#
# Copyright 2013 Intel Corp.
# Copyright 2014 Red Hat, 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.

import abc
import hashlib
from itertools import chain
from operator import methodcaller
import os

from oslo_config import cfg
from oslo_log import log
import oslo_messaging
from oslo_utils import fnmatch
from oslo_utils import timeutils
import six
from stevedore import extension
import yaml


from ceilometer.event.storage import models
from ceilometer.i18n import _, _LI, _LW
from ceilometer import publisher
from ceilometer.publisher import utils as publisher_utils
from ceilometer import sample as sample_util


OPTS = [
    cfg.StrOpt('pipeline_cfg_file',
               default="pipeline.yaml",
               help="Configuration file for pipeline definition."
               ),
    cfg.StrOpt('event_pipeline_cfg_file',
               default="event_pipeline.yaml",
               help="Configuration file for event pipeline definition."
               ),
    cfg.BoolOpt('refresh_pipeline_cfg',
                default=False,
                help="Refresh Pipeline configuration on-the-fly."
                ),
    cfg.BoolOpt('refresh_event_pipeline_cfg',
                default=False,
                help="Refresh Event Pipeline configuration on-the-fly."
                ),
    cfg.IntOpt('pipeline_polling_interval',
               default=20,
               help="Polling interval for pipeline file configuration"
                    " in seconds."
               ),
]

cfg.CONF.register_opts(OPTS)

LOG = log.getLogger(__name__)


class PipelineException(Exception):
    def __init__(self, message, pipeline_cfg):
        self.msg = message
        self.pipeline_cfg = pipeline_cfg

    def __str__(self):
        return 'Pipeline %s: %s' % (self.pipeline_cfg, self.msg)


@six.add_metaclass(abc.ABCMeta)
class PipelineEndpoint(object):

    def __init__(self, pipeline):
        self.filter_rule = oslo_messaging.NotificationFilter(
            publisher_id=pipeline.name)
        self.publish_context = PublishContext([pipeline])

    @abc.abstractmethod
    def sample(self, messages):
        pass


class SamplePipelineEndpoint(PipelineEndpoint):
    def sample(self, messages):
        samples = chain.from_iterable(m["payload"] for m in messages)
        samples = [
            sample_util.Sample(name=s['counter_name'],
                               type=s['counter_type'],
                               unit=s['counter_unit'],
                               volume=s['counter_volume'],
                               user_id=s['user_id'],
                               project_id=s['project_id'],
                               resource_id=s['resource_id'],
                               timestamp=s['timestamp'],
                               resource_metadata=s['resource_metadata'],
                               source=s.get('source'))
            for s in samples if publisher_utils.verify_signature(
                s, cfg.CONF.publisher.telemetry_secret)
        ]
        with self.publish_context as p:
            p(sorted(samples, key=methodcaller('get_iso_timestamp')))


class EventPipelineEndpoint(PipelineEndpoint):
    def sample(self, messages):
        events = chain.from_iterable(m["payload"] for m in messages)
        events = [
            models.Event(
                message_id=ev['message_id'],
                event_type=ev['event_type'],
                generated=timeutils.normalize_time(
                    timeutils.parse_isotime(ev['generated'])),
                traits=[models.Trait(name, dtype,
                                     models.Trait.convert_value(dtype, value))
                        for name, dtype, value in ev['traits']],
                raw=ev.get('raw', {}))
            for ev in events if publisher_utils.verify_signature(
                ev, cfg.CONF.publisher.telemetry_secret)
        ]
        try:
            with self.publish_context as p:
                p(events)
        except Exception:
            if not cfg.CONF.notification.ack_on_event_error:
                return oslo_messaging.NotificationResult.REQUEUE
            raise
        return oslo_messaging.NotificationResult.HANDLED


class _PipelineTransportManager(object):
    def __init__(self):
        self.transporters = []

