/* Copyright 2004 Roger Dingledine */
/* See LICENSE for licensing information */
/* $Id$ */

/**
 * \file rephist.c
 * \brief Basic history functionality for reputation module.
 **/

/* DOCDOC references to 'nicknames' in docs here are mostly wrong. */

#include "or.h"

/** History of an OR-\>OR link. */
typedef struct link_history_t {
  /** When did we start tracking this list? */
  time_t since;
  /** How many times did extending from OR1 to OR2 succeeed? */
  unsigned long n_extend_ok;
  /** How many times did extending from OR1 to OR2 fail? */
  unsigned long n_extend_fail;
} link_history_t;

/** History of an OR. */
typedef struct or_history_t {
  /** When did we start tracking this OR? */
  time_t since;
  /** How many times did we successfully connect? */
  unsigned long n_conn_ok;
  /** How many times did we try to connect and fail?*/
  unsigned long n_conn_fail;
  /** How many seconds have we been connected to this OR before
   * 'up_since'? */
  unsigned long uptime;
  /** How many seconds have we been unable to connect to this OR before
   * 'down_since'? */
  unsigned long downtime;
  /** If nonzero, we have been connected since this time. */
  time_t up_since;
  /** If nonzero, we have been unable to connect since this time. */
  time_t down_since;
  /** Map from lowercased OR2 name to a link_history_t for the link
   * from this OR to OR2. */
  strmap_t *link_history_map;
} or_history_t;

/** Map from lowercased OR nickname to or_history_t. */
static strmap_t *history_map = NULL;

/** Return the or_history_t for the named OR, creating it if necessary.
 */
static or_history_t *get_or_history(const char* id)
{
  or_history_t *hist;
  char hexid[HEX_DIGEST_LEN+1];
  base16_encode(hexid, HEX_DIGEST_LEN+1, id, DIGEST_LEN);

  hist = (or_history_t*) strmap_get(history_map, hexid);
  if (!hist) {
    hist = tor_malloc_zero(sizeof(or_history_t));
    hist->link_history_map = strmap_new();
    hist->since = time(NULL);
    strmap_set(history_map, hexid, hist);
  }
  return hist;
}

/** Return the link_history_t for the link from the first named OR to
 * the second, creating it if necessary.
 */
static link_history_t *get_link_history(const char *from_id,
                                        const char *to_id)
{
  or_history_t *orhist;
  link_history_t *lhist;
  char to_hexid[HEX_DIGEST_LEN+1];
  orhist = get_or_history(from_id);
  base16_encode(to_hexid, HEX_DIGEST_LEN+1, to_id, DIGEST_LEN);
  lhist = (link_history_t*) strmap_get(orhist->link_history_map, to_hexid);
  if (!lhist) {
    lhist = tor_malloc_zero(sizeof(link_history_t));
    lhist->since = time(NULL);
    strmap_set(orhist->link_history_map, to_hexid, lhist);
  }
  return lhist;
}

/** Update an or_history_t object <b>hist</b> so that its uptime/downtime
 * count is up-to-date as of <b>when</b>.
 */
static void update_or_history(or_history_t *hist, time_t when)
{
  tor_assert(hist);
  if (hist->up_since) {
    tor_assert(!hist->down_since);
    hist->uptime += (when - hist->up_since);
    hist->up_since = when;
  } else if (hist->down_since) {
    hist->downtime += (when - hist->down_since);
    hist->down_since = when;
  }
}

/** Initialize the static data structures for tracking history.
 */
void rep_hist_init(void)
{
  history_map = strmap_new();
}

/** Remember that an attempt to connect to the OR <b>nickname</b> failed at
 * <b>when</b>.
 */
void rep_hist_note_connect_failed(const char* id, time_t when)
{
  or_history_t *hist;
  hist = get_or_history(id);
  ++hist->n_conn_fail;
  if (hist->up_since) {
    hist->uptime += (when - hist->up_since);
    hist->up_since = 0;
  }
  if (!hist->down_since)
    hist->down_since = when;
}

