feat: Search endpoint

.github/workflows/ci.yml

@@ -88,7 +88,7 @@ jobs:
       - name: Check formatting
         run: mix format --check-formatted
       - name: Run tests
-        run: source envrc.example && mix test --cover
+        run: mix test --cover
       - name: Report test coverage
         uses: mbta/github-actions-report-lcov@v1
         with:

.gitignore

@@ -35,3 +35,6 @@ mobile_app_backend-*.tar
 npm-debug.log
 /assets/node_modules/
 
+# Local environment configuration
+.envrc
+

config/config.exs

@@ -21,6 +21,10 @@ config :mobile_app_backend, MobileAppBackendWeb.Endpoint,
   pubsub_server: MobileAppBackend.PubSub,
   live_view: [signing_salt: "EPNVgKKu"]
 
+config :mobile_app_backend, MobileAppBackend.Search.Algolia,
+  route_index: "routes_test",
+  stop_index: "stops_test"
+
 # Configure esbuild (the version is required)
 config :esbuild,
   version: "0.17.11",

config/runtime.exs

@@ -7,10 +7,17 @@ import Config
 # any compile-time configuration in here, as it won't be applied.
 # The block below contains prod specific runtime configuration.
 
-# mbta_v3_api configuration in disguise
-config :mobile_app_backend,
-  base_url: System.get_env("API_URL"),
-  api_key: System.get_env("API_KEY")
+if config_env() != :test do
+  # mbta_v3_api configuration in disguise
+  config :mobile_app_backend,
+    base_url: System.get_env("API_URL"),
+    api_key: System.get_env("API_KEY")
+
+  config :mobile_app_backend, MobileAppBackend.Search.Algolia,
+    app_id: System.get_env("ALGOLIA_APP_ID"),
+    search_key: System.get_env("ALGOLIA_SEARCH_KEY"),
+    base_url: System.get_env("ALGOLIA_READ_URL")
+end
 
 # ## Using releases
 #

config/test.exs

@@ -12,3 +12,11 @@ config :logger, level: :warning
 
 # Initialize plugs at runtime for faster test compilation
 config :phoenix, :plug_init_mode, :runtime
+
+config :mobile_app_backend,
+  base_url: "https://api-dev.mbtace.com/"
+
+config :mobile_app_backend, MobileAppBackend.Search.Algolia,
+  app_id: "fake_app",
+  search_key: "fake_key",
+  base_url: "fake_url"

envrc.template

@@ -0,0 +1,12 @@
+# Configuration for the [MBTA v3 API](https://github.com/mbta/api) 
+# Used for reading static and realtime GTFS data
+export API_URL=https://api-dev.mbtace.com/
+export API_KEY=
+
+
+# Configuration for [Alglolia](https://www.algolia.com/doc/rest-api/search/)
+# Used to power search bar
+export ALGOLIA_APP_ID=
+export ALGOLIA_SEARCH_KEY=
+export ALGOLIA_READ_URL=
+

