from fluents import dataset

_dim_annotation_handlers = {}

def get_dim_annotations(dimname, annotation, ids):
    """Returns a list of annotations corresponding to the given ids in 
    dimension dimname"""
    global _dim_annotation_handlers

    if _dim_annotation_handlers.has_key(dimname):
        return _dim_annotation_handlers[dimname].get_annotations(annotation, ids)
    return None

def set_dim_handler(dimname, handler):
    """Set the handler for the given dimension."""
    global _dim_annotation_handlers
    _dim_annotation_handlers[dimname] = handler
    
def get_dim_handler(dimname):
    """Get the handler for the given dimension."""
    global _dim_annotation_handlers
    if _dim_annotation_handlers.has_key(dimname):
        return _dim_annotation_handlers[dimname]
    else: 
        return None


class AnnotationHandler:
    def __init__(self):
        pass

    def get_annotations(self, annotationname, ids, default=None):
        return None

    def get_annotation_names(self):
        return []


class DictAnnotationHandler(AnnotationHandler):

    def __init__(self, d={}):
        self._dict = d
    
    def get_annotations(self, annotationname, ids, default=None):
        d = self._dict
        retval = []
        for id in ids:
            if d[annotationname].has_key(id):
                retval.append(d[annotationname][id])
            else:
                retval.append(default)
        return retval
    
    def add_annotations(self, annotationname, d):
        self._dict[annotationname] = d

    def get_annotation_names(self):
        return self._dict.keys()