//
//  DropdownSelect.swift
//  VDS
//
//  Created by Kanamarlapudi, Vasavi on 28/03/24.
//

import Foundation
import UIKit
import VDSCoreTokens
import Combine

/// A dropdown select is an expandable menu of predefined options that allows a customer to make a single selection.
@objc(VDSDropdownSelect)
open class DropdownSelect: 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: - Public Properties
    //--------------------------------------------------
    /// Override UIControl state to add the .error state if showSuccess is true and if showError is true.
    open override var state: UIControl.State {
        get {
            var state = super.state
            if dropdownField.isFirstResponder {
                state.insert(.focused)
            }
            
            return state
        }
    }
    
    /// If true, the label will be displayed inside the dropdown containerView. Otherwise, the label will be above the dropdown containerView like a normal text input.
    open var showInlineLabel: Bool = false { didSet { setNeedsUpdate() }}

    /// Allows unique ID to be passed to the element.
    open var selectId: Int? { didSet { setNeedsUpdate() }}
    
    /// Current SelectedItem Value
    open override var value: String? {
        selectedItem?.value
    }
    
    /// Current SelectedItem
    open var selectedItem: DropdownOptionModel? {
        guard let selectId else { return nil }
        return options[selectId]
    }
    
    /// Array of options to show
    open var options: [DropdownOptionModel] = [] { didSet { setNeedsUpdate() }}
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    internal var minWidthDefault = 66.0
    internal var minWidthInlineLabel = 102.0
    internal override var minWidth: CGFloat { showInlineLabel ? minWidthInlineLabel : minWidthDefault }
    internal override var maxWidth: CGFloat {        
        let frameWidth = frame.size.width
        return helperTextPlacement == .right ? (frameWidth - horizontalStackView.spacing) / 2 : frameWidth
    }
    
    /// The is used for the for adding the helperLabel to the right of the containerView.
    internal var horizontalStackView: UIStackView = {
        return UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.axis = .horizontal
            $0.distribution = .fillEqually
            $0.spacing = VDSLayout.space3X
            $0.alignment = .top
        }
    }()

    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    open var inlineDisplayLabel = Label().with {
        $0.setContentCompressionResistancePriority(.required, for: .vertical)
        $0.setContentCompressionResistancePriority(.required, for: .horizontal)
        $0.textAlignment = .left
        $0.textStyle = .boldBodyLarge
        $0.numberOfLines = 1
        $0.sizeToFit()
    }
    
    open var selectedOptionLabel = Label().with {
        $0.setContentCompressionResistancePriority(.required, for: .vertical)
        $0.setContentCompressionResistancePriority(.required, for: .horizontal)
        $0.textAlignment = .left
        $0.textStyle = .bodyLarge
        $0.numberOfLines = 1
    }

    open var dropdownField = UITextField().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.tintColor = UIColor.clear
        $0.font = TextStyle.bodyLarge.font
    }
    
    open var optionsPicker = UIPickerView()
    
    //--------------------------------------------------
    // MARK: - Constraints
    //--------------------------------------------------
    internal var inlineWidthConstraint: NSLayoutConstraint?

    //--------------------------------------------------
    // MARK: - Configuration Properties
    //--------------------------------------------------
    internal override var containerSize: CGSize { .init(width: minWidthDefault, height: 44) }
   
    //--------------------------------------------------
    // 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()
        
        fieldStackView.isAccessibilityElement = true
        inlineDisplayLabel.isAccessibilityElement = true

        dropdownField.width(0)
        inlineWidthConstraint = inlineDisplayLabel.widthAnchor.constraint(greaterThanOrEqualToConstant: 0)
        inlineWidthConstraint?.isActive = true
        
        // setting color config
        inlineDisplayLabel.textColorConfiguration = primaryColorConfiguration.eraseToAnyColorable()
        selectedOptionLabel.textColorConfiguration = primaryColorConfiguration.eraseToAnyColorable()
        
        // Options PickerView
        optionsPicker.delegate = self
        optionsPicker.dataSource = self
        optionsPicker.isHidden = true
        dropdownField.inputView = optionsPicker
        dropdownField.inputAccessoryView = {
            let accessView = UIView(frame: .init(origin: .zero, size: .init(width: UIScreen.main.bounds.width, height: containerSize.height)))
            accessView.backgroundColor = .white
            accessView.addBorder(side: .top, width: 1, color: .lightGray)
            let done = UIButton(type: .system)
            done.setTitle("Done", for: .normal)
            done.translatesAutoresizingMaskIntoConstraints = false
            done.addTarget(self, action: #selector(pickerDoneClicked), for: .touchUpInside)
            accessView.addSubview(done)
            done.pinCenterY()
                .pinTrailing(16)
            return accessView
        }()
        
        // tap gesture
        containerView
            .publisher(for: UITapGestureRecognizer())
            .sink { [weak self] _ in
                self?.launchPicker()
            }
            .store(in: &subscribers)
        containerView.height(44)
    }
    
    open override func getFieldContainer() -> UIView {
        let controlStackView = UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.axis = .horizontal
            $0.distribution = .fill
            $0.spacing = VDSFormControls.spaceInset
        }
        controlStackView.addArrangedSubview(dropdownField)
        controlStackView.addArrangedSubview(inlineDisplayLabel)
        controlStackView.addArrangedSubview(selectedOptionLabel)
        controlStackView.setCustomSpacing(0, after: dropdownField)
        controlStackView.setCustomSpacing(VDSLayout.space1X, after: inlineDisplayLabel)
        controlStackView.setCustomSpacing(VDSLayout.space3X, after: selectedOptionLabel)
        return controlStackView
    }
     