/** Remember that an attempt to connect to the OR <b>nickname</b> succeeded
 * at <b>when</b>.
 */
void rep_hist_note_connect_succeeded(const char* id, time_t when)
{
  or_history_t *hist;
  hist = get_or_history(id);
  ++hist->n_conn_ok;
  if (hist->down_since) {
    hist->downtime += (when - hist->down_since);
    hist->down_since = 0;
  }
  if (!hist->up_since)
    hist->up_since = when;
}

/** Remember that we intentionally closed our connection to the OR
 * <b>nickname</b> at <b>when</b>.
 */
void rep_hist_note_disconnect(const char* id, time_t when)
{
  or_history_t *hist;
  hist = get_or_history(id);
  ++hist->n_conn_ok;
  if (hist->up_since) {
    hist->uptime += (when - hist->up_since);
    hist->up_since = 0;
  }
}

/** Remember that our connection to the OR <b>id</b> had an error and
 * stopped working at <b>when</b>.
 */
void rep_hist_note_connection_died(const char* id, time_t when)
{
  or_history_t *hist;
  if(!id) {
    /* XXXX008 not so. */
    /* If conn has no nickname, it's either an OP, or it is an OR
     * which didn't complete its handshake (or did and was unapproved).
     * Ignore it.
     */
    return;
  }
  hist = get_or_history(id);
  if (hist->up_since) {
    hist->uptime += (when - hist->up_since);
    hist->up_since = 0;
  }
  if (!hist->down_since)
    hist->down_since = when;
}

/** Remember that we successfully extended from the OR <b>from_name</b> to
 * the OR <b>to_name</b>.
 */
void rep_hist_note_extend_succeeded(const char *from_id,
                                    const char *to_id)
{
  link_history_t *hist;
  /* log_fn(LOG_WARN, "EXTEND SUCCEEDED: %s->%s",from_name,to_name); */
  hist = get_link_history(from_id, to_id);
  ++hist->n_extend_ok;
}

/** Remember that we tried to extend from the OR <b>from_name</b> to the OR
 * <b>to_name</b>, but failed.
 */
void rep_hist_note_extend_failed(const char *from_id, const char *to_id)
{
  link_history_t *hist;
  /* log_fn(LOG_WARN, "EXTEND FAILED: %s->%s",from_name,to_name); */
  hist = get_link_history(from_id, to_id);
  ++hist->n_extend_fail;
}

/** Log all the reliability data we have rememberred, with the chosen
 * severity.
 */
void rep_hist_dump_stats(time_t now, int severity)
{
  strmap_iter_t *lhist_it;
  strmap_iter_t *orhist_it;
  const char *name1, *name2, *hexdigest1, *hexdigest2;
  or_history_t *or_history;
  link_history_t *link_history;
  void *or_history_p, *link_history_p;
  double uptime;
  char buffer[2048];
  int len;
  unsigned long upt, downt;
  routerinfo_t *r;

  log(severity, "--------------- Dumping history information:");

  for (orhist_it = strmap_iter_init(history_map); !strmap_iter_done(orhist_it);
       orhist_it = strmap_iter_next(history_map,orhist_it)) {
    strmap_iter_get(orhist_it, &hexdigest1, &or_history_p);
    or_history = (or_history_t*) or_history_p;

    if ((r = router_get_by_hexdigest(hexdigest1)))
      name1 = r->nickname;
    else
      name1 = "(unknown)";

    update_or_history(or_history, now);
    upt = or_history->uptime;
    downt = or_history->downtime;
    if (upt+downt) {
      uptime = ((double)upt) / (upt+downt);
    } else {
      uptime=1.0;
    }
    log(severity,
        "OR %s [%s]: %ld/%ld good connections; uptime %ld/%ld sec (%.2f%%)",
        name1, hexdigest1,
        or_history->n_conn_ok, or_history->n_conn_fail+or_history->n_conn_ok,
        upt, upt+downt, uptime*100.0);