    @staticmethod
    def hash_grouping(datapoint, grouping_keys):
        value = ''
        for key in grouping_keys or []:
            value += datapoint.get(key) if datapoint.get(key) else ''
        return hash(value)

    def add_transporter(self, transporter):
        self.transporters.append(transporter)

    def publisher(self):
        serializer = self.serializer
        hash_grouping = self.hash_grouping
        transporters = self.transporters
        filter_attr = self.filter_attr
        event_type = self.event_type

        class PipelinePublishContext(object):
            def __enter__(self):
                def p(data):
                    # TODO(gordc): cleanup so payload is always single
                    #              datapoint. we can't correctly bucketise
                    #              datapoints if batched.
                    data = [data] if not isinstance(data, list) else data
                    for datapoint in data:
                        serialized_data = serializer(datapoint)
                        for d_filter, grouping_keys, notifiers in transporters:
                            if d_filter(serialized_data[filter_attr]):
                                key = (hash_grouping(serialized_data,
                                                     grouping_keys)
                                       % len(notifiers))
                                notifier = notifiers[key]
                                notifier.sample({},
                                                event_type=event_type,
                                                payload=[serialized_data])
                return p

            def __exit__(self, exc_type, exc_value, traceback):
                pass

        return PipelinePublishContext()


class SamplePipelineTransportManager(_PipelineTransportManager):
    filter_attr = 'counter_name'
    event_type = 'ceilometer.pipeline'

    @staticmethod
    def serializer(data):
        return publisher_utils.meter_message_from_counter(
            data, cfg.CONF.publisher.telemetry_secret)


class EventPipelineTransportManager(_PipelineTransportManager):
    filter_attr = 'event_type'
    event_type = 'pipeline.event'

    @staticmethod
    def serializer(data):
        return publisher_utils.message_from_event(
            data, cfg.CONF.publisher.telemetry_secret)


class PublishContext(object):

    def __init__(self, pipelines=None):
        pipelines = pipelines or []
        self.pipelines = set(pipelines)

    def add_pipelines(self, pipelines):
        self.pipelines.update(pipelines)

    def __enter__(self):
        def p(data):
            for p in self.pipelines:
                p.publish_data(data)
        return p

    def __exit__(self, exc_type, exc_value, traceback):
        for p in self.pipelines:
            p.flush()


class Source(object):
    """Represents a source of samples or events."""

    def __init__(self, cfg):
        self.cfg = cfg

        try:
            self.name = cfg['name']
            self.sinks = cfg.get('sinks')
        except KeyError as err:
            raise PipelineException(
                "Required field %s not specified" % err.args[0], cfg)

    def __str__(self):
        return self.name

    def check_sinks(self, sinks):
        if not self.sinks:
            raise PipelineException(
                "No sink defined in source %s" % self,
                self.cfg)
        for sink in self.sinks:
            if sink not in sinks:
                raise PipelineException(
                    "Dangling sink %s from source %s" % (sink, self),
                    self.cfg)

    def check_source_filtering(self, data, d_type):
        """Source data rules checking

        - At least one meaningful datapoint exist
        - Included type and excluded type can't co-exist on the same pipeline
        - Included type meter and wildcard can't co-exist at same pipeline
        """
        if not data:
            raise PipelineException('No %s specified' % d_type, self.cfg)

        if ([x for x in data if x[0] not in '!*'] and
           [x for x in data if x[0] == '!']):
            raise PipelineException(
                'Both included and excluded %s specified' % d_type,
                cfg)

        if '*' in data and [x for x in data if x[0] not in '!*']:
            raise PipelineException(
                'Included %s specified with wildcard' % d_type,
                self.cfg)

    @staticmethod
    def is_supported(dataset, data_name):
        # Support wildcard like storage.* and !disk.*
        # Start with negation, we consider that the order is deny, allow
        if any(fnmatch.fnmatch(data_name, datapoint[1:])
               for datapoint in dataset if datapoint[0] == '!'):
            return False

        if any(fnmatch.fnmatch(data_name, datapoint)
               for datapoint in dataset if datapoint[0] != '!'):
            return True

        # if we only have negation, we suppose the default is allow
        return all(datapoint.startswith('!') for datapoint in dataset)


class EventSource(Source):
    """Represents a source of events.

    In effect it is a set of notification handlers capturing events for a set
    of matching notifications.
    """

    def __init__(self, cfg):
        super(EventSource, self).__init__(cfg)
        self.events = cfg.get('events')
        self.check_source_filtering(self.events, 'events')

    def support_event(self, event_name):
        return self.is_supported(self.events, event_name)


class SampleSource(Source):
    """Represents a source of samples.