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        
        updateInlineLabel()

        dropdownField.isUserInteractionEnabled = isReadOnly ? false : true
        selectedOptionLabel.surface = surface
        selectedOptionLabel.isEnabled = isEnabled
    }
        
    /// Resets to default settings.
    open override func reset() {
        super.reset()
        
        inlineDisplayLabel.textStyle = .boldBodyLarge
        selectedOptionLabel.textStyle = .bodyLarge
        showInlineLabel = false
        options = []
        selectId = nil
    }
    
    //--------------------------------------------------
    // MARK: - Public Methods
    //--------------------------------------------------
    
    open override func updateTitleLabel() {
        
        //update the local vars for the label since we no long have a model
        var attributes: [any LabelAttributeModel] = []
        var updatedLabelText = labelText
        
        updatedLabelText = showInlineLabel ? "" : updatedLabelText
        
        if let oldText = updatedLabelText, !isRequired, !oldText.hasSuffix("Optional")  {
            let optionColorAttr = ColorLabelAttribute(location: oldText.count + 1,
                                                      length: 8,
                                                      color: secondaryColorConfiguration.getColor(self))
            
            updatedLabelText = showInlineLabel ? "Optional" : "\(oldText) Optional"
            attributes.append(optionColorAttr)
        }
        
        if let tooltipModel {
            attributes.append(TooltipLabelAttribute(surface: surface, model: tooltipModel, presenter: self))
        }
        
        titleLabel.text = updatedLabelText
        titleLabel.attributes = attributes
        titleLabel.surface = surface
        titleLabel.isEnabled = isEnabled
    }
    
    open func updateInlineLabel() {
        
        inlineWidthConstraint?.isActive = false

        /// inline label text and selected option text separated by ':'
        if let labelText, !labelText.isEmpty {
            inlineDisplayLabel.text = showInlineLabel ? (labelText + ":") : ""
        } else {
            inlineDisplayLabel.text = showInlineLabel ? labelText : ""
        }
        inlineDisplayLabel.surface = surface
        inlineDisplayLabel.isEnabled = isEnabled
        
        /// Update width as per updated text size
        inlineWidthConstraint = inlineDisplayLabel.widthAnchor.constraint(equalToConstant: inlineDisplayLabel.intrinsicContentSize.width)
        inlineWidthConstraint?.isActive = true
        
        if let selectId, selectId < options.count {
            updateSelectedOptionLabel(option: options[selectId])
        }
    }
    
    open func updateSelectedOptionLabel(option: DropdownOptionModel? = nil) {
        selectedOptionLabel.text = option?.text ?? ""
    }
    
    open override func updateErrorLabel() {
        super.updateErrorLabel()
        if !showError && !hasInternalError || !optionsPicker.isHidden {
            statusIcon.name = .downCaret
        }
        statusIcon.surface = surface
        statusIcon.isHidden = isReadOnly ? true : false
        statusIcon.color = iconColorConfiguration.getColor(self)
    }
    
    open override func updateAccessibility() {
        super.updateAccessibility()
        fieldStackView.accessibilityLabel = "Dropdown Select, \(accessibilityLabelText)"
        fieldStackView.accessibilityHint = isReadOnly || !isEnabled ? "" : "Double tap to open."
        fieldStackView.accessibilityValue = value
    }
    
    open override var accessibilityElements: [Any]? {
        get {
            var elements = [Any]()
            elements.append(contentsOf: [titleLabel, fieldStackView])
            
            if showError {
                elements.append(statusIcon)
                if let errorText, !errorText.isEmpty {
                    elements.append(errorLabel)
                }
            }
            
            if let helperText, !helperText.isEmpty {
                elements.append(helperLabel)
            }
            
            return elements
        }
        
        set { super.accessibilityElements = newValue }
    }

    
    @objc open func pickerDoneClicked() {
        optionsPicker.isHidden = true
        dropdownField.resignFirstResponder()
        setNeedsUpdate()
        UIAccessibility.post(notification: .layoutChanged, argument: fieldStackView)
    }
        
    open override var canBecomeFirstResponder: Bool {
        return dropdownField.canBecomeFirstResponder
    }
   
    open override func becomeFirstResponder() -> Bool {
        return dropdownField.becomeFirstResponder()
    }
   
    open override var canResignFirstResponder: Bool {
        return dropdownField.canResignFirstResponder
    }
   
    open override func resignFirstResponder() -> Bool {
        return dropdownField.resignFirstResponder()
    }
}

//--------------------------------------------------
// MARK: - UIPickerView Delegate & Datasource
//--------------------------------------------------
extension DropdownSelect: UIPickerViewDelegate, UIPickerViewDataSource {

    internal func launchPicker() {
        if optionsPicker.isHidden {
            UIAccessibility.post(notification: .layoutChanged, argument: optionsPicker)
            dropdownField.becomeFirstResponder()
        } else {
            dropdownField.resignFirstResponder()
        }
        optionsPicker.isHidden = !optionsPicker.isHidden
        updateContainerView()
        updateErrorLabel()
    }
    
    public func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }
    
    public func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return options.count
    }
    
    public func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        guard options.count > row else { return nil }
        return options[row].text
    }
    
    public func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        guard options.count > row else { return }
        selectId = row
        updateSelectedOptionLabel(option: options[row])
        sendActions(for: .valueChanged)
    }
}