//
//  SelectorGroupHandlerBase.swift
//  VDS
//
//  Created by Matt Bruce on 9/8/22.
//

import Foundation
import UIKit
import Combine
import VDSCoreTokens

public protocol SelectorGroup {
    associatedtype SelectorItemType: Control
    var items: [SelectorItemType] { get set }
    var hasSelectedItem: Bool { get }
}

extension SelectorGroup {
    public var hasSelectedItem: Bool { items.filter { $0.isSelected == true }.count > 0 }
}

public protocol SelectorGroupMultiSelect: SelectorGroup, FormFieldable {}
extension SelectorGroupMultiSelect {
    /// Current Selected Control for this group.
    public var selectedItems: [SelectorItemType]? {
        let selected = items.filter{ $0.isSelected == true }
        guard selected.count > 0 else { return nil }
        return selected
    }
}

public protocol SelectorGroupSingleSelect: SelectorGroup, FormFieldable {}
extension SelectorGroupSingleSelect {
    /// Current Selected Control for this group.
    public var selectedItem: SelectorItemType? {
        return items.filter { $0.isSelected == true }.first
    }
}

/// Base Class used for any Grouped Form Control of a Selector Type.
open class SelectorGroupBase<SelectorItemType: Groupable>: Control, SelectorGroup, Changeable { 
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    open var mainStackView: UIStackView = {
        return UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.alignment = .fill
            $0.distribution = .fill
            $0.axis = .vertical
            $0.spacing = VDSLayout.space3X
        }
    }()

    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    /// Array of the HandlerType registered.
    /// Array of HandlerType that the user will have the ability to select from.
    open var items: [SelectorItemType] = [] {
        willSet {
            mainStackView.arrangedSubviews.forEach { $0.removeFromSuperview() }
        }
        
        didSet {
            for selector in items {
                selector.onClick = { [weak self] handler in
                    self?.didSelect(handler)
                    self?.setNeedsUpdate()
                }
                mainStackView.addArrangedSubview(selector)
            }
        }
    }

    open var onChangeSubscriber: AnyCancellable? 
        
    /// Whether the Control is enabled or not.
    override open var isEnabled: Bool {
        didSet {
            items.forEach { $0.isEnabled = isEnabled }
        }
    }
    
    ///The background tint that the component will be placed on. This will automatically adjust other elements as needed and takes “light” or “dark”
    override open var surface: Surface {
        didSet {
            items.forEach { handler in
                handler.surface = surface
            }
        }
    }
    
    //--------------------------------------------------
    // 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()
        
        addSubview(mainStackView)
        mainStackView
            .pinTop()
            .pinLeading()
            .pinTrailing()
            .pinBottom(0, .defaultHigh)
    }
    
    /// Handler for the Group to override on a select event.
    /// - Parameter selectedControl: Selected Control the user interacted.
    open func didSelect(_ selectedControl: SelectorItemType) {
        fatalError("Must override didSelect")
    }

    /// Helper method to execute the valueChanged event.
    open func valueChanged() {
        DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(100)) { [weak self] in
            self?.sendActions(for: .valueChanged)
        }
    }
    
    /// Resets to default settings.
    open override func reset() {
        super.reset()
        onChange = nil
        items.forEach{ $0.reset() }
    }
}