//
//  TextArea.swift
//  VDS
//
//  Created by Matt Bruce on 1/10/23.
//

import Foundation
import UIKit
import VDSTokens
import Combine

/// A text area is an input wherein a customer enters long-form information.
/// Use a text area when you want customers to enter text that’s longer than a single line.
@objc(VDSTextArea)
open class TextArea: 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: - Private Properties
    //--------------------------------------------------
    internal var minWidthConstraint: NSLayoutConstraint?
    internal var textViewHeightConstraint: NSLayoutConstraint?
    
    internal var inputFieldStackView: UIStackView = {
        return UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.axis = .horizontal
            $0.distribution = .fill
            $0.spacing = VDSLayout.space3X
        }
    }()
    
    internal var bottomStackView: UIStackView = {
        return UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.axis = .horizontal
            $0.distribution = .fill
            $0.alignment = .top
            $0.spacing = VDSLayout.space2X
        }
    }()
    
    open var characterCounterLabel = Label().with {
        $0.setContentCompressionResistancePriority(.required, for: .vertical)
        $0.textStyle = .bodySmall
        $0.textAlignment = .right
        $0.numberOfLines = 1
    }

    private var _minHeight: Height = .twoX
    
    open var minHeight: Height? {
        get { return _minHeight }
        set {
            if let newValue {
                _minHeight = newValue
            } else {
                _minHeight = .twoX
            }
            textViewHeightConstraint?.constant = _minHeight.value
            setNeedsUpdate()
        }
    }
    
    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    override var containerSize: CGSize { CGSize(width: 182, height: 88) }
    
    /// Enum used to describe the the height of TextArea.
    public enum Height: String, CaseIterable {
        case twoX = "2X"
        case fourX = "4X"
        case eightX = "8X"
        
        var value: CGFloat {
            switch self {
            case .twoX:
                88
            case .fourX:
                176
            case .eightX:
                352
            }
        }
    }

    /// The text of this TextArea.
    private var _text: String?
    open var text: String? {
        get { _text }
        set {
            if let newValue, newValue != _text {
                _text = newValue
                textView.text = newValue
                value = newValue
            }
            setNeedsUpdate()
        }
    }
    
    /// The value of this textField.
    open override var value: String? {
        didSet {
            if text != value {
                text = value
            }
        }
    }

    /// UITextView shown in the TextArea.
    open var textView = TextView().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.sizeToFit()
        $0.isScrollEnabled = false
    }
    
    open var maxLength: Int? {
        willSet {
            countRule.maxLength = newValue
        }
        
        didSet {
            setNeedsUpdate()
        }
    }
    
    /// Color configuration for error icon.
    internal var iconColorConfiguration = ControlColorConfiguration().with {
        $0.setSurfaceColors(VDSColor.elementsPrimaryOnlight, VDSColor.elementsPrimaryOndark, forState: .normal)
    }
    
    /// Color configuration for character counter's highlight background color
    internal var highlightBackgroundColor = ControlColorConfiguration().with {
        $0.setSurfaceColors(VDSColor.backgroundPrimaryDark, VDSColor.backgroundPrimaryLight, forState: .normal)
    }

    /// Color configuration for character counter's highlight text color
    internal var highlightTextColor = ControlColorConfiguration().with {
        $0.setSurfaceColors(VDSColor.elementsPrimaryOndark, VDSColor.elementsPrimaryOnlight, forState: .normal)
    }
    
    //--------------------------------------------------
    // MARK: - Overrides
    //--------------------------------------------------
    /// 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()
        isAccessibilityElement = false
        validator = FormFieldValidator<TextArea>(field: self, rules: [.init(countRule)])
        
        containerStackView.pinToSuperView(.uniform(VDSFormControls.spaceInset))
        minWidthConstraint = containerView.widthAnchor.constraint(greaterThanOrEqualToConstant: containerSize.width)
        minWidthConstraint?.isActive = true
        controlContainerView.addSubview(textView)
        textView
            .pinTop()
            .pinLeading()
            .pinTrailingLessThanOrEqualTo(nil, 0, .defaultHigh)
            .pinBottom(0, .defaultHigh)
        textView.isScrollEnabled = true
        textView.autocorrectionType = .no
        textViewHeightConstraint = textView.heightAnchor.constraint(greaterThanOrEqualToConstant: containerSize.height)
        textViewHeightConstraint?.isActive = true
        backgroundColorConfiguration.setSurfaceColors(VDSColor.feedbackSuccessBackgroundOnlight, VDSColor.feedbackSuccessBackgroundOndark, forState: .success)
        borderColorConfiguration.setSurfaceColors(VDSColor.feedbackSuccessOnlight, VDSColor.feedbackSuccessOndark, forState: .success)
        borderColorConfiguration.setSurfaceColors(VDSColor.elementsPrimaryOnlight, VDSColor.elementsPrimaryOndark, forState: .focused)
        textView.delegate = self
        characterCounterLabel.textColorConfiguration = primaryColorConfiguration.eraseToAnyColorable()
        bottomContainerStackView.spacing = VDSLayout.space2X
    }
    
    /// Resets to default settings.
    open override func reset() {
        super.reset()
        textView.text = ""
        characterCounterLabel.reset()
        characterCounterLabel.textStyle = .bodySmall
        setNeedsUpdate()
    }
    
