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

import Foundation
import UIKit
import VDSTokens

/// Calendar collection view cell for Date view
final class CalendarDateCollectionViewCell: UICollectionViewCell {
    
    ///Identifier for the Calendar Date Cell
    static let identifier: String = String(describing: CalendarDateCollectionViewCell.self)
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    internal var containerSize: CGSize { CGSize(width: 40, height: 40) }
    
    internal var containerView = View().with {
        $0.clipsToBounds = true
    }
    
    private lazy var stackView: UIStackView = {
        return UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.axis = .horizontal
            $0.distribution = .fill
            $0.alignment = .center
            $0.spacing = VDSLayout.space1X
            $0.setContentCompressionResistancePriority(.defaultHigh, for: .horizontal)
            $0.setContentHuggingPriority(.defaultHigh, for: .horizontal)
            $0.backgroundColor = .clear
        }
    }()
    
    private var numberLabel = Label().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.textAlignment = .center
        $0.textStyle = .bodySmall
    }
    
    private lazy var shapeLayer = CAShapeLayer()
    
    private let selectedTextColorConfiguration = SurfaceColorConfiguration(VDSColor.elementsPrimaryInverseOnlight, VDSColor.elementsPrimaryInverseOndark)
    private let selectedBackgroundColor = SurfaceColorConfiguration(VDSColor.backgroundPrimaryInverseLight, VDSColor.backgroundPrimaryInverseDark)
    private let selectedCellIndicatorColorConfiguration = SurfaceColorConfiguration(VDSColor.paletteGray65, VDSColor.paletteGray44)
    private let unselectedTextColorConfiguration = SurfaceColorConfiguration(VDSColor.elementsPrimaryOnlight, VDSColor.elementsPrimaryOndark)
    private let unselectedCellIndicatorColorConfiguration = SurfaceColorConfiguration(VDSColor.elementsSecondaryOnlight, VDSColor.elementsSecondaryOndark)
    private let disabledTextColorConfiguration = SurfaceColorConfiguration(VDSColor.interactiveDisabledOnlight, VDSColor.interactiveDisabledOndark)
    private let disabledBackgroundColor = SurfaceColorConfiguration(VDSFormControlsColor.backgroundOnlight, VDSFormControlsColor.backgroundOndark)
    
    private let currentDate = Date()
    
    //--------------------------------------------------
    // MARK: - Initializers
    //--------------------------------------------------
    override init(frame: CGRect) {
        super.init(frame: frame)
        setUp()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setUp()
    }
    
    /// Configuring the cell with default setup
    private func setUp() {
        isAccessibilityElement = false
        contentView.addSubview(containerView)
        containerView
            .pinTop()
            .pinBottom()
            .pinLeadingGreaterThanOrEqualTo()
            .pinTrailingLessThanOrEqualTo()
            .height(containerSize.height)
            .width(containerSize.width)
        containerView.centerXAnchor.constraint(equalTo: centerXAnchor).activate()
        
        // Number label
        containerView.addSubview(numberLabel)
        numberLabel.pinToSuperView()
        
        // Indicators
        containerView.addSubview(stackView)
        let topPos = containerSize.height * 0.7
        stackView.pinTop(topPos).pinBottom().pinTopGreaterThanOrEqualTo().pinTrailingLessThanOrEqualTo()
        stackView.centerXAnchor.constraint(equalTo: centerXAnchor).activate()
    }
    
    /// Updating UI based on selected date, modified indicators data along with surface
    /// Enable/disable cell based on min date, max date, active dates, inactive dates
    func update(with surface: Surface, indicators: [CalendarBase.CalendarIndicatorModel], text: String, indicatorCount: Int, selectedDate: Date, displayDate: Date, hideDate: Bool, minDate: Date, maxDate: Date, activeDates: [Date], inactiveDates: [Date]) {
        numberLabel.surface = surface
        numberLabel.text = text
        stackView.arrangedSubviews.forEach { $0.removeFromSuperview() }
              
