# compatibility with Python 2.6, for that we need unittest2 package,
# which is not available on 3.3 or 3.4
import warnings
from binascii import hexlify
try:
    import unittest2 as unittest
except ImportError:
    import unittest
from six import b
import hypothesis.strategies as st
from hypothesis import given, example
import pytest
from ._compat import str_idx_as_int
from .curves import NIST256p, NIST224p
from .der import remove_integer, UnexpectedDER, read_length, encode_bitstring,\
        remove_bitstring, remove_object, encode_oid


class TestRemoveInteger(unittest.TestCase):
    # DER requires the integers to be 0-padded only if they would be
    # interpreted as negative, check if those errors are detected
    def test_non_minimal_encoding(self):
        with self.assertRaises(UnexpectedDER):
            remove_integer(b('\x02\x02\x00\x01'))

    def test_negative_with_high_bit_set(self):
        with self.assertRaises(UnexpectedDER):
            remove_integer(b('\x02\x01\x80'))

    def test_minimal_with_high_bit_set(self):
        val, rem = remove_integer(b('\x02\x02\x00\x80'))

        self.assertEqual(val, 0x80)
        self.assertFalse(rem)

    def test_two_zero_bytes_with_high_bit_set(self):
        with self.assertRaises(UnexpectedDER):
            remove_integer(b('\x02\x03\x00\x00\xff'))

    def test_zero_length_integer(self):
        with self.assertRaises(UnexpectedDER):
            remove_integer(b('\x02\x00'))

    def test_empty_string(self):
        with self.assertRaises(UnexpectedDER):
            remove_integer(b(''))

    def test_encoding_of_zero(self):
        val, rem = remove_integer(b('\x02\x01\x00'))

        self.assertEqual(val, 0)
        self.assertFalse(rem)

    def test_encoding_of_127(self):
        val, rem = remove_integer(b('\x02\x01\x7f'))

        self.assertEqual(val, 127)
        self.assertFalse(rem)

    def test_encoding_of_128(self):
        val, rem = remove_integer(b('\x02\x02\x00\x80'))

        self.assertEqual(val, 128)
        self.assertFalse(rem)


class TestReadLength(unittest.TestCase):
    # DER requires the lengths between 0 and 127 to be encoded using the short
    # form and lengths above that encoded with minimal number of bytes
    # necessary
    def test_zero_length(self):
        self.assertEqual((0, 1), read_length(b('\x00')))

    def test_two_byte_zero_length(self):
        with self.assertRaises(UnexpectedDER):
            read_length(b('\x81\x00'))

    def test_two_byte_small_length(self):
        with self.assertRaises(UnexpectedDER):
            read_length(b('\x81\x7f'))

    def test_long_form_with_zero_length(self):
        with self.assertRaises(UnexpectedDER):
            read_length(b('\x80'))

    def test_smallest_two_byte_length(self):
        self.assertEqual((128, 2), read_length(b('\x81\x80')))

    def test_zero_padded_length(self):
        with self.assertRaises(UnexpectedDER):
            read_length(b('\x82\x00\x80'))

    def test_two_three_byte_length(self):
        self.assertEqual((256, 3), read_length(b'\x82\x01\x00'))

    def test_empty_string(self):
        with self.assertRaises(UnexpectedDER):
            read_length(b(''))

    def test_length_overflow(self):
        with self.assertRaises(UnexpectedDER):
            read_length(b('\x83\x01\x00'))


class TestEncodeBitstring(unittest.TestCase):
    # DER requires BIT STRINGS to include a number of padding bits in the
    # encoded byte string, that padding must be between 0 and 7

    def test_old_call_convention(self):
        """This is the old way to use the function."""
        warnings.simplefilter('always')
        with pytest.warns(DeprecationWarning) as warns:
            der = encode_bitstring(b'\x00\xff')

        self.assertEqual(len(warns), 1)
        self.assertIn("unused= needs to be specified",
            warns[0].message.args[0])

        self.assertEqual(der, b'\x03\x02\x00\xff')

    def test_new_call_convention(self):
        """This is how it should be called now."""
        warnings.simplefilter('always')
        with pytest.warns(None) as warns:
            der = encode_bitstring(b'\xff', 0)

        # verify that new call convention doesn't raise Warnings
        self.assertEqual(len(warns), 0)

        self.assertEqual(der, b'\x03\x02\x00\xff')

    def test_implicit_unused_bits(self):
        """
        Writing bit string with already included the number of unused bits.
        """
        warnings.simplefilter('always')
        with pytest.warns(None) as warns:
            der = encode_bitstring(b'\x00\xff', None)

