/*
 * Main balancing routine. This does not try to keep the same proxy for
 * the call if some proxies were disabled or enabled; proxy death considered
 * too rare. Otherwise we should implement "mature" HA clustering, which is
 * too expensive here.
 */
struct rtpp_node *
select_rtpp_node(str callid, int do_test)
{
	unsigned sum, weight_sum;
	struct rtpp_node* node;
	int was_forced, sumcut, found, constant_weight_sum;

	LM_INFO("entering select_rtpp_node\n");

	/* check last list version */
	if (my_version != *list_version && update_rtpp_proxies() < 0) {
		LM_ERR("cannot update rtpp proxies list\n");
		return 0;
	}
	
	if(!selected_rtpp_set){
		LM_ERR("script error -no valid set selected\n");
		return NULL;
	}
	/* Most popular case: 1 proxy, nothing to calculate */
	if (selected_rtpp_set->rtpp_node_count == 1) {
		LM_INFO("rtpproxy node count = 1\n");
		node = selected_rtpp_set->rn_first;
		if (node->rn_disabled && node->rn_recheck_ticks <= get_ticks())
			node->rn_disabled = rtpp_test(node, 1, 0);
		LM_INFO("result rtpp_test = %d\n", node->rn_disabled);
		return node->rn_disabled ? NULL : node;
	}

	/* XXX Use quick-and-dirty hashing algo */
	for(sum = 0; callid.len > 0; callid.len--)
		sum += callid.s[callid.len - 1];
	sum &= 0xff;

	was_forced = 0;
retry:
	LM_INFO("retrying to find rtpproxy\n");
	weight_sum = 0;
	constant_weight_sum = 0;
	found = 0;
	for (node=selected_rtpp_set->rn_first; node!=NULL; node=node->rn_next) {

		if (node->rn_disabled && node->rn_recheck_ticks <= get_ticks()){
			/* Try to enable if it's time to try. */
			node->rn_disabled = rtpp_test(node, 1, 0);
		}
		constant_weight_sum += node->rn_weight;
		if (!node->rn_disabled) {
			weight_sum += node->rn_weight;
			found = 1;
		}
	}
	if (found == 0) {
		/* No proxies? Force all to be redetected, if not yet */
		if (was_forced)
			return NULL;
		was_forced = 1;
		for(node=selected_rtpp_set->rn_first; node!=NULL; node=node->rn_next) {
			node->rn_disabled = rtpp_test(node, 1, 1);
		}
		goto retry;
	}
	sumcut = weight_sum ? sum % constant_weight_sum : -1;
	/*
	 * sumcut here lays from 0 to constant_weight_sum-1.
	 * Scan proxy list and decrease until appropriate proxy is found.
	 */
	was_forced = 0;
	for (node=selected_rtpp_set->rn_first; node!=NULL;) {
		if (sumcut < (int)node->rn_weight) {
			if (node->rn_disabled) {
				if (was_forced == 0) {
					/* appropriate proxy is disabled : redistribute on enabled ones */
					sumcut = weight_sum ? sum %  weight_sum : -1;
					node = selected_rtpp_set->rn_first;
					was_forced = 1;
				}
				continue;
			} else {
				goto found;
			}
		}
		sumcut -= node->rn_weight;
		node = node->rn_next;
	}
	/* No node list */
	return NULL;
found:
	LM_INFO("rtpproxy found\n");
	if (do_test) {
		LM_INFO("do_test enabled\n");
		node->rn_disabled = rtpp_test(node, node->rn_disabled, 0);
		if (node->rn_disabled)
			LM_INFO("going to retry\n");
			goto retry;
	}
	return node;
}