defmodule Cepis.Health do
  @moduledoc """
  The response of `GET /health`.

  Good for two things: checking that the API answers, and knowing **which
  version of the database** is live. The DNE database changes every two weeks;
  `dne` identifies it.
  """

  defstruct status: "", dne: "", ceps: 0, geo: 0, base_gerada_em: ""

  @type t :: %__MODULE__{
          status: String.t(),
          dne: String.t(),
          ceps: non_neg_integer(),
          geo: non_neg_integer(),
          base_gerada_em: String.t()
        }

  @doc """
  `true` when the API reports itself healthy.
  """
  @spec ok?(t()) :: boolean()
  def ok?(%__MODULE__{status: status}), do: status == "ok"

  @doc false
  @spec from_map(map()) :: t()
  def from_map(data) when is_map(data) do
    %__MODULE__{
      status: text(data, "status"),
      dne: text(data, "dne"),
      ceps: count(data, "ceps"),
      geo: count(data, "geo"),
      base_gerada_em: text(data, "base_gerada_em")
    }
  end

  defp text(data, key) do
    case Map.get(data, key) do
      value when is_binary(value) -> value
      value when is_number(value) -> to_string(value)
      _ -> ""
    end
  end

  defp count(data, key) do
    case Map.get(data, key) do
      value when is_integer(value) ->
        value

      value when is_float(value) ->
        trunc(value)

      value when is_binary(value) ->
        case Integer.parse(value) do
          {number, _} -> number
          :error -> 0
        end

      _ ->
        0
    end
  end
end