import ctypes
from typing import (
    TYPE_CHECKING,
    Any,
    Callable,
    Dict,
    Iterator,
    List,
    Literal,
    NamedTuple,
    Optional,
    Sequence,
    Tuple,
    Type,
)
from typing import Union as _UnionT

import comtypes

if TYPE_CHECKING:
    from _ctypes import _PyCSimpleType
    from ctypes import _CArgObject, _CDataType

    from comtypes import hints  # type: ignore
else:
    _PyCSimpleType = type(ctypes.c_int)
    _CArgObject = type(ctypes.byref(ctypes.c_int()))


DISPATCH_METHOD = 1
DISPATCH_PROPERTYGET = 2
DISPATCH_PROPERTYPUT = 4
DISPATCH_PROPERTYPUTREF = 8

PARAMFLAG_NONE = 0
PARAMFLAG_FIN = 1
PARAMFLAG_FOUT = 2
PARAMFLAG_FLCID = 4
PARAMFLAG_FRETVAL = 8
PARAMFLAG_FOPT = 16
PARAMFLAG_FHASDEFAULT = 32
PARAMFLAG_FHASCUSTDATA = 64

_PARAMFLAGS = {
    "in": PARAMFLAG_FIN,
    "out": PARAMFLAG_FOUT,
    "lcid": PARAMFLAG_FLCID,
    "retval": PARAMFLAG_FRETVAL,
    "optional": PARAMFLAG_FOPT,
}


def _encode_idl(names: Sequence[str]) -> int:
    """Sums up 'in', 'out', 'lcid', 'retval' and 'optional' values
    found in _PARAMFLAGS, ignoring all other PARAMFLAG_... stuff.
    """
    return sum([_PARAMFLAGS.get(n, 0) for n in names])


_NOTHING = object()


def _unpack_argspec(
    idl: List[str],
    typ: Type["_CDataType"],
    name: Optional[str] = None,
    defval: Any = _NOTHING,
) -> Tuple[List[str], Type["_CDataType"], Optional[str], Any]:
    return idl, typ, name, defval


def _resolve_argspec(
    items: Tuple["hints.ArgSpecElmType", ...],
) -> Tuple[Tuple["hints.ParamFlagType", ...], Tuple[Type["_CDataType"], ...]]:
    """Unpacks and converts from argspec to paramflags and argtypes.

    - paramflags is a sequence of `(pflags: int, argname: str, | None[, defval: Any])`.
    - argtypes is a sequence of `type[_CDataType]`.
    """
    from comtypes.automation import VARIANT

    paramflags = []
    argtypes = []
    for item in items:
        idl, typ, argname, defval = _unpack_argspec(*item)  # type: ignore
        pflags = _encode_idl(idl)
        if "optional" in idl:
            if defval is _NOTHING:
                if typ is VARIANT:
                    defval = VARIANT.missing
                elif typ is ctypes.POINTER(VARIANT):
                    defval = ctypes.pointer(VARIANT.missing)
                else:
                    # msg = f"'optional' only allowed for VARIANT and VARIANT*, not for {typ.__name__}"
                    # warnings.warn(msg, IDLWarning, stacklevel=2)
                    defval = typ()
        if defval is _NOTHING:
            paramflags.append((pflags, argname))
        else:
            paramflags.append((pflags, argname, defval))
        argtypes.append(typ)
    return tuple(paramflags), tuple(argtypes)


if TYPE_CHECKING:
    _VarFlags = Tuple[str, ...]
    _VarFlagsWithDispIdHelpstr = Tuple["dispid", "helpstring", hints.Unpack[_VarFlags]]
    _VarFlagsWithDispId = Tuple["dispid", hints.Unpack[_VarFlags]]
    _VarFlagsWithHelpstr = Tuple["helpstring", hints.Unpack[_VarFlags]]
    _DispIdlFlags = _UnionT[_VarFlagsWithDispIdHelpstr, _VarFlagsWithDispId]
    _ComIdlFlags = _UnionT[_VarFlags, _VarFlagsWithHelpstr]


class _ComMemberSpec(NamedTuple):
    """Specifier for a slot of COM method or property."""

