import asyncio
import collections
import contextlib
import tempfile
import warnings

import pytest
from py import path

from aiohttp.helpers import isasyncgenfunction
from aiohttp.web import Application

from .test_utils import unused_port as _unused_port
from .test_utils import (BaseTestServer, RawTestServer, TestClient, TestServer,
                         loop_context, setup_test_loop, teardown_test_loop)


try:
    import uvloop
except ImportError:  # pragma: no cover
    uvloop = None

try:
    import tokio
except ImportError:  # pragma: no cover
    tokio = None


def pytest_addoption(parser):
    parser.addoption(
        '--fast', action='store_true', default=False,
        help='run tests faster by disabling extra checks')
    parser.addoption(
        '--loop', action='store', default='pyloop',
        help='run tests with specific loop: pyloop, uvloop, tokio or all')
    parser.addoption(
        '--enable-loop-debug', action='store_true', default=False,
        help='enable event loop debug mode')


def pytest_fixture_setup(fixturedef):
    """
    Allow fixtures to be coroutines. Run coroutine fixtures in an event loop.
    """
    func = fixturedef.func

    if isasyncgenfunction(func):
        # async generator fixture
        is_async_gen = True
    elif asyncio.iscoroutinefunction(func):
        # regular async fixture
        is_async_gen = False
    else:
        # not an async fixture, nothing to do
        return

    strip_request = False
    if 'request' not in fixturedef.argnames:
        fixturedef.argnames += ('request',)
        strip_request = True

    def wrapper(*args, **kwargs):
        request = kwargs['request']
        if strip_request:
            del kwargs['request']

        # if neither the fixture nor the test use the 'loop' fixture,
        # 'getfixturevalue' will fail because the test is not parameterized
        # (this can be removed someday if 'loop' is no longer parameterized)
        if 'loop' not in request.fixturenames:
            raise Exception(
                "Asynchronous fixtures must depend on the 'loop' fixture or "
                "be used in tests depending from it."
            )

        _loop = request.getfixturevalue('loop')

        if is_async_gen:
            # for async generators, we need to advance the generator once,
            # then advance it again in a finalizer
            gen = func(*args, **kwargs)

            def finalizer():
                try:
                    return _loop.run_until_complete(gen.__anext__())
                except StopAsyncIteration:  # NOQA
                    pass

            request.addfinalizer(finalizer)
            return _loop.run_until_complete(gen.__anext__())
        else:
            return _loop.run_until_complete(func(*args, **kwargs))

    fixturedef.func = wrapper


@pytest.fixture
def fast(request):
    """--fast config option"""
    return request.config.getoption('--fast')


@pytest.fixture
def loop_debug(request):
    """--enable-loop-debug config option"""
    return request.config.getoption('--enable-loop-debug')


@contextlib.contextmanager
def _runtime_warning_context():
    """
    Context manager which checks for RuntimeWarnings, specifically to
    avoid "coroutine 'X' was never awaited" warnings being missed.

    If RuntimeWarnings occur in the context a RuntimeError is raised.
    """
    with warnings.catch_warnings(record=True) as _warnings:
        yield
        rw = ['{w.filename}:{w.lineno}:{w.message}'.format(w=w)
              for w in _warnings if w.category == RuntimeWarning]
        if rw:
            raise RuntimeError('{} Runtime Warning{},\n{}'.format(
                len(rw),
                '' if len(rw) == 1 else 's',
                '\n'.join(rw)
            ))


@contextlib.contextmanager
def _passthrough_loop_context(loop, fast=False):
    """
    setups and tears down a loop unless one is passed in via the loop
    argument when it's passed straight through.
    """
    if loop:
        # loop already exists, pass it straight through
        yield loop
    else:
        # this shadows loop_context's standard behavior
        loop = setup_test_loop()
        yield loop
        teardown_test_loop(loop, fast=fast)


def pytest_pycollect_makeitem(collector, name, obj):
    """
    Fix pytest collecting for coroutines.
    """
    if collector.funcnamefilter(name) and asyncio.iscoroutinefunction(obj):
        return list(collector._genfunctions(name, obj))


