"""
Like described in the :mod:`parso.python.tree` module,
there's a need for an ast like module to represent the states of parsed
modules.

But now there are also structures in Python that need a little bit more than
that. An ``Instance`` for example is only a ``Class`` before it is
instantiated. This class represents these cases.

So, why is there also a ``Class`` class here? Well, there are decorators and
they change classes in Python 3.

Representation modules also define "magic methods". Those methods look like
``py__foo__`` and are typically mappable to the Python equivalents ``__call__``
and others. Here's a list:

====================================== ========================================
**Method**                             **Description**
-------------------------------------- ----------------------------------------
py__call__(params: Array)              On callable objects, returns types.
py__bool__()                           Returns True/False/None; None means that
                                       there's no certainty.
py__bases__()                          Returns a list of base classes.
py__mro__()                            Returns a list of classes (the mro).
py__iter__()                           Returns a generator of a set of types.
py__class__()                          Returns the class of an instance.
py__getitem__(index: int/str)          Returns a a set of types of the index.
                                       Can raise an IndexError/KeyError.
py__file__()                           Only on modules. Returns None if does
                                       not exist.
py__package__()                        Only on modules. For the import system.
py__path__()                           Only on modules. For the import system.
py__get__(call_object)                 Only on instances. Simulates
                                       descriptors.
py__doc__(include_call_signature:      Returns the docstring for a context.
          bool)
====================================== ========================================

"""
from jedi._compatibility import use_metaclass
from jedi.parser_utils import get_parent_scope
from jedi.evaluate.cache import evaluator_method_cache, CachedMetaClass
from jedi.evaluate import compiled
from jedi.evaluate.lazy_context import LazyKnownContext
from jedi.evaluate.filters import ParserTreeFilter, TreeNameDefinition, \
    ContextName
from jedi.evaluate.base_context import ContextSet, iterator_to_context_set, \
    TreeContext


def apply_py__get__(context, base_context):
    try:
        method = context.py__get__
    except AttributeError:
        yield context
    else:
        for descriptor_context in method(base_context):
            yield descriptor_context


class ClassName(TreeNameDefinition):
    def __init__(self, parent_context, tree_name, name_context, apply_decorators):
        super(ClassName, self).__init__(parent_context, tree_name)
        self._name_context = name_context
        self._apply_decorators = apply_decorators

    @iterator_to_context_set
    def infer(self):
        # TODO this _name_to_types might get refactored and be a part of the
        # parent class. Once it is, we can probably just overwrite method to
        # achieve this.
        from jedi.evaluate.syntax_tree import tree_name_to_contexts
        inferred = tree_name_to_contexts(
            self.parent_context.evaluator, self._name_context, self.tree_name)

        for result_context in inferred:
            if self._apply_decorators:
                for c in apply_py__get__(result_context, self.parent_context):
                    yield c
            else:
                yield result_context


class ClassFilter(ParserTreeFilter):
    name_class = ClassName

    def __init__(self, *args, **kwargs):
        self._is_instance = kwargs.pop('is_instance')  # Python 2 :/
        super(ClassFilter, self).__init__(*args, **kwargs)

    def _convert_names(self, names):
        return [
            self.name_class(
                parent_context=self.context,
                tree_name=name,
                name_context=self._node_context,
                apply_decorators=not self._is_instance,
            ) for name in names
        ]

    def _equals_origin_scope(self):
        node = self._origin_scope
        while node is not None:
            if node == self._parser_scope or node == self.context:
                return True
            node = get_parent_scope(node)
        return False

    def _access_possible(self, name):
        return not name.value.startswith('__') or name.value.endswith('__') \
            or self._equals_origin_scope()

    def _filter(self, names):
        names = super(ClassFilter, self)._filter(names)
        return [name for name in names if self._access_possible(name)]


class ClassContext(use_metaclass(CachedMetaClass, TreeContext)):
    """
    This class is not only important to extend `tree.Class`, it is also a
    important for descriptors (if the descriptor methods are evaluated or not).
    """
    api_type = u'class'

    @evaluator_method_cache(default=())
    def py__mro__(self):
        def add(cls):
            if cls not in mro:
                mro.append(cls)

        mro = [self]
        # TODO Do a proper mro resolution. Currently we are just listing
        # classes. However, it's a complicated algorithm.
        for lazy_cls in self.py__bases__():
            # TODO there's multiple different mro paths possible if this yields
            # multiple possibilities. Could be changed to be more correct.
            for cls in lazy_cls.infer():
                # TODO detect for TypeError: duplicate base class str,
                # e.g.  `class X(str, str): pass`
                try:
                    mro_method = cls.py__mro__
                except AttributeError:
                    # TODO add a TypeError like:
                    """
                    >>> class Y(lambda: test): pass
                    Traceback (most recent call last):
                      File "<stdin>", line 1, in <module>
                    TypeError: function() argument 1 must be code, not str
                    >>> class Y(1): pass
                    Traceback (most recent call last):
                      File "<stdin>", line 1, in <module>
                    TypeError: int() takes at most 2 arguments (3 given)
                    """
                    pass
                else:
                    add(cls)
                    for cls_new in mro_method():
                        add(cls_new)
        return tuple(mro)

    @evaluator_method_cache(default=())
    def py__bases__(self):
        arglist = self.tree_node.get_super_arglist()
        if arglist:
            from jedi.evaluate import arguments
            args = arguments.TreeArguments(self.evaluator, self.parent_context, arglist)
            return [value for key, value in args.unpack() if key is None]
        else:
            return [LazyKnownContext(compiled.builtin_from_name(self.evaluator, u'object'))]

    def py__call__(self, params):
        from jedi.evaluate.context import TreeInstance
        return ContextSet(TreeInstance(self.evaluator, self.parent_context, self, params))

    def py__class__(self):
        return compiled.builtin_from_name(self.evaluator, u'type')

    def get_filters(self, search_global, until_position=None, origin_scope=None, is_instance=False):
        if search_global:
            yield ParserTreeFilter(
                self.evaluator,
                context=self,
                until_position=until_position,
                origin_scope=origin_scope
            )
        else:
            for cls in self.py__mro__():
                if isinstance(cls, compiled.CompiledObject):
                    for filter in cls.get_filters(is_instance=is_instance):
                        yield filter
                else:
                    yield ClassFilter(
                        self.evaluator, self, node_context=cls,
                        origin_scope=origin_scope,
                        is_instance=is_instance
                    )

    def is_class(self):
        return True

    def get_function_slot_names(self, name):
        for filter in self.get_filters(search_global=False):
            names = filter.get(name)
            if names:
                return names
        return []

    def get_param_names(self):
        for name in self.get_function_slot_names(u'__init__'):
            for context_ in name.infer():
                try:
                    method = context_.get_param_names
                except AttributeError:
                    pass
                else:
                    return list(method())[1:]
        return []

    @property
    def name(self):
        return ContextName(self, self.tree_node.name)