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/* Routing module helpers.
 * 
 * This file provides support for the rt_data structure manipulation.
 */

#include "fdproto-internal.h"

/* Structure that contains the routing data for a message */
struct rt_data {
	int		extracted;	/* if 0, candidates is ordered by diamid, otherwise the order is unspecified. This also counts the number of times the message was (re-)sent, as a side effect */
	struct fd_list	candidates;	/* All the candidates. Items are struct rtd_candidate. */
	struct fd_list	errors;		/* All errors received from other peers for this message */
};

/* Items of the errors list */
struct rtd_error {
	struct fd_list	chain;	/* link in the list, ordered by nexthop (fd_os_cmp) */
	DiamId_t 	nexthop;/* the peer the message was sent to */
	size_t		nexthoplen; /* cached string length */
	DiamId_t	erh;	/* the origin of the error */
	size_t		erhlen; /* cached string length */
	uint32_t	code;	/* the error code */
};

/* Create a new structure to store routing data */
int  fd_rtd_init(struct rt_data ** rtd)
{
	struct rt_data *new;
	TRACE_ENTRY("%p", rtd);
	CHECK_PARAMS(rtd);
	
	/* Alloc the structure */
	CHECK_MALLOC( new = malloc(sizeof(struct rt_data)) );
	memset(new, 0, sizeof(struct rt_data) );
	fd_list_init(&new->candidates, new);
	fd_list_init(&new->errors, new);
	
	*rtd = new;
	return 0;
}

/* Destroy the routing data */
void fd_rtd_free(struct rt_data ** rtd)
{
	struct rt_data *old;
	
	TRACE_ENTRY("%p", rtd);
	CHECK_PARAMS_DO(rtd, return );
	
	old = *rtd;
	*rtd = NULL;
	
	while (!FD_IS_LIST_EMPTY(&old->candidates)) {
		struct rtd_candidate * c = (struct rtd_candidate *) old->candidates.next;
		
		fd_list_unlink(&c->chain);
		free(c->diamid);
		free(c->realm);
		free(c);
	}
	
	while (!FD_IS_LIST_EMPTY(&old->errors)) {
		struct rtd_error * c = (struct rtd_error *) old->errors.next;
		
		fd_list_unlink(&c->chain);
		free(c->nexthop);
		free(c->erh);
		free(c);
	}
	
	free(old);
	
	return;
}

/* Add a peer to the candidates list. The source is our local peer list, so no need to care for the case here. */
int  fd_rtd_candidate_add(struct rt_data * rtd, DiamId_t peerid, size_t peeridlen, DiamId_t realm, size_t realmlen)
{
	struct fd_list * prev;
	struct rtd_candidate * new;
	
	TRACE_ENTRY("%p %p %zd %p %zd", rtd, peerid, peeridlen, realm, realmlen);
	CHECK_PARAMS(rtd && peerid && peeridlen);
	
	/* Since the peers are ordered when they are added (fd_g_activ_peers) we search for the position from the end -- this should be efficient */
	for (prev = rtd->candidates.prev; prev != &rtd->candidates; prev = prev->prev) {
		struct rtd_candidate * cp = (struct rtd_candidate *) prev;
		int cmp = fd_os_cmp(peerid, peeridlen, cp->diamid, cp->diamidlen);
		if (cmp > 0)
			break;
		if (cmp == 0)
			/* The candidate is already in the list */
			return 0;
	}
	
	/* Create the new entry */
	CHECK_MALLOC( new = malloc(sizeof(struct rtd_candidate)) );
	memset(new, 0, sizeof(struct rtd_candidate) );
	fd_list_init(&new->chain, new);
	CHECK_MALLOC( new->diamid = os0dup(peerid, peeridlen) )
	new->diamidlen = peeridlen;
	if (realm) {
		CHECK_MALLOC( new->realm = os0dup(realm, realmlen) )
		new->realmlen = realmlen;
	}
	
	/* insert in the list at the correct position */
	fd_list_insert_after(prev, &new->chain);
	
	return 0;
}

/* Remove a peer from the candidates (if it is found). Case insensitive search since the names are received from other peers */
void fd_rtd_candidate_del(struct rt_data * rtd, uint8_t * id, size_t idsz)
{
	struct fd_list * li;
	
	TRACE_ENTRY("%p %p %zd", rtd, id, idsz);
	CHECK_PARAMS_DO( rtd && id && idsz, return );
	
	if (!fd_os_is_valid_DiameterIdentity(id, idsz))
		/* it cannot be in the list */
		return;
	
	for (li = rtd->candidates.next; li != &rtd->candidates; li = li->next) {
		struct rtd_candidate * c = (struct rtd_candidate *) li;
		int cont;
		int cmp = fd_os_almostcasesrch(id, idsz, c->diamid, c->diamidlen, &cont);
		
		if (!cmp) {
			/* Found it! Remove it */
			fd_list_unlink(&c->chain);
			free(c->diamid);
			free(c->realm);
			free(c);
			break;
		}
		
		if (cont)
			continue;
		
		/* The list is guaranteed to be ordered only if not extracted */
		if (! rtd->extracted)
			break;
	}
	
	return;
}

/* If a peer returned a protocol error for this message, save it so that we don't try to send it there again.
 Case insensitive search since the names are received from other peers*/
int  fd_rtd_error_add(struct rt_data * rtd, DiamId_t sentto, size_t senttolen, uint8_t * origin, size_t originsz, uint32_t rcode, struct fd_list ** candidates, int * sendingattemtps)
{
	struct fd_list * li;
	int match = 0;
	