    restype: Optional[Type["_CDataType"]]
    name: str
    argtypes: Tuple[Type["_CDataType"], ...]
    paramflags: Optional[Tuple["hints.ParamFlagType", ...]]
    idlflags: _UnionT["_ComIdlFlags", "_DispIdlFlags"]
    doc: Optional[str]

    def is_prop(self) -> bool:
        return _is_spec_prop(self)


class _DispMemberSpec(NamedTuple):
    """Specifier for a slot of dispinterface method or property."""

    what: Literal["DISPMETHOD", "DISPPROPERTY"]
    name: str
    idlflags: "_DispIdlFlags"
    restype: Optional[Type["_CDataType"]]
    argspec: Tuple["hints.ArgSpecElmType", ...]

    @property
    def memid(self) -> int:
        try:
            return [x for x in self.idlflags if isinstance(x, int)][0]
        except IndexError:
            raise TypeError("no dispid found in idlflags")

    def is_prop(self) -> bool:
        return _is_spec_prop(self)


# Specifier of a slot of method or property.
# This should be `typing.Protocol` if supporting Py3.8+ only.
_MemberSpec = _UnionT[_ComMemberSpec, _DispMemberSpec]


def _is_spec_prop(m: _MemberSpec):
    return any(f in ("propget", "propput", "propputref") for f in m.idlflags)


################################################################
# IDL stuff


class helpstring(str):
    "Specifies the helpstring for a COM method or property."


class defaultvalue(object):
    "Specifies the default value for parameters marked optional."

    def __init__(self, value):
        self.value = value


class dispid(int):
    "Specifies the DISPID of a method or property."


# XXX STDMETHOD, COMMETHOD, DISPMETHOD, and DISPPROPERTY should return
# instances with more methods or properties, and should not behave as an unpackable.


def STDMETHOD(restype, name, argtypes=()) -> _ComMemberSpec:
    "Specifies a COM method slot without idlflags"
    return _ComMemberSpec(restype, name, argtypes, None, (), None)


def DISPMETHOD(idlflags, restype, name, *argspec) -> _DispMemberSpec:
    "Specifies a method of a dispinterface"
    return _DispMemberSpec("DISPMETHOD", name, tuple(idlflags), restype, argspec)


def DISPPROPERTY(idlflags, proptype, name) -> _DispMemberSpec:
    "Specifies a property of a dispinterface"
    return _DispMemberSpec("DISPPROPERTY", name, tuple(idlflags), proptype, ())


# tuple(idlflags) is for the method itself: (dispid, 'readonly')

# sample generated code:
#     DISPPROPERTY([5, 'readonly'], OLE_YSIZE_HIMETRIC, 'Height'),
#     DISPMETHOD(
#         [6], None, 'Render', ([], c_int, 'hdc'), ([], c_int, 'x'), ([], c_int, 'y')
#     )


def COMMETHOD(idlflags, restype, methodname, *argspec) -> _ComMemberSpec:
    """Specifies a COM method slot with idlflags.

    XXX should explain the sematics of the arguments.
    """
    # collect all helpstring instances
    # We should suppress docstrings when Python is started with -OO
    # join them together(does this make sense?) and replace by None if empty.
    helptext = "".join(t for t in idlflags if isinstance(t, helpstring)) or None
    paramflags, argtypes = _resolve_argspec(argspec)
    if "propget" in idlflags:
        name = f"_get_{methodname}"
    elif "propput" in idlflags:
        name = f"_set_{methodname}"
    elif "propputref" in idlflags:
        name = f"_setref_{methodname}"
    else:
        name = methodname
    return _ComMemberSpec(
        restype, name, argtypes, paramflags, tuple(idlflags), helptext
    )


