from http.cookiejar import CookieJar
import os

from pyramid import testing
from pyramid.paster import get_app, get_appsettings
from pytest import fixture
from redis import StrictRedis
from sqlalchemy import create_engine
from sqlalchemy.engine.url import make_url
from sqlalchemy.orm import sessionmaker
from sqlalchemy.orm.session import Session
from testing.redis import RedisServer  # noqa
from webtest import TestApp

from scripts.initialize_db import create_tables
from tildes.models.group import Group
from tildes.models.user import User


class NestedSessionWrapper(Session):
    """Wrapper that starts a new nested transaction on commit/rollback."""

    def commit(self):
        """Commit the transaction, then start a new nested one."""
        super().commit()
        self.begin_nested()

    def rollback(self):
        """Rollback the transaction, then start a new nested one."""
        super().rollback()
        self.begin_nested()

    def rollback_all_nested(self):
        """Rollback all nested transactions to return to "top-level"."""
        while self.transaction.parent:
            super().rollback()


@fixture(scope='session', autouse=True)
def pyramid_config():
    """Set up the Pyramid environment."""
    settings = get_appsettings('development.ini')
    config = testing.setUp(settings=settings)
    config.include('tildes.auth')

    yield config

    testing.tearDown()


@fixture(scope='session', autouse=True)
def overall_db_session(pyramid_config):
    """Handle setup and teardown of test database for testing session."""
    # read the database url from the pyramid INI file, and replace the db name
    sqlalchemy_url = pyramid_config.registry.settings['sqlalchemy.url']
    parsed_url = make_url(sqlalchemy_url)
    parsed_url.database = 'tildes_test'

    engine = create_engine(parsed_url)
    session_factory = sessionmaker(bind=engine)
    session = session_factory()

    create_tables(session.connection())

    # SQL init scripts need to be executed "manually" instead of using psql
    # like the normal database init process does, since the tables only exist
    # inside this transaction
    init_scripts_dir = 'sql/init/'
    for root, _, files in os.walk(init_scripts_dir):
        sql_files = [
            filename for filename in files
            if filename.endswith('.sql')
        ]
        for sql_file in sql_files:
            with open(os.path.join(root, sql_file)) as current_file:
                session.execute(current_file.read())

    # convert the Session to the wrapper class to enforce staying inside
    # nested transactions in the test functions
    session.__class__ = NestedSessionWrapper

    yield session

    # "Teardown" code at the end of testing session
    session.__class__ = Session
    session.rollback()


@fixture(scope='session')
def sdb(overall_db_session):
    """Testing-session-level db session with a nested transaction."""
    overall_db_session.begin_nested()

    yield overall_db_session

    overall_db_session.rollback_all_nested()


@fixture(scope='function')
def db(overall_db_session):
    """Function-level db session with a nested transaction."""
    overall_db_session.begin_nested()

    yield overall_db_session

    overall_db_session.rollback_all_nested()


@fixture(scope='session', autouse=True)
def overall_redis_session():
    """Create a session-level connection to a temporary redis server."""
    # list of redis modules that need to be loaded (would be much nicer to do
    # this automatically somehow, maybe reading from the real redis.conf?)
    redis_modules = [
        '/opt/redis-cell/libredis_cell.so',
    ]

    with RedisServer() as temp_redis_server:
        redis = StrictRedis(**temp_redis_server.dsn())

        for module in redis_modules:
            redis.execute_command('MODULE LOAD', module)

        yield redis


@fixture(scope='function')
def redis(overall_redis_session):
    """Create a function-level redis connection that wipes the db after use."""
    yield overall_redis_session

    overall_redis_session.flushdb()


@fixture(scope='session', autouse=True)
def session_user(sdb):
    """Create a user named 'SessionUser' in the db for test session."""
    # note that some tests may depend on this username/password having these
    # specific values, so make sure to search for and update those tests if you
    # change the username or password for any reason
    user = User('SessionUser', 'session user password')
    sdb.add(user)
    sdb.commit()

    yield user


@fixture(scope='session', autouse=True)
def session_user2(sdb):
    """Create a second user named 'OtherUser' in the db for test session.

    This is useful for cases where two different users are needed, such as
    when testing private messages.
    """
    user = User('OtherUser', 'other user password')
    sdb.add(user)
    sdb.commit()

    yield user


@fixture(scope='session', autouse=True)
def session_group(sdb):
    """Create a group named 'sessiongroup' in the db for test session."""
    group = Group('sessiongroup')
    sdb.add(group)
    sdb.commit()

    yield group


@fixture(scope='session')
def base_app(overall_redis_session, sdb):
    """Configure a base WSGI app that webtest can create TestApps based on."""
    testing_app = get_app('development.ini')

    # replace the redis connection used by the redis-sessions library with a
    # connection to the temporary server for this test session
    testing_app.app.registry._redis_sessions = overall_redis_session

    def redis_factory(request):
        # pylint: disable=unused-argument
        return overall_redis_session
    testing_app.app.registry['redis_connection_factory'] = redis_factory

    # replace the session factory function with one that will return the
    # testing db session (inside a nested transaction)
    def session_factory():
        return sdb
    testing_app.app.registry['db_session_factory'] = session_factory

    yield testing_app


@fixture(scope='session')
def webtest(base_app):
    """Create a webtest TestApp and log in as the SessionUser account in it."""
    # create the TestApp - note that specifying wsgi.url_scheme is necessary
    # so that the secure cookies from the session library will work
    app = TestApp(
        base_app,
        extra_environ={'wsgi.url_scheme': 'https'},
        cookiejar=CookieJar(),
    )

    # fetch the login page, fill in the form, and submit it (sets the cookie)
    login_page = app.get('/login')
    login_page.form['username'] = 'SessionUser'
    login_page.form['password'] = 'session user password'
    login_page.form.submit()

    yield app


@fixture(scope='session')
def webtest_loggedout(base_app):
    """Create a logged-out webtest TestApp (no cookies retained)."""
    yield TestApp(base_app)