# Copyright 2016 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# -*- coding: utf-8 -*- #
"""Directly processes text of cron.xml.

CronXmlParser is called with an XML string to produce a CronXml object
containing the data from the XML.

CronXmlParser: converts XML to CronXml objct
Cron: describes a single cron specified in cron.xml
"""

from __future__ import absolute_import
from __future__ import division
from __future__ import unicode_literals

from xml.etree import ElementTree

from googlecloudsdk.third_party.appengine.tools import xml_parser_utils
from googlecloudsdk.third_party.appengine.tools.app_engine_config_exception import AppEngineConfigException

# pylint: disable=g-import-not-at-top
from googlecloudsdk.third_party.appengine._internal import six_subset

# groc depends on antlr3 which is py2-only, so conditionally import based on
# python version. See comments under GrocValidator.Validate for more context.
if six_subset.PY2:
  from googlecloudsdk.third_party.appengine.googlecron import groc
  from googlecloudsdk.third_party.appengine.googlecron import groctimespecification
else:
  groc = None
  groctimespecification = None
# pylint: enable=g-import-not-at-top

_RETRY_PARAMETER_TAGS = ('job-retry-limit',
                         'job-age-limit',
                         'min-backoff-seconds',
                         'max-backoff-seconds',
                         'max-doublings')


def GetCronYaml(unused_application, cron_xml_str):
  return _MakeCronListIntoYaml(CronXmlParser().ProcessXml(cron_xml_str))


def _MakeCronListIntoYaml(cron_list):
  """Converts list of yaml statements describing cron jobs into a string."""
  statements = ['cron:']
  for cron in cron_list:
    statements += cron.ToYaml()
  return '\n'.join(statements) + '\n'


def _ProcessRetryParametersNode(node, cron):
  """Converts <retry-parameters> in node to cron.retry_parameters."""

  retry_parameters_node = xml_parser_utils.GetChild(node, 'retry-parameters')
  if retry_parameters_node is None:
    cron.retry_parameters = None
    return

  retry_parameters = _RetryParameters()
  cron.retry_parameters = retry_parameters
  for tag in _RETRY_PARAMETER_TAGS:
    if xml_parser_utils.GetChild(retry_parameters_node, tag) is not None:
      setattr(
          retry_parameters,
          tag.replace('-', '_'),
          xml_parser_utils.GetChildNodeText(retry_parameters_node, tag))


class CronXmlParser(object):
  """Provides logic for walking down XML tree and pulling data."""

  def ProcessXml(self, xml_str):
    """Parses XML string and returns object representation of relevant info.

    Args:
      xml_str: The XML string.
    Returns:
      A list of Cron objects containing information about cron jobs from the
      XML.
    Raises:
      AppEngineConfigException: In case of malformed XML or illegal inputs.
    """

    try:
      self.crons = []
      self.errors = []
      xml_root = ElementTree.fromstring(xml_str)
      if xml_root.tag != 'cronentries':
        raise AppEngineConfigException('Root tag must be <cronentries>')

      for child in xml_root.getchildren():
        self.ProcessCronNode(child)

      if self.errors:
        raise AppEngineConfigException('\n'.join(self.errors))

      return self.crons
    except ElementTree.ParseError:
      raise AppEngineConfigException('Bad input -- not valid XML')

  def ProcessCronNode(self, node):
    """Processes XML <cron> nodes into Cron objects.

    The following information is parsed out:
      description: Describing the purpose of the cron job.
      url: The location of the script.
      schedule: Written in groc; the schedule according to which the job is
        executed.
      timezone: The timezone that the schedule runs in.
      target: Which version of the app this applies to.

    Args:
      node: <cron> XML node in cron.xml.
    """
    tag = xml_parser_utils.GetTag(node)
    if tag != 'cron':
      self.errors.append('Unrecognized node: <%s>' % tag)
      return

    cron = Cron()
    cron.url = xml_parser_utils.GetChildNodeText(node, 'url')
    cron.timezone = xml_parser_utils.GetChildNodeText(node, 'timezone')
    cron.target = xml_parser_utils.GetChildNodeText(node, 'target')
    cron.description = xml_parser_utils.GetChildNodeText(node, 'description')
    cron.schedule = xml_parser_utils.GetChildNodeText(node, 'schedule')
    _ProcessRetryParametersNode(node, cron)

    validation_error = self._ValidateCronEntry(cron)
    if validation_error:
      self.errors.append(validation_error)
    else:
      self.crons.append(cron)

  def _ValidateCronEntry(self, cron):
    # TODO(user): consider timezone validation, not currently done by the
    # Java SDK.
    if not cron.url:
      return 'No URL for <cron> entry'
    if not cron.schedule:
      return "No schedule provided for <cron> entry with URL '%s'" % cron.url
    # If we're running on py3 and don't have access to groctimespecification,
    # then the server will still do the validation on the schedule property.
    if groc and groctimespecification:
      try:
        groctimespecification.GrocTimeSpecification(cron.schedule)
      except groc.GrocException:
        return ("Text '%s' in <schedule> node failed to parse,"
                ' for <cron> entry with url %s.'
                % (cron.schedule, cron.url))


class _RetryParameters(object):
  """Object that contains retry xml tags converted to object attributes."""

  def GetYamlStatementsList(self):
    """Converts retry parameter fields to a YAML statement list."""

    tag_statements = []
    field_names = (tag.replace('-', '_') for tag in _RETRY_PARAMETER_TAGS)
    for field in field_names:
      field_value = getattr(self, field, None)
      if field_value:
        tag_statements.append('    %s: %s' % (field, field_value))

    if not tag_statements:
      return ['  retry_parameters: {}']
    return ['  retry_parameters:'] + tag_statements


class Cron(object):
  """Instances contain information about individual cron entries."""
  TZ_GMT = 'UTC'

  def ToYaml(self):
    """Returns data from Cron object as a list of Yaml statements."""
    statements = [
        '- url: %s' % self._SanitizeForYaml(self.url),
        '  schedule: %s' % self._SanitizeForYaml(self.schedule)]
    for optional in ('target', 'timezone', 'description'):
      field = getattr(self, optional)
      if field:
        statements.append('  %s: %s' % (optional, self._SanitizeForYaml(field)))
    retry_parameters = getattr(self, 'retry_parameters', None)
    if retry_parameters:
      statements += retry_parameters.GetYamlStatementsList()
    return statements

  def _SanitizeForYaml(self, field):
    return "'%s'" % field.replace('\n', ' ').replace("'", "''")
