"""boundary.py - Classes for implementing region conditions

NOTE: I've only set it up for testing X values of constants and functions.
Although it should work for vectors/arrays of values, that implies
knowing info about the actual triangles, and that is not how the user should
operate.
"""


class Region:
    """Base class for modifying quantities based on a region.
    """   

    def __init__(self):
        pass
        
    def __call__(self, tag, elements, domain):
        msg = 'Generic class Boundary must be subclassed'
        raise msg


class Set_Region(Region):
    
    def __init__(self, tag, quantity, X, location='vertices'):
        """ 
        name: Name of quantity
        X: const or function 
        location: Where values are to be stored.
        Permissible options are: vertices, centroid
        """
        
        Region.__init__(self)
        self.tag = tag 
        self.quantity = quantity
        self.location = location
        self.X = X

    def __repr__(self):
        pass
    
    def __call__(self, tag, elements, domain):
        """
        """    
        if tag == self.tag:
            domain.set_quantity(self.quantity, self.X, indexes = elements)


class Add_Value_To_Region(Region):
    """
    Will add a value to the current quantity value.
    """
    
    def __init__(self, tag, quantity, X, location='vertex'):
        Region.__init__(self)
        self.tag = tag 
        self.quantity = quantity
        self.location = location
        self.X = X
        if callable(X):
            raise 'This class does not work with functions'  

    def __repr__(self):
        pass
    
    def __call__(self, tag, elements, domain):
        """
        """    
        if tag == self.tag:
            new_values = domain.get_quantity(self.quantity,
                                             indexes = elements) + self.X
            domain.set_quantity(self.quantity, new_values, indexes = elements)