# -*- coding: utf-8 -*-
"""
    celery.app.base
    ~~~~~~~~~~~~~~~

    Actual App instance implementation.

"""
from __future__ import absolute_import

import os
import threading
import warnings

from collections import defaultdict, deque
from contextlib import contextmanager
from copy import deepcopy
from operator import attrgetter

from amqp import promise
from billiard.util import register_after_fork
from kombu.clocks import LamportClock
from kombu.common import oid_from
from kombu.utils import cached_property, uuid

from celery import platforms
from celery import signals
from celery._state import (
    _task_stack, _tls, get_current_app, set_default_app,
    _register_app, get_current_worker_task,
)
from celery.exceptions import AlwaysEagerIgnored, ImproperlyConfigured
from celery.five import items, values
from celery.loaders import get_loader_cls
from celery.local import PromiseProxy, maybe_evaluate
from celery.utils.functional import first, maybe_list
from celery.utils.imports import instantiate, symbol_by_name
from celery.utils.objects import mro_lookup

from .annotations import prepare as prepare_annotations
from .builtins import shared_task, load_shared_tasks
from .defaults import DEFAULTS, find_deprecated_settings
from .registry import TaskRegistry
from .utils import (
    AppPickler, Settings, bugreport, _unpickle_app, _unpickle_app_v2, appstr,
)

__all__ = ['Celery']

_EXECV = os.environ.get('FORKED_BY_MULTIPROCESSING')
BUILTIN_FIXUPS = frozenset([
    'celery.fixups.django:fixup',
])

ERR_ENVVAR_NOT_SET = """\
The environment variable {0!r} is not set,
and as such the configuration could not be loaded.
Please set this variable and make it point to
a configuration module."""


def app_has_custom(app, attr):
    return mro_lookup(app.__class__, attr, stop=(Celery, object),
                      monkey_patched=[__name__])


def _unpickle_appattr(reverse_name, args):
    """Given an attribute name and a list of args, gets
    the attribute from the current app and calls it."""
    return get_current_app()._rgetattr(reverse_name)(*args)


class Celery(object):
    #: This is deprecated, use :meth:`reduce_keys` instead
    Pickler = AppPickler

    SYSTEM = platforms.SYSTEM
    IS_OSX, IS_WINDOWS = platforms.IS_OSX, platforms.IS_WINDOWS

    amqp_cls = 'celery.app.amqp:AMQP'
    backend_cls = None
    events_cls = 'celery.events:Events'
    loader_cls = 'celery.loaders.app:AppLoader'
    log_cls = 'celery.app.log:Logging'
    control_cls = 'celery.app.control:Control'
    task_cls = 'celery.app.task:Task'
    registry_cls = TaskRegistry
    _fixups = None
    _pool = None
    builtin_fixups = BUILTIN_FIXUPS

    def __init__(self, main=None, loader=None, backend=None,
                 amqp=None, events=None, log=None, control=None,
                 set_as_current=True, accept_magic_kwargs=False,
                 tasks=None, broker=None, include=None, changes=None,
                 config_source=None, fixups=None, task_cls=None,
                 autofinalize=True, **kwargs):
        self.clock = LamportClock()
        self.main = main
        self.amqp_cls = amqp or self.amqp_cls
        self.backend_cls = backend or self.backend_cls
        self.events_cls = events or self.events_cls
        self.loader_cls = loader or self.loader_cls
        self.log_cls = log or self.log_cls
        self.control_cls = control or self.control_cls
        self.task_cls = task_cls or self.task_cls
        self.set_as_current = set_as_current
        self.registry_cls = symbol_by_name(self.registry_cls)
        self.accept_magic_kwargs = accept_magic_kwargs
        self.user_options = defaultdict(set)
        self.steps = defaultdict(set)
        self.autofinalize = autofinalize

        self.configured = False
        self._config_source = config_source
        self._pending_defaults = deque()

        self.finalized = False
        self._finalize_mutex = threading.Lock()
        self._pending = deque()
        self._tasks = tasks
        if not isinstance(self._tasks, TaskRegistry):
            self._tasks = TaskRegistry(self._tasks or {})

