import * from "type"

type DateInterval = 'yyyy' // Year
    | 'q' // Quarter
    | 'm' // Month
    | 'y' // Day of year
    | 'd' // Day
    | 'w' // Weekday
    | 'ww' // Week of year
    | 'h' // Hour
    | 'n' // Minute
    | 's' //Second
    ;

type FirstDayOfWeek = Byte

type FirstWeekOfYear = Byte

/// Date Constants
declare {
    // Use National Language Support (NLS) API setting.
    const vbUseSystem: FirstDayOfWeek = 0

    // Sunday (default)
    const vbSunday: FirstDayOfWeek = 1

    // Monday
    const vbMonday: FirstDayOfWeek = 2

    // Tuesday
    const vbTuesday: FirstDayOfWeek = 3

    // Wednesday
    const vbWednesday: FirstDayOfWeek = 4

    // Thursday
    const vbThursday: FirstDayOfWeek = 5

    // Friday
    const vbFriday: FirstDayOfWeek = 6

    // Saturday
    const vbSaturday: FirstDayOfWeek = 7
}

/// Time Constants
declare {
    // Use National Language Support (NLS) API setting.
    const vbUseSystem: FirstWeekOfYear = 0

    // Start with the week in which January 1 occurs (default).
    const vbFirstJan1: FirstWeekOfYear = 1

    // Start with the week that has at least four days in the new year.
    const vbFirstFourDays: FirstWeekOfYear = 2

    // Start with the first full week of the new year.
    const vbFirstFullWeek: FirstWeekOfYear = 3
}

type DateFormat = Byte

/// Date Format Constants
declare {
    // Display a date and/or time. For real numbers, display a date and time.
    // If there is no fractional part, display only a date.
    // If there is no integer part, display time only.
    // Date and time display is determined by your system settings.
    const vbGeneralDate: DateFormat = 0

    // Display a date using the long date format specified in your computer's regional settings.
    const vbLongDate: DateFormat = 1

    // Display a date using the short date format specified in your computer's regional settings.
    const vbShortDate: DateFormat = 2

    // Display a time using the time format specified in your computer's regional settings.
    const vbLongTime: DateFormat = 3

    // Display a time using the 24-hour format (hh:mm).
    const vbShortTime: DateFormat = 4
}

// Returns the current system date.
declare fn Date() -> Date

// Returns a date to which a specified time interval has been added.
declare fn DateAdd(interval: DateInterval, number: num, date: Date) -> Date

// Returns the number of intervals between two dates.
declare fn DateDiff(interval: DateInterval, date1: Date, date2: Date, firstdayofweek?: FirstDayOfWeek, firstweekofyear?: FirstWeekOfYear) -> Date

// Returns the specified part of a given date.
declare fn DatePart(interval: DateInterval, date: Date, firstdayofweek?: FirstDayOfWeek, firstweekofyear?: FirstWeekOfYear) -> Date

// Returns a Variant of subtype Date for a specified year, month, and day.
declare fn DateSerial(year: num, month: num, day: num) -> Date

// Returns a Variant of subtype Date.
// Examples:
// ```hulo
// let d = DateValue("September 11, 1963")
// assert(d is Date)
// ```
declare fn DateValue(v: String) -> Date

// Returns a whole number between 1 and 31, inclusive, representing the day of the month.
// Examples:
// ```hulo
// let d = Day("October 19, 1962")
// assert_eq(d, 19)
// ```
declare fn Day(v: Date) -> Integer

/**
 * Returns a whole number between 0 and 23, inclusive, representing the hour of the day.
 * If the input is Null, the function returns Null.
 *
 * Examples:
 * ```hulo
 * let t = Now()
 * let h = Hour(t)
 * assert(h >= 0 && h <= 23)
 * ```
 */
declare fn Hour(time: Date) -> Integer

// Returns a whole number between 0 and 59, inclusive, representing the minute of the hour.
declare fn Minute(date: Date) -> Integer

// Returns a whole number between 1 and 12, inclusive, representing the month of the year.
declare fn Month(date: Date) -> Integer

// Returns a string indicating the specified month.
declare fn MonthName(month: num, abbreviate?: bool)

// Returns the current date and time according to the setting of your computer's system date and time.
declare fn Now() -> Date

// Returns a whole number between 0 and 59, inclusive, representing the second of the minute.
declare fn Second(date: Date) -> num

// Returns a Variant of subtype Date indicating the current system time.
declare fn Time() -> Date

// Returns the number of seconds that have elapsed since 12:00 AM (midnight).
declare fn Timer() -> num

// Returns a Variant of subtype Date containing the time for a specific hour, minute, and second.
declare fn TimeSerial(hour: num, minute: num, second: num) -> Date

// Returns a Variant of subtype Date containing the time.
declare fn TimeValue(time: Date) -> Date

// Returns a whole number representing the day of the week.
declare fn Weekday(date: Date, firstdayofweek?: FirstDayOfWeek) -> num

declare fn WeekdayName(weekday: num, abbreviate: bool?, firstdayofweek: FirstDayOfWeek) -> str

// Returns a whole number representing the year.
declare fn Year(date: Date) -> num