from __future__ import print_function, division, absolute_import

from .abstract import *
from .common import *
from ..typeconv import Conversion


class PyObject(Dummy):
    """
    A generic CPython object.
    """

    def is_precise(self):
        return False


class Phantom(Dummy):
    """
    A type that cannot be materialized.  A Phantom cannot be used as
    argument or return type.
    """


class Undefined(Dummy):
    """
    A type that is left imprecise.  This is used as a temporaray placeholder
    during type inference in the hope that the type can be later refined.
    """

    def is_precise(self):
        return False


class RawPointer(Opaque):
    """
    A raw pointer without any specific meaning.
    """


class Const(Dummy):
    """
    A compile-time constant, for (internal) use when a type is needed for
    lookup.
    """

    def __init__(self, value):
        self.value = value
        # We want to support constants of non-hashable values, therefore
        # fall back on the value's id() if necessary.
        try:
            hash(value)
        except TypeError:
            self._key = id(value)
        else:
            self._key = value
        super(Const, self).__init__("const(%r)" % (value,))

    @property
    def key(self):
        return type(self.value), self._key


class Omitted(Opaque):
    """
    An omitted function argument with a default value.
    """

    def __init__(self, value):
        self.value = value
        super(Omitted, self).__init__("omitted(default=%r)" % (value,))

    @property
    def key(self):
        return type(self.value), id(self.value)


class VarArg(Type):
    """
    Special type representing a variable number of arguments at the
    end of a function's signature.  Only used for signature matching,
    not for actual values.
    """

    def __init__(self, dtype):
        self.dtype = dtype
        super(VarArg, self).__init__("*%s" % dtype)

    @property
    def key(self):
        return self.dtype


class Module(Dummy):
    def __init__(self, pymod):
        self.pymod = pymod
        super(Module, self).__init__("Module(%s)" % pymod)

    @property
    def key(self):
        return self.pymod


class Macro(Type):
    def __init__(self, template):
        self.template = template
        cls = type(self)
        super(Macro, self).__init__("%s(%s)" % (cls.__name__, template))

    @property
    def key(self):
        return self.template


class MemInfoPointer(Type):
    """
    Pointer to a Numba "meminfo" (i.e. the information for a managed
    piece of memory).
    """
    mutable = True

    def __init__(self, dtype):
        self.dtype = dtype
        name = "memory-managed *%s" % dtype
        super(MemInfoPointer, self).__init__(name)

    @property
    def key(self):
        return self.dtype


class CPointer(Type):
    """
    Type class for pointers to other types.
    """
    mutable = True

    def __init__(self, dtype):
        self.dtype = dtype
        name = "%s*" % dtype
        super(CPointer, self).__init__(name)

    @property
    def key(self):
        return self.dtype


class EphemeralPointer(CPointer):
    """
    Type class for pointers which aren't guaranteed to last long - e.g.
    stack-allocated slots.  The data model serializes such pointers
    by copying the data pointed to.
    """


class EphemeralArray(Type):
    """
    Similar to EphemeralPointer, but pointing to an array of elements,
    rather than a single one.  The array size must be known at compile-time.
    """

    def __init__(self, dtype, count):
        self.dtype = dtype
        self.count = count
        name = "*%s[%d]" % (dtype, count)
        super(EphemeralArray, self).__init__(name)

    @property
    def key(self):
        return self.dtype, self.count


class Object(Type):
    # XXX unused?
    mutable = True

    def __init__(self, clsobj):
        self.cls = clsobj
        name = "Object(%s)" % clsobj.__name__
        super(Object, self).__init__(name)

    @property
    def key(self):
        return self.cls


class Optional(Type):
    """
    Type class for optional types, i.e. union { some type, None }
    """

    def __init__(self, typ):
        assert not isinstance(typ, (Optional, NoneType))
        self.type = typ
        name = "?%s" % typ
        super(Optional, self).__init__(name)

    @property
    def key(self):
        return self.type

    def can_convert_to(self, typingctx, other):
        if isinstance(other, Optional):
            return typingctx.can_convert(self.type, other.type)
        else:
            conv = typingctx.can_convert(self.type, other)
            if conv is not None:
                return max(conv, Conversion.safe)

    def can_convert_from(self, typingctx, other):
        if isinstance(other, NoneType):
            return Conversion.promote
        elif isinstance(other, Optional):
            return typingctx.can_convert(other.type, self.type)
        else:
            conv = typingctx.can_convert(other, self.type)
            if conv is not None:
                return max(conv, Conversion.promote)

    def unify(self, typingctx, other):
        if isinstance(other, Optional):
            unified = typingctx.unify_pairs(self.type, other.type)
        else:
            unified = typingctx.unify_pairs(self.type, other)

        if unified is not None:
            if isinstance(unified, Optional):
                return unified
            else:
                return Optional(unified)