    /// Container for the area in which the user interacts.
    open override func getContainer() -> UIView {
        inputFieldStackView.addArrangedSubview(containerView)
        return inputFieldStackView
    }
    
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        textView.isEditable = isEnabled
        textView.isEnabled = isEnabled
        textView.surface = surface
        
        //set the width constraints
        if let width  {
            widthConstraint?.constant = width
            widthConstraint?.isActive = true
            minWidthConstraint?.isActive = false
        } else {
            minWidthConstraint?.constant = containerSize.width
            widthConstraint?.isActive = false
            minWidthConstraint?.isActive = true
        }

        characterCounterLabel.text =  getCharacterCounterText()
        
        icon.size = .medium
        icon.color = iconColorConfiguration.getColor(self)
        containerView.layer.borderColor = readOnly ? readOnlyBorderColorConfiguration.getColor(self).cgColor : borderColorConfiguration.getColor(self).cgColor
        textView.isEditable = readOnly ? false : true
        textView.backgroundColor = backgroundColorConfiguration.getColor(self)
        textView.tintColor = iconColorConfiguration.getColor(self)
        characterCounterLabel.surface = surface
        highlightCharacterOverflow()
    }
    
    /// Container for the area showing helper text, error text, character count, maximum length value.
    open override func getBottomContainer() -> UIView {
        bottomStackView.addArrangedSubview(bottomContainerView)
        bottomStackView.addArrangedSubview(characterCounterLabel)
        return bottomStackView
    }
        
    /// Used to update any Accessibility properties.
    open override func updateAccessibility() {
        super.updateAccessibility()
        textView.accessibilityLabel = showError ? "error" : nil
        if showError {
            accessibilityElements = [titleLabel, textView, icon, errorLabel, helperLabel]
        } else {
            accessibilityElements = [titleLabel, textView, helperLabel]
        }
    }
    
    open override var canBecomeFirstResponder: Bool { true }

    open override func resignFirstResponder() -> Bool {
        if textView.isFirstResponder {
            textView.resignFirstResponder()
        }
        return super.resignFirstResponder()
    }
    
    //--------------------------------------------------
    // MARK: - Private Methods
    //--------------------------------------------------
    private func getCharacterCounterText() -> String? {
        let count = textView.text.count
        let countStr = (count > maxLength ?? 0) ? ("-" + "\(count-(maxLength ?? 0))") : "\(count)"
        if let maxLength, maxLength > 0 {
            if count > maxLength {
                return countStr
            } else {
                return ("\(countStr)" + "/" + "\(maxLength)")
            }
        } else {
            return nil
        }
    }
    
    open func highlightCharacterOverflow() {
        let count = textView.text.count
        guard let maxLength, maxLength > 0, count > maxLength else {
            textView.textAttributes = nil
            return
        }
        
        var textAttributes = [any LabelAttributeModel]()
        let location = maxLength
        let length = count - maxLength
        textAttributes.append(ColorLabelAttribute(location: location, length: length, color: highlightBackgroundColor.getColor(self), isForegroundColor: false))
        textAttributes.append(ColorLabelAttribute(location: location, length: length, color: highlightTextColor.getColor(self), isForegroundColor: true))
        
        textView.textAttributes = textAttributes
    }
    
    //--------------------------------------------------
    // MARK: - Validation
    //--------------------------------------------------
    var countRule = CharacterCountRule()
    
    class CharacterCountRule: Rule {
        var maxLength: Int?
        var errorMessage: String = "You have exceeded the character limit."
        
        func isValid(value: String?) -> Bool {
            guard let text = value, let maxLength, maxLength > 0 else { return true }
            return text.count <= maxLength
        }
    }
}

extension TextArea: UITextViewDelegate {
    //--------------------------------------------------
    // MARK: - UITextViewDelegate
    //--------------------------------------------------
    public func textViewDidChange(_ textView: UITextView) {
        
        //dynamic textView Height sizing based on Figma
        //if you want it to work "as-is" delete this code
        //since it will autogrow with the current settings
        if let textViewHeightConstraint, textView.isEditable {
            var height = textView.contentSize.height
            height = max(height, _minHeight.value)
            if height > Height.twoX.value && height <= Height.fourX.value {
                textViewHeightConstraint.constant = Height.fourX.value
            } else if height > Height.fourX.value {
                textViewHeightConstraint.constant = Height.eightX.value
            } else {
                textViewHeightConstraint.constant = Height.twoX.value
            }
        }
        
        //The exceeding characters will be highlighted to help users correct their entry.
        if let maxLength, maxLength > 0 {
            // allow - 20% of character limit
            let overflowLimit = Double(maxLength) * 0.20
            let allowCharCount = Int(overflowLimit) + maxLength

            if textView.text.count <= allowCharCount {
                highlightCharacterOverflow()

                //setting the value and firing control event
                text = textView.text
                sendActions(for: .valueChanged)
            } else {
                textView.text.removeLast()
                highlightCharacterOverflow()
            }
        } else {
            //setting the value and firing control event
            text = textView.text
            sendActions(for: .valueChanged)
        }
    }    
}