mvm_core_ui/MVMCoreUI/Molecules/MoleculeStackView.swift

//
//  MoleculeStackView.swift
//  MVMCoreUI
//
//  Created by Scott Pfeil on 2/11/19.
//  Copyright © 2019 Verizon Wireless. All rights reserved.
//

import UIKit

public class MoleculeStackView: ViewConstrainingView {
    var spacingBlock: ((Any) -> UIEdgeInsets)?
    var moleculesArray: [UIView]?
    var useMargins: Bool = false
    var alignment: UIStackView.Alignment = .fill
    var contentView: UIView = MVMCoreUICommonViewsUtility.commonView()
    
    private var spacingBetweenItems: [NSLayoutConstraint]?
    
    /// For setting the direction of the stack
    var axis: NSLayoutConstraint.Axis = .vertical {
        didSet {
            if axis != oldValue  {
                MVMCoreDispatchUtility.performBlock(onMainThread: {
                    // remove constraints
                    if self.axis == .vertical {
                        // layout vertical
                    } else {
                        // layout horizontal
                    }
                })
            }
        }
    }
    
    /// For setting the alignment perpendicular to the direction of the stack. Default fill for vertical and center for horizontal. Can be overriden at the item level.
    var itemAlignment: UIStackView.Alignment = .fill {
        didSet {
            if itemAlignment != oldValue  {
                MVMCoreDispatchUtility.performBlock(onMainThread: {
                    // remove constraints
                    if self.axis == .vertical {
                        // layout vertical
                    } else {
                        // layout horizontal
                    }
                })
            }
        }
    }
    
    var spacing: Float = 16 {
        didSet {
            if spacing != oldValue  {
                MVMCoreDispatchUtility.performBlock(onMainThread: {
                    // loop space bettwen constraints and update. skip custom ones...
                })
            }
        }
    }
    
    public func setAxisWithJSON(_ json: [AnyHashable: Any]?) {
        switch json?.optionalStringForKey("axis") {
        case "horizontal":
            axis = .horizontal
        default:
            axis = .vertical
        }
    }
    
    
    public func pinView(_ view: UIView, toView: UIView, attribute: NSLayoutConstraint.Attribute, relation: NSLayoutConstraint.Relation, priority: UILayoutPriority, constant: CGFloat) {
        let constraint = NSLayoutConstraint(item: view, attribute: attribute, relatedBy: relation, toItem: toView, attribute: attribute, multiplier: 1.0, constant: constant)
        constraint.priority = priority
        constraint.isActive = true
    }

    // MARK: - Inits
    public override init(frame: CGRect) {
        super.init(frame: frame)
    }
    
    public init(withJSON json: [AnyHashable: Any]?, delegateObject: MVMCoreUIDelegateObject?, additionalData: [AnyHashable : Any]?) {
        super.init(frame: CGRect.zero)
        setWithJSON(json, delegateObject: delegateObject, additionalData: additionalData)
    }
    
    public convenience init(withJSON json: [AnyHashable: Any]?, delegateObject: MVMCoreUIDelegateObject?, spacingBlock: ((Any) -> UIEdgeInsets)?) {
        self.init(withJSON: json, delegateObject: delegateObject, additionalData: nil)
        self.spacingBlock = spacingBlock
    }
    
    public required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    // MARK: - MFViewProtocol
    public override func setupView() {
        super.setupView()
        guard contentView.superview == nil else {
            return
        }
        translatesAutoresizingMaskIntoConstraints = false
        backgroundColor = .clear
        addConstrainedView(contentView)
        //self.setContentHuggingPriority(UILayoutPriority.required, for: NSLayoutConstraint.Axis.vertical)
        //self.setContentCompressionResistancePriority(UILayoutPriority.required, for: NSLayoutConstraint.Axis.vertical)
    }
    
    public override func updateView(_ size: CGFloat) {
        super.updateView(size)
        for view in subviews {
            if let mvmView = view as? MVMCoreViewProtocol {
                mvmView.updateView(size)
            }
        }
    }
    
