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lib/calendars/gregorian.ex
defmodule Calendars.Gregorian do
@moduledoc """
Documentation for the Gregorian calendar (DR4).
"""
@typep year :: integer
@typep month :: 1..12
@typep day :: 1..31
@type t :: {year, month, day}
@months [
"January", "February", "March", "April", "May", "June", "Juli", "August",
"September", "October", "November", "December"
]
@weekdays [
"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
]
@doc """
Returns the keyword used to access data in the DR4 sample data.
"""
def keyword, do: :gregorian
@doc """
Returns a Gregorian date from its parts.
"""
def date(year, month, day), do: {year, month, day}
@doc """
Returns the epoch of the Gregorian calendar.
"""
def epoch, do: Calixir.gregorian_epoch()
@doc """
Returns the number of days in the month of `_gregorian_date`.
"""
def days_in_month({year, 2, _day} = _gregorian_date), do: is_leap?(year) && 29 || 28
def days_in_month({_year, 4, _day} = _gregorian_date), do: 30
def days_in_month({_year, 6, _day} = _gregorian_date), do: 30
def days_in_month({_year, 9, _day} = _gregorian_date), do: 30
def days_in_month({_year, 11, _day} = _gregorian_date), do: 30
def days_in_month({_year, _, _day} = _gregorian_date), do: 31
@doc """
Converts `source_calendar_date` of the `source_calendar` into the
corresponding Gregorian date.
"""
def from_date(source_calendar_date, source_calendar) do
source_calendar_date |> source_calendar.to_fixed |> from_fixed
end
@doc """
Converts the `fixed` date in to the corresponding Gregorian date.
"""
def from_fixed(fixed) do
Calixir.gregorian_from_fixed(fixed)
end
@doc """
Converts the Julian Day number `jd` into the corresponding Gregorian date.
"""
def from_jd(jd) do
jd |> Calixir.fixed_from_jd |> from_fixed
end
@doc """
Returns true if the year of `_gregorian_date` is a Gregorian leap year.
"""
def is_leap?({year, _month, _day}= _gregorian_date) do
Calixir.gregorian_leap_year?(year)
end
@doc """
Returns true is the given `year` is a Gregorian leap year.
"""
def is_leap?(year) do
Calixir.gregorian_leap_year?(year)
end
@doc """
Converts `gregorian_date` into the corresponding date of
`target_calendar`.
"""
def to_date(gregorian_date, target_calendar) do
gregorian_date |> to_fixed |> target_calendar.from_fixed
end
@doc """
Converts `gregorian_date` into the corresponding `fixed` date.
"""
def to_fixed(gregorian_date) do
Calixir.fixed_from_gregorian(gregorian_date)
end
@doc """
Converts `gregorian_date` into the corresponding Julian Day number.
"""
def to_jd(gregorian_date) do
gregorian_date |> to_fixed |> Calixir.jd_from_fixed
end
# === Holidays
@doc """
Advent Sunday.
"""
def advent({g_year, _, _}), do: advent(g_year)
defdelegate advent(g_year), to: Calixir
@doc """
Christmas.
"""
def christmas({g_year, _, _}), do: christmas(g_year)
defdelegate christmas(g_year), to: Calixir
@doc """
Easter.
"""
def easter({g_year, _, _}), do: easter(g_year)
defdelegate easter(g_year), to: Calixir
@doc """
Epiphany.
"""
def epiphany({g_year, _, _}), do: epiphany(g_year)
defdelegate epiphany(g_year), to: Calixir
@doc """
Friday the 13th (first).
"""
def unlucky_fridays({g_year, _, _}), do: unlucky_fridays(g_year)
defdelegate unlucky_fridays(g_year), to: Calixir
@doc """
Daylight Saving End.
"""
def daylight_saving_end({g_year, _, _}), do: daylight_saving_end(g_year)
defdelegate daylight_saving_end(g_year), to: Calixir
@doc """
Daylight Saving Start.
"""
def daylight_saving_start({g_year, _, _}), do: daylight_saving_start(g_year)
defdelegate daylight_saving_start(g_year), to: Calixir
@doc """
Pentecost.
"""
def pentecost({g_year, _, _}), do: pentecost(g_year)
defdelegate pentecost(g_year), to: Calixir
@doc """
U.S. Election Day.
"""
def election_day({g_year, _, _}), do: election_day(g_year)
defdelegate election_day(g_year), to: Calixir
@doc """
U.S. Independence Day.
