# Copyright: See the LICENSE file.


"""factory_boy extensions for use with the Django framework."""


import functools
import io
import logging
import os

from django.core import files as django_files
from django.db import IntegrityError

from . import base, declarations, errors

logger = logging.getLogger('factory.generate')


DEFAULT_DB_ALIAS = 'default'  # Same as django.db.DEFAULT_DB_ALIAS


_LAZY_LOADS = {}


def get_model(app, model):
    """Wrapper around django's get_model."""
    if 'get_model' not in _LAZY_LOADS:
        _lazy_load_get_model()

    _get_model = _LAZY_LOADS['get_model']
    return _get_model(app, model)


def _lazy_load_get_model():
    """Lazy loading of get_model.

    get_model loads django.conf.settings, which may fail if
    the settings haven't been configured yet.
    """
    from django import apps as django_apps
    _LAZY_LOADS['get_model'] = django_apps.apps.get_model


class DjangoOptions(base.FactoryOptions):
    def _build_default_options(self):
        return super()._build_default_options() + [
            base.OptionDefault('django_get_or_create', (), inherit=True),
            base.OptionDefault('database', DEFAULT_DB_ALIAS, inherit=True),
        ]

    def _get_counter_reference(self):
        counter_reference = super()._get_counter_reference()
        if (counter_reference == self.base_factory
                and self.base_factory._meta.model is not None
                and self.base_factory._meta.model._meta.abstract
                and self.model is not None
                and not self.model._meta.abstract):
            # Target factory is for an abstract model, yet we're for another,
            # concrete subclass => don't reuse the counter.
            return self.factory
        return counter_reference

    def get_model_class(self):
        if isinstance(self.model, str) and '.' in self.model:
            app, model_name = self.model.split('.', 1)
            self.model = get_model(app, model_name)

        return self.model


class DjangoModelFactory(base.Factory):
    """Factory for Django models.

    This makes sure that the 'sequence' field of created objects is a new id.

    Possible improvement: define a new 'attribute' type, AutoField, which would
    handle those for non-numerical primary keys.
    """

    _options_class = DjangoOptions

    class Meta:
        abstract = True  # Optional, but explicit.

    @classmethod
    def _load_model_class(cls, definition):

        if isinstance(definition, str) and '.' in definition:
            app, model = definition.split('.', 1)
            return get_model(app, model)

        return definition

    @classmethod
    def _get_manager(cls, model_class):
        if model_class is None:
            raise errors.AssociatedClassError(
                f"No model set on {cls.__module__}.{cls.__name__}.Meta")

        try:
            manager = model_class.objects
        except AttributeError:
            # When inheriting from an abstract model with a custom
            # manager, the class has no 'objects' field.
            manager = model_class._default_manager

        if cls._meta.database != DEFAULT_DB_ALIAS:
            manager = manager.using(cls._meta.database)
        return manager

    @classmethod
    def _generate(cls, strategy, params):
        # Original params are used in _get_or_create if it cannot build an
        # object initially due to an IntegrityError being raised
        cls._original_params = params
        return super()._generate(strategy, params)

    @classmethod
    def _get_or_create(cls, model_class, *args, **kwargs):
        """Create an instance of the model through objects.get_or_create."""
        manager = cls._get_manager(model_class)

        assert 'defaults' not in cls._meta.django_get_or_create, (
            "'defaults' is a reserved keyword for get_or_create "
            "(in %s._meta.django_get_or_create=%r)"
            % (cls, cls._meta.django_get_or_create))

        key_fields = {}
        for field in cls._meta.django_get_or_create:
            if field not in kwargs:
                raise errors.FactoryError(
                    "django_get_or_create - "
                    "Unable to find initialization value for '%s' in factory %s" %
                    (field, cls.__name__))
            key_fields[field] = kwargs.pop(field)
        key_fields['defaults'] = kwargs

        try:
            instance, _created = manager.get_or_create(*args, **key_fields)
        except IntegrityError as e:
            get_or_create_params = {
                lookup: value
                for lookup, value in cls._original_params.items()
                if lookup in cls._meta.django_get_or_create
            }
            if get_or_create_params:
                try:
                    instance = manager.get(**get_or_create_params)
                except manager.model.DoesNotExist:
                    # Original params are not a valid lookup and triggered a create(),
                    # that resulted in an IntegrityError. Follow Django’s behavior.
                    raise e
            else:
                raise e

        return instance

    @classmethod
    def _create(cls, model_class, *args, **kwargs):
        """Create an instance of the model, and save it to the database."""
        if cls._meta.django_get_or_create:
            return cls._get_or_create(model_class, *args, **kwargs)

        manager = cls._get_manager(model_class)
        return manager.create(*args, **kwargs)

    @classmethod
    def _after_postgeneration(cls, instance, create, results=None):
        """Save again the instance if creating and at least one hook ran."""
        if create and results:
            # Some post-generation hooks ran, and may have modified us.
            instance.save()


class FileField(declarations.BaseDeclaration):
    """Helper to fill in django.db.models.FileField from a Factory."""

