defmodule TradeMachine.GMGradeV2.PTV.NonlinearV1 do
  @moduledoc """
  Interpretable nonlinear Player Transaction Value model.

  AVC's Player Market Value score establishes the basketball-value base.
  Contract Value Score then acts as a bounded multiplier, allowing an elite
  contract to amplify a scarce star without turning a low-impact bargain into
  a centerpiece.
  """

  @behaviour TradeMachine.GMGradeV2.PTVModel

  alias TradeMachine.GMGradeV2.PTV
  alias TradeMachine.Valuation.PlayerValueCurve

  @impl true
  def value(player_snapshot, context) when is_map(player_snapshot) and is_map(context) do
    document =
      case Map.fetch(context, :coefficients_document) do
        {:ok, frozen} -> frozen
        :error -> PTV.coefficients_document()
      end

    parameters = Map.fetch!(document, "curve_parameters")
    quality = score!(player_snapshot, :player_market_value)
    contract = score!(player_snapshot, :contract_value_score)
    curve = PlayerValueCurve.evaluate(quality, contract, parameters)

    %{
      ptv: curve.player_asset_value,
      confidence: if(Map.fetch!(document, "calibrated"), do: :model, else: :provisional),
      diagnostics: %{
        model: __MODULE__,
        version: Map.fetch!(document, "version"),
        calibrated: Map.fetch!(document, "calibrated"),
        valuation_foundation: %{
          player_market_value: quality,
          contract_value_score: contract,
          contract_value_tier: field(player_snapshot, :contract_value_tier),
          expected_salary: field(player_snapshot, :expected_salary),
          components: field(player_snapshot, :cvs_components)
        },
        transforms: %{
          quality_value: curve.quality_value,
          contract_multiplier: curve.contract_multiplier
        },
        curve_parameters: parameters
      }
    }
  end

  @impl true
  def info do
    document = PTV.coefficients_document()

    %{
      name: :nonlinear_v1,
      version: Map.fetch!(document, "version"),
      calibrated: Map.fetch!(document, "calibrated"),
      scale: :dav_equivalent,
      features: [:player_market_value, :contract_value_score]
    }
  end

  defp score!(snapshot, key) do
    case field(snapshot, key) do
      value when is_number(value) and value >= 0 and value <= 100 -> value * 1.0
      value -> raise ArgumentError, "#{key} must be between 0 and 100, got: #{inspect(value)}"
    end
  end

  defp field(snapshot, key), do: Map.get(snapshot, key, Map.get(snapshot, Atom.to_string(key)))
end