import inspect
import types
import operator as op
from collections import namedtuple

from jedi._compatibility import unicode, is_py3, is_py34, builtins, py_version
from jedi.evaluate.compiled.getattr_static import getattr_static


MethodDescriptorType = type(str.replace)
# These are not considered classes and access is granted even though they have
# a __class__ attribute.
NOT_CLASS_TYPES = (
    types.BuiltinFunctionType,
    types.CodeType,
    types.FrameType,
    types.FunctionType,
    types.GeneratorType,
    types.GetSetDescriptorType,
    types.LambdaType,
    types.MemberDescriptorType,
    types.MethodType,
    types.ModuleType,
    types.TracebackType,
    MethodDescriptorType
)

if is_py3:
    NOT_CLASS_TYPES += (
        types.MappingProxyType,
        types.SimpleNamespace
    )
    if is_py34:
        NOT_CLASS_TYPES += (types.DynamicClassAttribute,)


# Those types don't exist in typing.
MethodDescriptorType = type(str.replace)
WrapperDescriptorType = type(set.__iter__)
# `object.__subclasshook__` is an already executed descriptor.
object_class_dict = type.__dict__["__dict__"].__get__(object)
ClassMethodDescriptorType = type(object_class_dict['__subclasshook__'])

ALLOWED_DESCRIPTOR_ACCESS = (
    types.FunctionType,
    types.GetSetDescriptorType,
    types.MemberDescriptorType,
    MethodDescriptorType,
    WrapperDescriptorType,
    ClassMethodDescriptorType,
    staticmethod,
    classmethod,
)

_sentinel = object()

# Maps Python syntax to the operator module.
COMPARISON_OPERATORS = {
    '==': op.eq,
    '!=': op.ne,
    'is': op.is_,
    'is not': op.is_not,
    '<': op.lt,
    '<=': op.le,
    '>': op.gt,
    '>=': op.ge,
}

_OPERATORS = {
    '+': op.add,
    '-': op.sub,
}
_OPERATORS.update(COMPARISON_OPERATORS)


SignatureParam = namedtuple('SignatureParam', 'name has_default default has_annotation annotation')


def compiled_objects_cache(attribute_name):
    def decorator(func):
        """
        This decorator caches just the ids, oopposed to caching the object itself.
        Caching the id has the advantage that an object doesn't need to be
        hashable.
        """
        def wrapper(evaluator, obj, parent_context=None):
            cache = getattr(evaluator, attribute_name)
            # Do a very cheap form of caching here.
            key = id(obj)
            try:
                cache[key]
                return cache[key][0]
            except KeyError:
                # TODO wuaaaarrghhhhhhhh
                if attribute_name == 'mixed_cache':
                    result = func(evaluator, obj, parent_context)
                else:
                    result = func(evaluator, obj)
                # Need to cache all of them, otherwise the id could be overwritten.
                cache[key] = result, obj, parent_context
                return result
        return wrapper

    return decorator


@compiled_objects_cache('compiled_cache')
def create_access(evaluator, obj):
    return DirectObjectAccess(evaluator, obj)


class DirectObjectAccess(object):
    def __init__(self, evaluator, obj):
        self._evaluator = evaluator
        self._obj = obj

    def __repr__(self):
        return '%s(%s)' % (self.__class__.__name__, self._obj)

    def _create_access(self, obj):
        return create_access(self._evaluator, obj)

    def py__bool__(self):
        return bool(self._obj)

    def py__file__(self):
        try:
            return self._obj.__file__
        except AttributeError:
            return None

    def py__doc__(self, include_call_signature=False):
        return inspect.getdoc(self._obj) or ''

    def py__name__(self):
        if not _is_class_instance(self._obj) or \
                inspect.ismethoddescriptor(self._obj):  # slots
            cls = self._obj
        else:
            try:
                cls = self._obj.__class__
            except AttributeError:
                # happens with numpy.core.umath._UFUNC_API (you get it
                # automatically by doing `import numpy`.
                return None

        try:
            return cls.__name__
        except AttributeError:
            return None

    def py__mro__accesses(self):
        return tuple(self._create_access(cls) for cls in self._obj.__mro__[1:])

    def py__getitem__(self, index):
        if type(self._obj) not in (str, list, tuple, unicode, bytes, bytearray, dict):
            # Get rid of side effects, we won't call custom `__getitem__`s.
            return None

        return self._create_access(self._obj[index])

    def py__iter__list(self):
        if type(self._obj) not in (str, list, tuple, unicode, bytes, bytearray, dict):
            # Get rid of side effects, we won't call custom `__getitem__`s.
            return []

