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

@objc(VDSLabel)
public class Label: LabelBase {}

@objc(VDSLabelBase)
open class LabelBase: UILabel, Handlerable, ViewProtocol, Resettable {
    
    //--------------------------------------------------
    // MARK: - Combine Properties
    //--------------------------------------------------
    public var subject = PassthroughSubject<Void, Never>()
    public var subscribers = Set<AnyCancellable>()
    public var hasChanged: Bool = false
    
    //--------------------------------------------------
    // MARK: - Properties
    //--------------------------------------------------
    open var surface: Surface = .light { didSet { didChange() }}
    
    open var disabled: Bool = false { didSet { isEnabled = !disabled } }
        
    open var attributes: [any LabelAttributeModel]?  { didSet { didChange() }}
    
    open var typograpicalStyle: TypographicalStyle = .defaultStyle  { didSet { didChange() }}
    
    open var textPosition: TextPosition = .left { didSet { didChange() }}

    open override var isEnabled: Bool {
        get { !disabled }
        set {
            if disabled != !newValue {
                disabled = !newValue
            }
            isUserInteractionEnabled = isEnabled
            didChange()
        }
    }
    
    override open var text: String? {
        didSet {
            didChange()
        }
    }
    
    //--------------------------------------------------
    // MARK: - Configuration Properties
    //--------------------------------------------------
    public var textColorConfiguration: AnyColorable = DisabledSurfaceColorConfiguration().with {
        $0.disabled.lightColor = VDSColor.elementsSecondaryOnlight
        $0.disabled.darkColor = VDSColor.elementsSecondaryOndark
        $0.enabled.lightColor = VDSColor.elementsPrimaryOnlight
        $0.enabled.darkColor = VDSColor.elementsPrimaryOndark
    }.eraseToAnyColorable()
    
    //--------------------------------------------------
    // MARK: - Initializers
    //--------------------------------------------------
    required public init() {
        super.init(frame: .zero)
        initialSetup()
    }

    public override init(frame: CGRect) {
        super.init(frame: .zero)
        initialSetup()
    }
    
    public required init?(coder: NSCoder) {
        super.init(coder: coder)
        initialSetup()
    }
        
    //--------------------------------------------------
    // MARK: - Public Functions
    //--------------------------------------------------
    open func initialSetup() {
        backgroundColor = .clear
        numberOfLines = 0
        lineBreakMode = .byWordWrapping
        translatesAutoresizingMaskIntoConstraints = false
        accessibilityCustomActions = []
        accessibilityTraits = .staticText
        setup()
    }
    
    open func setup() {}
    
    open func reset() {
        surface = .light
        disabled = false
        attributes = nil
        typograpicalStyle = .defaultStyle
        textPosition = .left
        text = nil
        attributedText = nil
        accessibilityCustomActions = []
        accessibilityTraits = .staticText
        numberOfLines = 0
    }
           
    //--------------------------------------------------
    // MARK: - Overrides
    //--------------------------------------------------    
    open override func layoutSubviews() {
        super.layoutSubviews()
        updateView()
    }
    
    open func updateView() {
        textAlignment = textPosition.textAlignment
        textColor = textColorConfiguration.getColor(self)
        font = typograpicalStyle.font
        
        if let text =  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)
               
            //set the local lineHeight/lineSpacing attributes
            setStyleAttributes(attributedString: mutableText)
            
            if let attributes = attributes {
                //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? any LabelAttributeActionable{
                        //create a accessibleAction
                        let customAccessibilityAction = customAccessibilityAction(range: actionable.range, accessibleText: actionable.accessibleText)
                        
                        //create a wrapper for the attributes range, block and
                        actions.append(LabelAction(range: actionable.range, action: actionable.action, accessibilityID: customAccessibilityAction?.hashValue ?? -1))
                    }
                }
            }
                    
            //only enabled if enabled and has actions
            isUserInteractionEnabled = !disabled && !actions.isEmpty
            
            //set the attributed text
            attributedText = mutableText
        }
    }
    
    // MARK: - Private Attributes
    private func setStyleAttributes(attributedString: NSMutableAttributedString) {
        //get the range
        let entireRange = NSRange(location: 0, length: attributedString.length)
        
        //set letterSpacing
        if typograpicalStyle.letterSpacing > 0.0 {
            attributedString.addAttribute(.kern, value: typograpicalStyle.letterSpacing, range: entireRange)
        }
        
        //set lineHeight
        if typograpicalStyle.lineHeight > 0.0 {
            let lineHeight = typograpicalStyle.lineHeight
            let adjustment = lineHeight > font.lineHeight ? 2.0 : 1.0
            let baselineOffset = (lineHeight - font.lineHeight) / 2.0 / adjustment
            let paragraph = NSMutableParagraphStyle().with {
                $0.maximumLineHeight = lineHeight
                $0.minimumLineHeight = lineHeight
                $0.alignment = textPosition.textAlignment
                $0.lineBreakMode = lineBreakMode
            }
            attributedString.addAttribute(.baselineOffset, value: baselineOffset, range: entireRange)
            attributedString.addAttribute( .paragraphStyle, value: paragraph, range: entireRange)
            
        } else if textPosition != .left {
            let paragraph = NSMutableParagraphStyle().with {
                $0.alignment = textPosition.textAlignment
                $0.lineBreakMode = lineBreakMode
            }
            attributedString.addAttribute( .paragraphStyle, value: paragraph, range: entireRange)
        }
    }
                
    //--------------------------------------------------
    // 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 action: PassthroughSubject<Void, Never>
        var accessibilityId: Int = 0
        
        func performAction() {
            action.send()
        }
        
        init(range: NSRange, action: PassthroughSubject<Void, Never>, accessibilityID: Int = 0) {
            self.range = range
            self.action = action
            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, accessibleText: String? = nil) -> 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 = accessibleText ?? 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
    }
}