''' Provide a base class for objects that can have declarative, typed,
serializable properties.

.. note::
    These classes form part of the very low-level machinery that implements
    the Bokeh model and property system. It is unlikely that any of these
    classes or their methods will be applicable to any standard usage or to
    anyone who is not directly developing on Bokeh's own infrastructure.

'''
from __future__ import absolute_import

import logging
log = logging.getLogger(__name__)

import difflib
import inspect
from operator import itemgetter
import sys
from warnings import warn

from six import StringIO

from ..util.dependencies import import_optional
from ..util.future import with_metaclass
from ..util.string import nice_join
from .property.containers import PropertyValueContainer
from .property.descriptor_factory import PropertyDescriptorFactory
from .property.override import Override

_ABSTRACT_ADMONITION = '''
    .. note::
        This is an abstract base class used to help organize the hierarchy of Bokeh
        model types. **It is not useful to instantiate on its own.**

'''

_EXAMPLE_TEMPLATE = '''

    Example
    -------

    .. bokeh-plot:: ../%(path)s
        :source-position: below

'''

def abstract(cls):
    ''' A decorator to mark abstract base classes derived from |HasProps|.

    '''
    if not issubclass(cls, HasProps):
        raise TypeError("%s is not a subclass of HasProps" % cls.__name__)

    # running python with -OO will discard docstrings -> __doc__ is None
    if cls.__doc__ is not None:
        cls.__doc__ += _ABSTRACT_ADMONITION

    return cls

class MetaHasProps(type):
    ''' Specialize the construction of |HasProps| classes.

    This class is a `metaclass`_ for |HasProps| that is responsible for
    creating and adding the |PropertyDescriptor| instances that delegate
    validation and serialization to |Property| attributes.

    .. _metaclass: https://docs.python.org/3/reference/datamodel.html#metaclasses

    '''
    def __new__(meta_cls, class_name, bases, class_dict):
        '''

        '''
        names_with_refs = set()
        container_names = set()

        # Now handle all the Override
        overridden_defaults = {}
        for name, prop in class_dict.items():
            if not isinstance(prop, Override):
                continue
            if prop.default_overridden:
                overridden_defaults[name] = prop.default

        for name, default in overridden_defaults.items():
            del class_dict[name]

        generators = dict()
        for name, generator in class_dict.items():
            if isinstance(generator, PropertyDescriptorFactory):
                generators[name] = generator
            elif isinstance(generator, type) and issubclass(generator, PropertyDescriptorFactory):
                # Support the user adding a property without using parens,
                # i.e. using just the Property subclass instead of an
                # instance of the subclass
                generators[name] = generator.autocreate()

        dataspecs = {}
        new_class_attrs = {}

        for name, generator in generators.items():
            prop_descriptors = generator.make_descriptors(name)
            replaced_self = False
            for prop_descriptor in prop_descriptors:
                if prop_descriptor.name in generators:
                    if generators[prop_descriptor.name] is generator:
                        # a generator can replace itself, this is the
                        # standard case like `foo = Int()`
                        replaced_self = True
                        prop_descriptor.add_prop_descriptor_to_class(class_name, new_class_attrs, names_with_refs, container_names, dataspecs)
                    else:
                        # if a generator tries to overwrite another
                        # generator that's been explicitly provided,
                        # use the prop that was manually provided
                        # and ignore this one.
                        pass
                else:
                    prop_descriptor.add_prop_descriptor_to_class(class_name, new_class_attrs, names_with_refs, container_names, dataspecs)
            # if we won't overwrite ourselves anyway, delete the generator
            if not replaced_self:
                del class_dict[name]

        class_dict.update(new_class_attrs)

        class_dict["__properties__"] = set(new_class_attrs)
        class_dict["__properties_with_refs__"] = names_with_refs
        class_dict["__container_props__"] = container_names
        if len(overridden_defaults) > 0:
            class_dict["__overridden_defaults__"] = overridden_defaults
        if dataspecs:
            class_dict["__dataspecs__"] = dataspecs

        if "__example__" in class_dict:
            path = class_dict["__example__"]

