/* 
	 * Copyright (C) 2013-2014 Philipp Marek <philipp.marek@linbit.com>
	 * 
	 * This program is free software; you can redistribute it and/or
	 * modify it under the terms of the GNU General Public
	 * License as published by the Free Software Foundation; either
	 * version 2 of the License, or (at your option) any later version.
	 * 
	 * This software is distributed in the hope that it will be useful,
	 * but WITHOUT ANY WARRANTY; without even the implied warranty of
	 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
	 * General Public License for more details.
	 * 
	 * You should have received a copy of the GNU General Public License along
	 * with this program; if not, write to the Free Software Foundation, Inc.,
	 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	 */
	
	#ifndef _INLINE_FN_H
	#define _INLINE_FN_H
	
	#include <stdbool.h>
	#include <time.h>
	#include <sys/time.h>
	#include <assert.h>
	#include <string.h>
	#include "timer.h"
	#include "config.h"
	#include "transport.h"
	
	static inline bool
	is_auth_req(const struct booth_config *conf)
	{
	    return (conf != NULL) && (conf->authkey[0] != '\0');
	}
	
	static inline int
	get_local_id(void)
	{
		return local ? local->site_id : -1;
	}
	
	static inline uint32_t
	get_node_id(struct booth_site *node)
	{
		return node ? node->site_id : 0;
	}
	
	/** Returns number of seconds left, if any. */
	static inline int
	term_time_left(struct ticket_config *tk)
	{
		int left = 0;
	
		if (is_time_set(&tk->term_expires)) {
			left = time_left(&tk->term_expires);
		}
		return (left < 0) ? 0 : left;
	}
	
	static inline int
	leader_and_valid(struct ticket_config *tk)
	{
		if (tk->leader != local)
			return 0;
	
		return term_time_left(tk);
	}
	
	/** Is this some leader? */
	static inline int
	is_owned(const struct ticket_config *tk)
	{
		return (tk->leader && tk->leader != no_leader);
	}
	
	static inline int
	is_resend(struct ticket_config *tk)
	{
		timetype now;
	
		get_time(&now);
		return time_sub_int(&now, &tk->req_sent_at) >= tk->timeout;
	}
	
	static inline void
	init_header_bare(const struct booth_config *conf, struct boothc_header *h)
	{
		timetype now;
	
		assert(local && local->site_id);
		h->magic   = htonl(BOOTHC_MAGIC);
		h->version = htonl(BOOTHC_VERSION);
		h->from    = htonl(local->site_id);
		if (is_auth_req(conf)) {
			get_time(&now);
			h->opts  = htonl(BOOTH_OPT_AUTH);

			h->secs  = htonl(secs_since_epoch(&now));
			h->usecs = htonl(get_usecs(&now));
		} else {
			h->opts  = htonl(0);
			h->secs  = htonl(0);
			h->usecs = htonl(0);
		}
	}
	
	/* get the _real_ message length out of the header
	 */
	#define sendmsglen(msg) ntohl((msg)->header.length)
	
	static inline void
	init_header(const struct booth_config *conf, struct boothc_header *h, int cmd,
	            int request, int options, int result, int reason, int data_len)
	{
		init_header_bare(conf, h);
		h->length  = htonl(data_len -
			(is_auth_req(conf) ? 0 : sizeof(struct hmac)));
		h->cmd     = htonl(cmd);
		h->request = htonl(request);
		h->options = htonl(options);
		h->result  = htonl(result);
		h->reason  = htonl(reason);
	}
	
	#define my_last_term(tk) \
		(((tk)->state == ST_CANDIDATE && (tk)->last_valid_tk) ? \
		(tk)->last_valid_tk->current_term : (tk)->current_term)
	
	extern int TIME_RES, TIME_MULT;
	
	#define msg_term_time(msg) \
		ntohl((msg)->ticket.term_valid_for)*TIME_RES/TIME_MULT
	#define set_msg_term_time(msg, tk) \
		(msg)->ticket.term_valid_for = htonl(term_time_left(tk)*TIME_MULT/TIME_RES)
	
	static inline void
	init_ticket_msg(const struct booth_config *conf, struct boothc_ticket_msg *msg,
	                int cmd, int request, int rv, int reason,
	                struct ticket_config *tk)
	{
		assert(sizeof(msg->ticket.id) == sizeof(tk->name));
	
		init_header(conf, &msg->header, cmd, request, 0, rv, reason, sizeof(*msg));
	
		if (!tk) {
			memset(&msg->ticket, 0, sizeof(msg->ticket));
		} else {
			memcpy(msg->ticket.id, tk->name, sizeof(msg->ticket.id));
	
