defmodule Tilly.BDD.IntegerBoolOps do
  @moduledoc """
  BDD Operations module for BDDs where elements are integers and leaves are booleans.
  """

  @doc """
  Compares two integer elements.
  Returns `:lt`, `:eq`, or `:gt`.
  """
  def compare_elements(elem1, elem2) when is_integer(elem1) and is_integer(elem2) do
    cond do
      elem1 < elem2 -> :lt
      elem1 > elem2 -> :gt
      true -> :eq
    end
  end

  @doc """
  Checks if two integer elements are equal.
  """
  def equal_element?(elem1, elem2) when is_integer(elem1) and is_integer(elem2) do
    elem1 == elem2
  end

  @doc """
  Hashes an integer element.
  """
  def hash_element(elem) when is_integer(elem) do
    elem
  end

  @doc """
  Returns the leaf value representing emptiness (false).
  """
  def empty_leaf(), do: false

  @doc """
  Returns the leaf value representing universality (true).
  """
  def any_leaf(), do: true

  @doc """
  Checks if the leaf value represents emptiness.
  """
  def is_empty_leaf?(leaf_val) when is_boolean(leaf_val) do
    leaf_val == false
  end

  @doc """
  Computes the union of two boolean leaf values.
  The `_typing_ctx` is ignored for this simple ops module.
  """
  def union_leaves(_typing_ctx, leaf1, leaf2) when is_boolean(leaf1) and is_boolean(leaf2) do
    leaf1 or leaf2
  end

  @doc """
  Computes the intersection of two boolean leaf values.
  The `_typing_ctx` is ignored for this simple ops module.
  """
  def intersection_leaves(_typing_ctx, leaf1, leaf2)
      when is_boolean(leaf1) and is_boolean(leaf2) do
    leaf1 and leaf2
  end

  @doc """
  Computes the negation of a boolean leaf value.
  The `_typing_ctx` is ignored for this simple ops module.
  """
  def negation_leaf(_typing_ctx, leaf) when is_boolean(leaf) do
    not leaf
  end

  # def difference_leaves(_typing_ctx, leaf1, leaf2) when is_boolean(leaf1) and is_boolean(leaf2) do
  #   leaf1 and (not leaf2)
  # end

  @doc """
  Tests a leaf value to determine if it represents an empty, full, or other set.
  For boolean leaves with integers, this mirrors AtomBoolOps and StringBoolOps.
  Returns `:empty`, `:full`, or `:other`.
  """
  def test_leaf_value(true), do: :full
  def test_leaf_value(false), do: :empty
  # If integer BDDs could have non-boolean leaves that are not empty/full:
  # def test_leaf_value(_other_leaf_value), do: :other
end