# Copyright (c) 2014 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.

from contextlib import closing
import logging
import os
import urllib2

from autotest_lib.client.bin import test
from autotest_lib.client.common_lib import error
from autotest_lib.client.common_lib.cros import chrome
from autotest_lib.client.cros.video import histogram_parser


# Chrome flags to use fake camera and skip camera permission.
EXTRA_BROWSER_ARGS = ['--use-fake-device-for-media-stream',
                      '--use-fake-ui-for-media-stream']
FAKE_FILE_ARG = '--use-file-for-fake-video-capture="%s"'
DOWNLOAD_BASE = 'http://commondatastorage.googleapis.com/chromiumos-test-assets-public/crowd/'
VIDEO_NAME = 'crowd720_25frames.y4m'

RTC_VIDEO_DECODE = 'Media.RTCVideoDecoderInitDecodeSucces'
RTC_VIDEO_DECODE_BUCKET = 1
HISTOGRAMS_URL = 'chrome://histograms/'


class video_ChromeRTCHWDecodeUsed(test.test):
    """The test verifies HW Encoding for WebRTC video."""
    version = 1


    def start_loopback(self, cr):
        """
        Opens WebRTC loopback page.

        @param cr: Autotest Chrome instance.
        """
        tab = cr.browser.tabs[0]
        tab.Navigate(cr.browser.http_server.UrlOf(
            os.path.join(self.bindir, 'loopback.html')))
        tab.WaitForDocumentReadyStateToBeComplete()


    def assert_hardware_accelerated(self, cr):
        """
        Checks if WebRTC decoding is hardware accelerated.

        @param cr: Autotest Chrome instance.

        @raises error.TestError if decoding is not hardware accelerated.
        """
        parser = histogram_parser.HistogramParser(cr.browser.tabs.New(),
                                                  RTC_VIDEO_DECODE)
        buckets = parser.buckets

        if (not buckets or not buckets[RTC_VIDEO_DECODE_BUCKET]
                or buckets[RTC_VIDEO_DECODE_BUCKET].percent < 100.0):

            raise error.TestError('%s not found or not at 100 percent. %s'
                                  % RTC_VIDEO_DECODE, str(parser))


    def run_once(self):
        # Download test video.
        url = DOWNLOAD_BASE + VIDEO_NAME
        local_path = os.path.join(self.bindir, VIDEO_NAME)
        self.download_file(url, local_path)

        # Start chrome with test flags.
        EXTRA_BROWSER_ARGS.append(FAKE_FILE_ARG % local_path)
        with chrome.Chrome(extra_browser_args=EXTRA_BROWSER_ARGS) as cr:
            # Open WebRTC loopback page.
            cr.browser.SetHTTPServerDirectories(self.bindir)
            self.start_loopback(cr)

            # Make sure decode is hardware accelerated.
            self.assert_hardware_accelerated(cr)


    def download_file(self, url, local_path):
        """
        Downloads a file from the specified URL.

        @param url: URL of the file.
        @param local_path: the path that the file will be saved to.
        """
        logging.info('Downloading "%s" to "%s"', url, local_path)
        with closing(urllib2.urlopen(url)) as r, open(local_path, 'wb') as w:
            w.write(r.read())