# Copyright (c) 2013 The Chromium 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 httplib
import json
import logging
import re
import time
import urllib2

import common
from autotest_lib.client.common_lib import base_utils, global_config
from autotest_lib.server.cros.dynamic_suite import constants


_SHERIFF_JS = global_config.global_config.get_config_value(
    'NOTIFICATIONS', 'sheriffs', default='')
_LAB_SHERIFF_JS = global_config.global_config.get_config_value(
    'NOTIFICATIONS', 'lab_sheriffs', default='')
_CHROMIUM_BUILD_URL = global_config.global_config.get_config_value(
    'NOTIFICATIONS', 'chromium_build_url', default='')

LAB_GOOD_STATES = ('open', 'throttled')


class TestLabException(Exception):
    """Exception raised when the Test Lab blocks a test or suite."""
    pass


class ParseBuildNameException(Exception):
    """Raised when ParseBuildName() cannot parse a build name."""
    pass


def ParseBuildName(name):
    """Format a build name, given board, type, milestone, and manifest num.

    @param name: a build name, e.g. 'x86-alex-release/R20-2015.0.0'

    @return board: board the manifest is for, e.g. x86-alex.
    @return type: one of 'release', 'factory', or 'firmware'
    @return milestone: (numeric) milestone the manifest was associated with.
    @return manifest: manifest number, e.g. '2015.0.0'

    """
    match = re.match(r'([\w-]+)-(\w+)/R(\d+)-([\d.ab-]+)', name)
    if match and len(match.groups()) == 4:
        return match.groups()
    raise ParseBuildNameException('%s is a malformed build name.' % name)


def get_label_from_afe(hostname, label_prefix, afe):
    """Retrieve a host's specific label from the AFE.

    Looks for a host label that has the form <label_prefix>:<value>
    and returns the "<value>" part of the label. None is returned
    if there is not a label matching the pattern

    @param hostname: hostname of given DUT.
    @param label_prefix: prefix of label to be matched, e.g., |board:|
    @param afe: afe instance.
    @returns the label that matches the prefix or 'None'

    """
    labels = afe.get_labels(name__startswith=label_prefix,
                            host__hostname__in=[hostname])
    if labels and len(labels) == 1:
        return labels[0].name.split(label_prefix, 1)[1]


def get_board_from_afe(hostname, afe):
    """Retrieve given host's board from its labels in the AFE.

    Looks for a host label of the form "board:<board>", and
    returns the "<board>" part of the label.  `None` is returned
    if there is not a single, unique label matching the pattern.

    @param hostname: hostname of given DUT.
    @param afe: afe instance.
    @returns board from label, or `None`.

    """
    return get_label_from_afe(hostname, constants.BOARD_PREFIX, afe)


def get_build_from_afe(hostname, afe):
    """Retrieve the current build for given host from the AFE.

    Looks through the host's labels in the AFE to determine its build.

    @param hostname: hostname of given DUT.
    @param afe: afe instance.
    @returns The current build or None if it could not find it or if there
             were multiple build labels assigned to this host.

    """
    return get_label_from_afe(hostname, constants.VERSION_PREFIX, afe)


def get_sheriffs(lab_only=False):
    """
    Polls the javascript file that holds the identity of the sheriff and
    parses it's output to return a list of chromium sheriff email addresses.
    The javascript file can contain the ldap of more than one sheriff, eg:
    document.write('sheriff_one, sheriff_two').