def pytest_pyfunc_call(pyfuncitem):
    """
    Run coroutines in an event loop instead of a normal function call.
    """
    fast = pyfuncitem.config.getoption("--fast")
    if asyncio.iscoroutinefunction(pyfuncitem.function):
        existing_loop = pyfuncitem.funcargs.get('loop', None)
        with _runtime_warning_context():
            with _passthrough_loop_context(existing_loop, fast=fast) as _loop:
                testargs = {arg: pyfuncitem.funcargs[arg]
                            for arg in pyfuncitem._fixtureinfo.argnames}

                task = _loop.create_task(pyfuncitem.obj(**testargs))
                _loop.run_until_complete(task)

        return True


def pytest_generate_tests(metafunc):
    if 'loop_factory' not in metafunc.fixturenames:
        return

    loops = metafunc.config.option.loop
    avail_factories = {'pyloop': asyncio.new_event_loop}

    if uvloop is not None:  # pragma: no cover
        avail_factories['uvloop'] = uvloop.new_event_loop

    if tokio is not None:  # pragma: no cover
        avail_factories['tokio'] = tokio.new_event_loop

    if loops == 'all':
        loops = 'pyloop,uvloop?,tokio?'

    factories = {}
    for name in loops.split(','):
        required = not name.endswith('?')
        name = name.strip(' ?')
        if name not in avail_factories:  # pragma: no cover
            if required:
                raise ValueError(
                    "Unknown loop '%s', available loops: %s" % (
                        name, list(factories.keys())))
            else:
                continue
        factories[name] = avail_factories[name]
    metafunc.parametrize("loop_factory",
                         list(factories.values()),
                         ids=list(factories.keys()))


@pytest.fixture
def loop(loop_factory, fast, loop_debug):
    """Return an instance of the event loop."""
    with loop_context(loop_factory, fast=fast) as _loop:
        if loop_debug:
            _loop.set_debug(True)  # pragma: no cover
        yield _loop
    asyncio.set_event_loop(None)


@pytest.fixture
def unused_port():
    """Return a port that is unused on the current host."""
    return _unused_port


@pytest.yield_fixture
def test_server(loop):
    """Factory to create a TestServer instance, given an app.

    test_server(app, **kwargs)
    """
    servers = []

    async def go(app, *, port=None, **kwargs):
        server = TestServer(app, port=port)
        await server.start_server(loop=loop, **kwargs)
        servers.append(server)
        return server

    yield go

    async def finalize():
        while servers:
            await servers.pop().close()

    loop.run_until_complete(finalize())


@pytest.yield_fixture
def raw_test_server(loop):
    """Factory to create a RawTestServer instance, given a web handler.

    raw_test_server(handler, **kwargs)
    """
    servers = []

    async def go(handler, *, port=None, **kwargs):
        server = RawTestServer(handler, port=port)
        await server.start_server(loop=loop, **kwargs)
        servers.append(server)
        return server

    yield go

    async def finalize():
        while servers:
            await servers.pop().close()

    loop.run_until_complete(finalize())


@pytest.yield_fixture
def test_client(loop):
    """Factory to create a TestClient instance.

    test_client(app, **kwargs)
    test_client(server, **kwargs)
    test_client(raw_server, **kwargs)
    """
    clients = []

    async def go(__param, *args, server_kwargs=None, **kwargs):

        if isinstance(__param, collections.Callable) and \
                not isinstance(__param, (Application, BaseTestServer)):
            __param = __param(loop, *args, **kwargs)
            kwargs = {}
        else:
            assert not args, "args should be empty"

        if isinstance(__param, Application):
            server_kwargs = server_kwargs or {}
            server = TestServer(__param, loop=loop, **server_kwargs)
            client = TestClient(server, loop=loop, **kwargs)
        elif isinstance(__param, BaseTestServer):
            client = TestClient(__param, loop=loop, **kwargs)
        else:
            raise ValueError("Unknown argument type: %r" % type(__param))

        await client.start_server()
        clients.append(client)
        return client

    yield go

    async def finalize():
        while clients:
            await clients.pop().close()

    loop.run_until_complete(finalize())


@pytest.fixture
def shorttmpdir():
    """Provides a temporary directory with a shorter file system path than the
    tmpdir fixture.
    """
    tmpdir = path.local(tempfile.mkdtemp())
    yield tmpdir
    tmpdir.remove(rec=1)