        # If the class defins a custom __reduce_args__ we need to use
        # the old way of pickling apps, which is pickling a list of
        # args instead of the new way that pickles a dict of keywords.
        self._using_v1_reduce = app_has_custom(self, '__reduce_args__')

        # these options are moved to the config to
        # simplify pickling of the app object.
        self._preconf = changes or {}
        if broker:
            self._preconf['BROKER_URL'] = broker
        if include:
            self._preconf['CELERY_IMPORTS'] = include

        # - Apply fixups.
        self.fixups = set(self.builtin_fixups) if fixups is None else fixups
        # ...store fixup instances in _fixups to keep weakrefs alive.
        self._fixups = [symbol_by_name(fixup)(self) for fixup in self.fixups]

        if self.set_as_current:
            self.set_current()

        self.on_init()
        _register_app(self)

    def set_current(self):
        _tls.current_app = self

    def set_default(self):
        set_default_app(self)

    def __enter__(self):
        return self

    def __exit__(self, *exc_info):
        self.close()

    def close(self):
        self._maybe_close_pool()

    def on_init(self):
        """Optional callback called at init."""
        pass

    def start(self, argv=None):
        return instantiate(
            'celery.bin.celery:CeleryCommand',
            app=self).execute_from_commandline(argv)

    def worker_main(self, argv=None):
        return instantiate(
            'celery.bin.worker:worker',
            app=self).execute_from_commandline(argv)

    def task(self, *args, **opts):
        """Creates new task class from any callable."""
        if _EXECV and not opts.get('_force_evaluate'):
            # When using execv the task in the original module will point to a
            # different app, so doing things like 'add.request' will point to
            # a differnt task instance.  This makes sure it will always use
            # the task instance from the current app.
            # Really need a better solution for this :(
            from . import shared_task as proxies_to_curapp
            return proxies_to_curapp(*args, _force_evaluate=True, **opts)

        def inner_create_task_cls(shared=True, filter=None, **opts):
            _filt = filter  # stupid 2to3

            def _create_task_cls(fun):
                if shared:
                    cons = lambda app: app._task_from_fun(fun, **opts)
                    cons.__name__ = fun.__name__
                    shared_task(cons)
                if self.accept_magic_kwargs:  # compat mode
                    task = self._task_from_fun(fun, **opts)
                    if filter:
                        task = filter(task)
                    return task

                if self.finalized or opts.get('_force_evaluate'):
                    ret = self._task_from_fun(fun, **opts)
                else:
                    # return a proxy object that evaluates on first use
                    ret = PromiseProxy(self._task_from_fun, (fun, ), opts,
                                       __doc__=fun.__doc__)
                    self._pending.append(ret)
                if _filt:
                    return _filt(ret)
                return ret

            return _create_task_cls

        if len(args) == 1:
            if callable(args[0]):
                return inner_create_task_cls(**opts)(*args)
            raise TypeError('argument 1 to @task() must be a callable')
        if args:
            raise TypeError(
                '@task() takes exactly 1 argument ({0} given)'.format(
                    sum([len(args), len(opts)])))
        return inner_create_task_cls(**opts)

    def _task_from_fun(self, fun, **options):
        if not self.finalized and not self.autofinalize:
            raise RuntimeError('Contract breach: app not finalized')
        base = options.pop('base', None) or self.Task
        bind = options.pop('bind', False)

        T = type(fun.__name__, (base, ), dict({
            'app': self,
            'accept_magic_kwargs': False,
            'run': fun if bind else staticmethod(fun),
            '_decorated': True,
            '__doc__': fun.__doc__,
            '__module__': fun.__module__}, **options))()
        task = self._tasks[T.name]  # return global instance.
        return task

    def finalize(self, auto=False):
        with self._finalize_mutex:
            if not self.finalized:
                if auto and not self.autofinalize:
                    raise RuntimeError('Contract breach: app not finalized')
                self.finalized = True
                load_shared_tasks(self)

                pending = self._pending
                while pending:
                    maybe_evaluate(pending.popleft())

                for task in values(self._tasks):
                    task.bind(self)

