feat: allow for a configurable time zone database

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## [0.4.0](https://github.com/hopsor/open_hours/compare/v0.2.0...v0.4.0) (TBD)
+
+* Potentialy breaking chaneg: Make the timezone database configurable ([#41](https://github.com/hopsor/open_hours/pull/41))
+
 ## [0.3.0](https://github.com/hopsor/open_hours/compare/v0.2.0...v0.3.0) (2026-03-27)
 
 

README.md

@@ -13,11 +13,14 @@ The package can be installed by adding `open_hours` to your list of dependencies
 ```elixir
 def deps do
   [
-    {:open_hours, "~> 0.2.0"}
+    {:open_hours, "~> 0.4.0"}
   ]
 end
 ```
 
+If you do not already have a timezone database (eg tz or tzdata) configured for your Elixir application
+you will also need to do that. We recommend [TZ](https://tz.hexdocs.pm/readme.html)
+
 ## Usage
 
 In order to use OpenHours functions you first need a `Schedule` config:

lib/open_hours/offset.ex

@@ -98,7 +98,7 @@ defmodule OpenHours.Offset do
         duration
       )
       when schedule_tz != dt_tz do
-    {:ok, shifted} = DateTime.shift_zone(dt, schedule_tz, Tzdata.TimeZoneDatabase)
+    {:ok, shifted} = DateTime.shift_zone(dt, schedule_tz, OpenHours.TimeZoneDatabase.database())
     shift(schedule, shifted, duration)
   end
 
@@ -142,7 +142,7 @@ defmodule OpenHours.Offset do
     available = DateTime.diff(slot.ends_at, position)
 
     if available >= remaining_seconds do
-      DateTime.add(position, remaining_seconds, :second, Tzdata.TimeZoneDatabase)
+      DateTime.add(position, remaining_seconds, :second, OpenHours.TimeZoneDatabase.database())
     else
       shift_forward(schedule, slot.ends_at, remaining_seconds - available)
     end
@@ -160,7 +160,7 @@ defmodule OpenHours.Offset do
     available = DateTime.diff(position, slot.starts_at)
 
     if available >= remaining_seconds do
-      DateTime.add(position, -remaining_seconds, :second, Tzdata.TimeZoneDatabase)
+      DateTime.add(position, -remaining_seconds, :second, OpenHours.TimeZoneDatabase.database())
     else
       shift_backward(schedule, slot.starts_at, remaining_seconds - available)
     end
@@ -206,7 +206,7 @@ defmodule OpenHours.Offset do
   end
 
   defp snap_to_business_time(schedule, date, time, direction) do
-    dt = DateTime.new!(date, time, schedule.time_zone, Tzdata.TimeZoneDatabase)
+    dt = DateTime.new!(date, time, schedule.time_zone, OpenHours.TimeZoneDatabase.database())
 
     if Schedule.in_hours?(schedule, dt) do
       dt

lib/open_hours/schedule.ex

@@ -94,7 +94,7 @@ defmodule OpenHours.Schedule do
   @spec in_hours?(OpenHours.Schedule.t(), DateTime.t()) :: boolean()
   def in_hours?(%Schedule{time_zone: schedule_tz} = schedule, %DateTime{time_zone: date_tz} = at)
       when schedule_tz != date_tz do
-    {:ok, shifted_at} = DateTime.shift_zone(at, schedule_tz, Tzdata.TimeZoneDatabase)
+    {:ok, shifted_at} = DateTime.shift_zone(at, schedule_tz, OpenHours.TimeZoneDatabase.database())
     in_hours?(schedule, shifted_at)
   end
 

lib/open_hours/time_slot.ex

@@ -25,7 +25,7 @@ defmodule OpenHours.TimeSlot do
         %DateTime{} = ends_at
       )
       when schedule_tz != start_tz do
-    {:ok, shifted_starts_at} = DateTime.shift_zone(starts_at, schedule_tz, Tzdata.TimeZoneDatabase)
+    {:ok, shifted_starts_at} = DateTime.shift_zone(starts_at, schedule_tz, OpenHours.TimeZoneDatabase.database())
     between(schedule, shifted_starts_at, ends_at)
   end
 
@@ -35,7 +35,7 @@ defmodule OpenHours.TimeSlot do
         %DateTime{time_zone: end_tz} = ends_at
       )
       when schedule_tz != end_tz do
-    {:ok, shifted_ends_at} = DateTime.shift_zone(ends_at, schedule_tz, Tzdata.TimeZoneDatabase)
+    {:ok, shifted_ends_at} = DateTime.shift_zone(ends_at, schedule_tz, OpenHours.TimeZoneDatabase.database())
     between(schedule, starts_at, shifted_ends_at)
   end
 
@@ -110,7 +110,7 @@ defmodule OpenHours.TimeSlot do
 
   def stream_next(%Schedule{time_zone: schedule_tz} = schedule, %DateTime{time_zone: dt_tz} = at, opts)
       when schedule_tz != dt_tz do
-    {:ok, shifted} = DateTime.shift_zone(at, schedule_tz, Tzdata.TimeZoneDatabase)
+    {:ok, shifted} = DateTime.shift_zone(at, schedule_tz, OpenHours.TimeZoneDatabase.database())
     stream_next(schedule, shifted, opts)
   end
 