################################################################
# workarounds for ctypes functions and parameters


def _prepare_parameter(value: Any, atyp: Type["_CDataType"]) -> "_CDataType":
    # parameter was passed, call `from_param()` to
    # convert it to a `ctypes` type.
    if getattr(value, "_type_", None) is atyp:
        # Array of or pointer to type `atyp` was passed,
        # pointer to `atyp` expected.
        v = value
    elif type(atyp) is _PyCSimpleType:  # type: ignore
        # The `from_param` method of simple types
        # (`c_int`, `c_double`, ...) returns a `byref` object which
        # we cannot use since later it will be wrapped in a pointer.
        # Simply call the constructor with the argument in that case.
        v = atyp(value)
    else:
        v = atyp.from_param(value)
        assert not isinstance(v, _CArgObject)  # type: ignore
    return v


def _fix_inout_args(
    func: Callable[..., Any],
    argtypes: Tuple[Type["_CDataType"], ...],
    paramflags: Tuple["hints.ParamFlagType", ...],
) -> Callable[..., Any]:
    """This function provides a workaround for a bug in `ctypes`.

    [in, out] parameters must be converted with the argtype's `from_param`
    method BEFORE they are passed to the `_ctypes.build_callargs` function
    in `Modules/_ctypes/_ctypes.c`.
    """
    # For details see below.
    #
    # TODO: The workaround should be disabled when a ctypes
    # version is used where the bug is fixed.

    def call_with_inout(self, *args, **kw):
        args = list(args)
        # Indexed by order in the output
        outargs: Dict[int, "_CDataType"] = {}
        outnum = 0
        param_index = 0
        # Go through all expected arguments and match them to the provided arguments.
        # `param_index` first counts through the positional and then
        # through the keyword arguments.
        for i, info in enumerate(paramflags):
            direction = info[0]
            dir_in = bool(direction & PARAMFLAG_FIN)
            dir_out = bool(direction & PARAMFLAG_FOUT)
            is_positional = param_index < len(args)
            if not (dir_in or dir_out):
                # The original code here did not check for this special case and
                # effectively treated `(dir_in, dir_out) == (False, False)` and
                # `(dir_in, dir_out) == (True, False)` the same.
                # In order not to break legacy code we do the same.
                # One example of a function that has neither `dir_in` nor `dir_out`
                # set is `IMFAttributes.GetString`.
                dir_in = True
            if dir_in and dir_out:
                # This is an [in, out] parameter.
                #
                # Determine name and required type of the parameter.
                name = info[1]
                # [in, out] parameters are passed as pointers,
                # this is the pointed-to type:
                atyp: Type["_CDataType"] = getattr(argtypes[i], "_type_")

                # Get the actual parameter, either as positional or
                # keyword arg.

                if is_positional:
                    v = _prepare_parameter(args[param_index], atyp)
                    args[param_index] = v
                elif name in kw:
                    v = _prepare_parameter(kw[name], atyp)
                    kw[name] = v
                else:
                    # no parameter was passed, make an empty one of the required type
                    # and pass it as a keyword argument
                    v = atyp()
                    if name is not None:
                        kw[name] = v
                    else:
                        raise TypeError("Unnamed inout parameters cannot be omitted")
                outargs[outnum] = v
            if dir_out:
                outnum += 1
            if dir_in:
                param_index += 1

        rescode = func(self, *args, **kw)
        # If there is only a single output value, then do not expect it to
        # be iterable.

        # Our interpretation of this code
        # (jonschz, junkmd, see https://github.com/enthought/comtypes/pull/473):
        # - `outnum` counts the total number of 'out' and 'inout' arguments.
        # - `outargs` is a dict consisting of the supplied 'inout' arguments.
        # - The call to `func()` returns the 'out' and 'inout' arguments.
        #   Furthermore, it changes the variables in 'outargs' as a "side effect"
        # - In a perfect world, it should be fine to just return `rescode`.
        #   But we assume there is a reason why the original authors did not do that.
        #   Instead, they replace the 'inout' variables in `rescode` by those in
        #   'outargs', and call `__ctypes_from_outparam__()` on them.

