defmodule ExpressionEvaluatorTest do
  use ExUnit.Case
  doctest ExpressionEvaluator
  import ExpressionEvaluator

  test "evaluates individual numbers" do
    assert eval("1") == 1
  end

  test "evaluates negated numbers" do
    assert eval("-1") == -1
  end

  test "evaluates variables" do
    assert eval("x", %{"x" => 3}) == 3
  end

  test "evaluates negated variables" do
    assert eval("-x", %{"x" => 3}) == -3
    assert eval("-x", %{"x" => -3}) == 3
  end

  test "evaluates binary operations" do
    assert eval("1 + 2") == 3
    assert eval("3 - 2") == 1
    assert eval("3 * 2") == 6
    assert eval("10 / 2") == 5
  end

  test "floors division" do
    assert eval("3 / 2") == 1
  end

  test "obeys operator precedence" do
    assert eval("1 + 2 * 3") == 7
    assert eval("(1 + 2) * 3") == 9
    assert eval("12 - 6 / 2") == 9
    assert eval("(12 - 6) / 2") == 3
  end

  test "evaluates complex expressions" do
    assert eval("1 + 2 * (3 - ((4 / 2 + 5) * 6))") == -77
  end

  test "evaluates complex expressions with variables" do
    assert eval("x * ((4 - y) / 6 + z))", %{"x" => 2, "y" => -8, "z" => 5}) == 14
  end
end