mobilizon/lib/service/geospatial/nominatim.ex

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Elixir
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defmodule Mobilizon.Service.Geospatial.Nominatim do
@moduledoc """
[Nominatim](https://wiki.openstreetmap.org/wiki/Nominatim) backend.
"""
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alias Mobilizon.Addresses.Address
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alias Mobilizon.Service.Geospatial.Provider
alias Mobilizon.Service.HTTP.GeospatialClient
import Mobilizon.Service.Geospatial.Provider, only: [endpoint: 1]
require Logger
@behaviour Provider
@impl Provider
@doc """
Nominatim implementation for `c:Mobilizon.Service.Geospatial.Provider.geocode/3`.
"""
@spec geocode(String.t(), keyword()) :: list(Address.t())
def geocode(lon, lat, options \\ []) do
:geocode
|> build_url(%{lon: lon, lat: lat}, options)
|> fetch_features
end
@impl Provider
@doc """
Nominatim implementation for `c:Mobilizon.Service.Geospatial.Provider.search/2`.
"""
@spec search(String.t(), keyword()) :: list(Address.t())
def search(q, options \\ []) do
:search
|> build_url(%{q: q}, options)
|> fetch_features
end
@spec build_url(atom(), map(), list()) :: String.t()
defp build_url(method, args, options) do
limit = Keyword.get(options, :limit, 10)
lang = Keyword.get(options, :lang, "en")
endpoint = Keyword.get(options, :endpoint, endpoint(__MODULE__))
url =
case method do
:search ->
"#{endpoint}/search?format=geocodejson&q=#{URI.encode(args.q)}&limit=#{limit}&accept-language=#{lang}&addressdetails=1&namedetails=1"
:geocode ->
"#{endpoint}/reverse?format=geocodejson&lat=#{args.lat}&lon=#{args.lon}&accept-language=#{lang}&addressdetails=1&namedetails=1"
|> add_parameter(options, :zoom)
end
url
|> add_parameter(options, :country_code)
|> add_parameter(options, :api_key, api_key())
end
@spec fetch_features(String.t()) :: list(Address.t())
defp fetch_features(url) do
Logger.debug("Asking Nominatim with #{url}")
with {:ok, %{status: 200, body: body}} <- GeospatialClient.get(url),
%{"features" => features} <- body do
features |> process_data |> Enum.filter(& &1)
else
_ ->
Logger.error("Asking Nominatim with #{url}")
[]
end
end
defp process_data(features) do
features
|> Enum.map(fn %{
"geometry" => %{"coordinates" => coordinates},
"properties" => %{"geocoding" => geocoding}
} ->
address = process_address(geocoding)
%Address{address | geom: Provider.coordinates(coordinates)}
end)
end
defp process_address(geocoding) do
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%Address{
country: Map.get(geocoding, "country"),
locality:
Map.get(geocoding, "city") || Map.get(geocoding, "town") || Map.get(geocoding, "county"),
region: Map.get(geocoding, "state"),
description: description(geocoding),
postal_code: Map.get(geocoding, "postcode"),
type: Map.get(geocoding, "type"),
street: street_address(geocoding),
origin_id: "nominatim:" <> to_string(Map.get(geocoding, "osm_id"))
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}
end
@spec street_address(map()) :: String.t()
defp street_address(body) do
road =
cond do
Map.has_key?(body, "road") ->
Map.get(body, "road")
Map.has_key?(body, "street") ->
Map.get(body, "street")
Map.has_key?(body, "pedestrian") ->
Map.get(body, "pedestrian")
true ->
""
end
Map.get(body, "housenumber", "") <> " " <> road
end
@address29_classes ["amenity", "shop", "tourism", "leisure"]
@address29_categories ["office"]
@spec description(map()) :: String.t()
defp description(body) do
description = Map.get(body, "name")
address = Map.get(body, "address")
description =
if Map.has_key?(body, "namedetails"),
do: body |> Map.get("namedetails") |> Map.get("name", description),
else: description
description = if is_nil(description), do: street_address(body), else: description
if (Map.get(body, "category") in @address29_categories or
Map.get(body, "class") in @address29_classes) and Map.has_key?(address, "address29") do
Map.get(address, "address29")
else
description
end
end
@spec add_parameter(String.t(), Keyword.t(), atom()) :: String.t()
defp add_parameter(url, options, key, default \\ nil) do
value = Keyword.get(options, key, default)
if is_nil(value), do: url, else: do_add_parameter(url, key, value)
end
@spec do_add_parameter(String.t(), atom(), any()) :: String.t()
defp do_add_parameter(url, :zoom, zoom),
do: "#{url}&zoom=#{zoom}"
@spec do_add_parameter(String.t(), atom(), any()) :: String.t()
defp do_add_parameter(url, :country_code, country_code),
do: "#{url}&countrycodes=#{country_code}"
@spec do_add_parameter(String.t(), atom(), any()) :: String.t()
defp do_add_parameter(url, :api_key, api_key),
do: "#{url}&key=#{api_key}"
defp api_key do
Application.get_env(:mobilizon, __MODULE__) |> get_in([:api_key])
end
end