"""ctypes data-pointers as a data-format mechanism
"""
REGISTRY_NAME = 'ctypespointers'
import ctypes, _ctypes

from OpenGL import constants, constant
from OpenGL.arrays import formathandler
import operator

class CtypesPointerHandler( formathandler.FormatHandler ):
	"""Ctypes Pointer-type-specific data-type handler for OpenGL
	
	Because pointers do not have size information we can't use
	them for output of data, but they can be used for certain
	types of input...
	"""
	from_param = staticmethod( ctypes.byref )
	dataPointer = staticmethod( ctypes.addressof )
	HANDLED_TYPES = (ctypes._Pointer, )
	def voidDataPointer( cls, value ):
		"""Given value in a known data-pointer type, return void_p for pointer"""
		return ctypes.cast( value, ctypes.c_void_p )
	def zeros( self, dims, typeCode ):
		"""Return Numpy array of zeros in given size"""
		raise NotImplementedError( """Sized output doesn't yet work...""" )
	def ones( self, dims, typeCode='d' ):
		"""Return numpy array of ones in given size"""
		raise NotImplementedError( """Haven't got a good ones implementation yet""" )
	def arrayToGLType( self, value ):
		"""Given a value, guess OpenGL type of the corresponding pointer"""
		result = ARRAY_TO_GL_TYPE_MAPPING.get( value._type_ )
		if result is not None:
			return result
		raise TypeError(
			"""Don't know GL type for array of type %r, known types: %s\nvalue:%s"""%(
				value._type_, ARRAY_TO_GL_TYPE_MAPPING.keys(), value,
			)
		)
	def arraySize( self, value, typeCode = None ):
		"""Given a data-value, calculate dimensions for the array"""
		raise NotImplementedError( """Haven't got an arraySize implementation""" )
	def asArray( self, value, typecode=None ):
		"""Convert given value to an array value of given typecode"""
		return value
	def unitSize( self, value, typeCode=None ):
		"""Determine unit size of an array (if possible)"""
		return 1
	def dimensions( self, value, typeCode=None ):
		"""Determine dimensions of the passed array value (if possible)"""
		raise NotImplementedError( """Haven't got a dimensions implementation""" )


ARRAY_TO_GL_TYPE_MAPPING = {
	constants.GLdouble: constants.GL_DOUBLE,
	constants.GLfloat: constants.GL_FLOAT,
	constants.GLint: constants.GL_INT,
	constants.GLuint: constants.GL_UNSIGNED_INT,
	constants.GLshort: constants.GL_SHORT,
	constants.GLushort: constants.GL_UNSIGNED_SHORT,
		
	constants.GLchar: constants.GL_CHAR,
	constants.GLbyte: constants.GL_BYTE,
	constants.GLubyte: constants.GL_UNSIGNED_BYTE,
}
GL_TYPE_TO_ARRAY_MAPPING = {
	constants.GL_DOUBLE: constants.GLdouble,
	constants.GL_FLOAT: constants.GLfloat,
	constants.GL_INT: constants.GLint,
	constants.GL_UNSIGNED_INT: constants.GLuint,
	constants.GL_SHORT: constants.GLshort,
	constants.GL_UNSIGNED_SHORT: constants.GLushort,
		
	constants.GL_CHAR: constants.GLchar,
	constants.GL_BYTE: constants.GLbyte,
	constants.GL_UNSIGNED_BYTE: constants.GLubyte,
}
