//
//  InputStepper.swift
//  VDS
//
//  Created by Kanamarlapudi, Vasavi on 24/06/24.
//

import Foundation
import UIKit
import VDSCoreTokens
import Combine

/// A stepper is a two-segment control that people use to increase or decrease an incremental value.
@objc(VDSInputStepper)
open class InputStepper: EntryFieldBase {
    
    //--------------------------------------------------
    // 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: - Enums
    //--------------------------------------------------
    /// Enum used to describe the size of Input Stepper.
    public enum Size: String, CaseIterable {
        case large, small
    }
    
    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    /// Accepts a string or number value to control the width of input stepper.
    /// auto(default) - The control's width is determined by the combined width of the value, trailing text and padding
    /// Value - The control's width can be set to a fixed pixel or percentage value.
    open var controlWidth: String? = "auto" { didSet { setNeedsUpdate() } }

    /// Default value of the input stepper, defaults to '0'.
    open var defaultValue:Int = 0 { didSet { setNeedsUpdate() } }
    
    /// Allows an id to be passed to input stepper.
    open var id: Int? { didSet { setNeedsUpdate() } }
        
    /// Maximum value of the input stepper, defaults to '99'.
    open var maxValue:  Int? {
        get { return _maxValue }
        set {
            if let newValue, newValue <= 99 && newValue > 0 {
                _maxValue = newValue
            } else {
                _maxValue = 99
            }
            setNeedsUpdate()
        }
    }

    /// Minimum value of the input stepper, defaults to '0'.
    open var minValue: Int? {
        get { return _minValue }
        set {
            if let newValue, newValue >= 0 && newValue < 99 {
                _minValue = newValue
            } else {
                _minValue = 0
            }
            setNeedsUpdate()
        }
    }
    
    /// The size of the input stepper. Defaults to 'large'.
    open var size: Size = .large { 
        didSet {
            updateStepperContainerViewSize()
            setNeedsUpdate()
        }
    }
    
    /// Accepts any text or character to appear next to input stepper value.
    open var trailingText: String? { didSet { setNeedsUpdate() } }
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    internal var _maxValue: Int = 99
    internal var _minValue: Int = 0
    
    /// This is the view that will be wrapped with the border for userInteraction.
    /// The only subview of this view is the stepperStackView.
    internal var stepperContainerView = View().with {
        $0.isAccessibilityElement = true
    }
    
    internal var stepperStackView = UIStackView().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.axis = .horizontal
        $0.distribution = .fill
        $0.alignment = .fill
    }
    
    internal var decrementButton = ButtonIcon().with {
        $0.kind = .ghost
        $0.iconName =  Icon.Name(name: "minus")
        $0.iconOffset = .init(x: -2, y: 0)
        $0.customContainerSize = 32
        $0.icon.customSize = 16
        $0.backgroundColor = .clear
    }
    
    internal var incrementButton = ButtonIcon().with {
        $0.kind = .ghost
        $0.iconName = Icon.Name(name: "plus")
        $0.iconOffset = .init(x: 2, y: 0)
        $0.customContainerSize = 32
        $0.icon.customSize = 16
        $0.backgroundColor = .clear
    }
    
    internal var textLabel = Label().with {
        $0.setContentCompressionResistancePriority(.required, for: .vertical)
        $0.textStyle = .boldBodyLarge
        $0.numberOfLines = 1
        $0.lineBreakMode = .byTruncatingTail
    }

    //--------------------------------------------------
    // MARK: - Constraints
    //--------------------------------------------------
    internal var stepperWidthConstraint: NSLayoutConstraint?
    internal var stepperHeightConstraint: NSLayoutConstraint?

    //--------------------------------------------------
    // MARK: - Configuration Properties
    //--------------------------------------------------
    internal override var containerSize: CGSize { CGSize(width: size == .large ? largeMinWidth : smallMinWidth, height: size == .large ? largeMinHeight : smallMinHeight) }

    internal var largeMinWidth = 121
    internal var smallMinWidth = 90
    internal var largeMinHeight = 44
    internal var smallMinHeight = 32

    internal let labelColorConfiguration = SurfaceColorConfiguration(VDSColor.elementsPrimaryOnlight , VDSColor.elementsPrimaryOndark)
    internal let labelDisabledColorConfiguration = SurfaceColorConfiguration(VDSColor.interactiveDisabledOnlight , VDSColor.interactiveDisabledOndark)
    
    //--------------------------------------------------
    // MARK: - Lifecycle
    //--------------------------------------------------
    open override func initialSetup() {
        super.initialSetup()
    }
    
    /// Called once when a view is initialized and is used to Setup additional UI or other constants and configurations.
    open override func setup() {
        super.setup()
        
        // accessibility
        isAccessibilityElement = false
        accessibilityLabel = "Input Stepper"
        
        // Set initial states
        containerView.isEnabled = false
        statusIcon.isHidden = true

        // Add listeners
        decrementButton.onClick =  { _ in  self.decrementButtonClick() }
        incrementButton.onClick =  { _ in  self.incrementButtonClick() }