			msg->ticket.leader         = htonl(get_node_id(
				(tk->leader && tk->leader != no_leader) ? tk->leader :
					(tk->voted_for ? tk->voted_for : no_leader)));
			msg->ticket.term           = htonl(tk->current_term);
			set_msg_term_time(msg, tk);
		}
	}
	
	static inline struct booth_transport const *
	transport(const struct booth_config *conf)
	{
		return booth_transport + conf->proto;
	}
	
	static inline const char *
	site_string(const struct booth_site *site)
	{
		return site ? site->addr_string : "NONE";
	}
	
	static inline uint16_t
	site_port(const struct booth_site *site)
	{
		assert(site != NULL);
	
		if (site->family == AF_INET) {
			return ntohs(site->sa4.sin_port);
		} else if (site->family == AF_INET6) {
			return ntohs(site->sa6.sin6_port);
		} else {
			return 0;
		}
	}
	
	static inline const char *
	ticket_leader_string(const struct ticket_config *tk)
	{
		return site_string(tk->leader);
	}
	
	/* We allow half of the uint32_t to be used;
	 * half of that below, half of that above the current known "good" value.
	 *   0                                                     UINT32_MAX
	 *   |--------------------------+----------------+------------|
	 *                              |        |       |
	 *                              |--------+-------| allowed range
	 *                                       |
	 *                                       current commit index
	 *
	 * So, on overflow it looks like that:
	 *                                UINT32_MAX  0
	 *   |--------------------------+-----------||---+------------|
	 *                              |        |       |
	 *                              |--------+-------| allowed range
	 *                                       |
	 *                                       current commit index
	 *
	 * This should be possible by using the same datatype and relying
	 * on the under/overflow semantics.
	 *
	 *
	 * Having 30 bits available, and assuming an expire time of
	 * one minute and a (high) commit index step of 64 == 2^6 (because
	 * of weights), we get 2^24 minutes of range - which is ~750
	 * years. "Should be enough for everybody."
	 */
	static inline int
	index_is_higher_than(uint32_t c_high, uint32_t c_low)
	{
		uint32_t diff;
	
		if (c_high == c_low)
			return 0;
	
		diff = c_high - c_low;
		if (diff < UINT32_MAX/4)
			return 1;
	
		diff = c_low - c_high;
		if (diff < UINT32_MAX/4)
			return 0;
	
		assert(!"commit index out of range - invalid");
	}
	
	static inline uint32_t
	index_max2(uint32_t a, uint32_t b)
	{
		return index_is_higher_than(a, b) ? a : b;
	}
	
	static inline uint32_t
	index_max3(uint32_t a, uint32_t b, uint32_t c)
	{
		return index_max2( index_max2(a, b), c);
	}
	
	/* only invoked when ticket leader */
	static inline void
	get_next_election_time(struct ticket_config *tk, timetype *next)
	{
		assert(tk->leader == local);
	
		/* if last_renewal is not set, which is unusual, it may mean
		 * that the ticket never got updated, i.e. nobody acked
		 * ticket updates (say, due to a temporary connection
		 * problem)
		 * we may try a bit later again */
		if (!is_time_set(&tk->last_renewal)) {
			time_reset(next);
		} else {
			interval_add(&tk->last_renewal, tk->renewal_freq, next);
		}
	
		/* if delay_commit is earlier than next, then set next to
		 * delay_commit */
		if (is_time_set(&tk->delay_commit) &&
				time_cmp(next, &tk->delay_commit, >)) {
			copy_time(&tk->delay_commit, next);
		}
	}
	
	static inline void
	expect_replies(struct ticket_config *tk, int reply_type)
	{
		tk->retry_number = 0;
		tk->acks_expected = reply_type;
		tk->acks_received = local->bitmask;
		get_time(&tk->req_sent_at);
	}
	
	static inline void
	no_resends(struct ticket_config *tk)
	{
		tk->retry_number = 0;
		tk->acks_expected = 0;
	}
	
	static inline struct booth_site *
	my_vote(struct ticket_config *tk)
	{
		return tk->votes_for[ local->index ];
	}
	
	static inline int
	count_bits(uint64_t val)
	{
		return __builtin_popcount(val);
	}
	
	static inline int
	majority_of_bits(const struct booth_config *conf, struct ticket_config *tk,
	                 uint64_t val)
	{
		/* Use ">" to get majority decision, even for an even number
		 * of participants. */
		return (count_bits(val) * 2) > conf->site_count;
	}
	
	static inline int
	all_replied(const struct booth_config *conf, struct ticket_config *tk)
	{
		return (tk->acks_received ^ conf->all_bits) == 0;
	}
	
	static inline int
	all_sites_replied(const struct booth_config *conf, struct ticket_config *tk)
	{
		return ((tk->acks_received & conf->sites_bits) ^ conf->sites_bits) == 0;
	}
	
	#endif  // _INLINE_FN_H