#  Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      https://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

"""Tests string operations."""

import struct
import unittest

import rsa
from rsa import pkcs1
from rsa._compat import byte


class BinaryTest(unittest.TestCase):
    def setUp(self):
        (self.pub, self.priv) = rsa.newkeys(256)

    def test_enc_dec(self):
        message = struct.pack('>IIII', 0, 0, 0, 1)
        print("\tMessage:   %r" % message)

        encrypted = pkcs1.encrypt(message, self.pub)
        print("\tEncrypted: %r" % encrypted)

        decrypted = pkcs1.decrypt(encrypted, self.priv)
        print("\tDecrypted: %r" % decrypted)

        self.assertEqual(message, decrypted)

    def test_decoding_failure(self):
        message = struct.pack('>IIII', 0, 0, 0, 1)
        encrypted = pkcs1.encrypt(message, self.pub)

        # Alter the encrypted stream
        a = encrypted[5]
        self.assertIsInstance(a, int)

        altered_a = (a + 1) % 256
        encrypted = encrypted[:5] + byte(altered_a) + encrypted[6:]

        self.assertRaises(pkcs1.DecryptionError, pkcs1.decrypt, encrypted,
                          self.priv)

    def test_randomness(self):
        """Encrypting the same message twice should result in different
        cryptos.
        """

        message = struct.pack('>IIII', 0, 0, 0, 1)
        encrypted1 = pkcs1.encrypt(message, self.pub)
        encrypted2 = pkcs1.encrypt(message, self.pub)

        self.assertNotEqual(encrypted1, encrypted2)


class SignatureTest(unittest.TestCase):
    def setUp(self):
        (self.pub, self.priv) = rsa.newkeys(512)

    def test_sign_verify(self):
        """Test happy flow of sign and verify"""

        message = b'je moeder'
        signature = pkcs1.sign(message, self.priv, 'SHA-256')
        self.assertEqual('SHA-256', pkcs1.verify(message, signature, self.pub))

        signature = pkcs1.sign(message, self.priv, 'SHA3-256')
        self.assertEqual('SHA3-256', pkcs1.verify(message, signature, self.pub))

    def test_find_signature_hash(self):
        """Test happy flow of sign and find_signature_hash"""

        message = b'je moeder'
        signature = pkcs1.sign(message, self.priv, 'SHA-256')

        self.assertEqual('SHA-256', pkcs1.find_signature_hash(signature, self.pub))

    def test_alter_message(self):
        """Altering the message should let the verification fail."""

        signature = pkcs1.sign(b'je moeder', self.priv, 'SHA-256')
        self.assertRaises(pkcs1.VerificationError, pkcs1.verify,
                          b'mijn moeder', signature, self.pub)

    def test_sign_different_key(self):
        """Signing with another key should let the verification fail."""

        (otherpub, _) = rsa.newkeys(512)

        message = b'je moeder'
        signature = pkcs1.sign(message, self.priv, 'SHA-256')
        self.assertRaises(pkcs1.VerificationError, pkcs1.verify,
                          message, signature, otherpub)

    def test_multiple_signings(self):
        """Signing the same message twice should return the same signatures."""

        message = struct.pack('>IIII', 0, 0, 0, 1)
        signature1 = pkcs1.sign(message, self.priv, 'SHA-1')
        signature2 = pkcs1.sign(message, self.priv, 'SHA-1')

        self.assertEqual(signature1, signature2)

    def test_split_hash_sign(self):
        """Hashing and then signing should match with directly signing the message. """

        message = b'je moeder'
        msg_hash = pkcs1.compute_hash(message, 'SHA-256')
        signature1 = pkcs1.sign_hash(msg_hash, self.priv, 'SHA-256')

        # Calculate the signature using the unified method
        signature2 = pkcs1.sign(message, self.priv, 'SHA-256')

        self.assertEqual(signature1, signature2)

    def test_hash_sign_verify(self):
        """Test happy flow of hash, sign, and verify"""

        message = b'je moeder'
        msg_hash = pkcs1.compute_hash(message, 'SHA-224')
        signature = pkcs1.sign_hash(msg_hash, self.priv, 'SHA-224')

        self.assertTrue(pkcs1.verify(message, signature, self.pub))