defmodule TradeMachine.GMGradeV2.Pillars.AssetManagement do
  @moduledoc """
  Aggregates AVC's four Asset Management metrics.

  An uncalibrated player-involving Asset Exchange Value remains visible but is
  excluded under D-10. The other three weights are then renormalized from
  35/20/20 to exact proportions of their 75% subtotal.
  """

  alias TradeMachine.GMGradeV2.Pillars.AssetManagement.AssetExchangeValue
  alias TradeMachine.GMGradeV2.ModelVersion
  alias TradeMachine.GMGradeV2.Result.MetricResult
  alias TradeMachine.GMGradeV2.Result.PillarResult

  @full_weights %{
    draft_capital_value: 0.35,
    pick_quality: 0.20,
    asset_optionality: 0.20,
    asset_exchange_value: 0.25
  }

  @inventory_total 0.75
  @provisional_weights %{
    draft_capital_value: 0.35 / @inventory_total,
    pick_quality: 0.20 / @inventory_total,
    asset_optionality: 0.20 / @inventory_total,
    asset_exchange_value: 0.0
  }

  if abs(Enum.sum(Map.values(@full_weights)) - 1.0) > 1.0e-9 or
       abs(Enum.sum(Map.values(@provisional_weights)) - 1.0) > 1.0e-9 do
    raise "Asset Management weights must sum to 1.0"
  end

  @doc "Aggregates the four canonical metric results in published order."
  @spec score([MetricResult.t()]) :: PillarResult.t()
  def score(
        [
          %MetricResult{key: :draft_capital_value},
          %MetricResult{key: :pick_quality},
          %MetricResult{key: :asset_optionality},
          %MetricResult{key: :asset_exchange_value} = exchange
        ] = metric_results
      ) do
    provisional? = AssetExchangeValue.status(exchange) == :provisional
    weights = if(provisional?, do: @provisional_weights, else: @full_weights)
    scored_results = if(provisional?, do: Enum.take(metric_results, 3), else: metric_results)
    {strongest, weakest} = extrema(scored_results)

    %PillarResult{
      key: :asset_management,
      version: ModelVersion.model_version(),
      score: weighted_score(scored_results, weights),
      metric_results: metric_results,
      metric_weights: weights,
      provisional?: false,
      strongest: strongest.key,
      weakest: weakest.key,
      explanation: explanation(provisional?, strongest, weakest)
    }
  end

  @doc """
  Projects Asset Management for a state-only comparison.

  The four canonical metric slots and their full 35/20/20/25 weights are
  preserved, but Asset Exchange Value is fixed at neutral `50`. This deliberately
  ignores whether the canonical AEV result was provisional: transaction-path
  evidence must affect neither side of a Comparable State Score.
  """
  @spec comparable_score([MetricResult.t()]) :: float()
  def comparable_score(
        [
          %MetricResult{key: :draft_capital_value},
          %MetricResult{key: :pick_quality},
          %MetricResult{key: :asset_optionality},
          %MetricResult{key: :asset_exchange_value}
        ] = metric_results
      ) do
    metric_results
    |> Enum.map(fn
      %MetricResult{key: :asset_exchange_value} = result -> %{result | score: 50.0}
      result -> result
    end)
    |> weighted_score(@full_weights)
  end

  defp weighted_score(results, weights) when is_list(results) do
    Enum.reduce(results, 0.0, fn result, total ->
      total + result.score * Map.fetch!(weights, result.key)
    end)
  end

  defp extrema(results), do: {Enum.max_by(results, & &1.score), Enum.min_by(results, & &1.score)}

  defp explanation(
         true,
         %MetricResult{key: strongest, score: strongest_score},
         %MetricResult{key: weakest, score: weakest_score}
       ) do
    rendered_weights =
      [:draft_capital_value, :pick_quality, :asset_optionality]
      |> Enum.map_join("/", &((Map.fetch!(@provisional_weights, &1) * 100) |> Float.round(2)))

    "Asset Exchange Value is displayed but excluded until PTV is calibrated; " <>
      "the 35/20/20 inventory weights are renormalized to #{rendered_weights}. " <>
      "#{label(strongest)} is strongest at #{strongest_score}, while " <>
      "#{label(weakest)} is weakest at #{weakest_score}."
  end

  defp explanation(
         false,
         %MetricResult{key: strongest, score: strongest_score},
         %MetricResult{key: weakest, score: weakest_score}
       ) do
    "Asset Management applies the full 35/20/20/25 composition; " <>
      "#{label(strongest)} is strongest at #{strongest_score}, while " <>
      "#{label(weakest)} is weakest at #{weakest_score}."
  end

  defp label(:draft_capital_value), do: "Draft Capital Value"
  defp label(:pick_quality), do: "Pick Quality"
  defp label(:asset_optionality), do: "Asset Optionality"
  defp label(:asset_exchange_value), do: "Asset Exchange Value"
end