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

import Foundation
import VDSColorTokens
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.
@objc(VDSBreadcrumbs)
open class Breadcrumbs: View {
    
    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    /// Array of ``BreadcrumbItem`` views for the Breadcrumbs.
    open var breadcrumbs: [BreadcrumbItem] = []
    
    /// 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 }
        }
    }
    
    /// Current Surface and this is used to pass down to child objects that implement Surfacable
    override open var surface: Surface {
        didSet {
            breadcrumbs.forEach { $0.surface = surface }
        }
    }
    
    /// 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
    //--------------------------------------------------
    // Sizes are from InVision design specs.
    internal var containerSize: CGSize { CGSize(width: 45, height: 44) }
    
    internal var heightConstraint: NSLayoutConstraint?

    let layout: UICollectionViewFlowLayout = LeftAlignedCollectionViewFlowLayout().with {
        $0.estimatedItemSize = UICollectionViewFlowLayout.automaticSize
        $0.minimumInteritemSpacing = VDSLayout.Spacing.space1X.value
        $0.minimumLineSpacing = VDSLayout.Spacing.space1X.value
        $0.sectionInset = .zero
        $0.scrollDirection = .vertical
    }
    
    ///Collectionview to render Breadcrumb Items
    private lazy var collectionView: UICollectionView = {
        let collectionView = UICollectionView(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
    }()
    
    //--------------------------------------------------
    // 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()
        }
        
        breadcrumbs.removeAll()
        // Create new breadcrumb items from the models
        for model in breadcrumbModels {
            let breadcrumbItem = BreadcrumbItem()
            breadcrumbItem.text = model.text
            breadcrumbItem.link = model.link
            breadcrumbItem.isSelected = model.isSelected ?? false
            breadcrumbs.append(breadcrumbItem)
            breadcrumbItem.onClick = { [weak self] breadcrumb in
                guard let self else { return }
                if self.onBreadcrumbShouldSelect?(breadcrumb) ?? true {
                    model.onClick?(breadcrumb)
                    self.onBreadcrumbDidSelect?(breadcrumb)
                }
            }
        }
        setNeedsUpdate()
    }
    
    //------------------------------------------s--------
    // 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()
        //create the wrapping view
        heightConstraint = self.heightAnchor.constraint(equalToConstant: containerSize.height)
        heightConstraint?.priority = .defaultHigh
        heightConstraint?.isActive = true
    }

    /// Executed on initialization for this View.
    open override func initialSetup() {
        super.initialSetup()
        addSubview(collectionView)
        collectionView.pinToSuperView()
    }

    /// Resets to default settings.
    open override func reset() {
        super.reset()
        shouldUpdateView = false
        breadcrumbs.forEach { $0.reset() }
        shouldUpdateView = true
        setNeedsUpdate()
    }
    
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        collectionView.reloadData()
        heightConstraint?.constant = collectionView.collectionViewLayout.collectionViewContentSize.height
        heightConstraint?.isActive = true
    }
    
    open override func layoutSubviews() {
        super.layoutSubviews()
        // Accounts for any collection size changes
        DispatchQueue.main.async { [weak self] in
            guard let self else { return }
            self.collectionView.collectionViewLayout.invalidateLayout()
        }
    }
}

extension Breadcrumbs: UICollectionViewDelegate, UICollectionViewDataSource {
    //--------------------------------------------------
    // 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 hideSlash = (indexPath.row == breadcrumbs.count - 1 || breadcrumbs.count == 1)
        cell.update(surface: surface, hideSlash: hideSlash, breadCrumbItem: breadcrumbs[indexPath.row])
        return cell
    }
    
    public func collectionView(_ collectionView: UICollectionView, sizeForItemAtIndexPath indexPath: IndexPath) -> CGSize {
        breadcrumbs[indexPath.row].intrinsicContentSize
    }
}