import signal
import subprocess
import sys
from pathlib import Path
from unittest import mock, skipUnless

from django.db import connection
from django.db.backends.postgresql.client import DatabaseClient
from django.test import SimpleTestCase


class PostgreSqlDbshellCommandTestCase(SimpleTestCase):
    def settings_to_cmd_args_env(self, settings_dict, parameters=None):
        if parameters is None:
            parameters = []
        return DatabaseClient.settings_to_cmd_args_env(settings_dict, parameters)

    def test_basic(self):
        self.assertEqual(
            self.settings_to_cmd_args_env({
                'NAME': 'dbname',
                'USER': 'someuser',
                'PASSWORD': 'somepassword',
                'HOST': 'somehost',
                'PORT': '444',
            }), (
                ['psql', '-U', 'someuser', '-h', 'somehost', '-p', '444', 'dbname'],
                {'PGPASSWORD': 'somepassword'},
            )
        )

    def test_nopass(self):
        self.assertEqual(
            self.settings_to_cmd_args_env({
                'NAME': 'dbname',
                'USER': 'someuser',
                'HOST': 'somehost',
                'PORT': '444',
            }), (
                ['psql', '-U', 'someuser', '-h', 'somehost', '-p', '444', 'dbname'],
                {},
            )
        )

    def test_ssl_certificate(self):
        self.assertEqual(
            self.settings_to_cmd_args_env({
                'NAME': 'dbname',
                'USER': 'someuser',
                'HOST': 'somehost',
                'PORT': '444',
                'OPTIONS': {
                    'sslmode': 'verify-ca',
                    'sslrootcert': 'root.crt',
                    'sslcert': 'client.crt',
                    'sslkey': 'client.key',
                },
            }), (
                ['psql', '-U', 'someuser', '-h', 'somehost', '-p', '444', 'dbname'],
                {
                    'PGSSLCERT': 'client.crt',
                    'PGSSLKEY': 'client.key',
                    'PGSSLMODE': 'verify-ca',
                    'PGSSLROOTCERT': 'root.crt',
                },
            )
        )

    def test_column(self):
        self.assertEqual(
            self.settings_to_cmd_args_env({
                'NAME': 'dbname',
                'USER': 'some:user',
                'PASSWORD': 'some:password',
                'HOST': '::1',
                'PORT': '444',
            }), (
                ['psql', '-U', 'some:user', '-h', '::1', '-p', '444', 'dbname'],
                {'PGPASSWORD': 'some:password'},
            )
        )

    def test_accent(self):
        username = 'rôle'
        password = 'sésame'
        self.assertEqual(
            self.settings_to_cmd_args_env({
                'NAME': 'dbname',
                'USER': username,
                'PASSWORD': password,
                'HOST': 'somehost',
                'PORT': '444',
            }), (
                ['psql', '-U', username, '-h', 'somehost', '-p', '444', 'dbname'],
                {'PGPASSWORD': password},
            )
        )

    def test_parameters(self):
        self.assertEqual(
            self.settings_to_cmd_args_env({'NAME': 'dbname'}, ['--help']),
            (['psql', 'dbname', '--help'], {}),
        )

    @skipUnless(connection.vendor == 'postgresql', 'Requires a PostgreSQL connection')
    def test_sigint_handler(self):
        """SIGINT is ignored in Python and passed to psql to abort queries."""
        def _mock_subprocess_run(*args, **kwargs):
            handler = signal.getsignal(signal.SIGINT)
            self.assertEqual(handler, signal.SIG_IGN)

        sigint_handler = signal.getsignal(signal.SIGINT)
        # The default handler isn't SIG_IGN.
        self.assertNotEqual(sigint_handler, signal.SIG_IGN)
        with mock.patch('subprocess.run', new=_mock_subprocess_run):
            connection.client.runshell([])
        # dbshell restores the original handler.
        self.assertEqual(sigint_handler, signal.getsignal(signal.SIGINT))

    def test_crash_password_does_not_leak(self):
        # The password doesn't leak in an exception that results from a client
        # crash.
        args, env = self.settings_to_cmd_args_env({'PASSWORD': 'somepassword'}, [])
        fake_client = Path(__file__).with_name('fake_client.py')
        args[0:1] = [sys.executable, str(fake_client)]
        with self.assertRaises(subprocess.CalledProcessError) as ctx:
            subprocess.run(args, check=True, env=env)
        self.assertNotIn('somepassword', str(ctx.exception))