        # verify that new call convention doesn't raise Warnings
        self.assertEqual(len(warns), 0)

        self.assertEqual(der, b'\x03\x02\x00\xff')

    def test_explicit_unused_bits(self):
        der = encode_bitstring(b'\xff\xf0', 4)

        self.assertEqual(der, b'\x03\x03\x04\xff\xf0')

    def test_empty_string(self):
        self.assertEqual(encode_bitstring(b'', 0), b'\x03\x01\x00')

    def test_invalid_unused_count(self):
        with self.assertRaises(ValueError):
            encode_bitstring(b'\xff\x00', 8)

    def test_invalid_unused_with_empty_string(self):
        with self.assertRaises(ValueError):
            encode_bitstring(b'', 1)

    def test_non_zero_padding_bits(self):
        with self.assertRaises(ValueError):
            encode_bitstring(b'\xff', 2)


class TestRemoveBitstring(unittest.TestCase):
    def test_old_call_convention(self):
        """This is the old way to call the function."""
        warnings.simplefilter('always')
        with pytest.warns(DeprecationWarning) as warns:
            bits, rest = remove_bitstring(b'\x03\x02\x00\xff')

        self.assertEqual(len(warns), 1)
        self.assertIn("expect_unused= needs to be specified",
                      warns[0].message.args[0])

        self.assertEqual(bits, b'\x00\xff')
        self.assertEqual(rest, b'')

    def test_new_call_convention(self):
        warnings.simplefilter('always')
        with pytest.warns(None) as warns:
            bits, rest = remove_bitstring(b'\x03\x02\x00\xff', 0)

        self.assertEqual(len(warns), 0)

        self.assertEqual(bits, b'\xff')
        self.assertEqual(rest, b'')

    def test_implicit_unexpected_unused(self):
        warnings.simplefilter('always')
        with pytest.warns(None) as warns:
            bits, rest = remove_bitstring(b'\x03\x02\x00\xff', None)

        self.assertEqual(len(warns), 0)

        self.assertEqual(bits, (b'\xff', 0))
        self.assertEqual(rest, b'')

    def test_with_padding(self):
        ret, rest = remove_bitstring(b'\x03\x02\x04\xf0', None)

        self.assertEqual(ret, (b'\xf0', 4))
        self.assertEqual(rest, b'')

    def test_not_a_bitstring(self):
        with self.assertRaises(UnexpectedDER):
            remove_bitstring(b'\x02\x02\x00\xff', None)

    def test_empty_encoding(self):
        with self.assertRaises(UnexpectedDER):
            remove_bitstring(b'\x03\x00', None)

    def test_empty_string(self):
        with self.assertRaises(UnexpectedDER):
            remove_bitstring(b'', None)

    def test_no_length(self):
        with self.assertRaises(UnexpectedDER):
            remove_bitstring(b'\x03', None)

    def test_unexpected_number_of_unused_bits(self):
        with self.assertRaises(UnexpectedDER):
            remove_bitstring(b'\x03\x02\x00\xff', 1)

    def test_invalid_encoding_of_unused_bits(self):
        with self.assertRaises(UnexpectedDER):
            remove_bitstring(b'\x03\x03\x08\xff\x00', None)

    def test_invalid_encoding_of_empty_string(self):
        with self.assertRaises(UnexpectedDER):
            remove_bitstring(b'\x03\x01\x01', None)

    def test_invalid_padding_bits(self):
        with self.assertRaises(UnexpectedDER):
            remove_bitstring(b'\x03\x02\x01\xff', None)


class TestStrIdxAsInt(unittest.TestCase):
    def test_str(self):
        self.assertEqual(115, str_idx_as_int('str', 0))

    def test_bytes(self):
        self.assertEqual(115, str_idx_as_int(b'str', 0))

    def test_bytearray(self):
        self.assertEqual(115, str_idx_as_int(bytearray(b'str'), 0))


class TestEncodeOid(unittest.TestCase):
    def test_pub_key_oid(self):
        oid_ecPublicKey = encode_oid(1, 2, 840, 10045, 2, 1)
        self.assertEqual(hexlify(oid_ecPublicKey), b("06072a8648ce3d0201"))

    def test_nist224p_oid(self):
        self.assertEqual(hexlify(NIST224p.encoded_oid), b("06052b81040021"))

