#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You 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
#
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# 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
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"""
DirectRunner implementation of MetricResults. It is in charge not only of
responding to queries of current metrics, but also of keeping the common
state consistent.
"""
import threading
from collections import defaultdict

from apache_beam.metrics.cells import CounterAggregator
from apache_beam.metrics.cells import DistributionAggregator
from apache_beam.metrics.cells import GaugeAggregator
from apache_beam.metrics.execution import MetricKey
from apache_beam.metrics.execution import MetricResult
from apache_beam.metrics.metric import MetricResults


class DirectMetrics(MetricResults):
  def __init__(self):
    self._counters = defaultdict(
        lambda: DirectMetric(CounterAggregator()))
    self._distributions = defaultdict(
        lambda: DirectMetric(DistributionAggregator()))
    self._gauges = defaultdict(
        lambda: DirectMetric(GaugeAggregator()))

  def _apply_operation(self, bundle, updates, op):
    for k, v in updates.counters.items():
      op(self._counters[k], bundle, v)

    for k, v in updates.distributions.items():
      op(self._distributions[k], bundle, v)

    for k, v in updates.gauges.items():
      op(self._gauges[k], bundle, v)

  def commit_logical(self, bundle, updates):
    op = lambda obj, bundle, update: obj.commit_logical(bundle, update)
    self._apply_operation(bundle, updates, op)

  def commit_physical(self, bundle, updates):
    op = lambda obj, bundle, update: obj.commit_physical(bundle, update)
    self._apply_operation(bundle, updates, op)

  def update_physical(self, bundle, updates):
    op = lambda obj, bundle, update: obj.update_physical(bundle, update)
    self._apply_operation(bundle, updates, op)

  def query(self, filter=None):
    counters = [MetricResult(MetricKey(k.step, k.metric),
                             v.extract_committed(),
                             v.extract_latest_attempted())
                for k, v in self._counters.items()
                if self.matches(filter, k)]
    distributions = [MetricResult(MetricKey(k.step, k.metric),
                                  v.extract_committed(),
                                  v.extract_latest_attempted())
                     for k, v in self._distributions.items()
                     if self.matches(filter, k)]
    gauges = [MetricResult(MetricKey(k.step, k.metric),
                           v.extract_committed(),
                           v.extract_latest_attempted())
              for k, v in self._gauges.items()
              if self.matches(filter, k)]

    return {'counters': counters,
            'distributions': distributions,
            'gauges': gauges}


class DirectMetric(object):
  """ Keeps a consistent state for a single metric.

  It keeps track of the metric's physical and logical updates.
  It's thread safe.
  """
  def __init__(self, aggregator):
    self.aggregator = aggregator
    self._attempted_lock = threading.Lock()
    self.finished_attempted = aggregator.identity_element()
    self.inflight_attempted = {}
    self._committed_lock = threading.Lock()
    self.finished_committed = aggregator.identity_element()

  def commit_logical(self, bundle, update):
    with self._committed_lock:
      self.finished_committed = self.aggregator.combine(update,
                                                        self.finished_committed)

  def commit_physical(self, bundle, update):
    with self._attempted_lock:
      self.inflight_attempted[bundle] = update
      self.finished_attempted = self.aggregator.combine(update,
                                                        self.finished_attempted)
      del self.inflight_attempted[bundle]

  def update_physical(self, bundle, update):
    self.inflight_attempted[bundle] = update

  def extract_committed(self):
    return self.aggregator.result(self.finished_committed)

  def extract_latest_attempted(self):
    res = self.finished_attempted
    for _, u in self.inflight_attempted.items():
      res = self.aggregator.combine(res, u)

    return self.aggregator.result(res)
