import random

# these are "enums" for how the center of the scale is calculated
CENTERBOTTOM = 0				# scale about the center bottom of the object
CENTER = 1						# scale about the center of the object
ORIGIN = 2						# scale about the origin 

# these are the "parameters" of the script.
# change them here and then run the script
MinScale = 0.5					# the minimum value to scale
MaxScale = 2.0					# the maximum value to scale
									# the scale will be random between MinScale and MaxScale
UniformScale = True			# True makes X,Y and Z scale values the same, False lets X,Y and Z scale be all different
ScaleCenter = CENTERBOTTOM	# the center of the scale (chosen from list aboe)

# this is all for "Undo/Redo"
class undoData():
	def __init__(self):
		self.undoList = []
		self.readyForUndo = True
		
class undoScaleXform():
	def __init__(self, xform, node):
		self.xform = xform
		self.node = node
	def undo(self):
		mgDetach(self.xform)
	def redo(self):
		mgAppend(self.node, self.xform)
	def cleanup(self):
		mgDelete(self.xform)

def RedoFunc (db, undoData):
	for i in undoData.undoList:
		i.redo()
	undoData.readyForUndo = True
	mgEditorAddUndoForRedo (UndoFunc, UndoCleanupFunc, undoData)

def UndoFunc (db, undoData):
	for i in undoData.undoList:
		i.undo()
	undoData.readyForUndo = False
	mgEditorAddRedo (RedoFunc, UndoCleanupFunc, undoData)

def UndoCleanupFunc (db, reason, undoData):
	if (undoData.readyForUndo == False):
		for i in undoData.undoList:
			i.cleanup()

class randomScaleData():
	def __init__(self, db):
		self.undoData = undoData ()
	def appendUndo(self, xform, node):
		undoOne = undoScaleXform (xform, node)
		self.undoData.undoList.append (undoOne)

def RandomValueBetween(v1, v2):
	"""Return a random value between v1 and v2."""
	amount = random.random()		# between 0 and 1
	oneMinusAmount = 1.0 - amount
	r = (v1 * oneMinusAmount) + (v2 * amount)
	return r

def GetScaleCenter(node):
	"""Calculate scale center for a node."""
	c = mgMakeCoord3d(0.0, 0.0, 0.0)
	b, box = mgGetBounds(node)
	if (b) :
		if (ScaleCenter == CENTERBOTTOM):
			c = mgBoxGetCenterBottom(box)
		elif (ScaleCenter == CENTER):
			c = mgBoxGetCenter(box)
		elif (ScaleCenter == ORIGIN):
			c = mgMakeCoord3d(0.0, 0.0, 0.0)
	return c
	
def ApplyRandomScale(node, min, max):
	"""Create a scale transform with random values and attach to node."""
	xform = mgNewRec(fltXmScale)
	scaleX = RandomValueBetween(MinScale, MaxScale)
	if (UniformScale == True):
		scaleY = scaleX
		scaleZ = scaleX
	else:
		scaleY = RandomValueBetween(MinScale, MaxScale)
		scaleZ = RandomValueBetween(MinScale, MaxScale)
	center = GetScaleCenter(node)
	mgSetCoord3d(xform, fltXmScaleCenter, center.x, center.y, center.z)
	mgSetAttList(xform, fltXmScaleX, scaleX, fltXmScaleY, scaleY, fltXmScaleZ, scaleZ)
	mgAppend(node, xform)
	return xform
	
def RandomScale():
	toolName = "Random Scale"
	
	editorContext = mgNewEditorContext (toolName)

	if (not editorContext): 
		mgSendMessage (MMSG_ERROR, "Failed creating Editor Context")
		return

	mgSendMessage (MMSG_STATUS, "Editor Context Created");

	db = mgEditorGetDbRec (editorContext)
	geometry = mgGetSelectList (db)
	num = mgGetRecListCount (geometry)

	if (num == 0): 
		mgSendMessage (MMSG_ERROR, "Nothing Selected")
		return
 	data = randomScaleData (db)
	
	for i in range (0, num):
		rec,matrix = mgGetNextRecInList (geometry)
		xform = ApplyRandomScale(rec, MinScale, MaxScale)
		data.appendUndo(xform, rec)
		
	mgEditorAddUndo (editorContext, toolName,
					UndoFunc, UndoCleanupFunc, data.undoData) 

RandomScale()