//
//  Toggle.swift
//  VDS
//
//  Created by Matt Bruce on 7/22/22.
//

import Foundation
import UIKit
import VDSColorTokens
import Combine
/**
 A custom implementation of Apple's UISwitch.
 
 By default this class begins in the off state.
 
 Container: The background of the toggle control.
 Knob: The circular indicator that slides on the container.
 */
@objc(VDSToggle)
open class Toggle: Control, Changeable {
    //--------------------------------------------------
    // MARK: - Enums
    //--------------------------------------------------
    public enum TextSize: String, CaseIterable {
        case small, large
    }

    public enum TextWeight: String, CaseIterable {
        case regular, bold
    }

    public enum TextPosition: String, CaseIterable {
        case left, right
    }

    //--------------------------------------------------
    // MARK: - Initializers
    //--------------------------------------------------
    required public init() {
        super.init(frame: .zero)
    }
    
    public override init(frame: CGRect) {
        super.init(frame: .zero)
    }
    
    public required init?(coder: NSCoder) {
        super.init(coder: coder)
    }
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    private var stackView = UIStackView().with {
        $0.isUserInteractionEnabled = false
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.axis = .horizontal
        $0.distribution = .fill
    }
        
    private var toggleView = UIView().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
    }
    
    private var knobView = UIView().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.backgroundColor = .white
    }
    
    //--------------------------------------------------
    // MARK: - Configuration Properties
    //--------------------------------------------------    
    // Sizes are from InVision design specs.
    public let toggleSize = CGSize(width: 52, height: 24)
    public let toggleContainerSize = CGSize(width: 52, height: 44)
    public let knobSize = CGSize(width: 20, height: 20)

    private var toggleColorConfiguration = ControlColorConfiguration().with {
        $0.setSurfaceColors(VDSColor.elementsSecondaryOnlight, VDSColor.paletteGray44, forState: .normal)
        $0.setSurfaceColors(VDSColor.interactiveDisabledOnlight, VDSColor.interactiveDisabledOndark, forState: .disabled)
        $0.setSurfaceColors(VDSColor.paletteGreen26, VDSColor.paletteGreen34, forState: .selected)
    }
    
    private var knobColorConfiguration = ControlColorConfiguration().with {
        $0.setSurfaceColors(VDSColor.elementsPrimaryOndark, VDSColor.elementsPrimaryOndark, forState: .normal)
        $0.setSurfaceColors(VDSColor.paletteGray95, VDSColor.paletteGray44, forState: .disabled)
        $0.setSurfaceColors(VDSColor.elementsPrimaryOndark, VDSColor.elementsPrimaryOndark, forState: .selected)
    }
    
    private var textStyle: TextStyle {
        if textSize == .small {
            if textWeight == .bold {
                return .boldBodySmall
            } else {
                return .bodySmall
            }
        } else {
            if textWeight == .bold {
                return .boldBodyLarge
            } else {
                return .bodyLarge
            }
        }
    }
    
    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    public var onChangeSubscriber: AnyCancellable? {
        willSet {
            if let onChangeSubscriber {
                onChangeSubscriber.cancel()
            }
        }
    }
    
    open var label = Label().with {
        $0.setContentCompressionResistancePriority(.required, for: .vertical)
    }

    open var isOn: Bool {
        get { isSelected }
        set {
            if isSelected != newValue {
                isSelected = newValue
            }
            didChange()
        }
    }
    
    open var isAnimated: Bool = true { didSet { didChange() }}

    open var showText: Bool = false { didSet { didChange() }}
        
    open var onText: String = "On" { didSet { didChange() }}
    
    open var offText: String = "Off" { didSet { didChange() }}
    
    open var textSize: TextSize = .small { didSet { didChange() }}
    
    open var textWeight: TextWeight = .regular { didSet { didChange() }}
    
    open var textPosition: TextPosition = .left { didSet { didChange() }}

    open var inputId: String? { didSet { didChange() }}

    open var value: AnyHashable? { didSet { didChange() }}
        
    //--------------------------------------------------
    // MARK: - Constraints
    //--------------------------------------------------
    private var knobLeadingConstraint: NSLayoutConstraint?
    private var knobTrailingConstraint: NSLayoutConstraint?
    
    //functions
    //--------------------------------------------------
    // MARK: - Toggle
    //--------------------------------------------------
    private func constrainKnob(){
        self.knobLeadingConstraint?.isActive = false
        self.knobTrailingConstraint?.isActive = false
        if isOn {
            knobTrailingConstraint = toggleView.trailingAnchor.constraint(equalTo: knobView.trailingAnchor, constant: 2)
            knobLeadingConstraint = knobView.leadingAnchor.constraint(greaterThanOrEqualTo: toggleView.leadingAnchor)
        }  else {
            knobTrailingConstraint = toggleView.trailingAnchor.constraint(greaterThanOrEqualTo: knobView.trailingAnchor)
            knobLeadingConstraint = knobView.leadingAnchor.constraint(equalTo: toggleView.leadingAnchor, constant: 2)
        }
        knobTrailingConstraint?.isActive = true
        knobLeadingConstraint?.isActive = true
        self.layoutIfNeeded()
    }

