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

import UIKit
import VDSTokens

final class CalendarDateViewCell: UICollectionViewCell {
    
    ///Identifier for the Calendar Date Cell.
    static let identifier: String = String(describing: CalendarDateViewCell.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()
    }
    
    //--------------------------------------------------
    // MARK: - Private Methods
    //--------------------------------------------------
    /// 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]) {

        stackView.arrangedSubviews.forEach { $0.removeFromSuperview() }
        numberLabel.surface = surface
        numberLabel.text = text
        
        // enable/disable cells based on min date, max date and active/inactive dates.
        self.updateLabel(with:surface, displayDate: displayDate, minDate: minDate, maxDate: maxDate, activeDates: activeDates, inactiveDates: inactiveDates)
        
        // handling inactive dates.
        if inactiveDates.count > 0 {
            for x in (0...(inactiveDates.count-1)) {
                if (inactiveDates[x].monthInt == displayDate.monthInt) && (inactiveDates[x].yearInt == displayDate.yearInt) {
                    if let day:Int = Int(numberLabel.text), day == inactiveDates[x].dayInt {
                        disableLabel(with: surface)
                    }
                }
            }
        }
        
        // 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)) {
                // irrespective of month and year, if it needs to show indicators on every month - comment below first if condition, else uncomment it.
                // if (indicators[x].date.monthInt == displayDate.monthInt) && (indicators[x].date.yearInt == displayDate.yearInt) {
                    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) && (currentDate.yearInt == displayDate.yearInt) {
            numberLabel.textStyle = hideDate ? .bodySmall : .boldBodySmall
        } else {
            numberLabel.textStyle = .bodySmall
        }
    }
    
    // returns cell enabled state.
    func isDateEnabled() -> Bool {
        return numberLabel.isEnabled
    }
    
    func disableLabel(with surface: Surface) {
        numberLabel.isEnabled = false
        numberLabel.textColor = disabledTextColorConfiguration.getColor(surface)
        layer.backgroundColor = disabledBackgroundColor.getColor(surface).cgColor
    }
    
    func showActiveDates(with displayDate: Date, activeDates: [Date], inactiveDates: [Date]) {
        for x in (0...(activeDates.count-1)) {
            if (activeDates[x].monthInt == displayDate.monthInt) && (activeDates[x].yearInt == displayDate.yearInt ) {
                if let day:Int = Int(numberLabel.text), day == activeDates[x].dayInt {
                    numberLabel.isEnabled = true
                }
            }
        }
    }
    
    // handing active dates if exist, else enable numberLabel to display day.
    func handleActiveDates(with displayDate: Date, activeDates: [Date], inactiveDates: [Date]) {
        if activeDates.count > 0 && inactiveDates.count == 0 {
            showActiveDates(with: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
        } else {
            numberLabel.isEnabled = true
        }
    }
    
    // enable all days if no active dates, handing active dates if exist.
    func enableAllDaysAndCheckActiveDates(with surface:Surface, displayDate: Date, activeDates: [Date], inactiveDates: [Date]) {
        if activeDates.count > 0 && inactiveDates.count == 0 {
            disableLabel(with: surface)
            showActiveDates(with: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
        } else {
            numberLabel.isEnabled = true
        }
    }
    
    func minDateValidation(with surface:Surface, minDate: Date, displayDate: Date, activeDates: [Date], inactiveDates: [Date]) {
        // validate days to enable/disable with min date only.
        if let day:Int = Int(numberLabel.text), day < minDate.dayInt {
            disableLabel(with: surface)
        } else {
            numberLabel.isEnabled = false
            handleActiveDates(with: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
        }
    }
    
    func maxDateValidation(with surface:Surface, maxDate: Date, displayDate: Date, activeDates: [Date], inactiveDates: [Date]) {
        // validate days to enable/disable with max date only.
        if let day:Int = Int(numberLabel.text), day > maxDate.dayInt  {
            disableLabel(with: surface)
        } else {
            numberLabel.isEnabled = false
            handleActiveDates(with: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
        }
    }
    
    func minAndMaxDateValidation(with surface:Surface, minDate: Date, maxDate: Date, displayDate: Date, activeDates: [Date], inactiveDates: [Date]) {
        // validate days to enable/disable with min and max date.
        if let day:Int = Int(numberLabel.text), day < minDate.dayInt || day > maxDate.dayInt  {
            disableLabel(with: surface)
        } else {
            numberLabel.isEnabled = false
            handleActiveDates(with: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
        }
    }

    // enable/disable cells based on min date, max date and active/inactive dates.
    func updateLabel(with surface: Surface, displayDate: Date, minDate: Date, maxDate: Date, activeDates: [Date], inactiveDates: [Date]) {
        
        if (minDate.yearInt == displayDate.yearInt) && !(maxDate.yearInt == displayDate.yearInt) {
            // min year and max year are different, and matched to min year.
            if (minDate.monthInt == displayDate.monthInt) {
                // min year and max year are different, and matched to min year and min month.
                minDateValidation(with: surface, minDate: minDate, displayDate: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
            } else {
                // handing active dates - enable all days if no active dates.
                enableAllDaysAndCheckActiveDates(with: surface, displayDate: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
            }
        } else if (maxDate.yearInt == displayDate.yearInt) && !((minDate.yearInt == displayDate.yearInt)) {
            // min year and max year are different, and matched to max year.
            if (maxDate.monthInt == displayDate.monthInt) {
                // min year and max year are different, and matched to max year and max month.
                maxDateValidation(with: surface, maxDate: maxDate, displayDate: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
            } else {
                // handing active dates - enable all days if no active dates.
                enableAllDaysAndCheckActiveDates(with: surface, displayDate: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
            }
        } else if (minDate.yearInt == displayDate.yearInt) && (maxDate.yearInt == displayDate.yearInt) {
            // min year and max year same
            if (minDate.monthInt == displayDate.monthInt) && (maxDate.monthInt == displayDate.monthInt) {
                // min year and max year same, when choose dates in same month.
                minAndMaxDateValidation(with: surface, minDate: minDate, maxDate: maxDate, displayDate: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
              
            } else if (minDate.monthInt == displayDate.monthInt) || (maxDate.monthInt == displayDate.monthInt) {
                // min year and max year same, and choose dates in different months.
                if (minDate.monthInt == displayDate.monthInt) {
                    // min year and max year same, and matched to min month.
                    minDateValidation(with: surface, minDate: minDate, displayDate: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
                } else if (maxDate.monthInt == displayDate.monthInt) {
                    // min year and max year same, and matched to max month.
                    maxDateValidation(with: surface, maxDate: maxDate, displayDate: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
                }
            } else {
                // min year and max year same, and not matched to min or max month.
                // handing active dates - enable all days if no active dates.
                enableAllDaysAndCheckActiveDates(with: surface, displayDate: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
            }
        } else {
            // min year and max year are different, and not matched to min or max year.
            // handing active dates - enable all days if no active dates.
            enableAllDaysAndCheckActiveDates(with: surface, displayDate: displayDate, activeDates: activeDates, inactiveDates: inactiveDates)
        }
    }
    
    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
        }
    }
}