import ctypes, os, sys
from ctypes import *

_int_types = (c_int16, c_int32)
if hasattr(ctypes, 'c_int64'):
    # Some builds of ctypes apparently do not have c_int64
    # defined; it's a pretty good bet that these builds do not
    # have 64-bit pointers.
    _int_types += (c_int64,)
for t in _int_types:
    if sizeof(t) == sizeof(c_size_t):
        c_ptrdiff_t = t
del t
del _int_types

class c_void(Structure):
    # c_void_p is a buggy return type, converting to int, so
    # POINTER(None) == c_void_p is actually written as
    # POINTER(c_void), so it can be treated as a real pointer.
    _fields_ = [('dummy', c_int)]

def POINTER(obj):
    p = ctypes.POINTER(obj)

    # Convert None to a real NULL pointer to work around bugs
    # in how ctypes handles None on 64-bit platforms
    if not isinstance(p.from_param, classmethod):
        def from_param(cls, x):
            if x is None:
                return cls()
            else:
                return x
        p.from_param = classmethod(from_param)

    return p

String = c_char_p
ReturnString = c_char_p

# As of ctypes 1.0, ctypes does not support custom error-checking
# functions on callbacks, nor does it support custom datatypes on
# callbacks, so we must ensure that all callbacks return
# primitive datatypes.
#
# Non-primitive return values wrapped with UNCHECKED won't be
# typechecked, and will be converted to c_void_p.
def UNCHECKED(type):
    if (hasattr(type, "_type_") and isinstance(type._type_, str)
        and type._type_ != "P"):
        return type
    else:
        return c_void_p

# ctypes doesn't have direct support for variadic functions, so we have to write
# our own wrapper class
class _variadic_function(object):
    def __init__(self,func,restype,argtypes):
        self.func=func
        self.func.restype=restype
        self.argtypes=argtypes
    def _as_parameter_(self):
        # So we can pass this variadic function as a function pointer
        return self.func
    def __call__(self,*args):
        fixed_args=[]
        i=0
        for argtype in self.argtypes:
            # Typecheck what we can
            fixed_args.append(argtype.from_param(args[i]))
            i+=1
        return self.func(*fixed_args+list(args[i:]))