    In effect it is a set of pollsters and/or notification handlers emitting
    samples for a set of matching meters. Each source encapsulates meter name
    matching, polling interval determination, optional resource enumeration or
    discovery, and mapping to one or more sinks for publication.
    """

    def __init__(self, cfg):
        super(SampleSource, self).__init__(cfg)
        # Support 'counters' for backward compatibility
        self.meters = cfg.get('meters', cfg.get('counters'))
        try:
            self.interval = int(cfg.get('interval', 600))
        except ValueError:
            raise PipelineException("Invalid interval value", cfg)
        if self.interval <= 0:
            raise PipelineException("Interval value should > 0", cfg)

        self.resources = cfg.get('resources') or []
        if not isinstance(self.resources, list):
            raise PipelineException("Resources should be a list", cfg)

        self.discovery = cfg.get('discovery') or []
        if not isinstance(self.discovery, list):
            raise PipelineException("Discovery should be a list", cfg)
        self.check_source_filtering(self.meters, 'meters')

    def get_interval(self):
        return self.interval

    def support_meter(self, meter_name):
        return self.is_supported(self.meters, meter_name)


class Sink(object):
    """Represents a sink for the transformation and publication of data.

    Each sink config is concerned *only* with the transformation rules
    and publication conduits for data.

    In effect, a sink describes a chain of handlers. The chain starts
    with zero or more transformers and ends with one or more publishers.

    The first transformer in the chain is passed data from the
    corresponding source, takes some action such as deriving rate of
    change, performing unit conversion, or aggregating, before passing
    the modified data to next step.

    The subsequent transformers, if any, handle the data similarly.

    At the end of the chain, publishers publish the data. The exact
    publishing method depends on publisher type, for example, pushing
    into data storage via the message bus providing guaranteed delivery,
    or for loss-tolerant data UDP may be used.

    If no transformers are included in the chain, the publishers are
    passed data directly from the sink which are published unchanged.
    """

    def __init__(self, cfg, transformer_manager):
        self.cfg = cfg

        try:
            self.name = cfg['name']
            # It's legal to have no transformer specified
            self.transformer_cfg = cfg.get('transformers') or []
        except KeyError as err:
            raise PipelineException(
                "Required field %s not specified" % err.args[0], cfg)

        if not cfg.get('publishers'):
            raise PipelineException("No publisher specified", cfg)

        self.publishers = []
        for p in cfg['publishers']:
            if '://' not in p:
                # Support old format without URL
                p = p + "://"
            try:
                self.publishers.append(publisher.get_publisher(p,
                                                               self.NAMESPACE))
            except Exception:
                LOG.exception(_("Unable to load publisher %s"), p)

        self.multi_publish = True if len(self.publishers) > 1 else False
        self.transformers = self._setup_transformers(cfg, transformer_manager)

    def __str__(self):
        return self.name

    def _setup_transformers(self, cfg, transformer_manager):
        transformers = []
        for transformer in self.transformer_cfg:
            parameter = transformer['parameters'] or {}
            try:
                ext = transformer_manager[transformer['name']]
            except KeyError:
                raise PipelineException(
                    "No transformer named %s loaded" % transformer['name'],
                    cfg)
            transformers.append(ext.plugin(**parameter))
            LOG.info(_LI(
                "Pipeline %(pipeline)s: Setup transformer instance %(name)s "
                "with parameter %(param)s") % ({'pipeline': self,
                                                'name': transformer['name'],
                                                'param': parameter}))

        return transformers


class EventSink(Sink):

    NAMESPACE = 'ceilometer.event.publisher'

    def publish_events(self, events):
        if events:
            for p in self.publishers:
                try:
                    p.publish_events(events)
                except Exception:
                    LOG.exception(_("Pipeline %(pipeline)s: %(status)s"
                                    " after error from publisher %(pub)s") %
                                   ({'pipeline': self, 'status': 'Continue' if
                                     self.multi_publish else 'Exit', 'pub': p}
                                    ))
                    if not self.multi_publish:
                        raise

    @staticmethod
    def flush():
        """Flush data after all events have been injected to pipeline."""


