Fix day_of_week and add tests for it

Author: alisinabh

lib/jalaali.ex

@@ -7,6 +7,8 @@ defmodule Jalaali do
   """
 
   @days_offset 1721060
+  @breaks [-61, 9, 38, 199, 426, 686, 756, 818, 1111, 1181, 1210, 1635, 2060,
+          2097, 2192, 2262, 2324, 2394, 2456, 3178]
 
   @doc """
   Converts an erlang date from Gregorian to Jalaali date in erlang format
@@ -204,16 +206,13 @@ defmodule Jalaali do
   """
   @spec jal_cal(Integer.t) :: Map.t
   def jal_cal(jy) do
-    breaks = [-61, 9, 38, 199, 426, 686, 756, 818, 1111, 1181, 1210, 1635, 2060, 2097, 2192, 2262, 2324,
-                  2394, 2456,
-                  3178]
     gy = jy + 621
 
     if jy < -61 or jy >= 3178 do
       raise "Invalid Jalaali year #{jy}"
     end
 
-    {jump, jp, leap_j} = calc_jlimit(breaks, jy, {Enum.at(breaks, 0), -14}, 1)
+    {jump, jp, leap_j} = calc_jlimit(jy, {Enum.at(@breaks, 0), -14}, 1)
 
     n = jy - jp
 
@@ -246,15 +245,15 @@ defmodule Jalaali do
     %{leap: leap, gy: gy, march: march}
   end
 
-  @spec calc_jlimit(List.t, Integer.t, {Integer.t, Integer.t}, Integer.t) :: {Integer.t, Integer.t, Integer.t}
-  defp calc_jlimit(breaks, jy, {jp, leap_j}, index) do
-    jm = Enum.at(breaks, index)
+  @spec calc_jlimit(Integer.t, {Integer.t, Integer.t}, Integer.t) :: {Integer.t, Integer.t, Integer.t}
+  defp calc_jlimit(jy, {jp, leap_j}, index) do
+    jm = Enum.at(@breaks, index)
     jump = jm - jp
     cond do
       jy < jm ->
         {jump, jp, leap_j}
       true ->
-        calc_jlimit(breaks, jy, {jm, leap_j + div(jump, 33) * 8 + div(mod(jump, 33), 4)}, index + 1)
+        calc_jlimit(jy, {jm, leap_j + div(jump, 33) * 8 + div(mod(jump, 33), 4)}, index + 1)
     end
   end
 
@@ -279,21 +278,21 @@ defmodule Jalaali do
 
         jm = 7 + div(k, 30)
         jd = mod(k, 30) + 1
-        {jy, jm, jd} # HACK: remove duplication
+        {jy, jm, jd}
       r.leap == 1 ->
         jy = jy - 1
         k = k + 180
 
         jm = 7 + div(k, 30)
         jd = mod(k, 30) + 1
-        {jy, jm, jd} # HACK: remove duplication
+        {jy, jm, jd}
       true ->
         jy = jy - 1
         k = k + 179
 
         jm = 7 + div(k, 30)
         jd = mod(k, 30) + 1
-        {jy, jm, jd} # HACK: remove duplication
+        {jy, jm, jd}
     end
   end
 

lib/jalaali/calendar.ex

@@ -8,6 +8,11 @@ defmodule Jalaali.Calendar do
   @type year :: 0..9999
   @type month :: 1..12
   @type day :: 1..31
+  @type day_of_week :: 1..7
+  @type hour :: 0..23
+  @type minute :: 0..59
+  @type second :: 0..60
+  @type microsecond :: Integer.t
 
   @seconds_per_minute 60
   @seconds_per_hour 60 * 60
@@ -25,17 +30,32 @@ defmodule Jalaali.Calendar do
     Jalaali.is_leap_jalaali_year(year)
 
   @impl true
-  def day_of_week(year, month, day), do:
-    Calendar.ISO.day_of_week(year, month, day)
+  @spec day_of_week(year, month, day) :: day_of_week
+  @doc """
+  Returns day of week on a spesific set of year, month and day
+  """
+  def day_of_week(year, month, day) do
+    {:ok, date} = Date.new(year, month, day, __MODULE__)
+    iso_date = Date.convert!(date, Calendar.ISO)
+    Calendar.ISO.day_of_week(iso_date.year, iso_date.month, iso_date.day)
+  end
 
   @doc """
   Converts the given date into a string.
   """
   @impl true
+  @spec date_to_string(year, month, day) :: String.t
   def date_to_string(year, month, day) do
     zero_pad(year, 4) <> "-" <> zero_pad(month, 2) <> "-" <> zero_pad(day, 2)
   end
 
+  @doc """
+  Converts a Date struct to string human readable format
+
+   - Extended type of string date. e.g.: "2017-01-05" `:extended`
+   - Basic type of string date. e.g.: "20170105" `:basic`
+  """
+  @spec date_to_string(year, month, day, :extended | :basic) :: String.t
   def date_to_string(year, month, day, :extended), do:
     date_to_string(year, month, day)
 
@@ -44,15 +64,16 @@ defmodule Jalaali.Calendar do
   end
 
   @doc """
-  Converts the datetime (without time zone) into a string.
+  Converts the datetime (without time zone) into a human readable string.
   """
   @impl true
+  @spec naive_datetime_to_string(year, month, day, hour, minute, second, microsecond) :: String.t
   def naive_datetime_to_string(year, month, day, hour, minute, second, microsecond) do
    date_to_string(year, month, day) <> " " <> time_to_string(hour, minute, second, microsecond)
   end
 
   @doc """
-  Convers the datetime (with time zone) into a string.
+  Convers the datetime (with time zone) into a human readable string.
   """
   @impl true
   def datetime_to_string(year, month, day, hour, minute, second, microsecond,

mix.exs

@@ -1,7 +1,7 @@
 defmodule Jalaali.Mixfile do
   use Mix.Project
 
-  @version "0.2.0"
+  @version "0.2.1"
 
   def project do
     [app: :jalaali,

test/jalaali_test.exs

@@ -56,4 +56,35 @@ defmodule JalaaliTest do
 
     assert gre_to_jal == now_jal
   end
+
+  test "Day number" do
+    now = DateTime.utc_now()
+    jal_now = DateTime.convert!(now, Jalaali.Calendar)
+
+    assert Date.day_of_week(now) == Date.day_of_week(jal_now)
+  end
+
+  test "Day number in hundred days" do
+    unix = DateTime.to_unix(DateTime.utc_now()) + 100 * 24 * 60 * 60
+
+    now = DateTime.from_unix!(unix)
+    jal_date = DateTime.convert!(now, Jalaali.Calendar)
+
+    assert Date.day_of_week(now) == Date.day_of_week(jal_date)
+  end
+
+  test "Day number in hundred days ago" do
+    unix = DateTime.to_unix(DateTime.utc_now()) - 100 * 24 * 60 * 60
+
+    now = DateTime.from_unix!(unix)
+    jal_date = DateTime.convert!(now, Jalaali.Calendar)
+
+    assert Date.day_of_week(now) == Date.day_of_week(jal_date)
+  end
+
+  test "Day number on a specific date" do
+    {:ok, now} = Date.new(1321, 7, 7, Jalaali.Calendar)
+
+    assert Date.day_of_week(now) == 2
+  end
 end