//
//  CalendarLegendView.swift
//  VDS
//
//  Created by Kanamarlapudi, Vasavi on 29/04/24.
//

import Foundation
import UIKit
import VDSTokens
import Combine

/// Legend view to show array of indicators as calendar footer view.
open class CalendarLegendView: 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
    //--------------------------------------------------
    open var items: [CalendarIndicatorModel] = [] { didSet { setNeedsUpdate() } }
        
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    internal var containerSize: CGSize { CGSize(width: 320, height: 56) } //width:320/328

    internal var containerView = View().with {
        $0.clipsToBounds = true
    }
    
    private let flowLayout = UICollectionViewFlowLayout().with {
        $0.estimatedItemSize = UICollectionViewFlowLayout.automaticSize
        $0.minimumLineSpacing = VDSLayout.space1X
        $0.minimumInteritemSpacing = VDSLayout.space4X
        $0.scrollDirection = .vertical
    }
    open lazy var legendCollectionView = UICollectionView(frame: .zero, collectionViewLayout: flowLayout).with {
        $0.isScrollEnabled = false
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.showsVerticalScrollIndicator = false
        $0.showsHorizontalScrollIndicator = false
        $0.isAccessibilityElement = true
        $0.backgroundColor = .clear
        $0.delegate = self
        $0.dataSource = self
        $0.register(LegendCollectionViewCell.self, forCellWithReuseIdentifier: LegendCollectionViewCell.identifier)
    }
    
    //--------------------------------------------------
    // MARK: - Lifecycle
    //--------------------------------------------------
    open override func initialSetup() {
        super.initialSetup()
    }
    
    open override func setup() {
        super.setup()
        isAccessibilityElement = false
        
        addSubview(containerView)
        containerView
            .pinTop(VDSLayout.space6X)
            .pinBottom(VDSLayout.space4X)
            .pinLeadingGreaterThanOrEqualTo(leadingAnchor, VDSLayout.space5X, .defaultLow)
            .pinTrailingLessThanOrEqualTo(trailingAnchor, VDSLayout.space5X, .defaultHigh)
            .height(containerSize.height)
            .width(containerSize.width)
        
        containerView.centerXAnchor.constraint(equalTo: centerXAnchor).activate()
        
        // legend Collection View
        containerView.addSubview(legendCollectionView)
        legendCollectionView.pinToSuperView()

    }
    
    open override func updateView() {
        super.updateView()
        legendCollectionView.reloadData()
    }
    
    override open func layoutSubviews() {
        super.layoutSubviews()
    }
    
    open override func reset() {
        super.reset()
    }
}

extension CalendarLegendView: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
    
    public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return items.count
    }
    
    public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        guard collectionView == legendCollectionView,
              let cell = collectionView.dequeueReusableCell(withReuseIdentifier: LegendCollectionViewCell.identifier, for: indexPath) as? LegendCollectionViewCell,
              indexPath.row <= items.count else { return UICollectionViewCell() }
        let text = items[indexPath.row].label
        cell.updateTitle(text: text, color: VDSColor.elementsSecondaryOnlight, surface: surface, clearFullcircle: indexPath.row == 1, drawSemiCircle: indexPath.row == 2)
        return cell
    }
}

private class LegendCollectionViewCell: UICollectionViewCell {
    
    static let identifier: String = String(describing: LegendCollectionViewCell.self)
    
    private let textColorConfiguration = SurfaceColorConfiguration(VDSColor.elementsPrimaryOnlight, VDSColor.elementsPrimaryOndark)
    
    private let indicatorColorConfiguration = SurfaceColorConfiguration(VDSColor.elementsSecondaryOnlight, VDSColor.elementsSecondaryOndark)
    
    private var title = Label().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.textAlignment = .left
        $0.numberOfLines = 1
        $0.textStyle = .bodySmall
        $0.backgroundColor = .clear
        $0.isAccessibilityElement = false
    }
    private var legendIndicatorWrapper: View = View().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.backgroundColor = .clear
    }
    private var legendIndicator: View = View().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.backgroundColor = .clear
        $0.layer.borderWidth = 1.0
    }
    
    private lazy var stackView = UIStackView().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.distribution = .equalSpacing
        $0.spacing = VDSLayout.space2X
        $0.axis = .horizontal
        $0.backgroundColor = .clear
    }
    
    private lazy var shapeLayer = CAShapeLayer()
    
    //--------------------------------------------------
    // MARK: - Initializers
    //--------------------------------------------------
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupCell()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setupCell()
    }
        
    func setupCell() {
        addSubview(stackView)
        stackView.pinToSuperView()
        
        legendIndicatorWrapper.addSubview(legendIndicator)
        legendIndicator.pinLeading().pinTrailing().width(8).height(8).pinCenterY()
    
        stackView.addArrangedSubview(legendIndicatorWrapper)
        stackView.addArrangedSubview(title)
    }
    
    func updateTitle(text: String, color: UIColor, surface: Surface, clearFullcircle: Bool, drawSemiCircle: Bool) {
        title.text = text
        title.textColor = textColorConfiguration.getColor(surface)
        
        legendIndicator.backgroundColor = drawSemiCircle ? .clear : (clearFullcircle ? .clear : color)
        legendIndicator.layer.borderColor = indicatorColorConfiguration.getColor(surface).cgColor
        
        self.layoutIfNeeded()
        
        legendIndicator.layer.cornerRadius = legendIndicator.frame.size.height / 2.0
        
        guard drawSemiCircle else { return }
        
        let center = CGPoint(x: legendIndicator.frame.size.width/2, y: legendIndicator.frame.size.height/2)
        let path = UIBezierPath()
        path.move(to: center)
        path.addArc(withCenter: center, radius: center.x, startAngle: 2 * .pi, endAngle: .pi, clockwise: true)
        path.close()
        shapeLayer.path = path.cgPath
        shapeLayer.fillColor = color.cgColor
        
        guard legendIndicator.layer.sublayers?.contains(shapeLayer) ?? true else { return }
        legendIndicator.layer.addSublayer(shapeLayer)
    }
}