# -*- coding: utf-8 -*-

from __future__ import division, unicode_literals, print_function, absolute_import
import unittest

from pint.compat import tokenizer
from pint.pint_eval import build_eval_tree


class TestPintEval(unittest.TestCase):

    def _test_one(self, input_text, parsed):
        self.assertEqual(build_eval_tree(tokenizer(input_text)).to_string(), parsed)

    def test_build_eval_tree(self):
        self._test_one('3', '3')
        self._test_one('1 + 2', '(1 + 2)')
        # order of operations
        self._test_one('2 * 3 + 4', '((2 * 3) + 4)')
        # parentheses
        self._test_one('2 * (3 + 4)', '(2 * (3 + 4))')
        # more order of operations
        self._test_one('1 + 2 * 3 ** (4 + 3 / 5)', '(1 + (2 * (3 ** (4 + (3 / 5)))))')
        # nested parentheses at beginning
        self._test_one('1 * ((3 + 4) * 5)', '(1 * ((3 + 4) * 5))')
        # nested parentheses at end
        self._test_one('1 * (5 * (3 + 4))', '(1 * (5 * (3 + 4)))')
        # nested parentheses in middle
        self._test_one('1 * (5 * (3 + 4) / 6)', '(1 * ((5 * (3 + 4)) / 6))')
        # unary
        self._test_one('-1', '(- 1)')
        # unary
        self._test_one('3 * -1', '(3 * (- 1))')
        # double unary
        self._test_one('3 * --1', '(3 * (- (- 1)))')
        # parenthetical unary
        self._test_one('3 * -(2 + 4)', '(3 * (- (2 + 4)))')
        # parenthetical unary
        self._test_one('3 * -((2 + 4))', '(3 * (- (2 + 4)))')
        # implicit op
        self._test_one('3 4', '(3 4)')
        # implicit op, then parentheses
        self._test_one('3 (2 + 4)', '(3 (2 + 4))')
        # parentheses, then implicit
        self._test_one('(3 ** 4 ) 5', '((3 ** 4) 5)')
        # implicit op, then exponentiation
        self._test_one('3 4 ** 5', '(3 (4 ** 5))')
        # implicit op, then addition
        self._test_one('3 4 + 5', '((3 4) + 5)')
        # power followed by implicit
        self._test_one('3 ** 4 5', '((3 ** 4) 5)')
        # implicit with parentheses
        self._test_one('3 (4 ** 5)', '(3 (4 ** 5))')
        # exponent with e
        self._test_one('3e-1', '3e-1')
        # multiple units with exponents
        self._test_one('kg ** 1 * s ** 2', '((kg ** 1) * (s ** 2))')
        # multiple units with neg exponents
        self._test_one('kg ** -1 * s ** -2', '((kg ** (- 1)) * (s ** (- 2)))')
        # multiple units with neg exponents
        self._test_one('kg^-1 * s^-2', '((kg ^ (- 1)) * (s ^ (- 2)))')
        # multiple units with neg exponents, implicit op
        self._test_one('kg^-1 s^-2', '((kg ^ (- 1)) (s ^ (- 2)))')
        # nested power
        self._test_one('2 ^ 3 ^ 2', '(2 ^ (3 ^ 2))')
        # nested power
        self._test_one('gram * second / meter ** 2', '((gram * second) / (meter ** 2))')
        # nested power
        self._test_one('gram / meter ** 2 / second', '((gram / (meter ** 2)) / second)')
        # units should behave like numbers, so we don't need a bunch of extra tests for them
        # implicit op, then addition
        self._test_one('3 kg + 5', '((3 kg) + 5)')
