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

import sys
import time
import requests
from contextlib import contextmanager
from subprocess import Popen, STDOUT
from unittest import TestCase

import nose

from IPython.utils.tempdir import TemporaryDirectory

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

class NotebookTestBase(TestCase):
    """A base class for tests that need a running notebook.
    
    This creates an empty profile in a temp ipython_dir
    and then starts the notebook server with a separate temp notebook_dir.
    """

    port = 12341

    @classmethod
    def wait_until_alive(cls):
        """Wait for the server to be alive"""
        url = 'http://localhost:%i/api/notebooks' % cls.port
        for _ in range(int(MAX_WAITTIME/POLL_INTERVAL)):
            try:
                requests.get(url)
            except requests.exceptions.ConnectionError:
                if cls.notebook.poll() is not None:
                    raise RuntimeError("The notebook server exited with status %s" \
                                        % cls.notebook.poll())
                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"""
        for _ in range(int(MAX_WAITTIME/POLL_INTERVAL)):
            if cls.notebook.poll() is not None:
                return
            time.sleep(POLL_INTERVAL)
    
        raise TimeoutError("Undead notebook server")

    @classmethod
    def setup_class(cls):
        cls.ipython_dir = TemporaryDirectory()
        cls.notebook_dir = TemporaryDirectory()
        notebook_args = [
            sys.executable, '-c',
            'from IPython.html.notebookapp import launch_new_instance; launch_new_instance()',
            '--port=%d' % cls.port,
            '--port-retries=0',  # Don't try any other ports
            '--no-browser',
            '--ipython-dir=%s' % cls.ipython_dir.name,
            '--notebook-dir=%s' % cls.notebook_dir.name,
        ]
        cls.notebook = Popen(notebook_args,
            stdout=nose.iptest_stdstreams_fileno(),
            stderr=STDOUT,
        )
        cls.wait_until_alive()

    @classmethod
    def teardown_class(cls):
        cls.notebook.terminate()
        cls.ipython_dir.cleanup()
        cls.notebook_dir.cleanup()
        cls.wait_until_dead()

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


@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" % (real_status, status)
        if msg:
            assert msg in str(e), e
    else:
        assert False, "Expected HTTP error status"