    // MARK: - MVMCoreUIMoleculeViewProtocol
    open override func setWithJSON(_ json: [AnyHashable: Any]?, delegateObject: MVMCoreUIDelegateObject?, additionalData: [AnyHashable: Any]?) {
        super.setWithJSON(json, delegateObject: delegateObject, additionalData: additionalData)
        MVMCoreUIStackableViewController.remove(contentView.subviews)
        
        guard let molecules = json?.arrayForKey(KeyMolecules) as? [[String: Any]] else {
            return
        }
        
        // Sets the stack attributes
        setAxisWithJSON(json)
        spacing = json?["spacing"] as? Float ?? 16
        
        // Set the alignment for the stack in the containing view. The json driven value is for the axis direction alignment.
        if axis == .vertical {
            alignHorizontal(.fill)
            alignVertical(ViewConstrainingView.getAlignmentFor(json?.optionalStringForKey("alignment"), defaultAlignment: .fill))
        } else {
            alignHorizontal(ViewConstrainingView.getAlignmentFor(json?.optionalStringForKey("alignment"), defaultAlignment: .fill))
            alignVertical(.leading)
        }
        
        // Create the molecules and set the json.
        var previousObject = contentView
        for (index, map) in molecules.enumerated() {
            if let moleculeJSON = map.optionalDictionaryForKey(KeyMolecule), let molecule = MVMCoreUIMoleculeMappingObject.shared()?.createMolecule(forJSON: moleculeJSON, delegateObject: delegateObject, constrainIfNeeded: true) {
                contentView.addSubview(molecule)
                molecule.translatesAutoresizingMaskIntoConstraints = false
                
                let spacing = CGFloat(map["spacing"] as? Float ?? self.spacing)
                let percent = map["percent"] as? Int
                let verticalAlignment = ViewConstrainingView.getAlignmentFor(json?.optionalStringForKey("verticalAlignment"), defaultAlignment: (percent == nil && axis == .vertical ? UIStackView.Alignment.fill : UIStackView.Alignment.leading))
                let horizontalAlignment = ViewConstrainingView.getAlignmentFor(json?.optionalStringForKey("horizontalAlignment"), defaultAlignment: (axis == .vertical || percent == nil ? UIStackView.Alignment.fill : UIStackView.Alignment.leading))

                if let molecule = molecule as? MVMCoreUIViewConstrainingProtocol {
                    molecule.alignHorizontal?(horizontalAlignment)
                    molecule.alignVertical?(verticalAlignment)
                }
                if axis == .vertical {
                    if index == 0 {
                        pinView(molecule, toView: previousObject, attribute: .top, relation: .equal, priority: .required, constant: spacing)
                    } else {
                        NSLayoutConstraint(pinFirstView: previousObject, toSecondView: molecule, withConstant: spacing, directionVertical: true)?.isActive = true
                    }
                    pinView(molecule, toView: contentView, attribute: .leading, relation: .equal, priority: .required, constant: 0)
                    pinView(contentView, toView: molecule, attribute: .trailing, relation: .equal, priority: .required, constant: 0)
                    if let percent = percent {
                        molecule.heightAnchor.constraint(equalTo: contentView.heightAnchor, multiplier: CGFloat(percent)/100.0).isActive = true
                    }
                } else {
                    if index == 0 {
                        pinView(molecule, toView: previousObject, attribute: .leading, relation: .equal, priority: .required, constant: spacing)
                    } else {
                        NSLayoutConstraint(pinFirstView: previousObject, toSecondView: molecule, withConstant: spacing, directionVertical: false)?.isActive = true
                    }
                    pinView(molecule, toView: contentView, attribute: .top, relation: .equal, priority: .required, constant: 0)
                    pinView(contentView, toView: molecule, attribute: .bottom, relation: .equal, priority: .required, constant: 0)
                    if let percent = percent {
                        molecule.widthAnchor.constraint(equalTo: contentView.widthAnchor, multiplier: CGFloat(percent)/100.0).isActive = true
                    }
                }
                previousObject = molecule
            }
        }
        if axis == .vertical {
            pinView(contentView, toView: previousObject, attribute: .bottom, relation: .equal, priority: .required, constant: 0)
        } else {
            pinView(contentView, toView: previousObject, attribute: .right, relation: .equal, priority: .required, constant: 0)
        }
    }
}