"""
def independence_day({g_year, _, _}), do: independence_day(g_year)
defdelegate independence_day(g_year), to: Calixir
@doc """
U.S. Labor Day.
"""
def labor_day({g_year, _, _}), do: labor_day(g_year)
defdelegate labor_day(g_year), to: Calixir
@doc """
U.S. Memorial Day.
"""
def memorial_day({g_year, _, _}), do: memorial_day(g_year)
defdelegate memorial_day(g_year), to: Calixir
# === Additional Functions
@doc """
Returns end of the current month as a fixed date.
"""
def end_of_month({year, month, day} = g_date) do
days = days_in_month_of_date(g_date)
to_fixed({year, month, days})
end
@doc """
Returns end of the current week as a fixed date.
"""
def end_of_week({year, month, day} = g_date) do
fixed = to_fixed(g_date)
day_of_week = Calixir.day_of_week_from_fixed(fixed)
fixed + 6 - day_of_week
end
@doc """
Returns end of the current year as a fixed date.
"""
def end_of_year({year, month, day} = g_date) do
to_fixed({year, 12, 31})
end
@doc """
Returns start of the current year as a fixed date.
"""
def start_of_month({year, month, day} = g_date) do
to_fixed({year, month, 1})
end
@doc """
Returns start of the current week as a fixed date.
"""
def start_of_week({year, month, day} = g_date) do
fixed = to_fixed(g_date)
day_of_week = Calixir.day_of_week_from_fixed(fixed)
fixed - day_of_week
end
@doc """
Returns start of the current year as a fixed date.
"""
def start_of_year({year, month, day} = g_date) do
to_fixed({year, 1, 1})
end
def start_of_year(year) do
to_fixed({year, 1, 1})
end
@doc """
Returns the fixed date of today.
"""
def today(_), do: Date.utc_today() |> Date.to_erl() |> to_fixed
def today(), do: Date.utc_today() |> Date.to_erl() |> to_fixed
@doc """
Returns true, if `g_year` is a leap year.
"""
defdelegate leap_year?(g_year), to: Calixir, as: :gregorian_leap_year?
@doc """
Returns the name of the month from the Gregorian date `_g_date`.
"""
def name_of_month_from_date({_year, month, _day} = _g_date) do
case month do
1 -> :january
2 -> :february
3 -> :march
4 -> :april
5 -> :may
6 -> :june
7 -> :july
8 -> :august
9 -> :september
10 -> :october
11 -> :november
12 -> :december
end
end
@doc """
Returns the name of the month from the `fixed` date.
"""
def name_of_month_from_fixed(fixed) do
fixed |> from_fixed |> name_of_month_from_date
end
@doc """
Returns the quarter of the year from the Gregorian date `_g_date`.
"""
def quarter_from_date({_year, month, _day} = _g_date) do
cond do
month < 4 -> 1
month < 7 -> 2
month < 10 -> 3
true -> 4
end
end
@doc """
Returns the quarter of the year from the `fixed` date.
"""
def quarter_from_fixed(fixed) do
fixed |> from_fixed |> quarter_from_date
end
@doc """
Returns the number of days in the month of `_g_date`.
"""
def days_in_month_of_date({year, month, _day} = _g_date) do
case month do
1 -> 31
2 -> leap_year?(year) && 29 || 28
3 -> 31
4 -> 30
5 -> 31
6 -> 30
7 -> 31
8 -> 31
9 -> 30
10 -> 31
11 -> 30
12 -> 31
end
end
@doc """
Returns the number of days in the month of `fixed` date.
"""
def days_in_month_of_fixed(fixed) do
fixed |> from_fixed |> days_in_month_of_date
end
@doc """
Returns the number of days in the quarter of `g_date`.
"""
def days_in_quarter_of_date({year, _month, _day} = g_date) do
case quarter_from_date(g_date) do
1 -> leap_year?(year) && 91 || 90
2 -> 91
3 -> 92
4 -> 92
end
end
@doc """
Returns the number of days in the quarter of `fixed` date.
"""
def days_in_quarter_of_fixed(fixed) do
fixed |> from_fixed |> days_in_quarter_of_date
end
@doc """
Returns the English names of the months as list.
"""
def month_names_as_list(), do: @months
@doc """
Returns the English names of the weekdays as list.
"""
def day_names_as_list(), do: @weekdays
end