# Copyright 2015 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import utils

from autotest_lib.client.common_lib import error
from autotest_lib.client.cros.enterprise import enterprise_policy_base


class policy_ImagesAllowedForUrls(enterprise_policy_base.EnterprisePolicyTest):
    """Test ImagesAllowedForUrls policy effect on CrOS look & feel.

    This test verifies the behavior of Chrome OS with a range of valid values
    for the ImagesAllowedForUrls user policies. These values are covered by
    four test cases, named: NotSet_Block, 1Url_Allow, 2Urls_Block, and
    3Urls_Allow.

    When the policy value is None (as in case=NotSet_Block), then images are
    blocked on any page. When the value is set to a single domain (such as
    case=1Url_Allow), images are allowed on any page with that domain. When
    set to multiple domains (as in case=2Urls_Block or 3Urls_Allow), then
    images are allowed on any page with a domain that matches any of the
    listed domains.

    Two test cases (1Url_Allow, 3Urls_Allow) are designed to allow images
    to be shown on the test page. The other two test cases (NotSet_Block,
    2Urls_Block) are designed to block images on the test page.

    Note this test has a dependency on the DefaultImagesSetting policy, which
    is partially tested herein, and by the test policy_ImagesBlockedForUrls.
    For this test, we set DefaultImagesSetting=2. This blocks images on all
    pages except those with a domain listed in ImagesAllowedForUrls. For the
    test policy_ImagesBlockedForUrls, we set DefaultImagesSetting=1. That
    allows images to be shown on all pages except those with domains listed in
    ImagesBlockedForUrls.

    """
    version = 1

    def initialize(self, **kwargs):
        """Initialize this test."""
        self._initialize_test_constants()
        super(policy_ImagesAllowedForUrls, self).initialize(**kwargs)
        self.start_webserver()


    def _initialize_test_constants(self):
        """Initialize test-specific constants, some from class constants."""
        self.POLICY_NAME = 'ImagesAllowedForUrls'
        self.TEST_FILE = 'kittens.html'
        self.TEST_URL = '%s/%s' % (self.WEB_HOST, self.TEST_FILE)
        self.MINIMUM_IMAGE_WIDTH = 640

        self.URL1_DATA = [self.WEB_HOST]
        self.URL2_DATA = ['http://www.bing.com', 'https://www.yahoo.com']
        self.URL3_DATA = ['http://www.bing.com', self.WEB_HOST,
                          'https://www.yahoo.com']
        self.TEST_CASES = {
            'NotSet_Block': None,
            '1Url_Allow': self.URL1_DATA,
            '2Urls_Block': self.URL2_DATA,
            '3Urls_Allow': self.URL3_DATA
        }
        self.STARTUP_URLS = ['chrome://policy', 'chrome://settings']
        self.SUPPORTING_POLICIES = {
            'DefaultImagesSetting': 2,
            'BookmarkBarEnabled': False,
            'RestoreOnStartupURLs': self.STARTUP_URLS,
            'RestoreOnStartup': 4
        }


    def _wait_for_page_ready(self, tab):
        utils.poll_for_condition(
            lambda: tab.EvaluateJavaScript('pageReady'),
            exception=error.TestError('Test page is not ready.'))


    def _is_image_blocked(self, tab):
        image_width = tab.EvaluateJavaScript(
            "document.getElementById('kittens_id').naturalWidth")
        return image_width < self.MINIMUM_IMAGE_WIDTH


    def _test_images_allowed_for_urls(self, policy_value):
        """Verify CrOS enforces the ImagesAllowedForUrls policy.

        When ImagesAllowedForUrls is undefined, images shall be blocked on
        all pages. When ImagesAllowedForUrls contains one or more URLs, images
        shall be shown only on the pages whose domain matches any of the
        listed domains.

        @param policy_value: policy value for this case.

        """
        tab = self.navigate_to_url(self.TEST_URL)
        self._wait_for_page_ready(tab)
        image_is_blocked = self._is_image_blocked(tab)

        # String |WEB_HOST| shall be found in string |policy_value| for test
        # cases 1Url_Allow and 3Urls_Allow, but not for NotSet_Block and
        # 2Urls_Block.
        if policy_value is not None and self.WEB_HOST in policy_value:
            if image_is_blocked:
                raise error.TestFail('Image should not be blocked.')
        else:
            if not image_is_blocked:
                raise error.TestFail('Image should be blocked.')
        tab.Close()


    def run_once(self, case):
        """Setup and run the test configured for the specified test case.

        @param case: Name of the test case to run.

        """
        case_value = self.TEST_CASES[case]
        self.SUPPORTING_POLICIES[self.POLICY_NAME] = case_value
        self.setup_case(user_policies=self.SUPPORTING_POLICIES)
        self._test_images_allowed_for_urls(case_value)