# Credit https://gist.github.com/pardo/19d672235bbef6fa793a
import functools

from django.core.cache import cache


def debounced_wrap(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        key = kwargs.pop("key")  # it's required
        call_count = kwargs.pop("call_count", 1)
        count = cache.get(key, 1)
        if count > call_count:
            # someone called the function again before the this was executed
            return None
        # I'm the last call
        return func(*args, **kwargs)

    return wrapper


def debounced_task(key_generator):
    """
    :param func: must be the @debounced_wrap decorated with @task / @shared_task from celery
    :param key_generator: function that knows how to generate a key from
    args and kwargs passed to func or a constant str used in the cache
    key will be prepended with function module and name
    :return: function that calls apply_async on the task keep that in mind when send the arguments
    """

    def decorator(func):
        @functools.wraps(func)
        def wrapper(**kwargs):
            func_args = kwargs.get("args", [])
            func_kwargs = kwargs.get("kwargs", {})
            key = f"{func.__module__}.{func.__name__}.{key_generator(*func_args, **func_kwargs)}"
            cache.add(key, 0, 3600)
            call_count = cache.incr(key)
            func_kwargs.update({"key": key, "call_count": call_count})
            kwargs["args"] = func_args
            kwargs["kwargs"] = func_kwargs
            return func.apply_async(**kwargs)

        return wrapper

    return decorator