"""Base class for notebook tests."""

from __future__ import print_function

import os
import sys
import time
import requests
from contextlib import contextmanager
from threading import Thread, Event
from unittest import TestCase

pjoin = os.path.join

try:
    from unittest.mock import patch
except ImportError:
    from mock import patch #py2

from tornado.ioloop import IOLoop

import jupyter_core.paths
from ..notebookapp import NotebookApp
from ipython_genutils.tempdir import TemporaryDirectory

MAX_WAITTIME = 30   # seconds to wait for notebook server to start
POLL_INTERVAL = 0.1 # time between attempts

# TimeoutError is a builtin on Python 3. This can be removed when we stop
# supporting Python 2.
class TimeoutError(Exception):
    pass

class NotebookTestBase(TestCase):
    """A base class for tests that need a running notebook.
    
    This create some empty config and runtime directories
    and then starts the notebook server with them.
    """

    port = 12341
    config = None
    # run with a base URL that would be escaped,
    # to test that we don't double-escape URLs
    url_prefix = '/a%40b/'

    @classmethod
    def wait_until_alive(cls):
        """Wait for the server to be alive"""
        url = cls.base_url() + 'api/contents'
        for _ in range(int(MAX_WAITTIME/POLL_INTERVAL)):
            try:
                requests.get(url)
            except Exception as e:
                if not cls.notebook_thread.is_alive():
                    raise RuntimeError("The notebook server failed to start")
                time.sleep(POLL_INTERVAL)
            else:
                return

        raise TimeoutError("The notebook server didn't start up correctly.")
    
    @classmethod
    def wait_until_dead(cls):
        """Wait for the server process to terminate after shutdown"""
        cls.notebook_thread.join(timeout=MAX_WAITTIME)
        if cls.notebook_thread.is_alive():
            raise TimeoutError("Undead notebook server")

    @classmethod
    def setup_class(cls):
        cls.home_dir = TemporaryDirectory()
        data_dir = TemporaryDirectory()
        cls.env_patch = patch.dict('os.environ', {
            'HOME': cls.home_dir.name,
            'PYTHONPATH': os.pathsep.join(sys.path),
            'IPYTHONDIR': pjoin(cls.home_dir.name, '.ipython'),
            'JUPYTER_DATA_DIR' : data_dir.name
        })
        cls.env_patch.start()
        cls.path_patch = patch.object(jupyter_core.paths, 'SYSTEM_JUPYTER_PATH', [])
        cls.path_patch.start()
        cls.config_dir = TemporaryDirectory()
        cls.data_dir = data_dir
        cls.runtime_dir = TemporaryDirectory()
        cls.notebook_dir = TemporaryDirectory()
        
        started = Event()
        def start_thread():
            app = cls.notebook = NotebookApp(
                port=cls.port,
                port_retries=0,
                open_browser=False,
                config_dir=cls.config_dir.name,
                data_dir=cls.data_dir.name,
                runtime_dir=cls.runtime_dir.name,
                notebook_dir=cls.notebook_dir.name,
                base_url=cls.url_prefix,
                config=cls.config,
            )
            # don't register signal handler during tests
            app.init_signal = lambda : None
            # clear log handlers and propagate to root for nose to capture it
            # needs to be redone after initialize, which reconfigures logging
            app.log.propagate = True
            app.log.handlers = []
            app.initialize(argv=[])
            app.log.propagate = True
            app.log.handlers = []
            loop = IOLoop.current()
            loop.add_callback(started.set)
            try:
                app.start()
            finally:
                # set the event, so failure to start doesn't cause a hang
                started.set()
                app.session_manager.close()
        cls.notebook_thread = Thread(target=start_thread)
        cls.notebook_thread.start()
        started.wait()
        cls.wait_until_alive()

    @classmethod
    def teardown_class(cls):
        cls.notebook.stop()
        cls.wait_until_dead()
        cls.home_dir.cleanup()
        cls.config_dir.cleanup()
        cls.data_dir.cleanup()
        cls.runtime_dir.cleanup()
        cls.notebook_dir.cleanup()
        cls.env_patch.stop()
        cls.path_patch.stop()

    @classmethod
    def base_url(cls):
        return 'http://localhost:%i%s' % (cls.port, cls.url_prefix)


@contextmanager
def assert_http_error(status, msg=None):
    try:
        yield
    except requests.HTTPError as e:
        real_status = e.response.status_code
        assert real_status == status, \
                    "Expected status %d, got %d" % (status, real_status)
        if msg:
            assert msg in str(e), e
    else:
        assert False, "Expected HTTP error status"