"""
Test helper functions and base classes.
"""


import functools
import json
import os
import sys
from datetime import datetime
from unittest import SkipTest, TestCase

import requests
from bok_choy.javascript import js_defined
from bok_choy.page_object import XSS_INJECTION
from bok_choy.promise import EmptyPromise, Promise
from bok_choy.web_app_test import WebAppTest
from opaque_keys.edx.locator import CourseLocator
from path import Path as path
from pymongo import MongoClient  # lint-amnesty, pylint: disable=unused-import
from selenium.common.exceptions import StaleElementReferenceException
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.support.select import Select
from selenium.webdriver.support.ui import WebDriverWait

from capa.tests.response_xml_factory import MultipleChoiceResponseXMLFactory
from common.test.acceptance.fixtures.course import XBlockFixtureDesc
from common.test.acceptance.pages.common.auto_auth import AutoAuthPage
from xmodule.partitions.partitions import UserPartition

MAX_EVENTS_IN_FAILURE_OUTPUT = 20


def skip_if_browser(browser):
    """
    Method decorator that skips a test if browser is `browser`

    Args:
        browser (str): name of internet browser

    Returns:
        Decorated function

    """
    def decorator(test_function):
        """
        The decorator to be applied to the test function.
        """
        @functools.wraps(test_function)
        def wrapper(self, *args, **kwargs):
            if self.browser.name == browser:
                raise SkipTest(f'Skipping as this test will not work with {browser}')
            test_function(self, *args, **kwargs)
        return wrapper
    return decorator


def is_youtube_available():
    """
    Check if the required youtube urls are available.

    If a URL in `youtube_api_urls` is not reachable then subsequent URLs will not be checked.

    Returns:
        bool:

    """
    # TODO: Design and implement a better solution that is reliable and repeatable,
    # reflects how the application works in production, and limits the third-party
    # network traffic (e.g. repeatedly retrieving the js from youtube from the browser).

    youtube_api_urls = {
        'main': 'https://www.youtube.com/',
        'player': 'https://www.youtube.com/iframe_api',
        # For transcripts, you need to check an actual video, so we will
        # just specify our default video and see if that one is available.
        'transcript': 'http://video.google.com/timedtext?lang=en&v=3_yD_cEKoCk',
    }

    for url in youtube_api_urls.values():
        try:
            response = requests.get(url, allow_redirects=False)
        except requests.exceptions.ConnectionError:
            return False

        if response.status_code >= 300:
            return False

    return True


def is_focused_on_element(browser, selector):
    """
    Check if the focus is on the element that matches the selector.
    """
    return browser.execute_script(f"return $('{selector}').is(':focus')")


def load_data_str(rel_path):
    """
    Load a file from the "data" directory as a string.
    `rel_path` is the path relative to the data directory.
    """
    full_path = path(__file__).abspath().dirname() / "data" / rel_path
    with open(full_path) as data_file:
        return data_file.read()


def remove_file(filename):
    """
    Remove a file if it exists
    """
    if os.path.exists(filename):
        os.remove(filename)


def disable_animations(page):
    """
    Disable jQuery and CSS3 animations.
    """
    disable_jquery_animations(page)
    disable_css_animations(page)


def enable_animations(page):
    """
    Enable jQuery and CSS3 animations.
    """
    enable_jquery_animations(page)
    enable_css_animations(page)


@js_defined('window.jQuery')
def disable_jquery_animations(page):
    """
    Disable jQuery animations.
    """
    page.browser.execute_script("jQuery.fx.off = true;")


@js_defined('window.jQuery')
def enable_jquery_animations(page):
    """
    Enable jQuery animations.
    """
    page.browser.execute_script("jQuery.fx.off = false;")


def disable_css_animations(page):
    """
    Disable CSS3 animations, transitions, transforms.
    """
    page.browser.execute_script("""
        var id = 'no-transitions';

        // if styles were already added, just do nothing.
        if (document.getElementById(id)) {
            return;
        }

        var css = [
                '* {',
                    '-webkit-transition: none !important;',
                    '-moz-transition: none !important;',
                    '-o-transition: none !important;',
                    '-ms-transition: none !important;',
                    'transition: none !important;',
                    '-webkit-transition-property: none !important;',
                    '-moz-transition-property: none !important;',
                    '-o-transition-property: none !important;',
                    '-ms-transition-property: none !important;',
                    'transition-property: none !important;',
                    '-webkit-transform: none !important;',
                    '-moz-transform: none !important;',
                    '-o-transform: none !important;',
                    '-ms-transform: none !important;',
                    'transform: none !important;',
                    '-webkit-animation: none !important;',
                    '-moz-animation: none !important;',
                    '-o-animation: none !important;',
                    '-ms-animation: none !important;',
                    'animation: none !important;',
                '}'
            ].join(''),
            head = document.head || document.getElementsByTagName('head')[0],
            styles = document.createElement('style');

        styles.id = id;
        styles.type = 'text/css';
        if (styles.styleSheet){
          styles.styleSheet.cssText = css;
        } else {
          styles.appendChild(document.createTextNode(css));
        }

        head.appendChild(styles);
    """)


def enable_css_animations(page):
    """
    Enable CSS3 animations, transitions, transforms.
    """
    page.browser.execute_script("""
        var styles = document.getElementById('no-transitions'),
            head = document.head || document.getElementsByTagName('head')[0];

        head.removeChild(styles)
    """)


def select_option_by_text(select_browser_query, option_text, focus_out=False):
    """
    Chooses an option within a select by text (helper method for Select's select_by_visible_text method).

