from functools import wraps

from django.http import Http404
from django.utils.decorators import available_attrs
from django.core.urlresolvers import reverse, NoReverseMatch
from django.shortcuts import redirect

from waffle import flag_is_active, switch_is_active


def waffle_flag(flag_name, redirect_to=None):
    def decorator(view):
        @wraps(view, assigned=available_attrs(view))
        def _wrapped_view(request, *args, **kwargs):
            if flag_name.startswith('!'):
                active = not flag_is_active(request, flag_name[1:])
            else:
                active = flag_is_active(request, flag_name)

            if not active:
                response_to_redirect_to = get_response_to_redirect(redirect_to)
                if response_to_redirect_to:
                    return response_to_redirect_to
                else:
                    raise Http404

            return view(request, *args, **kwargs)
        return _wrapped_view
    return decorator


def waffle_switch(switch_name, redirect_to=None):
    def decorator(view):
        @wraps(view, assigned=available_attrs(view))
        def _wrapped_view(request, *args, **kwargs):
            if switch_name.startswith('!'):
                active = not switch_is_active(switch_name[1:])
            else:
                active = switch_is_active(switch_name)

            if not active:
                response_to_redirect_to = get_response_to_redirect(redirect_to)
                if response_to_redirect_to:
                    return response_to_redirect_to
                else:
                    raise Http404

            return view(request, *args, **kwargs)
        return _wrapped_view
    return decorator


def get_response_to_redirect(view):
    try:
        return redirect(reverse(view)) if view else None
    except NoReverseMatch:
        return None