    @param lab_only: if True, only pulls lab sheriff.
    @return: A list of chroium.org sheriff email addresses to cc on the bug.
             An empty list if failed to parse the javascript.
    """
    sheriff_ids = []
    sheriff_js_list = _LAB_SHERIFF_JS.split(',')
    if not lab_only:
        sheriff_js_list.extend(_SHERIFF_JS.split(','))

    for sheriff_js in sheriff_js_list:
        try:
            url_content = base_utils.urlopen('%s%s'% (
                _CHROMIUM_BUILD_URL, sheriff_js)).read()
        except (ValueError, IOError) as e:
            logging.warning('could not parse sheriff from url %s%s: %s',
                             _CHROMIUM_BUILD_URL, sheriff_js, str(e))
        except (urllib2.URLError, httplib.HTTPException) as e:
            logging.warning('unexpected error reading from url "%s%s": %s',
                             _CHROMIUM_BUILD_URL, sheriff_js, str(e))
        else:
            ldaps = re.search(r"document.write\('(.*)'\)", url_content)
            if not ldaps:
                logging.warning('Could not retrieve sheriff ldaps for: %s',
                                 url_content)
                continue
            sheriff_ids += ['%s@chromium.org' % alias.replace(' ', '')
                            for alias in ldaps.group(1).split(',')]
    return sheriff_ids


def remote_wget(source_url, dest_path, ssh_cmd):
    """wget source_url from localhost to dest_path on remote host using ssh.

    @param source_url: The complete url of the source of the package to send.
    @param dest_path: The path on the remote host's file system where we would
        like to store the package.
    @param ssh_cmd: The ssh command to use in performing the remote wget.
    """
    wget_cmd = ("wget -O - %s | %s 'cat >%s'" %
                (source_url, ssh_cmd, dest_path))
    base_utils.run(wget_cmd)


_MAX_LAB_STATUS_ATTEMPTS = 5
def _get_lab_status(status_url):
    """Grabs the current lab status and message.

    @returns The JSON object obtained from the given URL.

    """
    retry_waittime = 1
    for _ in range(_MAX_LAB_STATUS_ATTEMPTS):
        try:
            response = urllib2.urlopen(status_url)
        except IOError as e:
            logging.debug('Error occurred when grabbing the lab status: %s.',
                          e)
            time.sleep(retry_waittime)
            continue
        # Check for successful response code.
        if response.getcode() == 200:
            return json.load(response)
        time.sleep(retry_waittime)
    return None


def _decode_lab_status(lab_status, build):
    """Decode lab status, and report exceptions as needed.

    Take a deserialized JSON object from the lab status page, and
    interpret it to determine the actual lab status.  Raise
    exceptions as required to report when the lab is down.

    @param build: build name that we want to check the status of.

    @raises TestLabException Raised if a request to test for the given
                             status and build should be blocked.
    """
    # First check if the lab is up.
    if not lab_status['general_state'] in LAB_GOOD_STATES:
        raise TestLabException('Chromium OS Test Lab is closed: '
                               '%s.' % lab_status['message'])

    # Check if the build we wish to use is disabled.
    # Lab messages should be in the format of:
    #    Lab is 'status' [regex ...] (comment)
    # If the build name matches any regex, it will be blocked.
    build_exceptions = re.search('\[(.*)\]', lab_status['message'])
    if not build_exceptions:
        return
    for build_pattern in build_exceptions.group(1).split():
        if re.search(build_pattern, build):
            raise TestLabException('Chromium OS Test Lab is closed: '
                                   '%s matches %s.' % (
                                           build, build_pattern))
    return


def check_lab_status(build):
    """Check if the lab status allows us to schedule for a build.

    Checks if the lab is down, or if testing for the requested build
    should be blocked.

    @param build: Name of the build to be scheduled for testing.

    @raises TestLabException Raised if a request to test for the given
                             status and build should be blocked.

    """
    # Ensure we are trying to schedule on the actual lab.
    test_server_name = global_config.global_config.get_config_value(
              'SERVER', 'hostname')
    if not test_server_name.startswith('cautotest'):
        return

    # Download the lab status from its home on the web.
    status_url = global_config.global_config.get_config_value(
            'CROS', 'lab_status_url')
    json_status = _get_lab_status(status_url)
    if json_status is None:
        # We go ahead and say the lab is open if we can't get the status.
        logging.warn('Could not get a status from %s', status_url)
        return
    _decode_lab_status(json_status, build)