            # running python with -OO will discard docstrings -> __doc__ is None
            if "__doc__" in class_dict and class_dict["__doc__"] is not None:
                class_dict["__doc__"] += _EXAMPLE_TEMPLATE % dict(path=path)

        return super(MetaHasProps, meta_cls).__new__(meta_cls, class_name, bases, class_dict)

    def __init__(cls, class_name, bases, nmspc):
        if class_name == 'HasProps':
            return
        # Check for improperly overriding a Property attribute.
        # Overriding makes no sense except through the Override
        # class which can be used to tweak the default.
        # Historically code also tried changing the Property's
        # type or changing from Property to non-Property: these
        # overrides are bad conceptually because the type of a
        # read-write property is invariant.
        cls_attrs = cls.__dict__.keys() # we do NOT want inherited attrs here
        for attr in cls_attrs:
            for base in bases:
                if issubclass(base, HasProps) and attr in base.properties():
                    warn(('Property "%s" in class %s was overridden by a class attribute ' + \
                          '"%s" in class %s; it never makes sense to do this. ' + \
                          'Either %s.%s or %s.%s should be removed, or %s.%s should not ' + \
                          'be a Property, or use Override(), depending on the intended effect.') %
                         (attr, base.__name__, attr, class_name,
                          base.__name__, attr,
                          class_name, attr,
                          base.__name__, attr),
                         RuntimeWarning, stacklevel=2)

        if "__overridden_defaults__" in cls.__dict__:
            our_props = cls.properties()
            for key in cls.__dict__["__overridden_defaults__"].keys():
                if key not in our_props:
                    warn(('Override() of %s in class %s does not override anything.') % (key, class_name),
                         RuntimeWarning, stacklevel=2)

def accumulate_from_superclasses(cls, propname):
    ''' Traverse the class hierarchy and accumulate the special sets of names
    ``MetaHasProps`` stores on classes:

    Args:
        name (str) : name of the special attribute to collect.

            Typically meaningful values are: ``__container_props__``,
            ``__properties__``, ``__properties_with_refs__``

    '''
    cachename = "__cached_all" + propname
    # we MUST use cls.__dict__ NOT hasattr(). hasattr() would also look at base
    # classes, and the cache must be separate for each class
    if cachename not in cls.__dict__:
        s = set()
        for c in inspect.getmro(cls):
            if issubclass(c, HasProps) and hasattr(c, propname):
                base = getattr(c, propname)
                s.update(base)
        setattr(cls, cachename, s)
    return cls.__dict__[cachename]

def accumulate_dict_from_superclasses(cls, propname):
    ''' Traverse the class hierarchy and accumulate the special dicts
    ``MetaHasProps`` stores on classes:

    Args:
        name (str) : name of the special attribute to collect.

            Typically meaningful values are: ``__dataspecs__``,
            ``__overridden_defaults__``

    '''
    cachename = "__cached_all" + propname
    # we MUST use cls.__dict__ NOT hasattr(). hasattr() would also look at base
    # classes, and the cache must be separate for each class
    if cachename not in cls.__dict__:
        d = dict()
        for c in inspect.getmro(cls):
            if issubclass(c, HasProps) and hasattr(c, propname):
                base = getattr(c, propname)
                for k,v in base.items():
                    if k not in d:
                        d[k] = v
        setattr(cls, cachename, d)
    return cls.__dict__[cachename]

class HasProps(with_metaclass(MetaHasProps, object)):
    ''' Base class for all class types that have Bokeh properties.

