
/*
 * The olsr.org Optimized Link-State Routing daemon version 2 (olsrd2)
 * Copyright (c) 2004-2015, the olsr.org team - see HISTORY file
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
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 *   notice, this list of conditions and the following disclaimer.
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 *   notice, this list of conditions and the following disclaimer in
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 *   distribution.
 * * Neither the name of olsr.org, olsrd nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
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/**
 * @file
 */

#ifndef NHDP_HYSTERESIS_H_
#define NHDP_HYSTERESIS_H_

#include "common/common_types.h"
#include "subsystems/oonf_rfc5444.h"

#include "nhdp/nhdp_db.h"

/**
 * Output buffer for hysteresis data string representation
 */
struct nhdp_hysteresis_str {
  /*! text buffer for maximum length string representation */
  char buf[128];
};

/**
 * NHDP link hysteresis handler
 */
struct nhdp_hysteresis_handler {
  /*! name of the handler */
  const char *name;

  /**
   * callback to update link hysteresis pending and lost status.
   * Some implementations might also change their internal state
   * @param lnk nhdp link
   * @param context rfc5444 reader context
   */
  void (*update_hysteresis)(struct nhdp_link *lnk, struct rfc5444_reader_tlvblock_context *context);

  /**
   * callback to check if link is pending
   * @param lnk nhdp link
   * @return true if link is pending
   */
  bool (*is_pending)(struct nhdp_link *lnk);

  /**
   * callback to check if link is lost
   * @param lnk nhdp link
   * @return true if link is lost
   */
  bool (*is_lost)(struct nhdp_link *lnk);

  /**
   * callback to convert hysteresis state into string representation
   * @param buf buffer for text output
   * @param lnk nhdp link
   * @return pointer to buffer
   */
  const char *(*to_string)(struct nhdp_hysteresis_str *buf, struct nhdp_link *lnk);
};

EXPORT void nhdp_hysteresis_set_handler(struct nhdp_hysteresis_handler *);
EXPORT struct nhdp_hysteresis_handler *nhdp_hysteresis_get_handler(void);

/**
 * Update a links hysteresis because of an incoming NHDP Hello message
 * @param lnk pointer to NHDP link
 * @param context pointer to rfc5444 context (message context)
 */
static INLINE void
nhdp_hysteresis_update(struct nhdp_link *lnk, struct rfc5444_reader_tlvblock_context *context) {
  nhdp_hysteresis_get_handler()->update_hysteresis(lnk, context);
}

/**
 * @param lnk pointer to nhdp link
 * @return true if link is pending
 */
static INLINE bool
nhdp_hysteresis_is_pending(struct nhdp_link *lnk) {
  return nhdp_hysteresis_get_handler()->is_pending(lnk);
}

/**
 * @param lnk pointer to nhdp link
 * @return true if link is lost
 */
static INLINE bool
nhdp_hysteresis_is_lost(struct nhdp_link *lnk) {
  return nhdp_hysteresis_get_handler()->is_lost(lnk);
}

/**
 * @param buf pointer to nhdp hysteresis text buffer
 * @param lnk pointer to nhdp link
 * @return pointer to text description of nhdp links hysteresis status
 */
static INLINE const char *
nhdp_hysteresis_to_string(struct nhdp_hysteresis_str *buf, struct nhdp_link *lnk) {
  return nhdp_hysteresis_get_handler()->to_string(buf, lnk);
}

#endif /* NHDP_HYSTERESIS_H_ */
