mobilizon.chapril.org-mobil.../lib/service/timezone_detector.ex

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defmodule Mobilizon.Service.TimezoneDetector do
@moduledoc """
Detect the timezone from a point
"""
@type detectable :: Geo.Point.t() | Geo.PointZ.t() | {float() | float()}
@doc """
Detect the most appropriate timezone from a value, a geographic set of coordinates and a fallback
"""
@spec detect(String.t() | nil, detectable() | nil, String.t()) :: String.t()
def detect(tz, nil, fallback), do: detect(tz, fallback)
def detect(nil, geo, fallback) do
case TzWorld.timezone_at(geo) do
{:ok, timezone} ->
timezone
{:error, :time_zone_not_found} ->
fallback
end
end
def detect(timezone, geo, fallback) do
if Tzdata.zone_exists?(timezone) do
timezone
else
detect(nil, geo, fallback)
end
end
@spec detect(String.t() | nil, String.t()) :: String.t()
def detect(nil, fallback), do: fallback
def detect(timezone, fallback) do
if Tzdata.zone_exists?(timezone) do
timezone
else
fallback
end
end
end