    '''
    def __init__(self, **properties):
        '''

        '''
        super(HasProps, self).__init__()
        self._property_values = dict()
        self._unstable_default_values = dict()
        self._unstable_themed_values = dict()

        for name, value in properties.items():
            setattr(self, name, value)

    def __setattr__(self, name, value):
        ''' Intercept attribute setting on HasProps in order to special case
        a few situations:

        * short circuit all property machinery for ``_private`` attributes
        * suggest similar attribute names on attribute errors

        Args:
            name (str) : the name of the attribute to set on this object
            value (obj) : the value to set

        Returns:
            None

        '''
        # self.properties() below can be expensive so avoid it
        # if we're just setting a private underscore field
        if name.startswith("_"):
            super(HasProps, self).__setattr__(name, value)
            return

        props = sorted(self.properties())
        descriptor = getattr(self.__class__, name, None)

        if name in props or (descriptor is not None and descriptor.fset is not None):
            super(HasProps, self).__setattr__(name, value)
        else:
            matches, text = difflib.get_close_matches(name.lower(), props), "similar"

            if not matches:
                matches, text = props, "possible"

            raise AttributeError("unexpected attribute '%s' to %s, %s attributes are %s" %
                (name, self.__class__.__name__, text, nice_join(matches)))

    def __str__(self):
        return "%s(...)" % self.__class__.__name__

    __repr__ = __str__

    def equals(self, other):
        ''' Structural equality of models.

        Args:
            other (HasProps) : the other instance to compare to

        Returns:
            True, if properties are structurally equal, otherwise False

        '''

        # NOTE: don't try to use this to implement __eq__. Because then
        # you will be tempted to implement __hash__, which would interfere
        # with mutability of models. However, not implementing __hash__
        # will make bokeh unusable in Python 3, where proper implementation
        # of __hash__ is required when implementing __eq__.
        if not isinstance(other, self.__class__):
            return False
        else:
            return self.properties_with_values() == other.properties_with_values()

    def set_from_json(self, name, json, models=None, setter=None):
        ''' Set a property value on this object from JSON.

        Args:
            name: (str) : name of the attribute to set

            json: (JSON-value) : value to set to the attribute to

            models (dict or None, optional) :
                Mapping of model ids to models (default: None)

                This is needed in cases where the attributes to update also
                have values that have references.

            setter(ClientSession or ServerSession or None, optional) :
                This is used to prevent "boomerang" updates to Bokeh apps.

                In the context of a Bokeh server application, incoming updates
                to properties will be annotated with the session that is
                doing the updating. This value is propagated through any
                subsequent change notifications that the update triggers.
                The session can compare the event setter to itself, and
                suppress any updates that originate from itself.

        Returns:
            None

        '''
        if name in self.properties():
            log.trace("Patching attribute %r of %r with %r", name, self, json)
            descriptor = self.lookup(name)
            descriptor.set_from_json(self, json, models, setter)
        else:
            log.warn("JSON had attr %r on obj %r, which is a client-only or invalid attribute that shouldn't have been sent", name, self)

    def update(self, **kwargs):
        ''' Updates the object's properties from the given keyword arguments.

        Returns:
            None

        Examples:

            The following are equivalent:

            .. code-block:: python

                from bokeh.models import Range1d

                r = Range1d

                # set properties individually:
                r.start = 10
                r.end = 20

                # update properties together:
                r.update(start=10, end=20)

        '''
        for k,v in kwargs.items():
            setattr(self, k, v)

    def update_from_json(self, json_attributes, models=None, setter=None):
        ''' Updates the object's properties from a JSON attributes dictionary.

        Args:
            json_attributes: (JSON-dict) : attributes and values to update

            models (dict or None, optional) :
                Mapping of model ids to models (default: None)

                This is needed in cases where the attributes to update also
                have values that have references.

            setter(ClientSession or ServerSession or None, optional) :
                This is used to prevent "boomerang" updates to Bokeh apps.

                In the context of a Bokeh server application, incoming updates
                to properties will be annotated with the session that is
                doing the updating. This value is propagated through any
                subsequent change notifications that the update triggers.
                The session can compare the event setter to itself, and
                suppress any updates that originate from itself.

        Returns:
            None

        '''
        for k, v in json_attributes.items():
            self.set_from_json(k, v, models, setter)

    @classmethod
    def lookup(cls, name):
        ''' Find the ``PropertyDescriptor`` for a Bokeh property on a class,
        given the property name.

