Claudio Ortolina
104 lines
3.7 KiB
Elixir
104 lines
3.7 KiB
Elixir
defmodule Wikipedia.API.ErrorResponse do
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@moduledoc """
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Structured error response for Wikipedia/Wikidata API calls.
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Wikipedia exposes two API surfaces with different error paradigms:
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* **Action API** (`/w/api.php`, used by `get_wikipedia_title/2` and
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`get_article_extract/2`) returns **HTTP 200 with an error in the body**:
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`%{"error" => %{"code" => ..., "info" => ...}}`. Without body inspection
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the error would be silently returned as `{:ok, body}`.
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* **REST v1 API** (`/api/rest_v1/page/summary/:title`, used by
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`get_article_summary/2`) uses classic HTTP status codes.
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`from_response/1` handles classic HTTP errors. `from_action_api_body/2` is a
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dedicated entry point for the HTTP 200 + body-error case.
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## Non-error body shapes
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These are NOT errors and should continue to return `{:ok, body}`:
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* `%{"entities" => %{_id => %{"missing" => ""}}}` from `wbgetentities` —
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the facade converts this to `{:error, :no_english_wikipedia}` at a
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higher level.
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* `get_in(body, ["query", "pages", _, "extract"])` returning `nil` — a
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title exists but has no extract.
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The discriminator for an actual error is the literal top-level `"error"` key
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whose value is a map with both `"code"` and `"info"`.
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"""
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@behaviour MusicLibrary.ErrorResponse
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alias MusicLibrary.HttpError
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alias MusicLibrary.RetryDelay
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@type t :: %__MODULE__{
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status: integer() | nil,
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code: String.t() | nil,
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message: String.t() | nil,
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kind: HttpError.kind(),
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body: term(),
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retry_delay_seconds: pos_integer() | nil
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}
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defstruct [:status, :code, :message, :kind, :body, :retry_delay_seconds]
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@spec from_response(Req.Response.t() | map()) :: t()
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def from_response(%{status: status, body: body} = response) do
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%__MODULE__{
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status: status,
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code: extract_rest_code(body),
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message: extract_rest_message(body),
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kind: HttpError.default_kind(status),
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body: body,
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retry_delay_seconds: RetryDelay.retry_after_seconds(response)
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}
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end
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@spec from_action_api_body(map(), Req.Response.t() | map()) :: t()
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def from_action_api_body(body, response \\ %{})
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def from_action_api_body(%{"error" => %{"code" => code, "info" => info}} = body, response) do
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%__MODULE__{
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status: 200,
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code: code,
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message: info,
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kind: action_api_kind(code),
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body: body,
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retry_delay_seconds: RetryDelay.retry_after_seconds(response)
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}
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end
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@impl MusicLibrary.ErrorResponse
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@spec retryable?(t()) :: boolean()
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def retryable?(%__MODULE__{kind: kind}) when kind in [:rate_limit, :server_error, :timeout],
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do: true
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def retryable?(%__MODULE__{}), do: false
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@impl MusicLibrary.ErrorResponse
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@spec retry_delay_seconds(t()) :: pos_integer()
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def retry_delay_seconds(%__MODULE__{retry_delay_seconds: seconds}) when is_integer(seconds),
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do: seconds
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def retry_delay_seconds(%__MODULE__{kind: :rate_limit}), do: 30
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def retry_delay_seconds(%__MODULE__{kind: :server_error}), do: 30
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def retry_delay_seconds(%__MODULE__{kind: :timeout}), do: 10
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def retry_delay_seconds(%__MODULE__{}), do: 30
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defp action_api_kind("ratelimited"), do: :rate_limit
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defp action_api_kind("maxlag"), do: :rate_limit
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defp action_api_kind("readonly"), do: :server_error
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defp action_api_kind("internal_api_error_" <> _), do: :server_error
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defp action_api_kind(_), do: :client_error
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defp extract_rest_code(%{"httpCode" => code}), do: to_string(code)
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defp extract_rest_code(_), do: nil
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defp extract_rest_message(%{"messageTranslations" => %{"en" => msg}}), do: msg
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defp extract_rest_message(%{"detail" => msg}) when is_binary(msg), do: msg
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defp extract_rest_message(_), do: nil
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end
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