        if outnum == 1:  # rescode is not iterable
            # In this case, it is little faster than creating list with
            # `rescode = [rescode]` and getting item with index from the list.
            if len(outargs) == 1:
                rescode = rescode.__ctypes_from_outparam__()
            return rescode
        rescode = list(rescode)
        for outnum, o in outargs.items():
            rescode[outnum] = o.__ctypes_from_outparam__()
        return rescode

    return call_with_inout


################################################################


_PropFunc = Optional[Callable[..., Any]]
_DocType = Optional[str]


class PropertyMapping(object):
    def __init__(self):
        self._data: Dict[Tuple[str, _DocType, int], List[_PropFunc]] = {}

    def add_propget(
        self, name: str, doc: _DocType, nargs: int, func: Callable[..., Any]
    ) -> None:
        self._data.setdefault((name, doc, nargs), [None, None, None])[0] = func

    def add_propput(
        self, name: str, doc: _DocType, nargs: int, func: Callable[..., Any]
    ) -> None:
        self._data.setdefault((name, doc, nargs), [None, None, None])[1] = func

    def add_propputref(
        self, name: str, doc: _DocType, nargs: int, func: Callable[..., Any]
    ) -> None:
        self._data.setdefault((name, doc, nargs), [None, None, None])[2] = func

    def __iter__(self) -> Iterator[Tuple[str, _DocType, int, _PropFunc, _PropFunc]]:
        for (name, doc, nargs), (fget, propput, propputref) in self._data.items():
            if propput is not None and propputref is not None:
                # Create a setter method that examines the argument type
                # and calls 'propputref' if it is an Object (in the VB
                # sense), or call 'propput' otherwise.
                put, putref = propput, propputref

                def put_or_putref(self, *args):
                    if comtypes._is_object(args[-1]):
                        return putref(self, *args)
                    return put(self, *args)

                fset = put_or_putref
            elif propputref is not None:
                fset = propputref
            else:
                fset = propput
            yield (name, doc, nargs, fget, fset)


class PropertyGenerator(object):
    def __init__(self, cls_name: str) -> None:
        self._mapping = PropertyMapping()
        self._cls_name = cls_name

    def add(self, m: _MemberSpec, func: Callable[..., Any]) -> None:
        """Adds member spec and func to mapping."""
        if "propget" in m.idlflags:
            name, doc, nargs = self.to_propget_keys(m)
            self._mapping.add_propget(name, doc, nargs, func)
        elif "propput" in m.idlflags:
            name, doc, nargs = self.to_propput_keys(m)
            self._mapping.add_propput(name, doc, nargs, func)
        elif "propputref" in m.idlflags:
            name, doc, nargs = self.to_propputref_keys(m)
            self._mapping.add_propputref(name, doc, nargs, func)
        else:
            raise TypeError("no propflag found in idlflags")

    # The following code assumes that the docstrings for
    # propget and propput are identical.
    def __iter__(self) -> Iterator[Tuple[str, _UnionT[property, "named_property"]]]:
        for name, doc, nargs, fget, fset in self._mapping:
            if nargs == 0:
                prop = property(fget, fset, None, doc)
            else:
                # Hm, must be a descriptor where the __get__ method
                # returns a bound object having __getitem__ and
                # __setitem__ methods.
                prop = named_property(f"{self._cls_name}.{name}", fget, fset, doc)
            yield (name, prop)

    def to_propget_keys(self, m: _MemberSpec) -> Tuple[str, _DocType, int]:
        raise NotImplementedError

    def to_propput_keys(self, m: _MemberSpec) -> Tuple[str, _DocType, int]:
        raise NotImplementedError

    def to_propputref_keys(self, m: _MemberSpec) -> Tuple[str, _DocType, int]:
        raise NotImplementedError


class ComPropertyGenerator(PropertyGenerator):
    # XXX Hm.  What, when paramflags is None?
    # Or does have '0' values?
    # Seems we loose then, at least for properties...
    def to_propget_keys(self, m: _ComMemberSpec) -> Tuple[str, _DocType, int]:
        assert m.name.startswith("_get_")
        assert m.paramflags is not None
        nargs = len([f for f in m.paramflags if f[0] & 7 in (0, 1)])
        # XXX or should we do this?
        # nargs = len([f for f in paramflags if (f[0] & 1) or (f[0] == 0)])
        return m.name[len("_get_") :], m.doc, nargs

