vds_ios/VDS/Components/Label/Label.swift

//
//  VDSLabel.swift
//  VDS
//
//  Created by Matt Bruce on 7/28/22.
//

import Foundation
import UIKit
import VDSColorTokens
import Combine

public class Label:LabelBase<DefaultLabelModel>{}

open class LabelBase<ModelType: LabelModel>: UILabel, ModelHandlerable, Initable, Resettable {
    
    //--------------------------------------------------
    // MARK: - Combine Properties
    //--------------------------------------------------
    @Published public var model: ModelType
    private var cancellable: AnyCancellable?

    //--------------------------------------------------
    // MARK: - Properties
    //--------------------------------------------------
    @Proxy(\.model.attributes)
    open var attributes: [LabelAttributeModel]?

    @Proxy(\.model.fontCategory)
    open var fontCategory: FontCategory

    @Proxy(\.model.fontSize)
    open var fontSize: FontSize
    
    @Proxy(\.model.fontWeight)
    open var fontWeight: FontWeight

    @Proxy(\.model.textPosition)
    open var textPosition: TextPosition

    //can't use @Proxy here
    override open var text: String? {
        didSet {
            if model.text != oldValue {
                model.text = text
            }
        }
    }
    
    //--------------------------------------------------
    // MARK: - Configuration Properties
    //--------------------------------------------------
    private var textColorConfiguration: DisabledSurfaceColorConfiguration<ModelType> = {
        let config = DisabledSurfaceColorConfiguration<ModelType>()
        config.disabled.lightColor = VDSColor.elementsSecondaryOnlight
        config.disabled.darkColor = VDSColor.elementsSecondaryOndark
        config.enabled.lightColor = VDSColor.elementsPrimaryOnlight
        config.enabled.darkColor = VDSColor.elementsPrimaryOndark
        return config
    } ()
    
    //--------------------------------------------------
    // MARK: - Initializers
    //--------------------------------------------------
    required public convenience init() {
        self.init(frame: .zero)
        self.model = ModelType()
    }
    
    public required convenience init(with model: ModelType) {
        self.init()
        self.model = model
    }
    
    public override init(frame: CGRect) {
        self.model = ModelType()
        super.init(frame: frame)
        setup()
    }
    
    required public init?(coder: NSCoder) {
        self.model = ModelType()
        super.init(coder: coder)
        setup()
    }
    
    //--------------------------------------------------
    // MARK: - Public Functions
    //--------------------------------------------------
    open func setup() {
        backgroundColor = .clear
        numberOfLines = 0
        lineBreakMode = .byWordWrapping
        translatesAutoresizingMaskIntoConstraints = false
        accessibilityCustomActions = []
        accessibilityTraits = .staticText
        cancellable = $model.debounce(for: .seconds(Constants.ModelStateDebounce), scheduler: RunLoop.main).sink { [weak self] viewModel in
            self?.onStateChange(viewModel: viewModel)
        }
    }
    
    public func reset() {
        text = nil
        attributedText = nil
        textColor = .black
        font = FontStyle.RegularBodyLarge.font
        textAlignment = .left
        accessibilityCustomActions = []
        accessibilityTraits = .staticText
        numberOfLines = 0
    }
    
    //Modelable
    open func set(with model: ModelType) {
        self.model = model
    }
    
    //--------------------------------------------------
    // MARK: - State
    //--------------------------------------------------
    /// Follow the SwiftUI View paradigm
    /// - Parameter viewModel: state
    open func onStateChange(viewModel: ModelType) {
        textAlignment = viewModel.textPosition.textAlignment
        textColor = textColorConfiguration.getColor(viewModel)
       
        if let vdsFont = viewModel.font {
            font = vdsFont
        } else {
            font = FontStyle.defaultStyle.font
        }
        
        if let attributes = viewModel.attributes, let text = model.text, let font = font, let textColor = textColor {
            //clear the arrays holding actions
            accessibilityCustomActions = []
            actions = []
            
