defmodule Polymarket.Schemas.BestBidAskEvent do
  @moduledoc """
  Best bid/ask event.
  """

  use TypedEctoSchema

  alias Polymarket.Schemas.BestBidAskEvent
  alias Polymarket.Schemas.Coerce

  @primary_key false

  @derive Jason.Encoder
  typed_embedded_schema do
    field(:market, :string)
    field(:asset_id, :string)
    field(:best_bid, :float)
    field(:best_ask, :float)
    field(:spread, :float)
    # Unix epoch in milliseconds, delivered as a string (e.g. "1779660673012").
    field(:timestamp, :integer)
    field(:event_type, :string)
  end

  @required [:market, :asset_id, :best_bid, :best_ask, :spread, :timestamp, :event_type]

  @doc """
  Builds a `BestBidAskEvent` from a decoded (atom-keyed) websocket message.

  Constructs the struct directly — no `Ecto.Changeset` — for the websocket hot
  path. Numeric fields (delivered as JSON strings) are coerced via
  `Polymarket.Schemas.Coerce`. Returns `{:error, {:missing_fields, fields}}` when
  a required field is absent.
  """
  @spec from_attrs(map()) :: {:ok, t()} | {:error, {:missing_fields, [atom()]}}
  def from_attrs(attrs) do
    %BestBidAskEvent{
      market: attrs[:market],
      asset_id: attrs[:asset_id],
      best_bid: Coerce.to_float(attrs[:best_bid]),
      best_ask: Coerce.to_float(attrs[:best_ask]),
      spread: Coerce.to_float(attrs[:spread]),
      timestamp: Coerce.to_int(attrs[:timestamp]),
      event_type: attrs[:event_type]
    }
    |> Coerce.require_fields(@required)
  end
end