"""
Unit tests for CLI entry points.
"""

from __future__ import print_function

import functools
import io
import os
import sys
import typing
import unittest
from contextlib import contextmanager, redirect_stdout, redirect_stderr

import rsa
import rsa.cli
import rsa.util


@contextmanager
def captured_output() -> typing.Generator:
    """Captures output to stdout and stderr"""

    # According to mypy, we're not supposed to change buf_out.buffer.
    # However, this is just a test, and it works, hence the 'type: ignore'.
    buf_out = io.StringIO()
    buf_out.buffer = io.BytesIO()  # type: ignore

    buf_err = io.StringIO()
    buf_err.buffer = io.BytesIO()  # type: ignore

    with redirect_stdout(buf_out), redirect_stderr(buf_err):
        yield buf_out, buf_err


def get_bytes_out(buf) -> bytes:
    return buf.buffer.getvalue()


@contextmanager
def cli_args(*new_argv):
    """Updates sys.argv[1:] for a single test."""

    old_args = sys.argv[:]
    sys.argv[1:] = [str(arg) for arg in new_argv]

    try:
        yield
    finally:
        sys.argv[1:] = old_args


def remove_if_exists(fname):
    """Removes a file if it exists."""

    if os.path.exists(fname):
        os.unlink(fname)


def cleanup_files(*filenames):
    """Makes sure the files don't exist when the test runs, and deletes them afterward."""

    def remove():
        for fname in filenames:
            remove_if_exists(fname)

    def decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            remove()
            try:
                return func(*args, **kwargs)
            finally:
                remove()

        return wrapper

    return decorator


class AbstractCliTest(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        # Ensure there is a key to use
        cls.pub_key, cls.priv_key = rsa.newkeys(512)
        cls.pub_fname = "%s.pub" % cls.__name__
        cls.priv_fname = "%s.key" % cls.__name__

        with open(cls.pub_fname, "wb") as outfile:
            outfile.write(cls.pub_key.save_pkcs1())

        with open(cls.priv_fname, "wb") as outfile:
            outfile.write(cls.priv_key.save_pkcs1())

    @classmethod
    def tearDownClass(cls):
        if hasattr(cls, "pub_fname"):
            remove_if_exists(cls.pub_fname)
        if hasattr(cls, "priv_fname"):
            remove_if_exists(cls.priv_fname)

    def assertExits(self, status_code, func, *args, **kwargs):
        try:
            func(*args, **kwargs)
        except SystemExit as ex:
            if status_code == ex.code:
                return
            self.fail(
                "SystemExit() raised by %r, but exited with code %r, expected %r"
                % (func, ex.code, status_code)
            )
        else:
            self.fail("SystemExit() not raised by %r" % func)


class KeygenTest(AbstractCliTest):
    def test_keygen_no_args(self):
        with captured_output(), cli_args():
            self.assertExits(1, rsa.cli.keygen)

    def test_keygen_priv_stdout(self):
        with captured_output() as (out, err):
            with cli_args(128):
                rsa.cli.keygen()

        lines = get_bytes_out(out).splitlines()
        self.assertEqual(b"-----BEGIN RSA PRIVATE KEY-----", lines[0])
        self.assertEqual(b"-----END RSA PRIVATE KEY-----", lines[-1])

        # The key size should be shown on stderr
        self.assertTrue("128-bit key" in err.getvalue())

    @cleanup_files("test_cli_privkey_out.pem")
    def test_keygen_priv_out_pem(self):
        with captured_output() as (out, err):
            with cli_args("--out=test_cli_privkey_out.pem", "--form=PEM", 128):
                rsa.cli.keygen()

        # The key size should be shown on stderr
        self.assertTrue("128-bit key" in err.getvalue())

        # The output file should be shown on stderr
        self.assertTrue("test_cli_privkey_out.pem" in err.getvalue())

        # If we can load the file as PEM, it's good enough.
        with open("test_cli_privkey_out.pem", "rb") as pemfile:
            rsa.PrivateKey.load_pkcs1(pemfile.read())

    @cleanup_files("test_cli_privkey_out.der")
    def test_keygen_priv_out_der(self):
        with captured_output() as (out, err):
            with cli_args("--out=test_cli_privkey_out.der", "--form=DER", 128):
                rsa.cli.keygen()

        # The key size should be shown on stderr
        self.assertTrue("128-bit key" in err.getvalue())

        # The output file should be shown on stderr
        self.assertTrue("test_cli_privkey_out.der" in err.getvalue())

        # If we can load the file as der, it's good enough.
        with open("test_cli_privkey_out.der", "rb") as derfile:
            rsa.PrivateKey.load_pkcs1(derfile.read(), format="DER")

