/*
 *
 * (C) 2013-22 - ntop.org
 *
 *
 * 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 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

#include "ntop_includes.h"

/* **************************************************** */

SQLiteStoreManager::SQLiteStoreManager(int interface_id) {
  ifid = interface_id;
  iface = ntop->getInterfaceById(interface_id);
  db = NULL;
};

/* **************************************************** */

int SQLiteStoreManager::init(const char *db_file_full_path) {
  // db_file_full_path = (char*)":memory:"; 
  
  if(sqlite3_open(db_file_full_path, &db)) {
    ntop->getTrace()->traceEvent(TRACE_WARNING, "Unable to open %s: %s",
				 db_file_full_path, sqlite3_errmsg(db));
    db = NULL;
    return -1;
  }

  return 0;
}

/* **************************************************** */

NetworkInterface* SQLiteStoreManager::getNetworkInterface() {
  if(!iface)
    iface = ntop->getInterfaceById(ifid);
  return iface;
}

/* **************************************************** */

SQLiteStoreManager::~SQLiteStoreManager() {
  if(db) sqlite3_close(db);
}

/* **************************************************** */

/**
 * @brief Executes a database query on an already opened SQLite3 DB
 * @brief This function implements handling of a direct query on
 *        a SQLite3 database, hiding DB-specific syntax and error
 *        handling.
 *
 * @param db_query A string keeping the query to be executed.
 * @param callback Callback to be executed by the DB in case the query
 *                 execution is successful.
 * @param payload A pointer to be passed to the callback in case it
 *                is actually executed.
 *
 * @return Zero in case of success, nonzero in case of failure.
 */
int SQLiteStoreManager::exec_query(const char * db_query,
				   int (*callback)(void *, int, char **, char **),
				   void *payload) {
  char *zErrMsg = 0;

  if(!db) {
    ntop->getTrace()->traceEvent(TRACE_WARNING, "Database not initialized.");
    return(-1);
  }

  if(sqlite3_exec(db, db_query, callback, payload, &zErrMsg)) {
    ntop->getTrace()->traceEvent(TRACE_INFO, "SQL Error: %s", zErrMsg);
    ntop->getTrace()->traceEvent(TRACE_INFO, "Query: %s", db_query);
    sqlite3_free(zErrMsg);
    return 1;
  }

  return 0;
}

/* **************************************************** */
/*
  Executes a prepared statements and retries a fixed number of times upon
  certain errors. This allows some errors to be recovered such as SQLITE_BUSY (5)

  See https://www.sqlite.org/rescode.html
*/
int SQLiteStoreManager::exec_statement(sqlite3_stmt *stmt) {
  int rc;
  int max_retries = 5;
  bool retry = true;

  for(int cur_retries = 0; cur_retries < max_retries && retry; cur_retries++) {
    rc = sqlite3_step(stmt);

    switch(rc) {
    case SQLITE_ERROR:
    case SQLITE_ROW:
    case SQLITE_OK:
    case SQLITE_DONE:
      /* Stop immediately upon error or completion */
      retry = false;
      break;
    }
  }

  /*
    There are only a few non-error result codes:
    SQLITE_OK, SQLITE_ROW, and SQLITE_DONE.

    See https://www.sqlite.org/rescode.html#done
  */
  if(rc != SQLITE_OK && rc != SQLITE_DONE && rc != SQLITE_ROW)
    ntop->getTrace()->traceEvent(TRACE_ERROR, "SQL Error: [%d][%s (%d)]",
				 /* sqlite3_errstr(rc), */ rc,
				 sqlite3_errmsg(db), sqlite3_errcode(db));

  return rc;
}

/* **************************************************** */
/*
  Reclaims unused disk space and defragments tables and indices.
  Should be called as disk space and defragmentation are not run
  automatically by sqlite.
*/
int SQLiteStoreManager::optimizeStore() {
  char query[STORE_MANAGER_MAX_QUERY];
  int step;
  bool rc = false;
  sqlite3_stmt *stmt = NULL;

  m.lock(__FILE__, __LINE__);

  snprintf(query, sizeof(query), "VACUUM");

  if(sqlite3_prepare_v2(db, query, -1, &stmt, 0)) {
    ntop->getTrace()->traceEvent(TRACE_ERROR, "SQL Error: %s", sqlite3_errmsg(db));
    goto out;
  }

  if((step = exec_statement(stmt)) != SQLITE_DONE) {
    if(step != SQLITE_ERROR)
      rc = true;
  }

 out:
  if(stmt) sqlite3_finalize(stmt);
  m.unlock(__FILE__, __LINE__);

  return(rc);
}