    Wrap this in a Promise to prevent a StaleElementReferenceException
    from being raised while the DOM is still being rewritten
    """
    def select_option(query, value):
        """ Get the first select element that matches the query and select the desired value. """
        try:
            select = Select(query.first.results[0])
            select.select_by_visible_text(value)
            if focus_out:
                query.first.results[0].send_keys(Keys.TAB)
            return True
        except StaleElementReferenceException:
            return False

    msg = f'Selected option {option_text}'
    EmptyPromise(lambda: select_option(select_browser_query, option_text), msg).fulfill()


def get_selected_option_text(select_browser_query):
    """
    Returns the text value for the first selected option within a select.

    Wrap this in a Promise to prevent a StaleElementReferenceException
    from being raised while the DOM is still being rewritten
    """
    def get_option(query):
        """ Get the first select element that matches the query and return its value. """
        try:
            select = Select(query.first.results[0])
            return (True, select.first_selected_option.text)
        except StaleElementReferenceException:
            return (False, None)

    text = Promise(lambda: get_option(select_browser_query), 'Retrieved selected option text').fulfill()
    return text


def get_options(select_browser_query):
    """
    Returns all the options for the given select.
    """
    return Select(select_browser_query.first.results[0]).options


def generate_course_key(org, number, run):
    """
    Makes a CourseLocator from org, number and run
    """
    default_store = os.environ.get('DEFAULT_STORE', 'draft')
    return CourseLocator(org, number, run, deprecated=(default_store == 'draft'))


def select_option_by_value(browser_query, value, focus_out=False):
    """
    Selects a html select element by matching value attribute
    """
    select = Select(browser_query.first.results[0])
    select.select_by_value(value)

    def options_selected():
        """
        Returns True if all options in select element where value attribute
        matches `value`. if any option is not selected then returns False
        and select it. if value is not an option choice then it returns False.
        """
        all_options_selected = True
        has_option = False
        for opt in select.options:
            if opt.get_attribute('value') == value:
                has_option = True
                if not opt.is_selected():
                    all_options_selected = False
                    opt.click()
        if all_options_selected and not has_option:
            all_options_selected = False
        if focus_out:
            browser_query.first.results[0].send_keys(Keys.TAB)
        return all_options_selected

    # Make sure specified option is actually selected
    EmptyPromise(options_selected, "Option is selected").fulfill()


def create_multiple_choice_xml(correct_choice=2, num_choices=4):
    """
    Return the Multiple Choice Problem XML, given the name of the problem.
    """
    # all choices are incorrect except for correct_choice
    choices = [False for _ in range(num_choices)]
    choices[correct_choice] = True

    choice_names = [f'choice_{index}' for index in range(num_choices)]
    question_text = f'The correct answer is Choice {correct_choice}'

    return MultipleChoiceResponseXMLFactory().build_xml(
        question_text=question_text,
        choices=choices,
        choice_names=choice_names,
    )


def create_multiple_choice_problem(problem_name):
    """
    Return the Multiple Choice Problem Descriptor, given the name of the problem.
    """
    xml_data = create_multiple_choice_xml()
    return XBlockFixtureDesc(
        'problem',
        problem_name,
        data=xml_data,
        metadata={'rerandomize': 'always'}
    )


def auto_auth(browser, username, email, staff, course_id, **kwargs):
    """
    Logout and login with given credentials.
    """
    AutoAuthPage(browser, username=username, email=email, course_id=course_id, staff=staff, **kwargs).visit()


class EventsTestMixin(TestCase):
    """
    Helpers and setup for running tests that evaluate events emitted
    """
    def setUp(self):
        super().setUp()
        mongo_host = 'edx.devstack.mongo' if 'BOK_CHOY_HOSTNAME' in os.environ else 'localhost'
        self.event_collection = MongoClient(mongo_host)["test"]["events"]
        self.start_time = datetime.now()


class AcceptanceTest(WebAppTest):
    """
    The base class of all acceptance tests.
    """

