'''OpenGL extension ARB.shader_objects

This module customises the behaviour of the 
OpenGL.raw.GL.ARB.shader_objects to provide a more 
Python-friendly API
'''
from OpenGL import platform, constants, constant, arrays
from OpenGL import extensions, wrapper
from OpenGL.GL import glget
import ctypes
from OpenGL.raw.GL.ARB.shader_objects import *
### END AUTOGENERATED SECTION
EXTENSION_NAME = 'GL_ARB_shader_objects'
import OpenGL
from OpenGL.lazywrapper import lazy
from OpenGL import converters, error
GL_INFO_LOG_LENGTH_ARB = constant.Constant( 'GL_INFO_LOG_LENGTH_ARB', 0x8B84 )

glShaderSourceARB = platform.createExtensionFunction( 
	'glShaderSourceARB', dll=platform.GL,
	resultType=None, 
	argTypes=(constants.GLhandleARB, constants.GLsizei, ctypes.POINTER(ctypes.c_char_p), arrays.GLintArray,),
	doc = 'glShaderSourceARB( GLhandleARB(shaderObj), str( string) ) -> None',
	argNames = ('shaderObj', 'count', 'string', 'length',),
	extension = EXTENSION_NAME,
)
conv = converters.StringLengths( name='string' )
glShaderSourceARB = wrapper.wrapper(
	glShaderSourceARB
).setPyConverter(
	'count' # number of strings
).setPyConverter( 
	'length' # lengths of strings
).setPyConverter(
	'string', conv.stringArray
).setCResolver(
	'string', conv.stringArrayForC,
).setCConverter(
	'length', conv,
).setCConverter(
	'count', conv.totalCount,
)
del conv

for size in (1,2,3,4):
	for format,arrayType in (
		('f',arrays.GLfloatArray),
		('i',arrays.GLintArray),
	):
		name = 'glUniform%(size)s%(format)svARB'%globals()
		globals()[name] = arrays.setInputArraySizeType(
			globals()[name],
			None, # don't want to enforce size...
			arrayType, 
			'value',
		)
		del format, arrayType
	del size

@lazy( glGetObjectParameterivARB )
def glGetObjectParameterivARB( baseOperation, shader, pname ):
	"""Retrieve the integer parameter for the given shader"""
	status = arrays.GLintArray.zeros( (1,))
	status[0] = 1 
	baseOperation(
		shader, pname, status
	)
	return status[0]

@lazy( glGetObjectParameterfvARB )
def glGetObjectParameterfvARB( baseOperation, shader, pname ):
	"""Retrieve the float parameter for the given shader"""
	status = arrays.GLfloatArray.zeros( (1,))
	status[0] = 1.0
	baseOperation(shader, pname,status)
	return status[0]

def _afterCheck( key ):
	"""Generate an error-checking function for compilation operations"""
	def GLSLCheckError( 
		result,
		baseOperation=None,
		cArguments=None,
		*args
	):
		result = error.glCheckError( result, baseOperation, cArguments, *args )
		status = glGetObjectParameterivARB(
			cArguments[0], key
		)
		if not status:
			raise error.GLError( 
				result = result,
				baseOperation = baseOperation,
				cArguments = cArguments,
				description= glGetInfoLogARB( cArguments[0] )
			)
		return result
	return GLSLCheckError

if OpenGL.ERROR_CHECKING:
	glCompileShaderARB.errcheck = _afterCheck( GL_OBJECT_COMPILE_STATUS_ARB )
if OpenGL.ERROR_CHECKING:
	glLinkProgramARB.errcheck = _afterCheck( GL_OBJECT_LINK_STATUS_ARB )
## Not sure why, but these give invalid operation :(
##if glValidateProgramARB and OpenGL.ERROR_CHECKING:
##	glValidateProgramARB.errcheck = _afterCheck( GL_OBJECT_VALIDATE_STATUS_ARB )

@lazy( glGetInfoLogARB )
def glGetInfoLogARB( baseOperation, obj ):
	"""Retrieve the program/shader's error messages as a Python string
	
	returns string which is '' if no message
	"""
	length = int(glGetObjectParameterivARB(obj, GL_INFO_LOG_LENGTH_ARB))
	if length > 0:
		log = ctypes.create_string_buffer(length)
		baseOperation(obj, length, None, log)
		return log.value.strip('\000') # null-termination
	return ''

@lazy( glGetAttachedObjectsARB )
def glGetAttachedObjectsARB( baseOperation, obj ):
	"""Retrieve the attached objects as an array of GLhandleARB instances"""
	length= glGetObjectParameterivARB( obj, GL_OBJECT_ATTACHED_OBJECTS_ARB )
	if length > 0:
		storage = arrays.GLuintArray.zeros( (length,))
		baseOperation( obj, length, None, storage )
		return storage
	return arrays.GLuintArray.zeros( (0,))

@lazy( glGetShaderSourceARB )
def glGetShaderSourceARB( baseOperation, obj ):
	"""Retrieve the program/shader's source code as a Python string
	
	returns string which is '' if no source code
	"""
	length = int(glGetObjectParameterivARB(obj, GL_OBJECT_SHADER_SOURCE_LENGTH_ARB))
	if length > 0:
		source = ctypes.create_string_buffer(length)
		baseOperation(obj, length, None, source)
		return source.value.strip('\000') # null-termination
	return ''

@lazy( glGetActiveUniformARB )
def glGetActiveUniformARB(baseOperation, program, index):
	"""Retrieve the name, size and type of the uniform of the index in the program"""
	max_index = int(glGetObjectParameterivARB( program, GL_OBJECT_ACTIVE_UNIFORMS_ARB ))
	length = int(glGetObjectParameterivARB( program, GL_OBJECT_ACTIVE_UNIFORM_MAX_LENGTH_ARB))
	if index < max_index and index >= 0:
		if length > 0:
			name = ctypes.create_string_buffer(length)
			size = arrays.GLintArray.zeros( (1,))
			gl_type = arrays.GLuintArray.zeros( (1,))
			baseOperation(program, index, length, None, size, gl_type, name)
			return name.value, size[0], gl_type[0]
		raise ValueError( """No currently specified uniform names""" )
	raise IndexError, 'Index %s out of range 0 to %i' % (index, max_index - 1, )

@lazy( glGetUniformLocationARB )
def glGetUniformLocationARB( baseOperation, program, name ):
	"""Check that name is a string with a null byte at the end of it"""
	if not name:
		raise ValueError( """Non-null name required""" )
	elif name[-1] != '\000':
		name = name + '\000'
	return baseOperation( program, name )