class SampleSink(Sink):

    NAMESPACE = 'ceilometer.publisher'

    def _transform_sample(self, start, sample):
        try:
            for transformer in self.transformers[start:]:
                sample = transformer.handle_sample(sample)
                if not sample:
                    LOG.debug(
                        "Pipeline %(pipeline)s: Sample dropped by "
                        "transformer %(trans)s", {'pipeline': self,
                                                  'trans': transformer})
                    return
            return sample
        except Exception as err:
            # TODO(gordc): only use one log level.
            LOG.warning(_("Pipeline %(pipeline)s: "
                          "Exit after error from transformer "
                          "%(trans)s for %(smp)s") % ({'pipeline': self,
                                                       'trans': transformer,
                                                       'smp': sample}))
            LOG.exception(err)

    def _publish_samples(self, start, samples):
        """Push samples into pipeline for publishing.

        :param start: The first transformer that the sample will be injected.
                      This is mainly for flush() invocation that transformer
                      may emit samples.
        :param samples: Sample list.

        """

        transformed_samples = []
        if not self.transformers:
            transformed_samples = samples
        else:
            for sample in samples:
                LOG.debug(
                    "Pipeline %(pipeline)s: Transform sample "
                    "%(smp)s from %(trans)s transformer", {'pipeline': self,
                                                           'smp': sample,
                                                           'trans': start})
                sample = self._transform_sample(start, sample)
                if sample:
                    transformed_samples.append(sample)

        if transformed_samples:
            for p in self.publishers:
                try:
                    p.publish_samples(transformed_samples)
                except Exception:
                    LOG.exception(_(
                        "Pipeline %(pipeline)s: Continue after error "
                        "from publisher %(pub)s") % ({'pipeline': self,
                                                      'pub': p}))

    def publish_samples(self, samples):
        self._publish_samples(0, samples)

    def flush(self):
        """Flush data after all samples have been injected to pipeline."""

        for (i, transformer) in enumerate(self.transformers):
            try:
                self._publish_samples(i + 1,
                                      list(transformer.flush()))
            except Exception as err:
                LOG.warning(_(
                    "Pipeline %(pipeline)s: Error flushing "
                    "transformer %(trans)s") % ({'pipeline': self,
                                                 'trans': transformer}))
                LOG.exception(err)


@six.add_metaclass(abc.ABCMeta)
class Pipeline(object):
    """Represents a coupling between a sink and a corresponding source."""

    def __init__(self, source, sink):
        self.source = source
        self.sink = sink
        self.name = str(self)

    def __str__(self):
        return (self.source.name if self.source.name == self.sink.name
                else '%s:%s' % (self.source.name, self.sink.name))

    def flush(self):
        self.sink.flush()

    @property
    def publishers(self):
        return self.sink.publishers

    @abc.abstractmethod
    def publish_data(self, data):
        """Publish data from pipeline."""


class EventPipeline(Pipeline):
    """Represents a pipeline for Events."""

    def __str__(self):
        # NOTE(gordc): prepend a namespace so we ensure event and sample
        #              pipelines do not have the same name.
        return 'event:%s' % super(EventPipeline, self).__str__()

    def support_event(self, event_type):
        return self.source.support_event(event_type)

    def publish_data(self, events):
        if not isinstance(events, list):
            events = [events]
        supported = [e for e in events
                     if self.source.support_event(e.event_type)]
        self.sink.publish_events(supported)


class SamplePipeline(Pipeline):
    """Represents a pipeline for Samples."""

    def get_interval(self):
        return self.source.interval

    @property
    def resources(self):
        return self.source.resources

    @property
    def discovery(self):
        return self.source.discovery

    def support_meter(self, meter_name):
        return self.source.support_meter(meter_name)