class NoneType(Opaque):
    """
    The type for None.
    """

    def unify(self, typingctx, other):
        """
        Turn anything to a Optional type;
        """
        if isinstance(other, (Optional, NoneType)):
            return other
        return Optional(other)


class EllipsisType(Opaque):
    """
    The type for the Ellipsis singleton.
    """


class ExceptionClass(Callable, Phantom):
    """
    The type of exception classes (not instances).
    """

    def __init__(self, exc_class):
        assert issubclass(exc_class, BaseException)
        name = "%s" % (exc_class.__name__)
        self.exc_class = exc_class
        super(ExceptionClass, self).__init__(name)

    def get_call_type(self, context, args, kws):
        return self.get_call_signatures()[0][0]

    def get_call_signatures(self):
        from .. import typing
        return_type = ExceptionInstance(self.exc_class)
        return [typing.signature(return_type)], False

    @property
    def key(self):
        return self.exc_class


class ExceptionInstance(Phantom):
    """
    The type of exception instances.  *exc_class* should be the
    exception class.
    """

    def __init__(self, exc_class):
        assert issubclass(exc_class, BaseException)
        name = "%s(...)" % (exc_class.__name__,)
        self.exc_class = exc_class
        super(ExceptionInstance, self).__init__(name)

    @property
    def key(self):
        return self.exc_class


class SliceType(Type):

    def __init__(self, name, members):
        assert members in (2, 3)
        self.members = members
        self.has_step = members >= 3
        super(SliceType, self).__init__(name)

    @property
    def key(self):
        return self.members


class ClassInstanceType(Type):
    """
    The type of a jitted class *instance*.  It will be the return-type
    of the constructor of the class.
    """
    mutable = True
    name_prefix = "instance"

    def __init__(self, class_type):
        self.class_type = class_type
        name = "{0}.{1}".format(self.name_prefix, self.class_type.name)
        super(ClassInstanceType, self).__init__(name)

    def get_data_type(self):
        return ClassDataType(self)

    def get_reference_type(self):
        return self

    @property
    def key(self):
        return self.class_type.key

    @property
    def classname(self):
        return self.class_type.class_def.__name__

    @property
    def jitprops(self):
        return self.class_type.jitprops

    @property
    def jitmethods(self):
        return self.class_type.jitmethods

    @property
    def struct(self):
        return self.class_type.struct

    @property
    def methods(self):
        return self.class_type.methods


class ClassType(Callable, Opaque):
    """
    The type of the jitted class (not instance).  When the type of a class
    is called, its constructor is invoked.
    """
    mutable = True
    name_prefix = "jitclass"
    instance_type_class = ClassInstanceType

    def __init__(self, class_def, ctor_template_cls, struct, jitmethods,
                 jitprops):
        self.class_def = class_def
        self.ctor_template = self._specialize_template(ctor_template_cls)
        self.jitmethods = jitmethods
        self.jitprops = jitprops
        self.struct = struct
        self.methods = dict((k, v.py_func) for k, v in self.jitmethods.items())
        fielddesc = ','.join("{0}:{1}".format(k, v) for k, v in struct.items())
        name = "{0}.{1}#{2:x}<{3}>".format(self.name_prefix, class_def.__name__,
                                           id(class_def), fielddesc)
        super(ClassType, self).__init__(name)
        self.instance_type = self.instance_type_class(self)

    def get_call_type(self, context, args, kws):
        return self.ctor_template(context).apply(args, kws)

    def get_call_signatures(self):
        return (), True

    def _specialize_template(self, basecls):
        return type(basecls.__name__, (basecls,), dict(key=self))


class DeferredType(Type):
    """
    Represents a type that will be defined later.  It must be defined
    before it is materialized (used in the compiler).  Once defined, it
    behaves exactly as the type it is defining.
    """
    def __init__(self):
        self._define = None
        name = "{0}#{1}".format(type(self).__name__, id(self))
        super(DeferredType, self).__init__(name)

    def get(self):
        if self._define is None:
            raise RuntimeError("deferred type not defined")
        return self._define

    def define(self, typ):
        if self._define is not None:
            raise TypeError("deferred type already defined")
        if not isinstance(typ, Type):
            raise TypeError("arg is not a Type; got: {0}".format(type(typ)))
        self._define = typ

    def unify(self, typingctx, other):
        return typingctx.unify_pairs(self.get(), other)


class ClassDataType(Type):
    """
    Internal only.
    Represents the data of the instance.  The representation of
    ClassInstanceType contains a pointer to a ClassDataType which represents
    a C structure that contains all the data fields of the class instance.
    """
    def __init__(self, classtyp):
        self.class_type = classtyp
        name = "data.{0}".format(self.class_type.name)
        super(ClassDataType, self).__init__(name)