# Copyright 2015 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.

"""Provides a web interface for dumping graph data as JSON.

This is meant to be used with /load_from_prod in order to easily grab
data for a graph to a local server for testing.
"""

import base64
import json

from google.appengine.ext import ndb
from google.appengine.ext.ndb import model

from dashboard import request_handler
from dashboard import utils
from dashboard.models import anomaly
from dashboard.models import graph_data

_DEFAULT_MAX_POINTS = 500
# This is about the limit we want to return since we fetch many associated
# entities for each anomaly.
_DEFAULT_MAX_ANOMALIES = 30


class DumpGraphJsonHandler(request_handler.RequestHandler):
  """Handler for extracting entities from datastore."""

  def get(self):
    """Handles dumping dashboard data."""
    if self.request.get('sheriff'):
      self._DumpAnomalyDataForSheriff()
    elif self.request.get('test_path'):
      self._DumpTestData()
    else:
      self.ReportError('No parameters specified.')

  def _DumpTestData(self):
    """Dumps data for the requested test.

    Request parameters:
      test_path: A single full test path, including master/bot.
      num_points: Max number of Row entities (optional).
      end_rev: Ending revision number, inclusive (optional).

    Outputs:
      JSON array of encoded protobuf messages, which encode all of
      the datastore entities relating to one test (including Master, Bot,
      Test, Row, Anomaly and Sheriff entities).
    """
    test_path = self.request.get('test_path')
    num_points = int(self.request.get('num_points', _DEFAULT_MAX_POINTS))
    end_rev = self.request.get('end_rev')
    test_key = utils.TestKey(test_path)

    # List of datastore entities that will be dumped.
    entities = []

    entities.extend(self._GetTestAncestors([test_key]))

    # Get the Row entities.
    q = graph_data.Row.query()
    q = q.filter(graph_data.Row.parent_test == test_key)
    if end_rev:
      q = q.filter(graph_data.Row.revision <= int(end_rev))
    q = q.order(-graph_data.Row.revision)
    entities += q.fetch(limit=num_points)

    # Get the Anomaly and Sheriff entities.
    alerts = anomaly.Anomaly.query().filter(
        anomaly.Anomaly.test == test_key).fetch()
    sheriff_keys = {alert.sheriff for alert in alerts}
    sheriffs = [sheriff.get() for sheriff in sheriff_keys]
    entities += alerts
    entities += sheriffs

    # Convert the entities to protobuf message strings and output as JSON.
    protobuf_strings = map(EntityToBinaryProtobuf, entities)
    self.response.out.write(json.dumps(protobuf_strings))

  def _DumpAnomalyDataForSheriff(self):
    """Dumps Anomaly data for all sheriffs.

    Request parameters:
      sheriff: Sheriff name.
      num_points: Max number of Row entities (optional).
      num_alerts: Max number of Anomaly entities (optional).

    Outputs:
      JSON array of encoded protobuf messages, which encode all of
      the datastore entities relating to one test (including Master, Bot,
      Test, Row, Anomaly and Sheriff entities).
    """
    sheriff_name = self.request.get('sheriff')
    num_points = int(self.request.get('num_points', _DEFAULT_MAX_POINTS))
    num_anomalies = int(self.request.get('num_alerts', _DEFAULT_MAX_ANOMALIES))
    sheriff = ndb.Key('Sheriff', sheriff_name).get()
    if not sheriff:
      self.ReportError('Unknown sheriff specified.')
      return

    anomalies = self._FetchAnomalies(sheriff, num_anomalies)
    test_keys = [a.test for a in anomalies]

    # List of datastore entities that will be dumped.
    entities = []

    entities.extend(self._GetTestAncestors(test_keys))

    # Get the Row entities.
    entities.extend(self._FetchRowsAsync(test_keys, num_points))

    # Add the Anomaly and Sheriff entities.
    entities += anomalies
    entities.append(sheriff)

    # Convert the entities to protobuf message strings and output as JSON.
    protobuf_strings = map(EntityToBinaryProtobuf, entities)
    self.response.out.write(json.dumps(protobuf_strings))

  def _GetTestAncestors(self, test_keys):
    """Get the Test, Bot, and Master entities that are ancestors of test."""
    entities = []
    added_parents = set()
    for test_key in test_keys:
      parent = test_key.get()
      while parent:
        if parent.key not in added_parents:
          entities.append(parent)
          added_parents.add(parent.key)
        parent = parent.key.parent()
        if parent:
          parent = parent.get()
    return entities

  def _FetchRowsAsync(self, test_keys, num_points):
    """Fetches recent Row asychronously across all 'test_keys'."""
    rows = []
    futures = []
    for test_key in test_keys:
      q = graph_data.Row.query()
      q = q.filter(graph_data.Row.parent_test == test_key)
      q = q.order(-graph_data.Row.revision)
      futures.append(q.fetch_async(limit=num_points))
    ndb.Future.wait_all(futures)
    for future in futures:
      rows.extend(future.get_result())
    return rows

  def _FetchAnomalies(self, sheriff, num_anomalies):
    """Fetches recent anomalies for 'sheriff'."""
    q = anomaly.Anomaly.query(
        anomaly.Anomaly.sheriff == sheriff.key)
    q = q.order(-anomaly.Anomaly.timestamp)
    return q.fetch(limit=num_anomalies)


def EntityToBinaryProtobuf(entity):
  """Converts an ndb entity to a protobuf message in binary format."""
  # Encode in binary representation of the protocol buffer.
  message = ndb.ModelAdapter().entity_to_pb(entity).Encode()
  # Base64 encode the data to text format for json.dumps.
  return base64.b64encode(message)


def BinaryProtobufToEntity(pb_str):
  """Converts a protobuf message in binary format to an ndb entity.

  Args:
    pb_str: Binary encoded protocol buffer which is encoded as text.

  Returns:
    A ndb Entity.
  """
  message = model.entity_pb.EntityProto(base64.b64decode(pb_str))
  return ndb.ModelAdapter().pb_to_entity(message)