    def add_defaults(self, fun):
        if not callable(fun):
            d, fun = fun, lambda: d
        if self.configured:
            return self.conf.add_defaults(fun())
        self._pending_defaults.append(fun)

    def config_from_object(self, obj, silent=False, force=False):
        self._config_source = obj
        if force or self.configured:
            del(self.conf)
            return self.loader.config_from_object(obj, silent=silent)

    def config_from_envvar(self, variable_name, silent=False, force=False):
        module_name = os.environ.get(variable_name)
        if not module_name:
            if silent:
                return False
            raise ImproperlyConfigured(ERR_ENVVAR_NOT_SET.format(module_name))
        return self.config_from_object(module_name, silent=silent, force=force)

    def config_from_cmdline(self, argv, namespace='celery'):
        self.conf.update(self.loader.cmdline_config_parser(argv, namespace))

    def setup_security(self, allowed_serializers=None, key=None, cert=None,
                       store=None, digest='sha1', serializer='json'):
        from celery.security import setup_security
        return setup_security(allowed_serializers, key, cert,
                              store, digest, serializer, app=self)

    def autodiscover_tasks(self, packages, related_name='tasks', force=False):
        if force:
            return self._autodiscover_tasks(packages, related_name)
        signals.import_modules.connect(promise(
            self._autodiscover_tasks, (packages, related_name),
        ), weak=False, sender=self)

    def _autodiscover_tasks(self, packages, related_name='tasks', **kwargs):
        # argument may be lazy
        packages = packages() if callable(packages) else packages
        self.loader.autodiscover_tasks(packages, related_name)

    def send_task(self, name, args=None, kwargs=None, countdown=None,
                  eta=None, task_id=None, producer=None, connection=None,
                  router=None, result_cls=None, expires=None,
                  publisher=None, link=None, link_error=None,
                  add_to_parent=True, reply_to=None, **options):
        task_id = task_id or uuid()
        producer = producer or publisher  # XXX compat
        router = router or self.amqp.router
        conf = self.conf
        if conf.CELERY_ALWAYS_EAGER:  # pragma: no cover
            warnings.warn(AlwaysEagerIgnored(
                'CELERY_ALWAYS_EAGER has no effect on send_task'))
        options = router.route(options, name, args, kwargs)
        if connection:
            producer = self.amqp.TaskProducer(connection)
        with self.producer_or_acquire(producer) as P:
            self.backend.on_task_call(P, task_id)
            task_id = P.publish_task(
                name, args, kwargs, countdown=countdown, eta=eta,
                task_id=task_id, expires=expires,
                callbacks=maybe_list(link), errbacks=maybe_list(link_error),
                reply_to=reply_to or self.oid, **options
            )
        result = (result_cls or self.AsyncResult)(task_id)
        if add_to_parent:
            parent = get_current_worker_task()
            if parent:
                parent.add_trail(result)
        return result

    def connection(self, hostname=None, userid=None, password=None,
                   virtual_host=None, port=None, ssl=None,
                   connect_timeout=None, transport=None,
                   transport_options=None, heartbeat=None,
                   login_method=None, failover_strategy=None, **kwargs):
        conf = self.conf
        return self.amqp.Connection(
            hostname or conf.BROKER_URL,
            userid or conf.BROKER_USER,
            password or conf.BROKER_PASSWORD,
            virtual_host or conf.BROKER_VHOST,
            port or conf.BROKER_PORT,
            transport=transport or conf.BROKER_TRANSPORT,
            ssl=self.either('BROKER_USE_SSL', ssl),
            heartbeat=heartbeat,
            login_method=login_method or conf.BROKER_LOGIN_METHOD,
            failover_strategy=(
                failover_strategy or conf.BROKER_FAILOVER_STRATEGY
            ),
            transport_options=dict(
                conf.BROKER_TRANSPORT_OPTIONS, **transport_options or {}
            ),
            connect_timeout=self.either(
                'BROKER_CONNECTION_TIMEOUT', connect_timeout
            ),
        )
    broker_connection = connection

    @contextmanager
    def connection_or_acquire(self, connection=None, pool=True,
                              *args, **kwargs):
        if connection:
            yield connection
        else:
            if pool:
                with self.pool.acquire(block=True) as connection:
                    yield connection
            else:
                with self.connection() as connection:
                    yield connection
    default_connection = connection_or_acquire  # XXX compat