    strcpy(buffer, "    Good extend attempts: ");
    len = strlen(buffer);
    for (lhist_it = strmap_iter_init(or_history->link_history_map);
         !strmap_iter_done(lhist_it);
         lhist_it = strmap_iter_next(or_history->link_history_map, lhist_it)) {
      strmap_iter_get(lhist_it, &hexdigest2, &link_history_p);
      if ((r = router_get_by_hexdigest(hexdigest2)))
        name2 = r->nickname;
      else
        name2 = "(unknown)";

      link_history = (link_history_t*) link_history_p;
      len += snprintf(buffer+len, 2048-len, "%s(%ld/%ld); ", name2,
                      link_history->n_extend_ok,
                      link_history->n_extend_ok+link_history->n_extend_fail);
      if (len >= 2048) {
        buffer[2047]='\0';
        break;
      }
    }
    log(severity, buffer);
  }
}

#if 0
void write_rep_history(const char *filename)
{
  FILE *f = NULL;
  char *tmpfile;
  int completed = 0;
  or_history_t *or_history;
  link_history_t *link_history;
  strmap_iter_t *lhist_it;
  strmap_iter_t *orhist_it;
  void *or_history_p, *link_history_p;
  const char *name1;

  tmpfile = tor_malloc(strlen(filename)+5);
  strcpy(tmpfile, filename);
  strcat(tmpfile, "_tmp");

  f = fopen(tmpfile, "w");
  if (!f) goto done;
  for (orhist_it = strmap_iter_init(history_map); !strmap_iter_done(orhist_it);
       orhist_it = strmap_iter_next(history_map,orhist_it)) {
    strmap_iter_get(orhist_it, &name1, &or_history_p);
    or_history = (or_history_t*) or_history_p;
    fprintf(f, "link %s connected:u%ld failed:%uld uptime:%uld",
            name1, or_history->since1,
  }

 done:
  if (f)
    fclose(f);
  if (completed)
    replace_file(filename, tmpfile);
  else
    unlink(tmpfile);
  tor_free(tmpfile);
}
#endif

#define NUM_SECS_ROLLING_MEASURE 10
#define NUM_SECS_BW_SUM_IS_VALID (12*60*60) /* half a day */

/** We read <b>num_bytes</b> more bytes in second <b>when</b>.
 *
 * Add num_bytes to the current running total for <b>when</b>.
 *
 * <b>when</b> can go back to time, but it's safe to ignore calls
 * earlier than the latest <b>when</b> you've heard of.
 */
void rep_hist_note_bytes_written(int num_bytes, time_t when) {
/* Maybe a circular array for recent seconds, and step to a new point
 * every time a new second shows up. Or simpler is to just to have
 * a normal array and push down each item every second; it's short.
 */
/* When a new second has rolled over, compute the sum of the bytes we've
 * seen over when-1 to when-1-NUM_SECS_ROLLING_MEASURE, and stick it
 * somewhere. See rep_hist_bandwidth_assess() below.
 */

}

/** We wrote <b>num_bytes</b> more bytes in second <b>when</b>.
 * (like rep_hist_note_bytes_written() above)
 */
void rep_hist_note_bytes_read(int num_bytes, time_t when) {
/* if we're smart, we can make this func and the one above share code */
}

/**
 * Find the largest sums in the past NUM_SECS_BW_SUM_IS_VALID (roughly)
 * seconds. Find one sum for reading and one for writing. They don't have
 * to be at the same time).
 *
 * Return the smaller of these sums, divided by NUM_SECS_ROLLING_MEASURE.
 */
int rep_hist_bandwidth_assess(time_t when) {
/* To get a handle on space complexity, I promise I will call this
 * function at most every options.DirFetchPostPeriod seconds. So in
 * rep_hist_note_bytes_foo() above, you could keep a running max sum
 * for the current period, and when the period ends you can tuck its max away
 * in a circular array of more managable size. We lose a bit of precision,
 * but this is all guesswork anyway.
 */

  return 0;
}

/*
  Local Variables:
  mode:c
  indent-tabs-mode:nil
  c-basic-offset:2
  End:
*/