//
//  Breadcrumbs.swift
//  VDS
//
//  Created by Kanamarlapudi, Vasavi on 11/03/24.
//

import Foundation
import UIKit
import VDSCoreTokens
import Combine

/// A Breadcrumbs contains BreadcrumbItems. 
/// It contains Breadcrumb Item Default, Breadcrumb Item Selected, Separator.
/// Breadcrumbs are secondary navigation that use a hierarchy of internal links to tell customers where they are in an experience. Each breadcrumb links to its respective page, except for that of current page.
@objcMembers
@objc(VDSBreadcrumbs)
open class Breadcrumbs: View {
    
    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    /// Array of ``BreadcrumbItem`` views for the Breadcrumbs.
    open var breadcrumbs: [BreadcrumbItem] = [] { didSet { setNeedsUpdate() } }
    
    /// Array of ``BreadcurmbItemModel`` you are wanting to show.
    open var breadcrumbModels: [BreadcrumbItemModel] = [] { didSet { updateBreadcrumbItems() } }
    
    /// Whether this object is enabled or not
    override open var isEnabled: Bool {
        didSet {
            breadcrumbs.forEach { $0.isEnabled = isEnabled }
        }
    }
    
    open override var accessibilityElements: [Any]? {
        get {
            return [containerView, breadcrumbs]
        }
        set {}
    }
    
    /// A callback when the selected item changes. Passes parameters (crumb).
    open var onBreadcrumbDidSelect: ((BreadcrumbItem) -> Void)?
    
    /// A callback when the Tab determine if a item should be selected.
    open var onBreadcrumbShouldSelect:((BreadcrumbItem) -> Bool)?
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    fileprivate lazy var layout = ButtonGroupPositionLayout().with {
        $0.position = .left
        $0.delegate = self
        $0.axisSpacer = { _, _, _ in
            return VDSLayout.space1X
        }
        $0.verticalSpacer = { _, _ in
            return VDSLayout.space1X
        }
    }

    ///Collectionview to render Breadcrumb Items
    private lazy var collectionView: SelfSizingCollectionView = {
        let collectionView = SelfSizingCollectionView(frame: .zero, collectionViewLayout: layout)
        collectionView.isScrollEnabled = false
        collectionView.translatesAutoresizingMaskIntoConstraints = false
        collectionView.delegate = self
        collectionView.dataSource = self
        collectionView.showsHorizontalScrollIndicator = false
        collectionView.showsVerticalScrollIndicator = false
        collectionView.register(BreadcrumbCellItem.self, forCellWithReuseIdentifier: BreadcrumbCellItem.identifier)
        collectionView.backgroundColor = .clear
        return collectionView
    }()
    
    private let containerView = View().with {
        $0.isAccessibilityElement = true
        $0.accessibilityLabel = "Breadcrumbs"
    }
    
    //--------------------------------------------------
    // MARK: - Private Methods
    //--------------------------------------------------
    /// Removes all of the Breadcrumbs and creates new ones from the Breadcrumb Models property.
    private func updateBreadcrumbItems() {
        // Clear existing breadcrumbs
        for breadcrumbItem in breadcrumbs {
            breadcrumbItem.removeFromSuperview()
        }
        
        // Create new breadcrumb items from the models
        breadcrumbs = breadcrumbModels.compactMap({ model in
            let breadcrumbItem = BreadcrumbItem()
            breadcrumbItem.text = model.text
            breadcrumbItem.isSelected = model.selected
            breadcrumbItem.onClick = { [weak self] breadcrumb in
                guard let self, breadcrumb.isEnabled else { return }
                if self.onBreadcrumbShouldSelect?(breadcrumb) ?? true {
                    model.onClick?(breadcrumb)
                    self.onBreadcrumbDidSelect?(breadcrumb)
                }
            }
            return breadcrumbItem
        })
    }
    
    //------------------------------------------s--------
    // MARK: - Overrides
    //--------------------------------------------------
    /// Executed on initialization for this View.
    open override func setup() {
        super.setup()
        containerView.addSubview(collectionView)
        collectionView.pinToSuperView()
        addSubview(containerView)
        containerView.pinToSuperView()
    }
    
    /// Resets to default settings.
    open override func reset() {
        super.reset()
        breadcrumbs.forEach { $0.reset() }
    }
    
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        collectionView.reloadData()
    }
        
    open override func layoutSubviews() {
        //Turn off the ability to execute updateView() in the super
        //since we don't want an infinite loop
        shouldUpdateView = false
        super.layoutSubviews()
        shouldUpdateView = true

        // Accounts for any collection size changes
        DispatchQueue.main.async { [weak self] in
            guard let self else { return }
            self.collectionView.collectionViewLayout.invalidateLayout()
        }   
    }
    private var separatorWidth = Label().with { $0.text = "/"; $0.sizeToFit() }.intrinsicContentSize.width
    
}

extension Breadcrumbs: UICollectionViewDelegate, UICollectionViewDataSource, ButtongGroupPositionLayoutDelegate {
    //--------------------------------------------------
    // MARK: - UICollectionView Delegate & Datasource
    //--------------------------------------------------
    public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        breadcrumbs.count
    }
    
    public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: BreadcrumbCellItem.identifier, for: indexPath) as? BreadcrumbCellItem else { return UICollectionViewCell() }
        let breadcrumb = breadcrumbs[indexPath.row]
        breadcrumb.hideSlash = breadcrumb == breadcrumbs.first
        breadcrumb.surface = surface
        cell.update(breadCrumbItem: breadcrumb)
        return cell
    }

    public func collectionView(_ collectionView: UICollectionView, sizeForItemAtIndexPath indexPath: IndexPath) -> CGSize {

        let breadcrumb = breadcrumbs[indexPath.row]
        breadcrumb.hideSlash = breadcrumb == breadcrumbs.first

        let maxWidth = frame.width
        let intrinsicSize = breadcrumb.titleLabel!.sizeThatFits(.init(width: maxWidth, height: CGFloat.greatestFiniteMagnitude))
        let cellwidth = min(maxWidth, intrinsicSize.width)
        return .init(width: cellwidth, height: intrinsicSize.height)
    }

    public func collectionView(_ collectionView: UICollectionView, buttonBaseAtIndexPath indexPath: IndexPath) -> ButtonBase {
        breadcrumbs[indexPath.row]
    }
}