    @contextmanager
    def producer_or_acquire(self, producer=None):
        if producer:
            yield producer
        else:
            with self.amqp.producer_pool.acquire(block=True) as producer:
                yield producer
    default_producer = producer_or_acquire  # XXX compat

    def prepare_config(self, c):
        """Prepare configuration before it is merged with the defaults."""
        return find_deprecated_settings(c)

    def now(self):
        return self.loader.now(utc=self.conf.CELERY_ENABLE_UTC)

    def mail_admins(self, subject, body, fail_silently=False):
        if self.conf.ADMINS:
            to = [admin_email for _, admin_email in self.conf.ADMINS]
            return self.loader.mail_admins(
                subject, body, fail_silently, to=to,
                sender=self.conf.SERVER_EMAIL,
                host=self.conf.EMAIL_HOST,
                port=self.conf.EMAIL_PORT,
                user=self.conf.EMAIL_HOST_USER,
                password=self.conf.EMAIL_HOST_PASSWORD,
                timeout=self.conf.EMAIL_TIMEOUT,
                use_ssl=self.conf.EMAIL_USE_SSL,
                use_tls=self.conf.EMAIL_USE_TLS,
            )

    def select_queues(self, queues=None):
        return self.amqp.queues.select(queues)

    def either(self, default_key, *values):
        """Fallback to the value of a configuration key if none of the
        `*values` are true."""
        return first(None, values) or self.conf.get(default_key)

    def bugreport(self):
        return bugreport(self)

    def _get_backend(self):
        from celery.backends import get_backend_by_url
        backend, url = get_backend_by_url(
            self.backend_cls or self.conf.CELERY_RESULT_BACKEND,
            self.loader)
        return backend(app=self, url=url)

    def on_configure(self):
        """Callback calld when the app loads configuration"""
        pass

    def _get_config(self):
        self.on_configure()
        if self._config_source:
            self.loader.config_from_object(self._config_source)
        self.configured = True
        s = Settings({}, [self.prepare_config(self.loader.conf),
                          deepcopy(DEFAULTS)])

        # load lazy config dict initializers.
        pending = self._pending_defaults
        while pending:
            s.add_defaults(maybe_evaluate(pending.popleft()()))
        if self._preconf:
            for key, value in items(self._preconf):
                setattr(s, key, value)
        return s

    def _after_fork(self, obj_):
        self._maybe_close_pool()

    def _maybe_close_pool(self):
        if self._pool:
            self._pool.force_close_all()
            self._pool = None
            amqp = self.amqp
            if amqp._producer_pool:
                amqp._producer_pool.force_close_all()
                amqp._producer_pool = None

    def signature(self, *args, **kwargs):
        kwargs['app'] = self
        return self.canvas.signature(*args, **kwargs)

    def create_task_cls(self):
        """Creates a base task class using default configuration
        taken from this app."""
        return self.subclass_with_self(
            self.task_cls, name='Task', attribute='_app',
            keep_reduce=True, abstract=True,
        )

    def subclass_with_self(self, Class, name=None, attribute='app',
                           reverse=None, keep_reduce=False, **kw):
        """Subclass an app-compatible class by setting its app attribute
        to be this app instance.

        App-compatible means that the class has a class attribute that
        provides the default app it should use, e.g.
        ``class Foo: app = None``.

        :param Class: The app-compatible class to subclass.
        :keyword name: Custom name for the target class.
        :keyword attribute: Name of the attribute holding the app,
                            default is 'app'.

