commonMain.io.islandtime.calendar.WeekSettings.kt Maven / Gradle / Ivy

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A multiplatform library for working with dates and times

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package io.islandtime.calendar

import io.islandtime.DayOfWeek
import io.islandtime.locale.Locale

/**
 * Week-related calendar settings.
 * @property firstDayOfWeek The first day of the week.
 * @property minimumDaysInFirstWeek The minimum number of days required in the first week of the year.
 */
data class WeekSettings(
    val firstDayOfWeek: DayOfWeek,
    val minimumDaysInFirstWeek: Int
) {
    init {
        require(minimumDaysInFirstWeek in 1..7) { "minimumDaysInFirstWeek must be in 1..7" }
    }

    companion object {
        /**
         * Returns the definition of a week according to the current system settings. This may differ from the
         * definition associated with the default locale on platforms that allow this to be customized, such as iOS and
         * macOS.
         */
        fun systemDefault(): WeekSettings = systemDefaultWeekSettings()

        /**
         * The ISO-8601 calendar system's definition of a week, where the first day of the week is Monday and the first
         * week of the year has a minimum of 4 days.
         */
        val ISO = WeekSettings(DayOfWeek.MONDAY, minimumDaysInFirstWeek = 4)

        /**
         * A definition of a week that starts on Sunday with a minimum of 1 day in the first week of the year.
         */
        val SUNDAY_START = WeekSettings(DayOfWeek.SUNDAY, minimumDaysInFirstWeek = 1)
    }
}

/**
 * The default [WeekSettings] associated with this locale.
 */
expect val Locale.weekSettings: WeekSettings

internal expect fun systemDefaultWeekSettings(): WeekSettings
internal expect val Locale.firstDayOfWeek: DayOfWeek