//
//  AccessibilityCustomRotorable.swift
//  VDS
//
//  Created by Matt Bruce on 8/24/23.
//

import Foundation
import UIKit

public protocol CustomRotorable: UIViewController {
    var customRotors: [CustomRotorType] { get set }
}

extension CustomRotorable {
   
    internal func addCustomRotor(with name: String, for trait: UIAccessibilityTraits) {
        accessibilityCustomRotors = (accessibilityCustomRotors ?? []).filter { $0.name != name }
       
        let newRotor = UIAccessibilityCustomRotor(name: name) { [weak self] predicate in
            guard let self = self else { return nil }
           
            let elements = self.view.accessibleElements(with: trait)
           
            guard !elements.isEmpty else { return nil }

            let currentIndex = elements.firstIndex(where: { ($0 as AnyObject) === predicate.currentItem.targetElement })
            let count = elements.count
           
            let nextIndex: Int
            switch predicate.searchDirection {
            case .next:
                nextIndex = currentIndex.map { ($0 + 1) % count } ?? 0
            case .previous:
                nextIndex = currentIndex.map { ($0 - 1 + count) % count } ?? 0
            @unknown default:
                nextIndex = 0
            }
           
            guard let element = elements[nextIndex] as? NSObjectProtocol else { return nil }
            return UIAccessibilityCustomRotorItemResult(targetElement: element, targetRange: nil)
        }
       
        accessibilityCustomRotors?.append(newRotor)
    }
       
    public func loadCustomRotors() {
        customRotors.forEach { addCustomRotor(with: $0.name, for: $0.trait) }
    }
}

public extension UIView {
   
    func accessibleElements(with trait: UIAccessibilityTraits) -> [Any] {
        var elements: [Any] = []
       
        if isAccessibilityElement, accessibilityTraits.contains(trait) {
            elements.append(self)
        }
       
        if let customAccessibilityElements = accessibilityElements {
            elements.append(contentsOf: customAccessibilityElements.filter { element in
                if let element = element as? UIAccessibilityElement {
                    return element.accessibilityTraits.contains(trait)
                }
                return false
            })
        }

        subviews.forEach { elements.append(contentsOf: $0.accessibleElements(with: trait)) }

        return elements
    }
}

public struct CustomRotorType {
    public var name: String
    public var trait: UIAccessibilityTraits

    public init(name: String, trait: UIAccessibilityTraits) {
        self.name = name
        self.trait = trait
    }
}