        """
        Class = symbol_by_name(Class)
        reverse = reverse if reverse else Class.__name__

        def __reduce__(self):
            return _unpickle_appattr, (reverse, self.__reduce_args__())

        attrs = dict({attribute: self}, __module__=Class.__module__,
                     __doc__=Class.__doc__, **kw)
        if not keep_reduce:
            attrs['__reduce__'] = __reduce__

        return type(name or Class.__name__, (Class, ), attrs)

    def _rgetattr(self, path):
        return attrgetter(path)(self)

    def __repr__(self):
        return '<{0} {1}>'.format(type(self).__name__, appstr(self))

    def __reduce__(self):
        if self._using_v1_reduce:
            return self.__reduce_v1__()
        return (_unpickle_app_v2, (self.__class__, self.__reduce_keys__()))

    def __reduce_v1__(self):
        # Reduce only pickles the configuration changes,
        # so the default configuration doesn't have to be passed
        # between processes.
        return (
            _unpickle_app,
            (self.__class__, self.Pickler) + self.__reduce_args__(),
        )

    def __reduce_keys__(self):
        """Return keyword arguments used to reconstruct the object
        when unpickling."""
        return {
            'main': self.main,
            'changes': self.conf.changes,
            'loader': self.loader_cls,
            'backend': self.backend_cls,
            'amqp': self.amqp_cls,
            'events': self.events_cls,
            'log': self.log_cls,
            'control': self.control_cls,
            'accept_magic_kwargs': self.accept_magic_kwargs,
            'fixups': self.fixups,
            'config_source': self._config_source,
            'task_cls': self.task_cls,
        }

    def __reduce_args__(self):
        """Deprecated method, please use :meth:`__reduce_keys__` instead."""
        return (self.main, self.conf.changes,
                self.loader_cls, self.backend_cls, self.amqp_cls,
                self.events_cls, self.log_cls, self.control_cls,
                self.accept_magic_kwargs, self._config_source)

    @cached_property
    def Worker(self):
        return self.subclass_with_self('celery.apps.worker:Worker')

    @cached_property
    def WorkController(self, **kwargs):
        return self.subclass_with_self('celery.worker:WorkController')

    @cached_property
    def Beat(self, **kwargs):
        return self.subclass_with_self('celery.apps.beat:Beat')

    @cached_property
    def Task(self):
        return self.create_task_cls()

    @cached_property
    def annotations(self):
        return prepare_annotations(self.conf.CELERY_ANNOTATIONS)

    @cached_property
    def AsyncResult(self):
        return self.subclass_with_self('celery.result:AsyncResult')

    @cached_property
    def ResultSet(self):
        return self.subclass_with_self('celery.result:ResultSet')

    @cached_property
    def GroupResult(self):
        return self.subclass_with_self('celery.result:GroupResult')

    @cached_property
    def TaskSet(self):  # XXX compat
        """Deprecated! Please use :class:`celery.group` instead."""
        return self.subclass_with_self('celery.task.sets:TaskSet')

    @cached_property
    def TaskSetResult(self):  # XXX compat
        """Deprecated! Please use :attr:`GroupResult` instead."""
        return self.subclass_with_self('celery.result:TaskSetResult')

    @property
    def pool(self):
        if self._pool is None:
            register_after_fork(self, self._after_fork)
            limit = self.conf.BROKER_POOL_LIMIT
            self._pool = self.connection().Pool(limit=limit)
        return self._pool

    @property
    def current_task(self):
        return _task_stack.top

    @cached_property
    def oid(self):
        return oid_from(self)

    @cached_property
    def amqp(self):
        return instantiate(self.amqp_cls, app=self)

    @cached_property
    def backend(self):
        return self._get_backend()

    @cached_property
    def conf(self):
        return self._get_config()

    @cached_property
    def control(self):
        return instantiate(self.control_cls, app=self)

    @cached_property
    def events(self):
        return instantiate(self.events_cls, app=self)

    @cached_property
    def loader(self):
        return get_loader_cls(self.loader_cls)(app=self)

    @cached_property
    def log(self):
        return instantiate(self.log_cls, app=self)

    @cached_property
    def canvas(self):
        from celery import canvas
        return canvas

    @cached_property
    def tasks(self):
        self.finalize(auto=True)
        return self._tasks

    @cached_property
    def timezone(self):
        from celery.utils.timeutils import timezone
        conf = self.conf
        tz = conf.CELERY_TIMEZONE
        if not tz:
            return (timezone.get_timezone('UTC') if conf.CELERY_ENABLE_UTC
                    else timezone.local)
        return timezone.get_timezone(self.conf.CELERY_TIMEZONE)
App = Celery  # compat
