//
//  Calendar.swift
//  VDS
//
//  Created by Kanamarlapudi, Vasavi on 19/04/24.
//

import Foundation
import UIKit
import VDSTokens
import Combine

/// A calendar is a monthly view that lets customers select a single date.
@objc(VDSCalendar)
open class CalendarBase: View {
    
    //--------------------------------------------------
    // 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
    //--------------------------------------------------
    /// If set to true, the calendar will not have a border.
    open var hideContainerBorder: Bool = false
    
    /// If set to true, the calendar will not have current date indication.
    open var hideCurrentDateIndicator: Bool = false
    
    /// Enable specific days. Pass an array of string value in date format e.g. ['07/21/2024', '07/24/2024', 07/28/2024'].
    /// All other dates will be inactive
    open var activeDates: [Date] = []
    
    /// Disable specific days. Pass an array of string value in date format e.g. ['07/21/2024', '07/24/2024', 07/28/2024'].
    /// All other dates will be active.
    open var inactiveDates: [Date] = []
    
    /// If provided, the calendar will allow a selection to be made from this date forward. Defaults to today.
    open var minDate: Date?
    
    /// If provided, the calendar will allow a selection to be made up to this date.
    open var maxDate: Date?
    
    /// If provided, this is the date that will show as selected by the Calendar.
    /// If no value is provided, the current date will be used. If null is provided, no date will be selected.
    open var selectedDate: Date?
    
    /// If provided, the calendar will be rendered with transparent background.
    open var transparentBackground: Bool = false
    
    /// Array of ``CalendarIndicatorModel`` you are wanting to show on legend.
    open var indicators: [CalendarIndicatorModel] = [] { didSet { setNeedsUpdate() } }
    
//    /// Array of indicators for the legend.
//    open var indicatorData: [CalendarIndicatorModel] = [] { didSet { setNeedsUpdate() } }
    
    /// A callback when the selected date changes..
    open var onChangeSelectedDate: ((Date) -> String)?
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    internal var containerSize: CGSize { CGSize(width: 320, height: 376) } //width:320/328
    private let cellItemSize = CGSize(width: 40, height: 40)
    private let headerHeight = 104.0
    private let footerHeight = 56.0
    private let items = 35

    internal var containerView = View().with {
        $0.clipsToBounds = true
    }
    
    /// Collectionview to load calendar month view
    private lazy var collectionView: UICollectionView = {
        let collectionView = UICollectionView(frame: .zero, collectionViewLayout: UICollectionViewFlowLayout())
        collectionView.isScrollEnabled = false
        collectionView.translatesAutoresizingMaskIntoConstraints = false
        collectionView.delegate = self
        collectionView.dataSource = self
        collectionView.showsHorizontalScrollIndicator = false
        collectionView.showsVerticalScrollIndicator = false
        collectionView.register(CalendarDateCollectionViewCell.self, forCellWithReuseIdentifier: CalendarDateCollectionViewCell.identifier)
        collectionView.register(CalendarHeaderReusableView.self,
                                forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader,
                                withReuseIdentifier: CalendarHeaderReusableView.identifier)
        collectionView.register(CalendarFooterReusableView.self,
                                forSupplementaryViewOfKind: UICollectionView.elementKindSectionFooter,
                                withReuseIdentifier: CalendarFooterReusableView.identifier)
        return collectionView
    }()
    
    //--------------------------------------------------
    // MARK: - Lifecycle
    //--------------------------------------------------
    open override func initialSetup() {
        super.initialSetup()
    }
    
    open override func setup() {
        super.setup()
        isAccessibilityElement = false
        
        addSubview(containerView)
        containerView
            .pinTop()
            .pinBottom()
            .pinLeadingGreaterThanOrEqualTo()
            .pinTrailingLessThanOrEqualTo()
            .height(containerSize.height)
            .width(containerSize.width)
        
        containerView.centerXAnchor.constraint(equalTo: centerXAnchor).activate()
        
        // Calendar View
        containerView.addSubview(collectionView)
        collectionView.pinToSuperView()
    }
    
    open override func updateView() {
        super.updateView()
        collectionView.reloadData()
    }
    
    override open func layoutSubviews() {
        super.layoutSubviews()
    }
    
    open override func reset() {
        super.reset()
    }
}

extension CalendarBase: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
    //--------------------------------------------------
    // MARK: - UICollectionView Delegate & Datasource
    //--------------------------------------------------
    public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        items
    }
    
    public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: CalendarDateCollectionViewCell.identifier, for: indexPath) as? CalendarDateCollectionViewCell else { return UICollectionViewCell() }
        return cell
    }
    
    public func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        if kind == UICollectionView.elementKindSectionHeader {
            // Header
            guard let header =  collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: CalendarHeaderReusableView.identifier, for: indexPath) as? CalendarHeaderReusableView else {
                return UICollectionReusableView()
            }
            header.configure(with: true)
            return header
        } else {
            // Footer
            if kind == UICollectionView.elementKindSectionFooter {
                guard let footer =  collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: CalendarFooterReusableView.identifier, for: indexPath) as? CalendarFooterReusableView else {
                    return UICollectionReusableView()
                }
                footer.configure(with: indicators)
                return footer
            }
        }
        return UICollectionReusableView()
    }
    
    public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
        return CGSize(width: collectionView.frame.size.width, height: headerHeight)
    }
    
    public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
        return CGSize(width: collectionView.frame.size.width, height: footerHeight)
    }
    
    public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        return VDSLayout.space1X
    }
    
    public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return VDSLayout.space1X
    }
    
    public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return cellItemSize
    }
}