        lst = []
        for i, part in enumerate(self._obj):
            if i > 20:
                # Should not go crazy with large iterators
                break
            lst.append(self._create_access(part))
        return lst

    def py__class__(self):
        return self._create_access(self._obj.__class__)

    def py__bases__(self):
        return [self._create_access(base) for base in self._obj.__bases__]

    def get_repr(self):
        return repr(self._obj)

    def is_class(self):
        return inspect.isclass(self._obj)

    def ismethoddescriptor(self):
        return inspect.ismethoddescriptor(self._obj)

    def dir(self):
        return dir(self._obj)

    def has_iter(self):
        try:
            iter(self._obj)
            return True
        except TypeError:
            return False

    def is_allowed_getattr(self, name):
        try:
            attr, is_get_descriptor = getattr_static(self._obj, name)
        except AttributeError:
            raise
        else:
            if is_get_descriptor \
                    and not type(attr) in ALLOWED_DESCRIPTOR_ACCESS:
                # In case of descriptors that have get methods we cannot return
                # it's value, because that would mean code execution.
                return False
        return True

    def getattr(self, name, default=_sentinel):
        try:
            return self._create_access(getattr(self._obj, name))
        except AttributeError:
            # Happens e.g. in properties of
            # PyQt4.QtGui.QStyleOptionComboBox.currentText
            # -> just set it to None
            if default is _sentinel:
                raise
            return None

    def get_safe_value(self):
        if type(self._obj) in (float, int, str, unicode, slice, type(Ellipsis)):
            return self._obj
        raise ValueError

    def get_api_type(self):
        obj = self._obj
        if self.is_class():
            return 'class'
        elif inspect.ismodule(obj):
            return 'module'
        elif inspect.isbuiltin(obj) or inspect.ismethod(obj) \
                or inspect.ismethoddescriptor(obj) or inspect.isfunction(obj):
            return 'function'
        # Everything else...
        return 'instance'

    def get_access_path_tuples(self):
        path = self._get_objects_path()
        try:
            # Just provoke an AttributeError.
            result = [(o.__name__, o) for o in path]
        except AttributeError:
            return []
        else:
            return [(name, self._create_access(o)) for name, o in result]

    def _get_objects_path(self):
        def get():
            obj = self._obj
            yield obj
            try:
                obj = obj.__objclass__
            except AttributeError:
                pass
            else:
                yield obj

            try:
                # Returns a dotted string path.
                imp_plz = obj.__module__
            except AttributeError:
                # Unfortunately in some cases like `int` there's no __module__
                if not inspect.ismodule(obj):
                    yield builtins
            else:
                if imp_plz is None:
                    # Happens for example in `(_ for _ in []).send.__module__`.
                    yield builtins
                else:
                    try:
                        yield __import__(imp_plz)
                    except ImportError:
                        # __module__ can be something arbitrary that doesn't exist.
                        yield builtins

        return list(reversed(list(get())))

    def execute_operation(self, other, operator):
        op = _OPERATORS[operator]
        return self._create_access(op(self._obj, other._obj))

    def needs_type_completions(self):
        return inspect.isclass(self._obj) and self._obj != type

    def get_signature_params(self):
        obj = self._obj
        if py_version < 33:
            raise ValueError("inspect.signature was introduced in 3.3")
        if py_version == 34:
            # In 3.4 inspect.signature are wrong for str and int. This has
            # been fixed in 3.5. The signature of object is returned,
            # because no signature was found for str. Here we imitate 3.5
            # logic and just ignore the signature if the magic methods
            # don't match object.
            # 3.3 doesn't even have the logic and returns nothing for str
            # and classes that inherit from object.
            user_def = inspect._signature_get_user_defined_method
            if (inspect.isclass(obj)
                    and not user_def(type(obj), '__init__')
                    and not user_def(type(obj), '__new__')
                    and (obj.__init__ != object.__init__
                         or obj.__new__ != object.__new__)):
                raise ValueError

        signature = inspect.signature(obj)
        return [
            SignatureParam(
                name=p.name,
                has_default=p.default is not p.empty,
                default=self._create_access(p.default),
                has_annotation=p.annotation is not p.empty,
                annotation=self._create_access(p.annotation),
            ) for p in signature.parameters.values()
        ]

    def negate(self):
        return self._create_access(-self._obj)

    def dict_values(self):
        return [self._create_access(v) for v in self._obj.values()]

    def is_super_class(self, exception):
        return issubclass(exception, self._obj)


def _is_class_instance(obj):
    """Like inspect.* methods."""
    try:
        cls = obj.__class__
    except AttributeError:
        return False
    else:
        return cls != type and not issubclass(cls, NOT_CLASS_TYPES)