        // enable/disable cells based on min date, max date.
        if let day:Int = Int(numberLabel.text), day < minDate.dayInt || day > maxDate.dayInt {
            numberLabel.isEnabled = false
            numberLabel.textColor = disabledTextColorConfiguration.getColor(surface)
            layer.backgroundColor = disabledBackgroundColor.getColor(surface).cgColor
        } else {
            numberLabel.isEnabled = false
            // handing active dates
            if activeDates.count > 0 && inactiveDates.count == 0 {
                for x in (0...(activeDates.count-1)) {
                    if let day:Int = Int(numberLabel.text), day == activeDates[x].dayInt {
                        numberLabel.isEnabled = true
                    }
                }
            } else {
                numberLabel.isEnabled = true
            }
        }
        
        // handling inactive dates
        if inactiveDates.count > 0 {
            for x in (0...(inactiveDates.count-1)) {
                if (activeDates[x].monthInt == displayDate.monthInt) && (activeDates[x].yearInt == displayDate.yearInt) {
                    if let day:Int = Int(numberLabel.text), day == inactiveDates[x].dayInt {
                        numberLabel.isEnabled = false
                        numberLabel.textColor = disabledTextColorConfiguration.getColor(surface)
                        layer.backgroundColor = disabledBackgroundColor.getColor(surface).cgColor
                    }
                }
            }
        }
        
        // update text color, bg color, corner radius
        if (numberLabel.text == self.getDay(with: selectedDate)) && (selectedDate.monthInt == displayDate.monthInt) && (selectedDate.yearInt == displayDate.yearInt) && numberLabel.isEnabled {
            numberLabel.textColor = selectedTextColorConfiguration.getColor(surface)
            layer.backgroundColor = selectedBackgroundColor.getColor(surface).cgColor
            layer.cornerRadius = VDSFormControls.borderRadius
        } else {
            numberLabel.textColor = unselectedTextColorConfiguration.getColor(surface)
            layer.backgroundColor = nil
            layer.cornerRadius = 0
        }
        
        // add indicators
        if indicatorCount > 0 {
            for x in (0...(indicators.count-1)) {
                if (self.numberLabel.text == self.getDay(with: indicators[x].date)) {
                    let color = (numberLabel.text == self.getDay(with: selectedDate)) ? selectedCellIndicatorColorConfiguration.getColor(surface) : unselectedCellIndicatorColorConfiguration.getColor(surface)
                    addIndicator(with: color, surface: surface, clearFullCircle: (x == 1), drawSemiCircle: (x == 2))
                }
            }
        }
        
        // update text style for current date
        if (numberLabel.text == self.getDay(with: currentDate)) && (currentDate.monthInt == displayDate.monthInt) {
            numberLabel.textStyle = hideDate ? .bodySmall : .boldBodySmall
        } else {
            numberLabel.textStyle = .bodySmall
        }
    }
    
    //--------------------------------------------------
    // MARK: - Private Methods
    //--------------------------------------------------
    func addIndicator(with color: UIColor, surface: Surface, clearFullCircle: Bool, drawSemiCircle: Bool) {
        // add indicator
        let indicatorView: View = View().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.backgroundColor = .clear
            $0.layer.borderWidth = 1.0
        }
        indicatorView.pinLeading().pinTrailing().width(8).height(8).pinCenterY()
        stackView.addArrangedSubview(indicatorView)
        
        // update indicator
        indicatorView.backgroundColor = drawSemiCircle ? .clear : (clearFullCircle ? .clear : color)
        indicatorView.layer.borderColor = color.cgColor
        
        self.layoutIfNeeded()
        
        indicatorView.layer.cornerRadius = indicatorView.frame.size.height / 2.0
        
        guard drawSemiCircle else { return }
        
        let center = CGPoint(x: indicatorView.frame.size.width/2, y: indicatorView.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 indicatorView.layer.sublayers?.contains(shapeLayer) ?? true else { return }
        indicatorView.layer.addSublayer(shapeLayer)
    }
    
    func getDay(with date: Date) -> String {
        if #available(iOS 15.0, *) {
            return date.formatted(.dateTime.day())
        } else {
            // Fallback on earlier versions
            let dateFormatter: DateFormatter = DateFormatter()
            dateFormatter.dateFormat = "d"
            let day: String = dateFormatter.string(from: date)
            return day
        }
    }
}