//
//  Date+Extension.swift
//  VDS
//
//  Created by Kanamarlapudi, Vasavi on 26/04/24.
//

import Foundation

extension Date {
    
    static var firstDayOfWeek = Calendar.current.firstWeekday
    
    /// Capitalizes the first letter of the day of the week
    static var capitalizedFirstLettersOfWeekdays: [String] {
        let calendar = Calendar.current
        let weekdays = calendar.shortWeekdaySymbols
        
        return weekdays.map { weekday in
            guard let firstLetter = weekday.first else { return "" }
            return String(firstLetter).capitalized
        }
    }
    
    /// Returns all month names
    static var fullMonthNames: [String] {
        let dateFormatter = DateFormatter()
        dateFormatter.locale = Locale.current
        
        return (1...12).compactMap { month in
            dateFormatter.setLocalizedDateFormatFromTemplate("MMMM")
            let date = Calendar.current.date(from: DateComponents(year: 2000, month: month, day: 1))
            return date.map { dateFormatter.string(from: $0) }
        }
    }

    var startOfMonth: Date {
        Calendar.current.dateInterval(of: .month, for: self)!.start
    }
    
    var endOfMonth: Date {
        let lastDay = Calendar.current.dateInterval(of: .month, for: self)!.end
        return Calendar.current.date(byAdding: .day, value: -1, to: lastDay)!
    }
    
    /// Get the number of days of the month
    var numberOfDaysInMonth: Int {
        Calendar.current.component(.day, from: endOfMonth)
    }
    
    var firstWeekDayBeforeStart: Date {
        let startOfMonthWeekday = Calendar.current.component(.weekday, from: startOfMonth)
        var numberFromPreviousMonth = startOfMonthWeekday - Self.firstDayOfWeek
        if numberFromPreviousMonth < 0 {
            numberFromPreviousMonth += 7 // Adjust to a 0-6 range if negative
        }
        return Calendar.current.date(byAdding: .day, value: -numberFromPreviousMonth, to: startOfMonth)!
    }
    
    /// Get the days of the month to display
    var calendarDisplayDays: [Date] {
        var days: [Date] = []
        // Start with days from the previous month to fill the grid
        let firstDisplayDay = firstWeekDayBeforeStart
        var day = firstDisplayDay
        while day < startOfMonth {
            days.append(day)
            day = Calendar.current.date(byAdding: .day, value: 1, to: day)!
        }
        // Add days of the current month
        for dayOffset in 0..<numberOfDaysInMonth {
            let newDay = Calendar.current.date(byAdding: .day, value: dayOffset, to: startOfMonth)
            days.append(newDay!)
        }
        return days
    }
    
    /// Returns the year value of the given date
    var yearInt: Int {
        Calendar.current.component(.year, from: self)
    }
    
    /// Returns the month value of the given date
    var monthInt: Int {
        Calendar.current.component(.month, from: self)
    }
    
    /// Returns the day value of the given date
    var dayInt: Int {
        Calendar.current.component(.day, from: self)
    }
    
    /// Check if the date falls between the given dates
    func isBetweeen(date date1: Date, andDate date2: Date) -> Bool {
        return date1.compare(self) == self.compare(date2)
    }
    
    /// Returns the month name of the given date
    func getMonthName(date: Date) -> String {
        let names = Date.fullMonthNames
        return names[date.monthInt - 1]
    }

}