from sqlalchemy import util, exceptions
import types
from sqlalchemy.orm import mapper
    
def _monkeypatch_session_method(name, ctx, class_):
    def do(self, *args, **kwargs):
        session = ctx.current
        return getattr(session, name)(self, *args, **kwargs)
    try:
        do.__name__ = name
    except:
        pass
    if not hasattr(class_, name): 
        setattr(class_, name, do)
        
def assign_mapper(ctx, class_, *args, **kwargs):
    extension = kwargs.pop('extension', None)
    if extension is not None:
        extension = util.to_list(extension)
        extension.append(ctx.mapper_extension)
    else:
        extension = ctx.mapper_extension

    validate = kwargs.pop('validate', False)
    
    if not isinstance(getattr(class_, '__init__'), types.MethodType):
        def __init__(self, **kwargs):
             for key, value in kwargs.items():
                 if validate:
                     if not self.mapper.get_property(key, resolve_synonyms=False, raiseerr=False):
                         raise exceptions.ArgumentError("Invalid __init__ argument: '%s'" % key)
                 setattr(self, key, value)
        class_.__init__ = __init__
    
    class query(object):
        def __getattr__(self, key):
            return getattr(ctx.current.query(class_), key)
        def __call__(self):
            return ctx.current.query(class_)

    if not hasattr(class_, 'query'): 
        class_.query = query()
    
    for name in ['refresh', 'expire', 'delete', 'expunge', 'update']:
        _monkeypatch_session_method(name, ctx, class_)

    m = mapper(class_, extension=extension, *args, **kwargs)
    class_.mapper = m
    return m