    private func updateToggle() {
        let toggleColor = toggleColorConfiguration.getColor(self)
        let knobColor = knobColorConfiguration.getColor(self)
        
        if disabled || !isAnimated {
            toggleView.backgroundColor = toggleColor
            knobView.backgroundColor = knobColor
            constrainKnob()
        } else {
            UIView.animate(withDuration: 0.2, delay: 0.0, options: .curveEaseIn, animations: {
                self.toggleView.backgroundColor = toggleColor
                self.knobView.backgroundColor = knobColor
            }, completion: nil)
            
            UIView.animate(withDuration: 0.33, delay: 0, usingSpringWithDamping: 0.7, initialSpringVelocity: 0.5, options: [], animations: { [weak self] in
                self?.constrainKnob()
            }, completion: nil)
        }
    }
    
    //--------------------------------------------------
    // MARK: - Labels
    //--------------------------------------------------
    private func updateLabel() {

        stackView.spacing = showText ? 12 : 0
        
        if stackView.subviews.contains(label) {
            label.removeFromSuperview()
        }
        
        if showText {
            label.textPosition = textPosition == .left ? .left : .right
            label.textStyle = textStyle
            label.text = isOn ? onText : offText
            label.surface = surface
            label.disabled = disabled
            
            if textPosition == .left {
                stackView.insertArrangedSubview(label, at: 0)
            } else {
                stackView.addArrangedSubview(label)
            }
        }
    }
    
    //--------------------------------------------------
    // MARK: - Lifecycle
    //--------------------------------------------------
    open override func initialSetup() {
        super.initialSetup()
        onClick = { control in
            control.toggle()
        }
    }
    
    open override func setup() {
        super.setup()
                
        isAccessibilityElement = true
        accessibilityTraits = .button
        addSubview(stackView)

        //set the h/w to container size, since the width "can" grow if text is there
        //allow this to be greaterThanEqualTo
        heightAnchor.constraint(equalToConstant: toggleContainerSize.height).isActive = true
        widthAnchor.constraint(greaterThanOrEqualToConstant: toggleContainerSize.width).isActive = true
        
        //create the container for the toggle/knob
        let toggleContainerView = UIView()
        toggleContainerView.translatesAutoresizingMaskIntoConstraints = false
        toggleContainerView.backgroundColor = .clear
        toggleContainerView.widthAnchor.constraint(equalToConstant: toggleContainerSize.width).isActive = true
        toggleContainerView.heightAnchor.constraint(equalToConstant: toggleContainerSize.height).isActive = true
        
        //adding views
        toggleContainerView.addSubview(toggleView)
        toggleView.addSubview(knobView)
        stackView.addArrangedSubview(toggleContainerView)

        //adding constraints
        toggleView.heightAnchor.constraint(equalToConstant: toggleSize.height).isActive = true
        toggleView.widthAnchor.constraint(equalToConstant: toggleSize.width).isActive = true
        toggleView.layer.cornerRadius = toggleSize.height / 2.0
        toggleView.bottomAnchor.constraint(greaterThanOrEqualTo: knobView.bottomAnchor).isActive = true
        toggleView.centerXAnchor.constraint(equalTo: toggleContainerView.centerXAnchor).isActive = true
        toggleView.centerYAnchor.constraint(equalTo: toggleContainerView.centerYAnchor).isActive = true

        knobView.layer.cornerRadius = knobSize.height / 2.0
        knobView.heightAnchor.constraint(equalToConstant: knobSize.height).isActive = true
        knobView.widthAnchor.constraint(equalToConstant: knobSize.width).isActive = true
        knobView.centerYAnchor.constraint(equalTo: toggleView.centerYAnchor).isActive = true
        knobView.topAnchor.constraint(greaterThanOrEqualTo: toggleView.topAnchor).isActive = true
     
        //pin stackview to edges
        stackView.pinToSuperView()
    }
    
    open override func reset() {
        super.reset()
        label.reset()
        isOn = false
        
        isAnimated = true
        showText = false
        onText = "On"
        offText = "Off"
        textSize = .small
        textWeight = .regular
        textPosition = .left
        inputId = nil
        value = nil
        
        toggleView.backgroundColor = toggleColorConfiguration.getColor(self)
        knobView.backgroundColor = knobColorConfiguration.getColor(self)
    }
  
    /// This will toggle the state of the Toggle and execute the actionBlock if provided.
    open func toggle() {
        isOn.toggle()
        sendActions(for: .valueChanged)
    }
               
    //--------------------------------------------------
    // MARK: - State
    //--------------------------------------------------    
    open override func updateView() {
        updateLabel()
        updateToggle()
        updateAccessibilityLabel()
    }
    
    open override func updateAccessibilityLabel() {
        setAccessibilityLabel(for: [label])
    }
}