .trailing
        case "center":
            return .center
        case "fill":
            return .fill
        default:
            return nil
        }
    }
}

class Container: View {
    var model: ContainerModelProtocol?
    var view: UIView?
    let containerHelper = ContainerHelper()
}

// MARK: - MVMCoreViewProtocol
extension Container {
    open override func updateView(_ size: CGFloat) {
        super.updateView(size)
        (view as? MVMCoreViewProtocol)?.updateView(size)
        MFStyler.setMarginsFor(self, size: size, defaultHorizontal: true, top: 0, bottom: 0)
    }
        
    /// Will be called only once.
    open override func setupView() {
        super.setupView()
        backgroundColor = .clear
    }
}

// MARK: - MVMCoreUIMoleculeViewProtocol
extension Container {
    override func setWithJSON(_ json: [AnyHashable : Any]?, delegateObject: MVMCoreUIDelegateObject?, additionalData: [AnyHashable : Any]?) {
        if let horizontalAlignmentString = json?.optionalStringForKey("horizontalAlignment"), let alignment = ContainerHelper.getAlignment(for: horizontalAlignmentString) {
            containerHelper.alignHorizontal(alignment)
        } else if let alignment = (view as? MVMCoreUIViewConstrainingProtocol)?.horizontalAlignment {
            containerHelper.alignHorizontal(alignment)
        }
    }
}