# -*- coding: utf-8 -*-
# SPDX-License-Identifier: MIT
""" The FedmsgConsumer class that acts as a consumer entry point for fedmsg-hub.
This class reads and processes messages from the message bus it is configured
to use.
"""

from __future__ import absolute_import
import itertools

try:
    # python3
    import queue
except ImportError:
    # python2
    import Queue as queue

import koji
import fedmsg.consumers
import moksha.hub
import sqlalchemy.exc

from module_build_service import log, conf
from module_build_service.common import models
from module_build_service.common.errors import IgnoreMessage
import module_build_service.common.messaging
from module_build_service.common.messaging import default_messaging_backend
import module_build_service.common.monitor as monitor

from module_build_service.scheduler import events
from module_build_service.scheduler.db_session import db_session
from module_build_service.scheduler.handlers import components, repos, modules, greenwave, tags


def no_op_handler(*args, **kwargs):
    return True


ON_BUILD_CHANGE_HANDLERS = {
    koji.BUILD_STATES["BUILDING"]: no_op_handler,
    koji.BUILD_STATES["COMPLETE"]: components.build_task_finalize,
    koji.BUILD_STATES["FAILED"]: components.build_task_finalize,
    koji.BUILD_STATES["CANCELED"]: components.build_task_finalize,
    koji.BUILD_STATES["DELETED"]: no_op_handler,
}

ON_MODULE_CHANGE_HANDLERS = {
    models.BUILD_STATES["init"]: modules.init,
    models.BUILD_STATES["wait"]: modules.wait,
    models.BUILD_STATES["build"]: no_op_handler,
    models.BUILD_STATES["failed"]: modules.failed,
    models.BUILD_STATES["done"]: modules.done,
    # XXX: DIRECT TRANSITION TO READY
    models.BUILD_STATES["ready"]: no_op_handler,
    models.BUILD_STATES["garbage"]: no_op_handler,
}

# Only one kind of repo change event, though...
ON_REPO_CHANGE_HANDLER = repos.done
ON_TAG_CHANGE_HANDLER = tags.tagged
ON_DECISION_UPDATE_HANDLER = greenwave.decision_update


class MBSConsumer(fedmsg.consumers.FedmsgConsumer):
    """ This is triggered by running fedmsg-hub. This class is responsible for
    ingesting and processing messages from the message bus.
    """

    config_key = "mbsconsumer"

    # It is set to the id of currently handled module build. It is used to
    # group all the log messages associated with single module build to
    # per module build log file.
    current_module_build_id = None

    def __init__(self, hub):
        # Topic setting needs to be done *before* the call to `super`.

        prefixes = conf.messaging_topic_prefix  # This is a list.
        services = default_messaging_backend["services"]
        suffix = default_messaging_backend["topic_suffix"]
        self.topic = [
            "{}.{}{}".format(prefix.rstrip("."), category, suffix)
            for prefix, category in itertools.product(prefixes, services)
        ]
        if not self.topic:
            self.topic = "*"
        log.debug("Setting topics: {}".format(", ".join(self.topic)))

        # The call to `super` takes action based on the setting of topics above
        super(MBSConsumer, self).__init__(hub)

        # Our call to `super` above should have initialized an `incoming` queue
        # for us.. but in certain test situations, it does not.  So here,
        # establish a fake `incoming` queue.
        if not hasattr(self, "incoming"):
            self.incoming = queue.Queue()

        # These two values are typically provided either by the unit tests or
        # by the local build command.  They are empty in the production environ
        self.stop_condition = hub.config.get("mbsconsumer.stop_condition")
        initial_messages = hub.config.get("mbsconsumer.initial_messages", [])
        for msg in initial_messages:
            self.incoming.put(msg)

        # Furthermore, extend our initial messages with any that were queued up
        # in the test environment before our hub was initialized.
        while module_build_service.common.messaging._initial_messages:
            msg = module_build_service.common.messaging._initial_messages.pop(0)
            self.incoming.put(msg)

        self.sanity_check()

    def shutdown(self):
        log.info("Scheduling shutdown.")
        from moksha.hub.reactor import reactor

        reactor.callFromThread(self.hub.stop)
        reactor.callFromThread(reactor.stop)

    def validate(self, message):
        if conf.messaging == "fedmsg":
            # If this is a faked internal message, don't bother.
            if "event" in message:
                log.info("Skipping crypto validation for %r", message)
                return
            # Otherwise, if it is a real message from the network, pass it
            # through crypto validation.
            super(MBSConsumer, self).validate(message)

    def validate_event(self, event):
        # task_id is required for koji_build_change event
        if event["event"] == "koji_build_change" and event["task_id"] is None:
            raise IgnoreMessage(
                "Ignore koji_build_change event from message {}, which has a null task_id".format(
                    event["msg_id"])
            )

    def consume(self, message):
        monitor.messaging_rx_counter.inc()

