#!/usr/bin/env python
#
# Copyright 2007 Google Inc.
#
# 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.
#

"""Generates and emails daily exception reports.

See google/appengine/ext/ereporter/__init__.py for usage details.

Valid query string arguments to the report_generator script include:
delete:   Set to 'false' to prevent deletion of exception records from the
          datastore after sending a report. Defaults to 'true'.
debug:    Set to 'true' to return the report in the response instead of
          emailing it.
date:     The date to generate the report for, in yyyy-mm-dd format. Defaults to
          yesterday's date. Useful for debugging.
max_results: Maximum number of entries to include in a report.
sender:   The email address to use as the sender. Must be an administrator.
to:       If specified, send reports to this address. If not specified, all
          admins are sent the report.
versions: 'all' to report on all minor versions, or 'latest' for the latest.
"""





import datetime
import itertools
import os
import re
from xml.sax import saxutils

from google.appengine.api import mail
from google.appengine.ext import db
from google.appengine.ext import ereporter
from google.appengine.ext import webapp
from google.appengine.ext.webapp import template
from google.appengine.ext.webapp.util import run_wsgi_app


def isTrue(val):
  """Determines if a textual value represents 'true'.

  Args:
    val: A string, which may be 'true', 'yes', 't', '1' to indicate True.
  Returns:
    True or False
  """
  val = val.lower()
  return val == 'true' or val == 't' or val == '1' or val == 'yes'


class ReportGenerator(webapp.RequestHandler):
  """Handler class to generate and email an exception report."""

  DEFAULT_MAX_RESULTS = 100

  def __init__(self, send_mail=mail.send_mail,
               mail_admins=mail.send_mail_to_admins):
    super(ReportGenerator, self).__init__()

    self.send_mail = send_mail
    self.send_mail_to_admins = mail_admins

  def GetQuery(self, order=None):
    """Creates a query object that will retrieve the appropriate exceptions.

    Returns:
      A query to retrieve the exceptions required.
    """
    q = ereporter.ExceptionRecord.all()
    q.filter('date =', self.yesterday)
    q.filter('major_version =', self.major_version)
    if self.version_filter.lower() == 'latest':
      q.filter('minor_version =', self.minor_version)
    if order:
      q.order(order)
    return q

  def GenerateReport(self, exceptions):
    """Generates an HTML exception report.

    Args:
      exceptions: A list of ExceptionRecord objects. This argument will be
        modified by this function.
    Returns:
      An HTML exception report.
    """
    exceptions.sort(key=lambda e: (e.minor_version, -e.count))
    versions = [(minor, list(excs)) for minor, excs
                in itertools.groupby(exceptions, lambda e: e.minor_version)]

    template_values = {
        'version_filter': self.version_filter,
        'version_count': len(versions),

        'exception_count': sum(len(excs) for _, excs in versions),

        'occurrence_count': sum(y.count for x in versions for y in x[1]),
        'app_id': self.app_id,
        'major_version': self.major_version,
        'date': self.yesterday,
        'versions': versions,
    }
    path = os.path.join(os.path.dirname(__file__), 'templates', 'report.html')
    return template.render(path, template_values)

  def SendReport(self, report):
    """Emails an exception report.

    Args:
      report: A string containing the report to send.
    """
    subject = ('Daily exception report for app "%s", major version "%s"'
               % (self.app_id, self.major_version))
    report_text = saxutils.unescape(re.sub('<[^>]+>', '', report))
    mail_args = {
        'sender': self.sender,
        'subject': subject,
        'body': report_text,
        'html': report,
    }
    if self.to:
      mail_args['to'] = self.to
      self.send_mail(**mail_args)
    else:
      self.send_mail_to_admins(**mail_args)

  def get(self):
    self.version_filter = self.request.GET.get('versions', 'all')
    self.sender = self.request.GET['sender']
    self.to = self.request.GET.get('to', None)
    report_date = self.request.GET.get('date', None)
    if report_date:
      self.yesterday = datetime.date(*[int(x) for x in report_date.split('-')])
    else:
      self.yesterday = datetime.date.today() - datetime.timedelta(days=1)
    self.app_id = os.environ['APPLICATION_ID']
    version = os.environ['CURRENT_VERSION_ID']
    self.major_version, self.minor_version = version.rsplit('.', 1)
    self.minor_version = int(self.minor_version)
    self.max_results = int(self.request.GET.get('max_results',
                                                self.DEFAULT_MAX_RESULTS))
    self.debug = isTrue(self.request.GET.get('debug', 'false'))
    self.delete = isTrue(self.request.GET.get('delete', 'true'))

    try:
      exceptions = self.GetQuery(order='-minor_version').fetch(self.max_results)
    except db.NeedIndexError:
      exceptions = self.GetQuery().fetch(self.max_results)

    if exceptions:
      report = self.GenerateReport(exceptions)
      if self.debug:
        self.response.out.write(report)
      else:
        self.SendReport(report)

      if self.delete:
        db.delete(exceptions)


application = webapp.WSGIApplication([('.*', ReportGenerator)])


def main():
  run_wsgi_app(application)


if __name__ == '__main__':
  main()