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feat: add OpenTripPlanner client based on dotcom code
1 parent f19e785 commit f70d280

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‎config/config.exs‎

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@@ -51,6 +51,8 @@ config :logger, :console,
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# Use Jason for JSON parsing in Phoenix
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config :phoenix, :json_library, Jason
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config :mobile_app_backend, timezone: "America/New_York"
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# Import environment specific config. This must remain at the bottom
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# of this file so it overrides the configuration defined above.
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import_config "#{config_env()}.exs"

‎lib/open_trip_planner_client.ex‎

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defmodule OpenTripPlannerClient do
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@moduledoc """
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Fetches data from the OpenTripPlanner API.
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## Configuration
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```elixir
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config :mobile_app_backend,
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otp_url: "http://localhost:8080",
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timezone: "America/New_York"
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```
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"""
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require Logger
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alias OpenTripPlannerClient.{Itinerary, ItineraryTag, NamedPosition, ParamsBuilder, Parser}
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@behaviour OpenTripPlannerClient.Behaviour
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@type error :: OpenTripPlannerClient.Behaviour.error()
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@type plan_opt :: OpenTripPlannerClient.Behaviour.plan_opt()
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@impl true
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@doc """
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Generate a trip plan with the given endpoints and options.
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"""
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@spec plan(NamedPosition.t(), NamedPosition.t(), [plan_opt()]) ::
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{:ok, Itinerary.t()} | {:error, error()}
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def plan(from, to, opts) do
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accessible? = Keyword.get(opts, :wheelchair_accessible?, false)
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{postprocess_opts, opts} = Keyword.split(opts, [:tags])
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with {:ok, params} <- ParamsBuilder.build_params(from, to, opts) do
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param_string = Enum.map_join(params, "\n", fn {key, val} -> ~s{#{key}: #{val}} end)
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graphql_query = """
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{
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plan(
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#{param_string}
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)
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#{itinerary_shape()}
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}
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"""
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root_url =
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Keyword.get(opts, :root_url, Application.fetch_env!(:mobile_app_backend, :otp_url))
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graphql_url = "#{root_url}/otp/routers/default/index/"
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with {:ok, body} <- send_request(graphql_url, graphql_query),
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{:ok, itineraries} <- Parser.parse_ql(body, accessible?) do
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tags = Keyword.get(postprocess_opts, :tags, [])
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result =
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Enum.reduce(tags, itineraries, fn tag, itineraries ->
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ItineraryTag.apply_tag(tag, itineraries)
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end)
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{:ok, result}
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end
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end
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end
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defp send_request(url, query) do
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with {:ok, response} <- log_response(url, query),
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%{status: 200, body: body} <- response do
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{:ok, body}
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else
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%{status: _} = response ->
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{:error, response}
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error ->
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error
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end
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end
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defp log_response(url, query) do
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graphql_req =
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Req.new(base_url: url)
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|> AbsintheClient.attach()
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{duration, response} =
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:timer.tc(
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Req,
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:post,
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[graphql_req, [graphql: query]]
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)
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_ =
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Logger.info(fn ->
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"#{__MODULE__}.plan_response url=#{url} query=#{inspect(query)} #{status_text(response)} duration=#{duration / :timer.seconds(1)}"
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end)
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response
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end
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defp status_text({:ok, %{status: code}}) do
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"status=#{code}"
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end
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defp status_text({:error, error}) do
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"status=error error=#{inspect(error)}"
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end
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defp itinerary_shape do
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"""
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{
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routingErrors {
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code
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description
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}
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itineraries {
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accessibilityScore
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startTime
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endTime
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duration
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legs {
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mode
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startTime
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endTime
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distance
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duration
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intermediateStops {
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id
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gtfsId
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name
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desc
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lat
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lon
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code
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locationType
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}
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transitLeg
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headsign
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realTime
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realtimeState
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agency {
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id
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gtfsId
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name
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}
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alerts {
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id
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alertHeaderText
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alertDescriptionText
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}
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fareProducts {
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id
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product {
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id
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name
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riderCategory {
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id
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name
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}
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}
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}
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from {
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name
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lat
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lon
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departureTime
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arrivalTime
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stop {
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gtfsId
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}
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}
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to {
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name
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lat
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lon
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departureTime
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arrivalTime
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stop {
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gtfsId
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}
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}
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route {
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gtfsId
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longName
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shortName
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desc
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color
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textColor
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}
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trip {
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gtfsId
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}
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steps {
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distance
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streetName
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lat
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lon
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relativeDirection
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stayOn
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}
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legGeometry {
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points
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}
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}
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}
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}
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"""
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end
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end

‎lib/open_trip_planner_client/behaviour.ex‎

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defmodule OpenTripPlannerClient.Behaviour do
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@moduledoc """
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A behaviour that specifies the API for the `OpenTripPlannerClient`.
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May be useful for testing with libraries like [Mox](https://hex.pm/packages/mox).
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"""
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alias OpenTripPlannerClient.{Itinerary, ItineraryTag, NamedPosition}
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@type plan_opt ::
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{:arrive_by, DateTime.t()}
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| {:depart_at, DateTime.t()}
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| {:wheelchair_accessible?, boolean}
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| {:optimize_for, :less_walking | :fewest_transfers}
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| {:tags, [ItineraryTag.t()]}
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@type error ::
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:outside_bounds
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| :timeout
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| :no_transit_times
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| :too_close
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| :location_not_accessible
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| :path_not_found
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| :unknown
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@callback plan(from :: NamedPosition.t(), to :: NamedPosition.t(), opts :: [plan_opt()]) ::
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{:ok, Itinerary.t()} | {:error, error()}
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end