        Args:
            name (str) : name of the property to search for

        Returns:
            PropertyDescriptor : descriptor for property named ``name``

        '''
        return getattr(cls, name)

    @classmethod
    def properties_with_refs(cls):
        ''' Collect the names of all properties on this class that also have
        references.

        This method *always* traverses the class hierarchy and includes
        properties defined on any parent classes.

        Returns:
            set[str] : names of properties that have references

        '''
        return accumulate_from_superclasses(cls, "__properties_with_refs__")

    @classmethod
    def properties_containers(cls):
        ''' Collect the names of all container properties on this class.

        This method *always* traverses the class hierarchy and includes
        properties defined on any parent classes.

        Returns:
            set[str] : names of container properties

        '''
        return accumulate_from_superclasses(cls, "__container_props__")

    @classmethod
    def properties(cls, with_bases=True):
        ''' Collect the names of properties on this class.

        This method *optionally* traverses the class hierarchy and includes
        properties defined on any parent classes.

        Args:
            with_bases (bool, optional) :
                Whether to include properties defined on parent classes in
                the results. (default: True)

        Returns:
           set[str] : property names

        '''
        if with_bases:
            return accumulate_from_superclasses(cls, "__properties__")
        else:
            return set(cls.__properties__)

    @classmethod
    def dataspecs(cls):
        ''' Collect the names of all ``DataSpec`` properties on this class.

        This method *always* traverses the class hierarchy and includes
        properties defined on any parent classes.

        Returns:
            set[str] : names of DataSpec properties

        '''
        return set(cls.dataspecs_with_props().keys())

    @classmethod
    def dataspecs_with_props(cls):
        ''' Collect a dict mapping the names of all ``DataSpec`` properties
        on this class to the associated properties.

        This method *always* traverses the class hierarchy and includes
        properties defined on any parent classes.

        Returns:
            dict[str, DataSpec] : mapping of names and ``DataSpec`` properties

        '''
        return accumulate_dict_from_superclasses(cls, "__dataspecs__")

    def properties_with_values(self, include_defaults=True):
        ''' Collect a dict mapping property names to their values.

        This method *always* traverses the class hierarchy and includes
        properties defined on any parent classes.

        Non-serializable properties are skipped and property values are in
        "serialized" format which may be slightly different from the values
        you would normally read from the properties; the intent of this method
        is to return the information needed to losslessly reconstitute the
        object instance.

        Args:
            include_defaults (bool, optional) :
                Whether to include properties that haven't been explicitly set
                since the object was created. (default: True)

        Returns:
           dict : mapping from property names to their values

        '''
        return self.query_properties_with_values(lambda prop: prop.serialized, include_defaults)

    @classmethod
    def _overridden_defaults(cls):
        ''' Returns a dictionary of defaults that have been overridden.

        This is an implementation detail of Property.

        '''
        return accumulate_dict_from_superclasses(cls, "__overridden_defaults__")

    def query_properties_with_values(self, query, include_defaults=True):
        ''' Query the properties values of |HasProps| instances with a
        predicate.

        Args:
            query (callable) :
                A callable that accepts property descriptors and returns True
                or False

            include_defaults (bool, optional) :
                Whether to include properties that have not been explicitly
                set by a user (default: True)

        Returns:
            dict : mapping of property names and values for matching properties

        '''
        themed_keys = set()
        result = dict()
        if include_defaults:
            keys = self.properties()
        else:
            # TODO (bev) For now, include unstable default values. Things rely on Instances
            # always getting serialized, even defaults, and adding unstable defaults here
            # accomplishes that. Unmodified defaults for property value containers will be
            # weeded out below.
            keys = set(self._property_values.keys()) | set(self._unstable_default_values.keys())
            if self.themed_values():
                themed_keys = set(self.themed_values().keys())
                keys |= themed_keys

        for key in keys:
            descriptor = self.lookup(key)
            if not query(descriptor):
                continue

            value = descriptor.serializable_value(self)
            if not include_defaults and key not in themed_keys:
                if isinstance(value, PropertyValueContainer) and key in self._unstable_default_values:
                    continue
            result[key] = value

        return result