"""General client side utilities.

This module contains utility functions, used primarily by advanced COM
programmers, or other COM modules.
"""
import pythoncom
from win32com.client import Dispatch, _get_good_object_

PyIDispatchType = pythoncom.TypeIIDs[pythoncom.IID_IDispatch]

def WrapEnum(ob, resultCLSID = None):
	"""Wrap an object in a VARIANT enumerator.  

	All VT_DISPATCHs returned by the enumerator are converted to wrapper objects
	(which may be either a class instance, or a dynamic.Dispatch type object).

	"""
	if type(ob) != pythoncom.TypeIIDs[pythoncom.IID_IEnumVARIANT]:
		ob = ob.QueryInterface(pythoncom.IID_IEnumVARIANT)
	return EnumVARIANT(ob, resultCLSID)

class Enumerator:
	"""A class that provides indexed access into an Enumerator

	By wrapping a PyIEnum* object in this class, you can perform
	natural looping and indexing into the Enumerator.

	Looping is very efficient, but it should be noted that although random 
	access is supported, the underlying object is still an enumerator, so 
	this will force many reset-and-seek operations to find the requested index.

	"""
	def __init__(self, enum):
		self._oleobj_ = enum # a PyIEnumVARIANT
		self.index = -1
	def __getitem__(self, index):
		return self.__GetIndex(index)
	def __call__(self, index):
		return self.__GetIndex(index)
	
	def __GetIndex(self, index):
		if type(index)!=type(0): raise TypeError("Only integer indexes are supported for enumerators")
		# NOTE
		# In this context, self.index is users purely as a flag to say 
		# "am I still in sequence".  The user may call Next() or Reset() if they
		# so choose, in which case self.index will not be correct (although we
		# still want to stay in sequence)
		if index != self.index + 1:
			# Index requested out of sequence.
			self._oleobj_.Reset()
			if index: self._oleobj_.Skip(index) # if asked for item 1, must skip 1, Python always zero based.
		self.index = index
		result = self._oleobj_.Next(1)
		if len(result):
			return self._make_retval_(result[0])
		raise IndexError("list index out of range")
	def Next(self, count=1):
		ret = self._oleobj_.Next(count)
		realRets = []
		for r in ret:
			realRets.append(self._make_retval_(r))
		return tuple(realRets) # Convert back to tuple.
	def Reset(self):
		return self._oleobj_.Reset()
	def Clone(self):
		return self.__class__( self._oleobj_.Clone(), self.resultCLSID)
	def _make_retval_(self, result):
		return result

class EnumVARIANT(Enumerator):
	def __init__(self, enum, resultCLSID = None):
		self.resultCLSID = resultCLSID
		Enumerator.__init__(self, enum)
	def _make_retval_(self, result):
		return _get_good_object_(result, resultCLSID = self.resultCLSID)

class Iterator:
	def __init__(self, enum, resultCLSID = None):
		self.resultCLSID = resultCLSID
		self._iter_ = iter(enum.QueryInterface(pythoncom.IID_IEnumVARIANT))
	def __iter__(self):
		return self
	def __next__(self):
		return _get_good_object_(next(self._iter_), resultCLSID = self.resultCLSID)
