import numpy
import os
#from basinzoom import *
from ContourToMesh import *
from MatlabFuncs import *

def FlagElements(md,region):
	"""
	FLAGELEMENTS - flag the elements in an region

	   The region can be given with an exp file, a list of elements.

	   Usage: 
	      flag=FlagElements(md,region);

	   Example:
	      flag=FlagElements(md,'all');
	      flag=FlagElements(md,'');
	      flag=FlagElements(md,'Domain.exp');
	      flag=FlagElements(md,'~Domain.exp');
	      flag=FlagElements(md,md.mask.elementongroundedice);
	"""

	if   isinstance(region,(str,unicode)):
		if   not region:
			flag=numpy.zeros(md.mesh.numberofelements,'bool')
			invert=0
		elif strcmpi(region,'all'):
			flag=numpy.ones(md.mesh.numberofelements,'bool')
			invert=0
		else:
			#make sure that we actually don't want the elements outside the domain outline!
			if strcmpi(region[0],'~'):
				region=region[1:]
				invert=1
			else:
				invert=0

			#does the region domain outline exist or do we have to look for xlim,ylim in basinzoom?
			if not os.path.exists(region):
				if len(region)>3 and not strcmp(region[-4:],'.exp'):
					raise IOError("Error: File 'region' not found!" % region)
				raise RuntimeError("FlagElements.py calling basinzoom.py is not complete.")
				xlim,ylim=basinzoom('basin',region)
				flag_nodes=numpy.logical_and(numpy.logical_and(md.mesh.x<xlim[1],md.mesh.x>xlim[0]),numpy.logical_and(md.mesh.y<ylim[1],md.mesh.y>ylim[0])).astype(float)
				flag=numpy.prod(flag_nodes[md.mesh.elements],axis=1)
			else:
				#ok, flag elements
				[flag,dum]=ContourToMesh(md.mesh.elements[:,0:3].copy(),md.mesh.x.reshape(-1,1),md.mesh.y.reshape(-1,1),region,'element',1)

		if invert:
			flag=numpy.logical_not(flag)

	elif isinstance(region,numpy.ndarray) or isinstance(region,bool):
		if not numpy.size(region,0)==md.mesh.numberofelements:
			raise TypeError("Flaglist for region must be of same size as number of elements in model.")
		flag=region

	else:
		raise TypeError("Invalid region option")

	return flag