lib/mobile_app_backend/search/algolia/api.ex

@@ -0,0 +1,101 @@
+defmodule MobileAppBackend.Search.Algolia.Api do
+  @moduledoc """
+  Client for the Algolia API.
+  See https://www.algolia.com/doc/rest-api/search/
+  Relies on configuration from :mobile_app_backend, MobileAppBackend.Search.Algolia
+  """
+  @algolia_api_version 1
+  alias MobileAppBackend.Search.Algolia
+  require Logger
+
+  @spec multi_index_search([Algolia.QueryPayload.t()]) ::
+          {:ok, [any()]} | {:error, any}
+  @doc """
+  Perform the given index queries and return a flattened list of parsed results
+  """
+  def multi_index_search(queries) do
+    perform_request_fn =
+      Application.get_env(
+        :mobile_app_backend,
+        :algolia_perform_request_fn,
+        &make_request/3
+      )
+
+    body = multi_query_encoded_payload(queries)
+
+    with {:ok, url} <- multi_index_url(),
+         {:ok, headers} <- headers(),
+         {:ok, response} <- perform_request_fn.(url, body, headers) do
+      parse_results(response.body)
+    else
+      error ->
+        Logger.error("#{__MODULE__} search_failed. reason=#{inspect(error)}")
+        {:error, :search_failed}
+    end
+  end
+
+  defp make_request(url, body, headers) do
+    Req.post(url, body: body, headers: headers)
+  end
+
+  defp parse_results(%{"results" => results_per_index}) do
+    {:ok,
+     Enum.flat_map(results_per_index, fn index_results ->
+       hits = index_results["hits"]
+
+       cond do
+         index_results["index"] === Algolia.Index.index_name(:route) ->
+           Enum.map(hits, &Algolia.RouteResult.parse(&1))
+
+         index_results["index"] === Algolia.Index.index_name(:stop) ->
+           Enum.map(hits, &Algolia.StopResult.parse(&1))
+
+         true ->
+           []
+       end
+     end)}
+  end
+
+  defp parse_results(_bad_format) do
+    {:error, :malformed_results}
+  end
+
+  defp multi_query_encoded_payload(queries) do
+    encoded_query_payloads = Enum.map(queries, &encode_query_payload/1)
+
+    Jason.encode!(%{
+      "requests" => encoded_query_payloads
+    })
+  end
+
+  defp encode_query_payload(query) do
+    %{
+      "indexName" => query.index_name,
+      "params" => URI.encode_query(query.params)
+    }
+  end
+
+  defp multi_index_url do
+    case Application.get_env(:mobile_app_backend, MobileAppBackend.Search.Algolia)[:base_url] do
+      nil -> {:error, :base_url_not_configured}
+      base_url -> {:ok, Path.join(base_url, "#{@algolia_api_version}/indexes/*/queries")}
+    end
+  end
+
+  @spec headers :: {:ok, [{String.t(), String.t()}]} | {:error, any}
+  defp headers do
+    config = Application.get_env(:mobile_app_backend, MobileAppBackend.Search.Algolia)
+    app_id = config[:app_id]
+    search_key = config[:search_key]
+
+    if is_nil(app_id) || is_nil(search_key) do
+      {:error, :missing_algolia_config}
+    else
+      {:ok,
+       [
+         {"X-Algolia-API-Key", search_key},
+         {"X-Algolia-Application-Id", app_id}
+       ]}
+    end
+  end
+end

lib/mobile_app_backend/search/algolia/index.ex

@@ -0,0 +1,13 @@
+defmodule MobileAppBackend.Search.Algolia.Index do
+  @spec index_name(:stop | :route) :: String.t() | nil
+  @doc """
+  Get the name of the Algolia index to query for the given data type
+  """
+  def index_name(:stop) do
+    Application.get_env(:mobile_app_backend, MobileAppBackend.Search.Algolia)[:stop_index]
+  end
+
+  def index_name(:route) do
+    Application.get_env(:mobile_app_backend, MobileAppBackend.Search.Algolia)[:route_index]
+  end
+end

lib/mobile_app_backend/search/algolia/query_payload.ex

@@ -0,0 +1,51 @@
+defmodule MobileAppBackend.Search.Algolia.QueryPayload do
+  @moduledoc """
+  The data expected by Algolia for search queries.
+  """
+  alias MobileAppBackend.Search.Algolia
+  @type supported_index :: :stop | :route
+
+  @type t :: %__MODULE__{
+          index_name: String.t(),
+          params: map()
+        }
+
+  @default_params %{"hitsPerPage" => 5, "clickAnalytics" => true}
+
+  defstruct index_name: "",
+            params: %{}
+
+  @spec for_index(supported_index, String.t()) :: t()
+  def for_index(:route, query) do
+    Algolia.Index.index_name(:route)
+    |> new(query)
+    |> with_hit_size(5)
+  end
+
+  def for_index(:stop, query) do
+    Algolia.Index.index_name(:stop)
+    |> new(query)
+    |> with_hit_size(2)
+  end
+
+  defp new(index_name, query) do
+    track_analytics? =
+      Application.get_env(:mobile_app_backend, MobileAppBackend.Search.Algolia)[:track_analytics?] ||
+        false
+
+    %__MODULE__{
+      index_name: index_name,
+      params:
+        @default_params
+        |> Map.put("analytics", track_analytics?)
+        |> Map.put("query", query)
+    }
+  end
+
+  defp with_hit_size(query_payload, hitSize) do
+    %__MODULE__{
+      query_payload
+      | params: Map.put(query_payload.params, "hitsPerPage", hitSize)
+    }
+  end
+end