            //create the primary string
            let startingAttributes = [NSAttributedString.Key.font: font, NSAttributedString.Key.foregroundColor: textColor]
            let mutableText = NSMutableAttributedString(string: text, attributes: startingAttributes)
            
            //loop through the models attributes
            for attribute in attributes {
                
                //add attribute on the string
                attribute.setAttribute(on: mutableText)
                
                //see if the attribute is Actionable
                if let actionable = attribute as? LabelAttributeActionable{
                    //create a accessibleAction
                    let customAccessibilityAction = customAccessibilityAction(range: actionable.range)
                    
                    //create a wrapper for the attributes range, block and
                    actions.append(LabelAction(range: actionable.range, actionBlock: actionable.action, accessibilityID: customAccessibilityAction?.hashValue ?? -1))
                }
            }
            
            //only enabled if enabled and has actions
            isUserInteractionEnabled = !viewModel.disabled && !actions.isEmpty
            
            //set the attributed text
            attributedText = mutableText
        } else {
            text = viewModel.text
        }
    }
            
    //--------------------------------------------------
    // MARK: - Actionable
    //--------------------------------------------------
    private var tapGesture: UITapGestureRecognizer? {
        willSet {
            if let tapGesture = tapGesture, newValue == nil {
                removeGestureRecognizer(tapGesture)
            } else if let gesture = newValue, tapGesture == nil {
                addGestureRecognizer(gesture)
            }
        }
    }
    
    private struct LabelAction {
        var range: NSRange
        var actionBlock: Blocks.ActionBlock
        var accessibilityId: Int = 0
        
        func performAction() {
            actionBlock()
        }
        
        init(range: NSRange, actionBlock: @escaping Blocks.ActionBlock, accessibilityID: Int = 0) {
            self.range = range
            self.actionBlock = actionBlock
            self.accessibilityId = accessibilityID
        }
    }

    private var actions: [LabelAction] = [] {
        didSet {
            if actions.isEmpty {
                tapGesture = nil
            } else {
                //add tap gesture
                if tapGesture == nil {
                    let singleTap = UITapGestureRecognizer(target: self, action: #selector(textLinkTapped))
                    singleTap.numberOfTapsRequired = 1
                    tapGesture = singleTap
                }
                if actions.count > 1 {
                    actions.sort { first, second in
                        return first.range.location < second.range.location
                    }
                }
            }
        }
    }
    
    @objc private func textLinkTapped(_ gesture: UITapGestureRecognizer) {
        for actionable in actions {
            // This determines if we tapped on the desired range of text.
            if gesture.didTapAttributedTextInLabel(self, inRange: actionable.range) {
                actionable.performAction()
                return
            }
        }
    }
    
    //--------------------------------------------------
    // MARK: - Accessibility For Actions
    //--------------------------------------------------
    private func customAccessibilityAction(range: NSRange) -> UIAccessibilityCustomAction? {
        
        guard let text = text else { return nil }
        //TODO: accessibilityHint for Label
//        if accessibilityHint == nil {
//            accessibilityHint = MVMCoreUIUtility.hardcodedString(withKey: "swipe_to_select_with_action_hint")
//        }
        
        let actionText = NSString(string: text).substring(with: range)
        let accessibleAction = UIAccessibilityCustomAction(name: actionText, target: self, selector: #selector(accessibilityCustomAction(_:)))
        accessibilityCustomActions?.append(accessibleAction)
        
        return accessibleAction
    }
    
    @objc public func accessibilityCustomAction(_ action: UIAccessibilityCustomAction) {
        
        for actionable in actions {
            if action.hash == actionable.accessibilityId {
                actionable.performAction()
                return
            }
        }
    }
    
    open override func accessibilityActivate() -> Bool {
        
        guard let accessibleActions = accessibilityCustomActions else { return false }
        
        for actionable in actions {
            for action in accessibleActions {
                if action.hash == actionable.accessibilityId {
                    actionable.performAction()
                    return true
                }
            }
        }
        
        return false
    }
}