import inspect, os, sys
DEBUG = int(os.environ.get('DEBUG_MYPRODUCT', 0))

##
## Debugging
##

def ObserverProxy(method_names):
    class Proxy:
        def __init__(self):
            self._observers = []
        def add_observer(self, observer):
            self._observers.append(observer)
        def remove_observer(self, observer):
            self._observers.remove(observer)

    def create_method_proxy(method_name):
        def method_proxy(self, *args, **kwargs):
            for observer in self._observers:
                getattr(observer, method_name)(*args, **kwargs)
        return method_proxy

    for method_name in method_names:
        setattr(Proxy, method_name, create_method_proxy(method_name))

    return Proxy()


debugobserver = ObserverProxy(["write", "close"])
debugobserver.add_observer(sys.stdout)
#debugobserver.add_observer(open('myproduct-debug.log','a'))

    
    
def debug(s, tabs=0, steps=(1,), f=False):
    if DEBUG or f:
        inspect_dbg = []
        if type(steps)==type(1):
            steps = range(1, steps+1)
        for i in steps:
            try:
                #caller_module = inspect.stack()[i][1]
                caller_method = inspect.stack()[i][3]
                caller_method_line = inspect.stack()[i][2]
            except IndexError:
                break
            inspect_dbg.append("%s:%s"%(caller_method, caller_method_line))
        out = "\t"*tabs + "%s (%s)"%(s, ", ".join(inspect_dbg))
        print >>debugobserver, out