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        # Use long messages so that failures show actual and expected values
        self.longMessage = True  # pylint: disable=invalid-name

    def tearDown(self):
        self._save_console_log()
        super().tearDown()

    def _save_console_log(self):
        """
        Retrieve any JS errors caught by our error handler in the browser
        and save them to a log file.  This is a workaround for Firefox not
        supporting the Selenium log capture API yet; for details, see
        https://github.com/mozilla/geckodriver/issues/284
        """
        browser_name = os.environ.get('SELENIUM_BROWSER', 'firefox')
        if browser_name != 'firefox':
            return
        result = sys.exc_info()
        exception_type = result[0]

        # Do not save for skipped tests.
        if exception_type is SkipTest:
            return

        # If the test failed, save the browser console log.
        # The exception info will either be an assertion error (on failure)
        # or an actual exception (on error)
        if result != (None, None, None):
            logs = self.browser.execute_script("return window.localStorage.getItem('console_log_capture');")
            if not logs:
                return
            logs = json.loads(logs)

            log_dir = os.environ.get('SELENIUM_DRIVER_LOG_DIR')
            if log_dir and not os.path.exists(log_dir):
                os.makedirs(log_dir)

            log_path = os.path.join(log_dir, f'{self.id()}_browser.log')
            with open(log_path, 'w') as browser_log:
                for (message, url, line_no, col_no, stack) in logs:
                    browser_log.write("{}:{}:{}: {}\n    {}\n".format(
                        url,
                        line_no,
                        col_no,
                        message,
                        (stack or "").replace('\n', '\n    ')
                    ))


class UniqueCourseTest(AcceptanceTest):
    """
    Test that provides a unique course ID.
    """

    def setUp(self):
        super().setUp()

        self.course_info = {
            'org': 'test_org',
            'number': self.unique_id,
            'run': 'test_run',
            'display_name': 'Test Course' + XSS_INJECTION + self.unique_id
        }

    @property
    def course_id(self):
        """
        Returns the serialized course_key for the test
        """
        # TODO - is there a better way to make this agnostic to the underlying default module store?
        default_store = os.environ.get('DEFAULT_STORE', 'draft')
        course_key = CourseLocator(
            self.course_info['org'],
            self.course_info['number'],
            self.course_info['run'],
            deprecated=(default_store == 'draft')
        )
        return str(course_key)


class YouTubeConfigError(Exception):
    """
    Error occurred while configuring YouTube Stub Server.
    """
    pass  # lint-amnesty, pylint: disable=unnecessary-pass


class YouTubeStubConfig:
    """
    Configure YouTube Stub Server.
    """

    YOUTUBE_HOSTNAME = os.environ.get('BOK_CHOY_HOSTNAME', '127.0.0.1')
    PORT = 9080
    URL = f'http://{YOUTUBE_HOSTNAME}:{PORT}/'

    @classmethod
    def configure(cls, config):
        """
        Allow callers to configure the stub server using the /set_config URL.

        Arguments:
            config (dict): Configuration dictionary.

        Raises:
            YouTubeConfigError

        """
        youtube_stub_config_url = cls.URL + 'set_config'

        config_data = {param: json.dumps(value) for param, value in config.items()}
        response = requests.put(youtube_stub_config_url, data=config_data)

        if not response.ok:
            raise YouTubeConfigError(
                'YouTube Server Configuration Failed. URL {}, Configuration Data: {}, Status was {}'.format(
                    youtube_stub_config_url, config, response.status_code))

    @classmethod
    def reset(cls):
        """
        Reset YouTube Stub Server Configurations using the /del_config URL.

        Raises:
            YouTubeConfigError

        """
        youtube_stub_config_url = cls.URL + 'del_config'

        response = requests.delete(youtube_stub_config_url)

        if not response.ok:
            raise YouTubeConfigError(
                'YouTube Server Configuration Failed. URL: {} Status was {}'.format(
                    youtube_stub_config_url, response.status_code))

    @classmethod
    def get_configuration(cls):
        """
        Allow callers to get current stub server configuration.

        Returns:
            dict

        """
        youtube_stub_config_url = cls.URL + 'get_config'

        response = requests.get(youtube_stub_config_url)

        if response.ok:
            return json.loads(response.content.decode('utf-8'))
        else:
            return {}


def click_and_wait_for_window(page, element):
    """
    To avoid a race condition, click an element that launces a new window, and
    wait for that window to launch.
    To check this, make sure the number of window_handles increases by one.

    Arguments:
    page (PageObject): Page object to perform method on
    element (WebElement): Clickable element that triggers the new window to open
    """
    num_windows = len(page.browser.window_handles)
    element.click()
    WebDriverWait(page.browser, 10).until(
        lambda driver: len(driver.window_handles) > num_windows
    )


def create_user_partition_json(partition_id, name, description, groups, scheme="random"):
    """
    Helper method to create user partition JSON. If scheme is not supplied, "random" is used.
    """
    # All that is persisted about a scheme is its name.
    class MockScheme:
        name = scheme

    return UserPartition(
        partition_id, name, description, groups, MockScheme()
    ).to_json()