lib/mobile_app_backend/search/algolia/route_result.ex

@@ -0,0 +1,29 @@
+defmodule MobileAppBackend.Search.Algolia.RouteResult do
+  @moduledoc """
+  Data returned by Algolia for route search hits
+  """
+  @derive Jason.Encoder
+
+  @type t :: %__MODULE__{
+          type: :route,
+          id: String.t(),
+          name: String.t(),
+          long_name: String.t(),
+          route_type: number(),
+          rank: number()
+        }
+
+  defstruct [:type, :id, :name, :long_name, :route_type, :rank]
+
+  @spec parse(map()) :: t()
+  def parse(result_response) do
+    %__MODULE__{
+      type: :route,
+      id: result_response["route"]["id"],
+      name: result_response["route"]["name"],
+      long_name: result_response["route"]["long_name"],
+      route_type: result_response["route"]["type"],
+      rank: result_response["rank"]
+    }
+  end
+end

lib/mobile_app_backend/search/algolia/stop_result.ex

@@ -0,0 +1,31 @@
+defmodule MobileAppBackend.Search.Algolia.StopResult do
+  @moduledoc """
+  Data returned by Algolia for stop search hits
+  """
+  @derive Jason.Encoder
+
+  @type t :: %__MODULE__{
+          type: :stop,
+          id: String.t(),
+          name: String.t(),
+          rank: number(),
+          zone: String.t() | nil,
+          station?: boolean(),
+          routes: [%{type: number(), icon: String.t()}]
+        }
+
+  defstruct [:type, :id, :name, :rank, :zone, :station?, :routes]
+
+  @spec parse(map()) :: t()
+  def parse(result_response) do
+    %__MODULE__{
+      type: :stop,
+      id: result_response["stop"]["id"],
+      name: result_response["stop"]["name"],
+      rank: result_response["rank"],
+      zone: result_response["stop"]["zone"],
+      station?: result_response["stop"]["station?"],
+      routes: Enum.map(result_response["routes"], &%{type: &1["type"], icon: &1["icon"]})
+    }
+  end
+end

lib/mobile_app_backend_web/controllers/search_controller.ex

@@ -0,0 +1,36 @@
+defmodule MobileAppBackendWeb.SearchController do
+  @moduledoc false
+  use MobileAppBackendWeb, :controller
+  alias MobileAppBackend.Search.Algolia
+
+  alias Plug.Conn
+
+  @spec query(Conn.t(), map) :: Conn.t()
+  def query(%Conn{} = conn, %{"query" => ""}) do
+    json(conn, %{data: []})
+  end
+
+  def query(%Conn{} = conn, %{"query" => query}) do
+    queries = [
+      Algolia.QueryPayload.for_index(:route, query),
+      Algolia.QueryPayload.for_index(:stop, query)
+    ]
+
+    algolia_query_fn =
+      Application.get_env(
+        :mobile_app_backend,
+        :algolia_multi_index_search_fn,
+        &Algolia.Api.multi_index_search/1
+      )
+
+    case algolia_query_fn.(queries) do
+      {:ok, response} ->
+        json(conn, %{data: response})
+
+      {:error, _error} ->
+        conn
+        |> put_status(:internal_server_error)
+        |> json(%{error: "search_failed"})
+    end
+  end
+end

lib/mobile_app_backend_web/router.ex

@@ -27,8 +27,8 @@ defmodule MobileAppBackendWeb.Router do
   # Other scopes may use custom stacks.
   scope "/api", MobileAppBackendWeb do
     pipe_through :api
-
     get("/nearby", NearbyController, :show)
+    get("/search/query", SearchController, :query)
   end
 
   # Enable LiveDashboard in development