# подгружаются основные определения
require_relative './task16-math'

class Pi < Number
  PI = Math::PI
end

class Sin < MathExpression
  def initialize(e = Number.new(1)) # e - выражение, для которого ищется синус
    @e = e  # - аргумент
  end

  def eval env
    e = @e.eval env
    e.evalExp
  end

  def derivative var
    e = @e.derivative var
    e.multiply #cos @sin

  end

end

class Cos < MathExpression

end






# ПРИМЕРЫ
puts(Derivative.new(
        Multiply.new(
          Add.new(
            Add.new(
              Multiply.new(Number.new(2),
                           Variable.new("x")),
              Multiply.new(Number.new(3),
                           Variable.new("y"))),
            Negate.new(Variable.new("z"))),
          Add.new(Number.new(5),
                  Variable.new("x"))),
        "x"))

puts(Let.new("a", Multiply.new(Number.new(2),
                               Variable.new("x")),        # a = 2x
       Let.new("b", Multiply.new(Number.new(3),
                                 Variable.new("y")),      # b = 3y
         Let.new("e", Add.new(Variable.new("a"),
                              Variable.new("b")),         # e = a + b
            Multiply.new(Multiply.new(Variable.new("e"),
                                      Variable.new("e")),
                         Variable.new("e"))))))

puts(Let.new("a", Multiply.new(Number.new(2),
                               Variable.new("x")),   # a = 2x
       Let.new("b", Multiply.new(Number.new(3),
                                 Variable.new("y")), # b = 3y
         Let.new("cube",                             # cube(e) = e * e * e
                 MyFunc.new(nil, "e",
                   Multiply.new(Multiply.new(Variable.new("e"),
                                             Variable.new("e")),
                                Variable.new("e"))),
           # вычисление cube(a + b) + cube(b)
           Add.new(Call.new(Variable.new("cube"),        # вызов cube(a + b)
                            Add.new(Variable.new("a"),
                                    Variable.new("b"))),
                   Call.new(Variable.new("cube"),        # вызов cube(b)
                            Variable.new("b")))))))

# вычисление выражений
puts(Derivative.new(
        Multiply.new(
          Add.new(
            Add.new(
              Multiply.new(Number.new(2),
                           Variable.new("x")),
              Multiply.new(Number.new(3),
                           Variable.new("y"))),
            Negate.new(Variable.new("z"))),
          Add.new(Number.new(5),
                  Variable.new("x"))),
        "x").eval_exp)

puts(Let.new("a", Multiply.new(Number.new(2),
                               Variable.new("x")),        # a = 2x
       Let.new("b", Multiply.new(Number.new(3),
                                 Variable.new("y")),      # b = 3y
         Let.new("e", Add.new(Variable.new("a"),
                              Variable.new("b")),         # e = a + b
            Multiply.new(Multiply.new(Variable.new("e"),
                                      Variable.new("e")),
                         Variable.new("e"))))).eval_exp)

puts(Let.new("a", Multiply.new(Number.new(2),
                               Variable.new("x")),   # a = 2x
       Let.new("b", Multiply.new(Number.new(3),
                                 Variable.new("y")), # b = 3y
         Let.new("cube",                             # cube(e) = e * e * e
                 MyFunc.new(nil, "e",
                   Multiply.new(Multiply.new(Variable.new("e"),
                                             Variable.new("e")),
                                Variable.new("e"))),
           # вычисление cube(a + b) + cube(b)
           Add.new(Call.new(Variable.new("cube"),        # вызов cube(a + b)
                            Add.new(Variable.new("a"),
                                    Variable.new("b"))),
                   Call.new(Variable.new("cube"),        # вызов cube(b)
                            Variable.new("b")))))).eval_exp)