    def _validate_volume(self, s):
        volume = s.volume
        if volume is None:
            LOG.warning(_LW(
                'metering data %(counter_name)s for %(resource_id)s '
                '@ %(timestamp)s has no volume (volume: None), the sample will'
                ' be dropped')
                % {'counter_name': s.name,
                   'resource_id': s.resource_id,
                   'timestamp': s.timestamp if s.timestamp else 'NO TIMESTAMP'}
            )
            return False
        if not isinstance(volume, (int, float)):
            try:
                volume = float(volume)
            except ValueError:
                LOG.warning(_LW(
                    'metering data %(counter_name)s for %(resource_id)s '
                    '@ %(timestamp)s has volume which is not a number '
                    '(volume: %(counter_volume)s), the sample will be dropped')
                    % {'counter_name': s.name,
                       'resource_id': s.resource_id,
                       'timestamp': (
                           s.timestamp if s.timestamp else 'NO TIMESTAMP'),
                       'counter_volume': volume}
                )
                return False
        return True

    def publish_data(self, samples):
        if not isinstance(samples, list):
            samples = [samples]
        supported = [s for s in samples if self.source.support_meter(s.name)
                     and self._validate_volume(s)]
        self.sink.publish_samples(supported)


SAMPLE_TYPE = {'pipeline': SamplePipeline,
               'source': SampleSource,
               'sink': SampleSink}

EVENT_TYPE = {'pipeline': EventPipeline,
              'source': EventSource,
              'sink': EventSink}


class ConfigManagerBase(object):
    """Base class for managing configuration file refresh"""

    def __init__(self):
        self.cfg_loc = None

    def load_config(self, cfg_info):
        """Load a configuration file and set its refresh values."""
        if isinstance(cfg_info, dict):
            conf = cfg_info
        else:
            if not os.path.exists(cfg_info):
                cfg_info = cfg.CONF.find_file(cfg_info)
            with open(cfg_info) as fap:
                data = fap.read()

            conf = yaml.safe_load(data)
            self.cfg_loc = cfg_info
            self.cfg_mtime = self.get_cfg_mtime()
            self.cfg_hash = self.get_cfg_hash()
        LOG.info("Config file: %s", conf)
        return conf

    def get_cfg_mtime(self):
        """Return modification time of cfg file"""
        return os.path.getmtime(self.cfg_loc) if self.cfg_loc else None

    def get_cfg_hash(self):
        """Return hash of configuration file"""
        if not self.cfg_loc:
            return None

        with open(self.cfg_loc) as fap:
            data = fap.read()
        if six.PY3:
            data = data.encode('utf-8')

        file_hash = hashlib.md5(data).hexdigest()
        return file_hash

    def cfg_changed(self):
        """Returns hash of changed cfg else False."""
        mtime = self.get_cfg_mtime()
        if mtime > self.cfg_mtime:
            LOG.info(_LI('Configuration file has been updated.'))
            self.cfg_mtime = mtime
            _hash = self.get_cfg_hash()
            if _hash != self.cfg_hash:
                LOG.info(_LI("Detected change in configuration."))
                return _hash
        return False


class PipelineManager(ConfigManagerBase):
    """Pipeline Manager

    Pipeline manager sets up pipelines according to config file

    Usually only one pipeline manager exists in the system.

    """

    def __init__(self, cfg_info, transformer_manager, p_type=SAMPLE_TYPE):
        """Setup the pipelines according to config.

        The configuration is supported as follows:

        Decoupled: the source and sink configuration are separately
        specified before being linked together. This allows source-
        specific configuration, such as resource discovery, to be
        kept focused only on the fine-grained source while avoiding
        the necessity for wide duplication of sink-related config.

        The configuration is provided in the form of separate lists
        of dictionaries defining sources and sinks, for example:

        {"sources": [{"name": source_1,
                      "interval": interval_time,
                      "meters" : ["meter_1", "meter_2"],
                      "resources": ["resource_uri1", "resource_uri2"],
                      "sinks" : ["sink_1", "sink_2"]
                     },
                     {"name": source_2,
                      "interval": interval_time,
                      "meters" : ["meter_3"],
                      "sinks" : ["sink_2"]
                     },
                    ],
         "sinks": [{"name": sink_1,
                    "transformers": [
                           {"name": "Transformer_1",
                         "parameters": {"p1": "value"}},

                           {"name": "Transformer_2",
                            "parameters": {"p1": "value"}},
                          ],
                     "publishers": ["publisher_1", "publisher_2"]
                    },
                    {"name": sink_2,
                     "publishers": ["publisher_3"]
                    },
                   ]
        }

        The interval determines the cadence of sample injection into
        the pipeline where samples are produced under the direct control
        of an agent, i.e. via a polling cycle as opposed to incoming
        notifications.