        # Sometimes, the messages put into our queue are artificially put there
        # by other parts of our own codebase.  If they are already abstracted
        # messages, then just use them as-is.  If they are not already
        # instances of our message abstraction base class, then first transform
        # them before proceeding.
        if "event" in message:
            event_info = message
        else:
            try:
                event_info = self.get_abstracted_event_info(message)
                self.validate_event(event_info)
            except IgnoreMessage as e:
                log.debug(str(e))
                return

        if event_info is None:
            return

        # Primary work is done here.
        try:
            self.process_message(event_info)
            monitor.messaging_rx_processed_ok_counter.inc()
        except sqlalchemy.exc.OperationalError as error:
            monitor.messaging_rx_failed_counter.inc()
            if "could not translate host name" in str(error):
                log.exception(
                    "SQLAlchemy can't resolve DNS records. Scheduling fedmsg-hub to shutdown.")
                self.shutdown()
            else:
                raise
        except Exception:
            monitor.messaging_rx_failed_counter.inc()
        finally:
            db_session.remove()

        if self.stop_condition and self.stop_condition(message):
            self.shutdown()

    @staticmethod
    def get_abstracted_event_info(message):
        parser = default_messaging_backend.get("parser")
        if parser:
            try:
                return parser.parse(message)
            except IgnoreMessage:
                pass
        else:
            raise ValueError("{0} backend does not define a message parser".format(conf.messaging))

    def sanity_check(self):
        """ On startup, make sure our implementation is sane. """
        # Ensure we have every state covered
        for state in models.BUILD_STATES:
            if models.BUILD_STATES[state] not in ON_MODULE_CHANGE_HANDLERS:
                raise KeyError("Module build states %r not handled." % state)
        for state in koji.BUILD_STATES:
            if koji.BUILD_STATES[state] not in ON_BUILD_CHANGE_HANDLERS:
                raise KeyError("Koji build states %r not handled." % state)

    def _map_message(self, db_session, event_info):
        """Map message to its corresponding event handler and module build"""

        event = event_info["event"]

        if event == events.KOJI_BUILD_CHANGE:
            handler = ON_BUILD_CHANGE_HANDLERS[event_info["build_new_state"]]
            build = models.ComponentBuild.from_component_event(
                db_session, event_info["task_id"], event_info["module_build_id"])
            if build:
                build = build.module_build
            return handler, build

        if event == events.KOJI_REPO_CHANGE:
            return (
                ON_REPO_CHANGE_HANDLER,
                models.ModuleBuild.get_by_tag(db_session, event_info["tag_name"])
            )

        if event == events.KOJI_TAG_CHANGE:
            return (
                ON_TAG_CHANGE_HANDLER,
                models.ModuleBuild.get_by_tag(db_session, event_info["tag_name"])
            )

        if event == events.MBS_MODULE_STATE_CHANGE:
            state = event_info["module_build_state"]
            valid_module_build_states = list(models.BUILD_STATES.values())
            if state not in valid_module_build_states:
                raise ValueError("state={}({}) is not in {}.".format(
                    state, type(state), valid_module_build_states
                ))
            return (
                ON_MODULE_CHANGE_HANDLERS[state],
                models.ModuleBuild.get_by_id(db_session, event_info["module_build_id"])
            )

        if event == events.GREENWAVE_DECISION_UPDATE:
            return (
                ON_DECISION_UPDATE_HANDLER,
                greenwave.get_corresponding_module_build(event_info["subject_identifier"])
            )

        return None, None

    def process_message(self, event_info):
        # Choose a handler for this message
        handler, build = self._map_message(db_session, event_info)

        if handler is None:
            log.debug("No event handler associated with msg %s", event_info["msg_id"])
            return

        idx = "%s: %s, %s" % (
            handler.__name__, event_info["event"], event_info["msg_id"])

        if handler is no_op_handler:
            log.debug("Handler is NO_OP: %s", idx)
            return

        if not build:
            log.debug("No module associated with msg %s", event_info["msg_id"])
            return

        MBSConsumer.current_module_build_id = build.id

        log.info("Calling %s", idx)

        kwargs = event_info.copy()
        kwargs.pop("event")

        try:
            if conf.celery_broker_url:
                # handlers are also Celery tasks, when celery_broker_url is configured,
                # call "delay" method to run the handlers as Celery async tasks
                func = getattr(handler, "delay")
                func(**kwargs)
            else:
                handler(**kwargs)
        except Exception as e:
            log.exception("Could not process message handler.")
            db_session.rollback()
            db_session.refresh(build)
            build.transition(
                db_session,
                conf,
                state=models.BUILD_STATES["failed"],
                state_reason=str(e),
                failure_type="infra",
            )
            db_session.commit()

            # Allow caller to do something when error is occurred.
            raise
        finally:
            MBSConsumer.current_module_build_id = None
            log.debug("Done with %s", idx)


def get_global_consumer():
    """ Return a handle to the active consumer object, if it exists. """
    hub = moksha.hub._hub
    if not hub:
        raise ValueError("No global moksha-hub obj found.")

    for consumer in hub.consumers:
        if isinstance(consumer, MBSConsumer):
            return consumer

    raise ValueError("No MBSConsumer found among %r." % len(hub.consumers))


def work_queue_put(msg):
    """ Artificially put a message into the work queue of the consumer. """
    consumer = get_global_consumer()
    consumer.incoming.put(msg)