‎lib/open_trip_planner_client/itinerary.ex‎

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defmodule OpenTripPlannerClient.Itinerary do
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@moduledoc """
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A trip at a particular time.
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An Itinerary is a single trip, with the legs being the different types of
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travel. Itineraries are separate even if they use the same modes but happen
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at different times of day.
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"""
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alias OpenTripPlannerClient.Leg
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@enforce_keys [:start, :stop]
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defstruct [
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:start,
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:stop,
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legs: [],
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accessible?: false,
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tags: MapSet.new()
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]
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@type t :: %__MODULE__{
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start: DateTime.t(),
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stop: DateTime.t(),
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legs: [Leg.t()],
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accessible?: boolean,
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tags: MapSet.t(atom())
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}
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@doc "Gets the time in seconds between the start and stop of the itinerary."
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@spec duration(t()) :: integer()
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def duration(%__MODULE__{start: start, stop: stop}) do
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DateTime.diff(stop, start, :second)
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end
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@doc "Total walking distance over all legs, in meters"
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@spec walking_distance(t) :: float
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def walking_distance(itinerary) do
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itinerary
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|> Enum.map(&Leg.walking_distance/1)
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|> Enum.sum()
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end
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@doc "Determines if two itineraries represent the same sequence of legs at the same time"
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@spec same_itinerary?(t, t) :: boolean
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def same_itinerary?(itinerary_1, itinerary_2) do
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itinerary_1.start == itinerary_2.start && itinerary_1.stop == itinerary_2.stop &&
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same_legs?(itinerary_2, itinerary_2)
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end
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@spec same_legs?(t, t) :: boolean
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defp same_legs?(%__MODULE__{legs: legs_1}, %__MODULE__{legs: legs_2}) do
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Enum.count(legs_1) == Enum.count(legs_2) &&
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legs_1 |> Enum.zip(legs_2) |> Enum.all?(fn {l1, l2} -> Leg.same_leg?(l1, l2) end)
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end
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defimpl Enumerable do
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alias OpenTripPlannerClient.Leg
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def count(%@for{legs: legs}) do
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Enumerable.count(legs)
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end
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def member?(%@for{legs: legs}, element) do
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Enumerable.member?(legs, element)
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end
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def reduce(%@for{legs: legs}, acc, fun) do
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Enumerable.reduce(legs, acc, fun)
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end
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def slice(%@for{legs: legs}) do
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Enumerable.slice(legs)
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end
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end
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end

‎lib/open_trip_planner_client/itinerary_tag.ex‎

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defmodule OpenTripPlannerClient.ItineraryTag do
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@moduledoc """
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Logic for a tag which can be applied to itineraries which are the best by some criterion.
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"""
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alias OpenTripPlannerClient.Itinerary
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@callback optimal :: :max | :min
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@callback score(Itinerary.t()) :: number() | nil
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@callback tag :: atom()
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@type t :: module()
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@doc """
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Applies the tag defined by the given module to the itinerary with the optimal score.
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If multiple itineraries are optimal, they will each get the tag.
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If all itineraries have a score of nil, nothing gets the tag.
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"""
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@spec apply_tag(t(), [Itinerary.t()]) :: [Itinerary.t()]
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def apply_tag(tag_module, itineraries) do
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scores = itineraries |> Enum.map(&tag_module.score/1)
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{min_score, max_score} = Enum.min_max(scores |> Enum.reject(&is_nil/1), fn -> {nil, nil} end)
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best_score =
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case tag_module.optimal() do
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:max -> max_score
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:min -> min_score
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end
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Enum.zip(itineraries, scores)
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|> Enum.map(fn {itinerary, score} ->
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if not is_nil(score) and score == best_score do
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update_in(itinerary.tags, &MapSet.put(&1, tag_module.tag()))
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else
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itinerary
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end
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end)
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end
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end

‎lib/open_trip_planner_client/itinerary_tag/earliest_arrival.ex‎

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defmodule OpenTripPlannerClient.ItineraryTag.EarliestArrival do
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@moduledoc false
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@behaviour OpenTripPlannerClient.ItineraryTag
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alias OpenTripPlannerClient.Itinerary
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@impl OpenTripPlannerClient.ItineraryTag
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def optimal, do: :min
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@impl OpenTripPlannerClient.ItineraryTag
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def score(%Itinerary{} = itinerary) do
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itinerary.stop |> DateTime.to_unix()
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end
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@impl OpenTripPlannerClient.ItineraryTag
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def tag, do: :earliest_arrival
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end

‎lib/open_trip_planner_client/itinerary_tag/least_walking.ex‎

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defmodule OpenTripPlannerClient.ItineraryTag.LeastWalking do
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@moduledoc false
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@behaviour OpenTripPlannerClient.ItineraryTag
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alias OpenTripPlannerClient.Itinerary
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@impl OpenTripPlannerClient.ItineraryTag
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def optimal, do: :min
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@impl OpenTripPlannerClient.ItineraryTag
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def score(%Itinerary{} = itinerary) do
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Itinerary.walking_distance(itinerary)
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end
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@impl OpenTripPlannerClient.ItineraryTag
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def tag, do: :least_walking
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end

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