@@ -158,7 +158,7 @@ defmodule OpenHours.TimeSlot do
 
   def stream_previous(%Schedule{time_zone: schedule_tz} = schedule, %DateTime{time_zone: dt_tz} = at, opts)
       when schedule_tz != dt_tz do
-    {:ok, shifted} = DateTime.shift_zone(at, schedule_tz, Tzdata.TimeZoneDatabase)
+    {:ok, shifted} = DateTime.shift_zone(at, schedule_tz, OpenHours.TimeZoneDatabase.database())
     stream_previous(schedule, shifted, opts)
   end
 
@@ -210,8 +210,8 @@ defmodule OpenHours.TimeSlot do
     |> get_intervals_for(day)
     |> Enum.map(fn {interval_start, interval_end} ->
       %TimeSlot{
-        starts_at: DateTime.new!(day, interval_start, schedule.time_zone, Tzdata.TimeZoneDatabase),
-        ends_at: DateTime.new!(day, interval_end, schedule.time_zone, Tzdata.TimeZoneDatabase)
+        starts_at: DateTime.new!(day, interval_start, schedule.time_zone, OpenHours.TimeZoneDatabase.database()),
+        ends_at: DateTime.new!(day, interval_end, schedule.time_zone, OpenHours.TimeZoneDatabase.database())
       }
     end)
   end

lib/open_hours/time_zone_database.ex

@@ -0,0 +1,21 @@
+defmodule OpenHours.TimeZoneDatabase do
+  @moduledoc """
+  Resolves the configured `Calendar.TimeZoneDatabase` implementation.
+
+  By default, the Elixir global time zone database is used (set via
+  `Calendar.put_time_zone_database/1`). You can override this for OpenHours
+  specifically by setting:
+
+      config :open_hours, :time_zone_database, Tz.TimeZoneDatabase
+
+  Any module that implements the `Calendar.TimeZoneDatabase` behaviour can be used.
+  """
+
+  @doc """
+  Returns the configured time zone database module.
+  """
+  @spec database() :: module()
+  def database do
+    Application.get_env(:open_hours, :time_zone_database, Calendar.get_time_zone_database())
+  end
+end

mix.exs

@@ -1,7 +1,7 @@
 defmodule OpenHours.MixProject do
   use Mix.Project
 
-  @version "0.3.0"
+  @version "0.4.0"
 
   def project do
     [
@@ -19,14 +19,15 @@ defmodule OpenHours.MixProject do
   # Run "mix help compile.app" to learn about applications.
   def application do
     [
-      extra_applications: [:logger, :tzdata]
+      extra_applications: [:logger]
     ]
   end
 
   # Run "mix help deps" to learn about dependencies.
   defp deps do
     [
-      {:tzdata, "~> 1.1"},
+      {:tzdata, "~> 1.1", optional: true},
+      {:tz, "~> 0.28", optional: true},
       {:ex_doc, "~> 0.31", only: :dev, runtime: false}
     ]
   end

mix.lock

@@ -14,6 +14,7 @@
   "parse_trans": {:hex, :parse_trans, "3.4.1", "6e6aa8167cb44cc8f39441d05193be6e6f4e7c2946cb2759f015f8c56b76e5ff", [:rebar3], [], "hexpm", "620a406ce75dada827b82e453c19cf06776be266f5a67cff34e1ef2cbb60e49a"},
   "rangex": {:git, "https://github.com/openapi-ro/rangex.git", "a92b03f8f075d73fef1bbbf4b1c088feaff8724b", [tag: "master"]},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.7", "354c321cf377240c7b8716899e182ce4890c5938111a1296add3ec74cf1715df", [:make, :mix, :rebar3], [], "hexpm", "fe4c190e8f37401d30167c8c405eda19469f34577987c76dde613e838bbc67f8"},
+  "tz": {:hex, :tz, "0.28.2", "6c47f3d1a8ee5c33a1d8f0ba49e5a851b0a30c408a587d907aff6e71228b3b32", [:mix], [{:castore, "~> 0.1 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:mint, "~> 1.6", [hex: :mint, repo: "hexpm", optional: true]}], "hexpm", "a6bf7355a33f0a7511602ab4566432ac0901d8abff81e94e455bca19708a0c87"},
   "tzdata": {:hex, :tzdata, "1.1.3", "b1cef7bb6de1de90d4ddc25d33892b32830f907e7fc2fccd1e7e22778ab7dfbc", [:mix], [{:hackney, "~> 1.17", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "d4ca85575a064d29d4e94253ee95912edfb165938743dbf002acdf0dcecb0c28"},
   "unicode_util_compat": {:hex, :unicode_util_compat, "0.7.0", "bc84380c9ab48177092f43ac89e4dfa2c6d62b40b8bd132b1059ecc7232f9a78", [:rebar3], [], "hexpm", "25eee6d67df61960cf6a794239566599b09e17e668d3700247bc498638152521"},
 }

test/test_helper.exs

@@ -1 +1,3 @@
+Application.put_env(:elixir, :time_zone_database, Tz.TimeZoneDatabase)
+
 ExUnit.start()