    def to_propput_keys(self, m: _ComMemberSpec) -> Tuple[str, _DocType, int]:
        assert m.name.startswith("_set_")
        assert m.paramflags is not None
        nargs = len([f for f in m.paramflags if f[0] & 7 in (0, 1)]) - 1
        return m.name[len("_set_") :], m.doc, nargs

    def to_propputref_keys(self, m: _ComMemberSpec) -> Tuple[str, _DocType, int]:
        assert m.name.startswith("_setref_")
        assert m.paramflags is not None
        nargs = len([f for f in m.paramflags if f[0] & 7 in (0, 1)]) - 1
        return m.name[len("_setref_") :], m.doc, nargs


class DispPropertyGenerator(PropertyGenerator):
    def to_propget_keys(self, m: _DispMemberSpec) -> Tuple[str, _DocType, int]:
        return m.name, None, len(m.argspec)

    def to_propput_keys(self, m: _DispMemberSpec) -> Tuple[str, _DocType, int]:
        return m.name, None, len(m.argspec) - 1

    def to_propputref_keys(self, m: _DispMemberSpec) -> Tuple[str, _DocType, int]:
        return m.name, None, len(m.argspec) - 1


class ComMemberGenerator(object):
    def __init__(self, cls_name: str, vtbl_offset: int, iid: "comtypes.GUID") -> None:
        self._vtbl_offset = vtbl_offset
        self._iid = iid
        self._props = ComPropertyGenerator(cls_name)
        # sequence of (name: str, func: Callable, raw_func: Callable, is_prop: bool)
        self._mths: List[Tuple[str, Callable[..., Any], Callable[..., Any], bool]] = []
        self._member_index = 0

    def add(self, m: _ComMemberSpec) -> None:
        proto = ctypes.WINFUNCTYPE(m.restype, *m.argtypes)
        # a low level unbound method calling the com method.
        # attach it with a private name (__com_AddRef, for example),
        # so that custom method implementations can call it.
        vidx = self._member_index + self._vtbl_offset
        # If the method returns a HRESULT, we pass the interface iid,
        # so that we can request error info for the interface.
        iid = self._iid if m.restype == ctypes.HRESULT else None
        raw_func = proto(vidx, m.name, None, iid)  # low level
        func = self._fix_args(m, proto(vidx, m.name, m.paramflags, iid))  # high level
        func.__doc__ = m.doc
        func.__name__ = m.name  # for pyhelp
        is_prop = m.is_prop()
        if is_prop:
            self._props.add(m, func)
        self._mths.append((m.name, func, raw_func, is_prop))
        self._member_index += 1

    def _fix_args(
        self, m: _ComMemberSpec, func: Callable[..., Any]
    ) -> Callable[..., Any]:
        """This is a workaround. See `_fix_inout_args` docstring and comments."""
        if m.paramflags:
            dirflags = [(p[0] & (PARAMFLAG_FIN | PARAMFLAG_FOUT)) for p in m.paramflags]
            if (PARAMFLAG_FIN | PARAMFLAG_FOUT) in dirflags:
                return _fix_inout_args(func, m.argtypes, m.paramflags)
        return func

    def methods(self):
        return iter(self._mths)

    def properties(self):
        return iter(self._props)


class DispMemberGenerator(object):
    def __init__(self, cls_name: str) -> None:
        self._props = DispPropertyGenerator(cls_name)
        # sequence of (name: str, func_or_prop: Callable | property, is_prop: bool)
        self._items: List[Tuple[str, _UnionT[Callable[..., Any], property], bool]] = []

    def add(self, m: _DispMemberSpec) -> None:
        if m.what == "DISPPROPERTY":  # DISPPROPERTY
            assert not m.argspec  # XXX does not yet work for properties with parameters
            is_prop = True
            accessor = self._make_disp_property(m)
            self._items.append((m.name, accessor, is_prop))
        else:  # DISPMETHOD
            func = self._make_disp_method(m)
            func.__name__ = m.name
            is_prop = m.is_prop()
            if is_prop:
                self._props.add(m, func)
            else:
                self._items.append((m.name, func, is_prop))