	TRACE_ENTRY("%p %p %zd %p %zd %u %p %p", rtd, sentto, senttolen, origin, originsz, rcode, candidates, sendingattemtps);
	CHECK_PARAMS( rtd && sentto && senttolen ); /* origin may be NULL */
	
	/* First add the new error entry */
	for (li = rtd->errors.next; li != &rtd->errors; li = li->next) {
		struct rtd_error * e = (struct rtd_error *) li;
		int cmp = fd_os_cmp(sentto, senttolen, e->nexthop, e->nexthoplen);
		if (cmp > 0)
			continue;
		if (!cmp)
			match = 1;
		break;
	}
	
	/* If we already had this entry, we should not have sent the message again to this peer... anyway, let's close our eyes. */
	/* in the normal case, we save the error */
	if (!match) {
		/* Add a new entry in the error list */
		struct rtd_error * new;
		CHECK_MALLOC( new = malloc(sizeof(struct rtd_error)) );
		memset(new, 0, sizeof(struct rtd_error));
		fd_list_init(&new->chain, NULL);

		CHECK_MALLOC(new->nexthop = os0dup(sentto, senttolen));
		new->nexthoplen = senttolen;
		
		if (origin) {
			if (!originsz) {
				originsz=strlen((char *)origin);
			} else {
				if (!fd_os_is_valid_DiameterIdentity(origin, originsz)){
					TRACE_DEBUG(FULL, "Received error %d from peer with invalid Origin-Host AVP, not saved", rcode);
					origin = NULL;
					goto after_origin;
				}
			}
			CHECK_MALLOC_DO( new->erh = (DiamId_t)os0dup(origin, originsz), { free(new); return __ret__; });
			new->erhlen = originsz;
		}
after_origin:
		new->code = rcode;
		fd_list_insert_before(li, &new->chain);
	}
	
	/* Finally, remove this (these) peers from the candidate list */
	fd_rtd_candidate_del(rtd, (os0_t)sentto, senttolen);
	if (origin)
		fd_rtd_candidate_del(rtd, origin, originsz);
	
	if (candidates)
		*candidates = &rtd->candidates;
	
	if (sendingattemtps)
		*sendingattemtps = rtd->extracted;
	
	/* Done! */
	return 0;
}

/* Only retrieve the number of times this message has been processed by the routing-out mechanism (i.e. number of times it was failed over) */
int  fd_rtd_get_nb_attempts(struct rt_data * rtd, int * sendingattemtps)
{
	TRACE_ENTRY("%p %p", rtd, sendingattemtps);
	CHECK_PARAMS( rtd && sendingattemtps );
	
	*sendingattemtps = rtd->extracted;
	
	/* Done! */
	return 0;
}

/* Extract the list of valid candidates, and initialize their scores */
void fd_rtd_candidate_extract(struct rt_data * rtd, struct fd_list ** candidates, int ini_score)
{
	struct fd_list * li;
	
	TRACE_ENTRY("%p %p", rtd, candidates);
	CHECK_PARAMS_DO( candidates, return );
	CHECK_PARAMS_DO( rtd, { *candidates = NULL; return; } );
	
	*candidates = &rtd->candidates;
	
	/* Reset all scores to INITIAL score */
	for (li = rtd->candidates.next; li != &rtd->candidates; li = li->next) {
		struct rtd_candidate * c = (struct rtd_candidate *) li;
		c->score = ini_score;
	}
	
	rtd->extracted += 1;
	return;
}

/* Reorder the list of peers. If several peer have the same highest score, they are randomized. */
int  fd_rtd_candidate_reorder(struct fd_list * candidates)
{
	struct fd_list unordered = FD_LIST_INITIALIZER(unordered), *li;
	struct fd_list highest = FD_LIST_INITIALIZER(highest);
	int hs = -1;
	
	TRACE_ENTRY("%p", candidates);
	CHECK_PARAMS( candidates );
	
	/* First, move all items from candidates to the unordered list */
	fd_list_move_end(&unordered, candidates);
	
	/* Now extract each element from unordered and add it back to list ordered by score */
	while (!FD_IS_LIST_EMPTY(&unordered)) {
		struct rtd_candidate * c = (struct rtd_candidate *) unordered.next;
		
		fd_list_unlink(&c->chain);
		
		/* If this candidate has a higher score than the previous ones */
		if (c->score > hs) {
			/* Then we move the previous high score items at end of the list */
			fd_list_move_end(candidates, &highest);
			
			/* And the new high score is set */
			hs = c->score;
		}
		
		/* If this candidate equals the higher score, add it into highest list at a random place */
		if (c->score == hs) {
			if (rand() & 1) {
				fd_list_insert_after(&highest, &c->chain);
			} else {
				fd_list_insert_before(&highest, &c->chain);
			}
		/* Otherwise, insert at normal place in the list */
		} else {
			/* Find the position in ordered candidates list */
			for (li = candidates->next; li != candidates; li = li->next) {
				struct rtd_candidate * cnext = (struct rtd_candidate *) li;
				if (cnext->score >= c->score)
					break;
			}

			/* Add the element there */
			fd_list_insert_before(li, &c->chain);
		}
	}
	
	/* Now simply move back all the "highest" candidates at the end of the list */
	fd_list_move_end(candidates, &highest);
	
	return 0;
}