    DEFAULT_FILENAME = 'example.dat'

    def _make_data(self, params):
        """Create data for the field."""
        return params.get('data', b'')

    def _make_content(self, params):
        path = ''

        _content_params = [params.get('from_path'), params.get('from_file'), params.get('from_func')]
        if len([p for p in _content_params if p]) > 1:
            raise ValueError(
                "At most one argument from 'from_file', 'from_path', and 'from_func' should "
                "be non-empty when calling factory.django.FileField."
            )

        if params.get('from_path'):
            path = params['from_path']
            with open(path, 'rb') as f:
                content = django_files.base.ContentFile(f.read())

        elif params.get('from_file'):
            f = params['from_file']
            content = django_files.File(f)
            path = content.name

        elif params.get('from_func'):
            func = params['from_func']
            content = django_files.File(func())
            path = content.name

        else:
            data = self._make_data(params)
            content = django_files.base.ContentFile(data)

        if path:
            default_filename = os.path.basename(path)
        else:
            default_filename = self.DEFAULT_FILENAME

        filename = params.get('filename', default_filename)
        return filename, content

    def evaluate(self, instance, step, extra):
        """Fill in the field."""
        filename, content = self._make_content(extra)
        return django_files.File(content.file, filename)


class ImageField(FileField):
    DEFAULT_FILENAME = 'example.jpg'

    def _make_data(self, params):
        # ImageField (both django's and factory_boy's) require PIL.
        # Try to import it along one of its known installation paths.
        from PIL import Image

        width = params.get('width', 100)
        height = params.get('height', width)
        color = params.get('color', 'blue')
        image_format = params.get('format', 'JPEG')
        image_palette = params.get('palette', 'RGB')

        thumb_io = io.BytesIO()
        with Image.new(image_palette, (width, height), color) as thumb:
            thumb.save(thumb_io, format=image_format)
        return thumb_io.getvalue()


class mute_signals:
    """Temporarily disables and then restores any django signals.

    Args:
        *signals (django.dispatch.dispatcher.Signal): any django signals

    Examples:
        with mute_signals(pre_init):
            user = UserFactory.build()
            ...

        @mute_signals(pre_save, post_save)
        class UserFactory(factory.Factory):
            ...

        @mute_signals(post_save)
        def generate_users():
            UserFactory.create_batch(10)
    """

    def __init__(self, *signals):
        self.signals = signals
        self.paused = {}

    def __enter__(self):
        for signal in self.signals:
            logger.debug('mute_signals: Disabling signal handlers %r',
                         signal.receivers)

            # Note that we're using implementation details of
            # django.signals, since arguments to signal.connect()
            # are lost in signal.receivers
            self.paused[signal] = signal.receivers
            signal.receivers = []

    def __exit__(self, exc_type, exc_value, traceback):
        for signal, receivers in self.paused.items():
            logger.debug('mute_signals: Restoring signal handlers %r',
                         receivers)

            signal.receivers = receivers
            with signal.lock:
                # Django uses some caching for its signals.
                # Since we're bypassing signal.connect and signal.disconnect,
                # we have to keep messing with django's internals.
                signal.sender_receivers_cache.clear()
        self.paused = {}

    def copy(self):
        return mute_signals(*self.signals)

    def __call__(self, callable_obj):
        if isinstance(callable_obj, base.FactoryMetaClass):
            # Retrieve __func__, the *actual* callable object.
            callable_obj._create = self.wrap_method(callable_obj._create.__func__)
            callable_obj._generate = self.wrap_method(callable_obj._generate.__func__)
            return callable_obj

        else:
            @functools.wraps(callable_obj)
            def wrapper(*args, **kwargs):
                # A mute_signals() object is not reentrant; use a copy every time.
                with self.copy():
                    return callable_obj(*args, **kwargs)
            return wrapper

    def wrap_method(self, method):
        @classmethod
        @functools.wraps(method)
        def wrapped_method(*args, **kwargs):
            # A mute_signals() object is not reentrant; use a copy every time.
            with self.copy():
                return method(*args, **kwargs)
        return wrapped_method
