calixir

defmodule Calixir.Holidays do
  @moduledoc """

  This module provides the holiday data contained in the sample

  data file `holiday-list.csv` of calendrica-4.0 as Elixir data.



  The data consist of a list of holiday lists with the holiday dates

  ranging from 2000 to 2103.



  Each holiday list has the following structure:



  `[:holiday_function, holiday_name, date_2000, ..., date_2103]`



  `:holiday_function` is the name of the function to calculate the dates.

  `holiday_name` is a string, giving the common name of the holiday.

  `date_nnnn` is the Gregorian date `{year, month, day}` of the holiday

  or `{year, 0, 0}` if no such holiday exists in that year.

  """

  import Calixir.HolidaysTableMaker

  @holiday_file   "holiday-list.csv"
  @holiday_dates  holiday_dates_from_file(@holiday_file)

  @doc """

  Returns the complete list of holiday lists.

  Each holiday list starts with the atom used for the holiday and

  its common name. Then follow the Gregorian dates of the holiday

  for the years 2000 to 2103.



  ```

  [

    [

      :advent,

      "Advent Sunday",

      {2000, 12, 3},

      {2001, 12, 2},

      {2002, 12, 1},

      ...

    ],

    [

      :bahai_new_year,

      "Baha'i New Year",

      {2000, 3, 21},

      {2001, 3, 21},

      {2002, 3, 21},

      ...

    ],

    ...

  ]

  ```

  """
  def holiday_dates, do: @holiday_dates

  @doc """

  Returns a list of the holiday functions used to calculate holidays.

  """
  def holiday_functions() do
    holiday_dates()
    |> Enum.map(&(Enum.at(&1, 0)))
    |> Enum.sort
  end

  @doc """

  Outputs a list of the holiday functions used to calculate holidays.

  ```

  advent

  astronomical_easter

  bahai_new_year

  birkath_ha_hama

  birth_of_the_bab

  chinese_new_year

  christmas

  classical_passover_eve

  coptic_christmas

  daylight_saving_end

  daylight_saving_start

  diwali

  dragon_festival

  easter

  eastern_orthodox_christmas

  election_day

  epiphany

  feast_of_ridvan

  hanukkah

  hindu_lunar_new_year

  icelandic_summer

  icelandic_winter

  independence_day

  kajeng_keliwon

  labor_day

  mawlid

  memorial_day

  mesha_samkranti

  naw_ruz

  nowruz

  observational_hebrew_first_of_nisan

  orthodox_easter

  passover

  pentecost

  purim

  qing_ming

  rama

  sacred_wednesdays

  sh_ela

  shiva

  ta_anit_esther

  tibetan_new_year

  tishah_be_av

  tumpek

  unlucky_fridays

  yom_ha_zikkaron

  yom_kippur

  ```

  """
  def holiday_functions_to_io do
    holiday_functions()
    |> Enum.join("\n")
    |> IO.puts
  end

  @doc """

  Returns a list of the common names of the holidays.

  """
  def holiday_names do
    holiday_dates()
    |> Enum.map(&(Enum.at(&1, 1)))
    |> Enum.sort
  end

  @doc """

  Outputs a list of the common names of the holidays.

  ```

  Advent Sunday

  Baha'i New Year

  Birkath ha-Hama

  Birth of the Bab

  Birthday of Rama

  Chinese New Year

  Christmas

  Christmas (Coptic)

  Christmas (Orthodox)

  Diwali

  Dragon Festival

  Easter

  Easter (Astronomical)

  Easter (Orthodox)

  Epiphany

  Feast of Naw-Ruz

  Feast of Ridvan

  Friday the 13th (first)

  Great Night of Shiva

  Hanukkah (first day)

  Hindu Lunar New Year

  Icelandic Summer

  Icelandic Winter

  Kajeng Keliwon (first)

  Losar

  Mawlid

  Mesha Samkranti (date)

  Nowruz

  Observ. Hebrew 1 Nisan

  Passover

  Passover Eve (Classical)

  Pentecost

  Purim

  Qingming

  Sacred Wednesday (first)

  Sh'ela

  Ta'anit Esther

  Tishah be-Av

  Tumpek (first)

  U.S. Daylight Savings End

  U.S. Daylight Savings Start

  U.S. Election Day

  U.S. Independence Day

  U.S. Labor Day

  U.S. Memorial Day

  Yom Kippur

  Yom ha-Zikkaron

  ```

  """
  def holiday_names_to_io do
    holiday_names()
    |> Enum.join("\n")
    |> IO.puts
  end

  @doc """

  Returns the list with the dates of the holiday given by the function `holiday`.

  """
  def dates_of_holiday(holiday) do
    holiday_dates()
    |> Enum.filter(&(Enum.at(&1, 0) == holiday))
    |> Enum.at(0)
    |> Enum.drop(2)
  end

end