        Valid meter format is '*', '!meter_name', or 'meter_name'.
        '*' is wildcard symbol means any meters; '!meter_name' means
        "meter_name" will be excluded; 'meter_name' means 'meter_name'
        will be included.

        The 'meter_name" is Sample name field.

        Valid meters definition is all "included meter names", all
        "excluded meter names", wildcard and "excluded meter names", or
        only wildcard.

        The resources is list of URI indicating the resources from where
        the meters should be polled. It's optional and it's up to the
        specific pollster to decide how to use it.

        Transformer's name is plugin name in setup.cfg.

        Publisher's name is plugin name in setup.cfg

        """
        super(PipelineManager, self).__init__()
        cfg = self.load_config(cfg_info)
        self.pipelines = []
        if not ('sources' in cfg and 'sinks' in cfg):
            raise PipelineException("Both sources & sinks are required",
                                    cfg)
        LOG.info(_LI('detected decoupled pipeline config format'))

        unique_names = set()
        sources = []
        for s in cfg.get('sources'):
            name = s.get('name')
            if name in unique_names:
                raise PipelineException("Duplicated source names: %s" %
                                        name, self)
            else:
                unique_names.add(name)
                sources.append(p_type['source'](s))
        unique_names.clear()

        sinks = {}
        for s in cfg.get('sinks'):
            name = s.get('name')
            if name in unique_names:
                raise PipelineException("Duplicated sink names: %s" %
                                        name, self)
            else:
                unique_names.add(name)
                sinks[s['name']] = p_type['sink'](s, transformer_manager)
        unique_names.clear()

        for source in sources:
            source.check_sinks(sinks)
            for target in source.sinks:
                pipe = p_type['pipeline'](source, sinks[target])
                if pipe.name in unique_names:
                    raise PipelineException(
                        "Duplicate pipeline name: %s. Ensure pipeline"
                        " names are unique. (name is the source and sink"
                        " names combined)" % pipe.name, cfg)
                else:
                    unique_names.add(pipe.name)
                    self.pipelines.append(pipe)
        unique_names.clear()

    def publisher(self):
        """Build a new Publisher for these manager pipelines.

        :param context: The context.
        """
        return PublishContext(self.pipelines)


class PollingManager(ConfigManagerBase):
    """Polling Manager

    Polling manager sets up polling according to config file.
    """

    def __init__(self, cfg_info):
        """Setup the polling according to config.

        The configuration is the sources half of the Pipeline Config.
        """
        super(PollingManager, self).__init__()
        cfg = self.load_config(cfg_info)
        self.sources = []
        if not ('sources' in cfg and 'sinks' in cfg):
            raise PipelineException("Both sources & sinks are required",
                                    cfg)
        LOG.info(_LI('detected decoupled pipeline config format'))

        unique_names = set()
        for s in cfg.get('sources'):
            name = s.get('name')
            if name in unique_names:
                raise PipelineException("Duplicated source names: %s" %
                                        name, self)
            else:
                unique_names.add(name)
                self.sources.append(SampleSource(s))
        unique_names.clear()


def setup_event_pipeline(transformer_manager=None):
    """Setup event pipeline manager according to yaml config file."""
    default = extension.ExtensionManager('ceilometer.transformer')
    cfg_file = cfg.CONF.event_pipeline_cfg_file
    return PipelineManager(cfg_file, transformer_manager or default,
                           EVENT_TYPE)


def setup_pipeline(transformer_manager=None):
    """Setup pipeline manager according to yaml config file."""
    default = extension.ExtensionManager('ceilometer.transformer')
    cfg_file = cfg.CONF.pipeline_cfg_file
    return PipelineManager(cfg_file, transformer_manager or default,
                           SAMPLE_TYPE)


def setup_polling():
    """Setup polling manager according to yaml config file."""
    cfg_file = cfg.CONF.pipeline_cfg_file
    return PollingManager(cfg_file)


def get_pipeline_grouping_key(pipe):
    keys = []
    for transformer in pipe.sink.transformers:
        keys += transformer.grouping_keys
    return list(set(keys))