        // setting color config
        textLabel.textColorConfiguration = primaryColorConfiguration.eraseToAnyColorable()
    }
    
    open override func getFieldContainer() -> UIView {
        stepperStackView.addArrangedSubview(decrementButton)
        stepperStackView.addArrangedSubview(textLabel)
        stepperStackView.addArrangedSubview(incrementButton)

        // Set space between decrement button, label, and increment button relative to input Stepper size.
        let space = size == .large ? VDSLayout.space3X : VDSLayout.space2X
        stepperStackView.setCustomSpacing(space, after: decrementButton)
        stepperStackView.setCustomSpacing(space, after: textLabel)

        // Update Edge insets relative to input Stepper size.
        stepperStackView.pinToSuperView(.uniform(size == .large ? 6.0 : VDSLayout.space1X))
        
        // stepperContainerView for controls in EntryFieldBase.controlContainerView
        stepperContainerView.addSubview(stepperStackView)
        
        stepperWidthConstraint = stepperContainerView.widthAnchor.constraint(equalToConstant: containerSize.width)
        stepperWidthConstraint?.deactivate()
        stepperHeightConstraint = stepperContainerView.heightAnchor.constraint(equalToConstant: containerSize.height)
        stepperHeightConstraint?.deactivate()
        
        return stepperContainerView
    }
    
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        statusIcon.isHidden = true
        updateConstraintsToFieldStackView(flag: false)

        // Update label text, style, color, ande surface.
        textLabel.text = String(defaultValue) + " " + (trailingText ?? "")
        textLabel.textStyle = size == .large ? .boldBodyLarge : .boldBodySmall
        textLabel.textColorConfiguration = !isEnabled ? labelDisabledColorConfiguration.eraseToAnyColorable() : labelColorConfiguration.eraseToAnyColorable()
        textLabel.surface = surface

        // Update increment and decrement button.
        updateButtonStates()
        
        // Update stepper container border and corner radius.
        setControlWidth(controlWidth)
        updateContainerView(flag: false)
    }
    
    /// Resets to default settings.
    open override func reset() {
        super.reset()
        textLabel.reset()
        textLabel.textStyle = .boldBodyLarge
        textLabel.text = ""
        controlWidth = nil
        minValue = nil
        maxValue = nil
        trailingText = nil
        helperTextPlacement = .bottom
    }
    
    //--------------------------------------------------
    // MARK: - Private Methods
    //--------------------------------------------------
    internal func checkDefaultValue() {
        defaultValue = defaultValue > _maxValue ? _maxValue : defaultValue < _minValue ? _minValue : defaultValue
    }
    
    internal func decrementButtonClick() {
        defaultValue = defaultValue - 1
        checkDefaultValue()
        updateButtonStates()
    }
    
    internal func incrementButtonClick() {
        defaultValue = defaultValue + 1
        checkDefaultValue()
        updateButtonStates()
    }
    
    internal func updateButtonStates() {
        decrementButton.customContainerSize = size == .large ? 32 : 24
        incrementButton.customContainerSize = size == .large ? 32 : 24
        decrementButton.surface = surface
        incrementButton.surface = surface

        if isReadOnly || !isEnabled {
            decrementButton.isEnabled = false
            incrementButton.isEnabled = false
        } else {
            decrementButton.isEnabled = defaultValue > _minValue ? true : false
            incrementButton.isEnabled = defaultValue < _maxValue ? true : false
        }
    }
    
    // Update edge insets and height when size changes.
    internal func updateStepperContainerViewSize() {
        updateButtonStates()
        
        // Update Edge insets if size changes applied.
        stepperStackView.removeFromSuperview()
        stepperContainerView.addSubview(stepperStackView)
        stepperStackView.pinToSuperView(.uniform(size == .large ? 6.0 : VDSLayout.space1X))
        
        // Update height if size changes applied.
        stepperHeightConstraint?.deactivate()
        stepperHeightConstraint = stepperContainerView.heightAnchor.constraint(equalToConstant: containerSize.height)
        stepperHeightConstraint?.activate()
    }
    
    // Set control width to input stepper.
    internal func setControlWidth(_ text: String?) {
        if let text, text == "auto" {
            stepperWidthConstraint?.deactivate()
        } else if let controlWidth = Int(text ?? "") {
            // Set controlWidth provided which is either pixel or percentage
            let width = width ?? CGFloat(containerView.frame.size.width)
            updateStepperContainerWidth(controlWidth: CGFloat(controlWidth), width: width)
        } 
    }
    
    // Handling the controlwidth without going beyond the width of the parent container.
    internal func updateStepperContainerWidth(controlWidth: CGFloat, width: CGFloat) {
        if controlWidth >= containerSize.width && controlWidth <= width {
            stepperWidthConstraint?.deactivate()
            stepperWidthConstraint?.constant = controlWidth
            stepperWidthConstraint?.activate()
        } else if controlWidth >= width {
            stepperWidthConstraint?.deactivate()
            stepperWidthConstraint?.constant = width
            stepperWidthConstraint?.activate()
        }
    }
}