vds_ios/VDS/Components/Calendar/CalendarHeaderView.swift

//
//  CalendarHeaderView.swift
//  VDS
//
//  Created by Kanamarlapudi, Vasavi on 30/04/24.
//

import Foundation
import UIKit
import VDSTokens

/// Header view to display month and year along with days of week
open class CalendarHeaderView: 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
    //--------------------------------------------------
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    internal var containerSize: CGSize { CGSize(width: 304, height: 88) } //width:320/328
    
    private lazy var stackView = UIStackView().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.distribution = .fill
        $0.spacing = VDSLayout.space1X
        $0.axis = .vertical
        $0.backgroundColor = .clear
    }
    
    private lazy var monthYearHeaderStackView = UIStackView().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.distribution = .fill
        $0.spacing = VDSLayout.space1X
        $0.axis = .horizontal
        $0.backgroundColor = .clear
    }
    
    internal var containerView = View().with {
        $0.clipsToBounds = true
        $0.backgroundColor = .clear
    }
    internal var monthView = View()
    internal var previousMonthView = View()
    internal var nextMonthView = View()
    internal var daysView = View()
    internal let daysOfWeek = Date.capitalizedFirstLettersOfWeekdays
    
    internal var previousButton = ButtonIcon().with {
        $0.kind = .ghost
        $0.iconName = .leftCaret
        $0.iconOffset = .init(x: -2, y: 0)
        $0.icon.size = .small
        $0.size = .small
    }
    
    internal var nextButton = ButtonIcon().with {
        $0.kind = .ghost
        $0.iconName = .rightCaret
        $0.iconOffset = .init(x: 2, y: 0)
        $0.icon.size = .small
        $0.size = .small
    }
    
    internal var monthYearLabel = Label().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.textAlignment = .center
        $0.numberOfLines = 1
        $0.textStyle = .boldBodySmall
        $0.backgroundColor = .clear
        $0.isAccessibilityElement = false
    }
    
    private lazy var daysCollectionView: 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.backgroundColor = .clear
        collectionView.register(collectionViewCell.self, forCellWithReuseIdentifier: collectionViewCell.identifier)
        return collectionView
    }()
    
    internal var monthYearLabelTextColorConfiguration = SurfaceColorConfiguration(VDSColor.elementsPrimaryOnlight, VDSColor.elementsPrimaryOndark)
    
    //--------------------------------------------------
    // MARK: - Lifecycle
    //--------------------------------------------------
    open override func initialSetup() {
        super.initialSetup()
    }
    
    open override func setup() {
        super.setup()
        isAccessibilityElement = false
        
        // stackView
        addSubview(containerView)
        containerView
            .pinTop()
            .pinBottom()
            .pinLeadingGreaterThanOrEqualTo()
            .pinTrailingLessThanOrEqualTo()
            .height(containerSize.height)
            .width(containerSize.width)
        containerView.centerXAnchor.constraint(equalTo: centerXAnchor).activate()
        
        // stackview
        containerView.addSubview(stackView)
        stackView
            .pinTop()
            .pinLeading()
            .pinTrailing()
            .pinBottom(VDSLayout.space1X)
        stackView.centerXAnchor.constraint(equalTo: containerView.centerXAnchor).activate()
        
        // month label view, previous and next buttons
        stackView.addArrangedSubview(monthView)
        monthView.backgroundColor = .clear
        monthView.heightAnchor.constraint(equalToConstant: 40).isActive = true
        
        // month Header stack view
        monthView.addSubview(monthYearHeaderStackView)
        monthYearHeaderStackView.pinToSuperView()

        // previous button
        monthYearHeaderStackView.addArrangedSubview(previousMonthView)
        previousMonthView.widthAnchor.constraint(equalToConstant: 40).activate()
        previousMonthView.addSubview(previousButton)
        
        // month year label
        monthYearHeaderStackView.addArrangedSubview(monthYearLabel)
        
        // next button
        monthYearHeaderStackView.addArrangedSubview(nextMonthView)
        nextMonthView.widthAnchor.constraint(equalToConstant: 40).activate()
        nextMonthView.addSubview(nextButton)
        
        // days Collection View
        stackView.addArrangedSubview(daysCollectionView)
        daysCollectionView.widthAnchor.constraint(equalTo: widthAnchor).activate()
        daysCollectionView.heightAnchor.constraint(equalTo: monthView.heightAnchor).activate()
        daysCollectionView.centerXAnchor.constraint(equalTo: containerView.centerXAnchor).activate()
    }
    
    open override func updateView() {
        super.updateView()
        monthYearLabel.surface = surface
        previousButton.surface = surface
        nextButton.surface = surface
        daysCollectionView.reloadData()
        monthYearLabel.text = "May 2024"
        monthYearLabel.textColor = monthYearLabelTextColorConfiguration.getColor(surface)
    }
    
    override open func layoutSubviews() {
        super.layoutSubviews()
    }
    
    open override func reset() {
        super.reset()
    }
}

extension CalendarHeaderView: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
    
    public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return daysOfWeek.count
    }
    
    public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: collectionViewCell.identifier, for: indexPath) as? collectionViewCell else { return UICollectionViewCell() }
        cell.updateTitle(text: daysOfWeek[indexPath.row], surface: surface)
        return cell
    }
    
    public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: 40, height: 40)
    }
    
    public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return VDSLayout.space1X
    }
    
    public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        return VDSLayout.space1X
    }
}

private class collectionViewCell: UICollectionViewCell {
    
    static let identifier: String = String(describing: collectionViewCell.self)
    
    private let textColorConfiguration = SurfaceColorConfiguration(VDSColor.elementsSecondaryOnlight, VDSColor.elementsSecondaryOndark)
    
    private var title = Label().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.textAlignment = .center
        $0.numberOfLines = 1
        $0.textStyle = .bodySmall
        $0.backgroundColor = .clear
        $0.isAccessibilityElement = false
    }
    
    //--------------------------------------------------
    // MARK: - Initializers
    //--------------------------------------------------
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupCell()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setupCell()
    }
    
    func setupCell() {
        addSubview(title)
        title.pinToSuperView()
    }
    
    func updateTitle(text: String, surface: Surface) {
        title.surface = surface
        title.text = text
        title.textColor = textColorConfiguration.getColor(surface)
        title.backgroundColor = .clear
    }
}