    def _make_disp_property(self, m: _DispMemberSpec) -> property:
        # XXX doc string missing in property
        memid = m.memid

        def fget(obj):
            return obj.Invoke(memid, _invkind=DISPATCH_PROPERTYGET)

        if "readonly" in m.idlflags:
            return property(fget)

        def fset(obj, value):
            # Detect whether to use PUT or PUTREF
            is_ref = comtypes._is_object(value)
            invkind = DISPATCH_PROPERTYPUTREF if is_ref else DISPATCH_PROPERTYPUT
            return obj.Invoke(memid, value, _invkind=invkind)

        return property(fget, fset)

    # Should the funcs/mths we create have restype and/or argtypes attributes?
    def _make_disp_method(self, m: _DispMemberSpec) -> Callable[..., Any]:
        memid = m.memid
        if "propget" in m.idlflags:

            def getfunc(obj, *args, **kw):
                return obj.Invoke(memid, _invkind=DISPATCH_PROPERTYGET, *args, **kw)

            return getfunc
        elif "propput" in m.idlflags:

            def putfunc(obj, *args, **kw):
                return obj.Invoke(memid, _invkind=DISPATCH_PROPERTYPUT, *args, **kw)

            return putfunc
        elif "propputref" in m.idlflags:

            def putreffunc(obj, *args, **kw):
                return obj.Invoke(memid, _invkind=DISPATCH_PROPERTYPUTREF, *args, **kw)

            return putreffunc
        # a first attempt to make use of the restype.  Still, support for
        # named arguments and default argument values should be added.
        if hasattr(m.restype, "__com_interface__"):
            interface = m.restype.__com_interface__  # type: ignore

            def comitffunc(obj, *args, **kw):
                result = obj.Invoke(memid, _invkind=DISPATCH_METHOD, *args, **kw)
                if result is None:
                    return
                return result.QueryInterface(interface)

            return comitffunc

        def func(obj, *args, **kw):
            return obj.Invoke(memid, _invkind=DISPATCH_METHOD, *args, **kw)

        return func

    def items(self):
        return iter(self._items)

    def properties(self):
        return iter(self._props)


################################################################
# helper classes for COM propget / propput
# Should they be implemented in C for speed?


class bound_named_property(object):
    def __init__(self, name, fget, fset, instance):
        self.name = name
        self.instance = instance
        self.fget = fget
        self.fset = fset

    def __getitem__(self, index):
        if self.fget is None:
            raise TypeError("unsubscriptable object")
        if isinstance(index, tuple):
            return self.fget(self.instance, *index)
        elif index == comtypes._all_slice:
            return self.fget(self.instance)
        else:
            return self.fget(self.instance, index)

    def __call__(self, *args):
        if self.fget is None:
            raise TypeError("object is not callable")
        return self.fget(self.instance, *args)

    def __setitem__(self, index, value):
        if self.fset is None:
            raise TypeError("object does not support item assignment")
        if isinstance(index, tuple):
            self.fset(self.instance, *(index + (value,)))
        elif index == comtypes._all_slice:
            self.fset(self.instance, value)
        else:
            self.fset(self.instance, index, value)

    def __repr__(self):
        return f"<bound_named_property {self.name!r} at {id(self):x}>"

    def __iter__(self):
        """Explicitly disallow iteration."""
        msg = f"{self.name!r} is not iterable"
        raise TypeError(msg)


class named_property(object):
    def __init__(self, name, fget=None, fset=None, doc=None):
        self.name = name
        self.fget = fget
        self.fset = fset
        self.__doc__ = doc

    def __get__(self, instance, owner=None):
        if instance is None:
            return self
        return bound_named_property(self.name, self.fget, self.fset, instance)

    # Make this a data descriptor
    def __set__(self, instance):
        raise AttributeError("Unsettable attribute")

    def __repr__(self):
        return f"<named_property {self.name!r} at {id(self):x}>"