    def test_nist256p_oid(self):
        self.assertEqual(hexlify(NIST256p.encoded_oid),
                         b"06082a8648ce3d030107")

    def test_large_second_subid(self):
        # from X.690, section 8.19.5
        oid = encode_oid(2, 999, 3)
        self.assertEqual(oid, b'\x06\x03\x88\x37\x03')

    def test_with_two_subids(self):
        oid = encode_oid(2, 999)
        self.assertEqual(oid, b'\x06\x02\x88\x37')

    def test_zero_zero(self):
        oid = encode_oid(0, 0)
        self.assertEqual(oid, b'\x06\x01\x00')

    def test_with_wrong_types(self):
        with self.assertRaises((TypeError, AssertionError)):
            encode_oid(0, None)

    def test_with_small_first_large_second(self):
        with self.assertRaises(AssertionError):
            encode_oid(1, 40)

    def test_small_first_max_second(self):
        oid = encode_oid(1, 39)
        self.assertEqual(oid, b'\x06\x01\x4f')

    def test_with_invalid_first(self):
        with self.assertRaises(AssertionError):
            encode_oid(3, 39)


class TestRemoveObject(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        cls.oid_ecPublicKey = encode_oid(1, 2, 840, 10045, 2, 1)

    def test_pub_key_oid(self):
        oid, rest = remove_object(self.oid_ecPublicKey)
        self.assertEqual(rest, b'')
        self.assertEqual(oid, (1, 2, 840, 10045, 2, 1))

    def test_with_extra_bytes(self):
        oid, rest = remove_object(self.oid_ecPublicKey + b'more')
        self.assertEqual(rest, b'more')
        self.assertEqual(oid, (1, 2, 840, 10045, 2, 1))

    def test_with_large_second_subid(self):
        # from X.690, section 8.19.5
        oid, rest = remove_object(b'\x06\x03\x88\x37\x03')
        self.assertEqual(rest, b'')
        self.assertEqual(oid, (2, 999, 3))

    def test_with_padded_first_subid(self):
        with self.assertRaises(UnexpectedDER):
            remove_object(b'\x06\x02\x80\x00')

    def test_with_padded_second_subid(self):
        with self.assertRaises(UnexpectedDER):
            remove_object(b'\x06\x04\x88\x37\x80\x01')

    def test_with_missing_last_byte_of_multi_byte(self):
        with self.assertRaises(UnexpectedDER):
            remove_object(b'\x06\x03\x88\x37\x83')

    def test_with_two_subids(self):
        oid, rest = remove_object(b'\x06\x02\x88\x37')
        self.assertEqual(rest, b'')
        self.assertEqual(oid, (2, 999))

    def test_zero_zero(self):
        oid, rest = remove_object(b'\x06\x01\x00')
        self.assertEqual(rest, b'')
        self.assertEqual(oid, (0, 0))

    def test_empty_string(self):
        with self.assertRaises(UnexpectedDER):
            remove_object(b'')

    def test_missing_length(self):
        with self.assertRaises(UnexpectedDER):
            remove_object(b'\x06')

    def test_empty_oid(self):
        with self.assertRaises(UnexpectedDER):
            remove_object(b'\x06\x00')

    def test_empty_oid_overflow(self):
        with self.assertRaises(UnexpectedDER):
            remove_object(b'\x06\x01')

    def test_with_wrong_type(self):
        with self.assertRaises(UnexpectedDER):
            remove_object(b'\x04\x02\x88\x37')

    def test_with_too_long_length(self):
        with self.assertRaises(UnexpectedDER):
            remove_object(b'\x06\x03\x88\x37')


@st.composite
def st_oid(draw, max_value=2**512, max_size=50):
    """
    Hypothesis strategy that returns valid OBJECT IDENTIFIERs as tuples

    :param max_value: maximum value of any single sub-identifier
    :param max_size: maximum length of the generated OID
    """
    first = draw(st.integers(min_value=0, max_value=2))
    if first < 2:
        second = draw(st.integers(min_value=0, max_value=39))
    else:
        second = draw(st.integers(min_value=0, max_value=max_value))
    rest = draw(st.lists(st.integers(min_value=0, max_value=max_value),
                         max_size=max_size))
    return (first, second) + tuple(rest)


@given(st_oid())
def test_oids(ids):
    encoded_oid = encode_oid(*ids)
    decoded_oid, rest = remove_object(encoded_oid)
    assert rest == b''
    assert decoded_oid == ids