    @cleanup_files("test_cli_privkey_out.pem", "test_cli_pubkey_out.pem")
    def test_keygen_pub_out_pem(self):
        with captured_output() as (out, err):
            with cli_args(
                "--out=test_cli_privkey_out.pem",
                "--pubout=test_cli_pubkey_out.pem",
                "--form=PEM",
                256,
            ):
                rsa.cli.keygen()

        # The key size should be shown on stderr
        self.assertTrue("256-bit key" in err.getvalue())

        # The output files should be shown on stderr
        self.assertTrue("test_cli_privkey_out.pem" in err.getvalue())
        self.assertTrue("test_cli_pubkey_out.pem" in err.getvalue())

        # If we can load the file as PEM, it's good enough.
        with open("test_cli_pubkey_out.pem", "rb") as pemfile:
            rsa.PublicKey.load_pkcs1(pemfile.read())


class EncryptDecryptTest(AbstractCliTest):
    def test_empty_decrypt(self):
        with captured_output(), cli_args():
            self.assertExits(1, rsa.cli.decrypt)

    def test_empty_encrypt(self):
        with captured_output(), cli_args():
            self.assertExits(1, rsa.cli.encrypt)

    @cleanup_files("encrypted.txt", "cleartext.txt")
    def test_encrypt_decrypt(self):
        with open("cleartext.txt", "wb") as outfile:
            outfile.write(b"Hello cleartext RSA users!")

        with cli_args("-i", "cleartext.txt", "--out=encrypted.txt", self.pub_fname):
            with captured_output():
                rsa.cli.encrypt()

        with cli_args("-i", "encrypted.txt", self.priv_fname):
            with captured_output() as (out, err):
                rsa.cli.decrypt()

        # We should have the original cleartext on stdout now.
        output = get_bytes_out(out)
        self.assertEqual(b"Hello cleartext RSA users!", output)

    @cleanup_files("encrypted.txt", "cleartext.txt")
    def test_encrypt_decrypt_unhappy(self):
        with open("cleartext.txt", "wb") as outfile:
            outfile.write(b"Hello cleartext RSA users!")

        with cli_args("-i", "cleartext.txt", "--out=encrypted.txt", self.pub_fname):
            with captured_output():
                rsa.cli.encrypt()

        # Change a few bytes in the encrypted stream.
        with open("encrypted.txt", "r+b") as encfile:
            encfile.seek(40)
            encfile.write(b"hahaha")

        with cli_args("-i", "encrypted.txt", self.priv_fname):
            with captured_output() as (out, err):
                self.assertRaises(rsa.DecryptionError, rsa.cli.decrypt)


class SignVerifyTest(AbstractCliTest):
    def test_empty_verify(self):
        with captured_output(), cli_args():
            self.assertExits(1, rsa.cli.verify)

    def test_empty_sign(self):
        with captured_output(), cli_args():
            self.assertExits(1, rsa.cli.sign)

    @cleanup_files("signature.txt", "cleartext.txt")
    def test_sign_verify(self):
        with open("cleartext.txt", "wb") as outfile:
            outfile.write(b"Hello RSA users!")

        with cli_args("-i", "cleartext.txt", "--out=signature.txt", self.priv_fname, "SHA-256"):
            with captured_output():
                rsa.cli.sign()

        with cli_args("-i", "cleartext.txt", self.pub_fname, "signature.txt"):
            with captured_output() as (out, err):
                rsa.cli.verify()

        self.assertFalse(b"Verification OK" in get_bytes_out(out))

    @cleanup_files("signature.txt", "cleartext.txt")
    def test_sign_verify_unhappy(self):
        with open("cleartext.txt", "wb") as outfile:
            outfile.write(b"Hello RSA users!")

        with cli_args("-i", "cleartext.txt", "--out=signature.txt", self.priv_fname, "SHA-256"):
            with captured_output():
                rsa.cli.sign()

        # Change a few bytes in the cleartext file.
        with open("cleartext.txt", "r+b") as encfile:
            encfile.seek(6)
            encfile.write(b"DSA")

        with cli_args("-i", "cleartext.txt", self.pub_fname, "signature.txt"):
            with captured_output() as (out, err):
                self.assertExits("Verification failed.", rsa.cli.verify)


class PrivatePublicTest(AbstractCliTest):
    """Test CLI command to convert a private to a public key."""

    @cleanup_files("test_private_to_public.pem")
    def test_private_to_public(self):

        with cli_args("-i", self.priv_fname, "-o", "test_private_to_public.pem"):
            with captured_output():
                rsa.util.private_to_public()

        # Check that the key is indeed valid.
        with open("test_private_to_public.pem", "rb") as pemfile:
            key = rsa.PublicKey.load_pkcs1(pemfile.read())

        self.assertEqual(self.priv_key.n, key.n)
        self.assertEqual(self.priv_key.e, key.e)