//
// ZoneMinder MySQL Implementation, $Date$, $Revision$
// Copyright (C) 2001-2008 Philip Coombes
//
// 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 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
#include "zm_db.h"

#include "zm_logger.h"
#include "zm_signal.h"
#include <cstdlib>
#include <unistd.h>

MYSQL dbconn;
std::mutex db_mutex;
zmDbQueue  dbQueue;
unsigned long db_thread_id;

bool zmDbConnected = false;

bool zmDbConnect() {
  // For some reason having these lines causes memory corruption and crashing on newer debian/ubuntu
  // But they really need to be here in order to prevent a double open of mysql
  if (zmDbConnected)  {
    //Warning("Calling zmDbConnect when already connected");
    return true;
  }

  if (!mysql_init(&dbconn)) {
    Error("Can't initialise database connection: %s", mysql_error(&dbconn));
    return false;
  }

  if ( !staticConfig.DB_SSL_CA_CERT.empty() ) {
    mysql_options(&dbconn, MYSQL_OPT_SSL_KEY,    staticConfig.DB_SSL_CLIENT_KEY.c_str());
    mysql_options(&dbconn, MYSQL_OPT_SSL_CERT,   staticConfig.DB_SSL_CLIENT_CERT.c_str());
    mysql_options(&dbconn, MYSQL_OPT_SSL_CA,     staticConfig.DB_SSL_CA_CERT.c_str());
  }

  std::string::size_type colonIndex = staticConfig.DB_HOST.find(":");
  if ( colonIndex == std::string::npos ) {
    if ( !mysql_real_connect(
           &dbconn,
           staticConfig.DB_HOST.c_str(),
           staticConfig.DB_USER.c_str(),
           staticConfig.DB_PASS.c_str(),
           nullptr, 0, nullptr, 0) ) {
      Error("Can't connect to server: %s", mysql_error(&dbconn));
      mysql_close(&dbconn);
      return false;
    }
  } else {
    std::string dbHost = staticConfig.DB_HOST.substr(0, colonIndex);
    std::string dbPortOrSocket = staticConfig.DB_HOST.substr(colonIndex+1);
    if ( dbPortOrSocket[0] == '/' ) {
      if ( !mysql_real_connect(
             &dbconn,
             nullptr,
             staticConfig.DB_USER.c_str(),
             staticConfig.DB_PASS.c_str(),
             nullptr, 0, dbPortOrSocket.c_str(), 0) ) {
        Error("Can't connect to server: %s", mysql_error(&dbconn));
        mysql_close(&dbconn);
        return false;
      }
    } else {
      if ( !mysql_real_connect(
             &dbconn,
             dbHost.c_str(),
             staticConfig.DB_USER.c_str(),
             staticConfig.DB_PASS.c_str(),
             nullptr,
             atoi(dbPortOrSocket.c_str()),
             nullptr, 0) ) {
        Error("Can't connect to server: %s", mysql_error(&dbconn));
        mysql_close(&dbconn);
        return false;
      }
    }
  }
  if ( mysql_select_db(&dbconn, staticConfig.DB_NAME.c_str()) ) {
    Error("Can't select database: %s", mysql_error(&dbconn));
    mysql_close(&dbconn);
    return false;
  }
  if (mysql_query(&dbconn, "SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED")) {
    Error("Can't set isolation level: %s", mysql_error(&dbconn));
  }
  mysql_set_character_set(&dbconn, "utf8");
  db_thread_id = mysql_thread_id(&dbconn);
  zmDbConnected = true;
  return zmDbConnected;
}

/* Calls to zmDbReconnect must have the lock. */
bool zmDbReconnect() {
  if (zmDbConnected) {
    mysql_close(&dbconn);
    zmDbConnected = false;
  }
  if (zmDbConnect()) {
    Debug(1, "Reconnected to db...");
  } else {
    Debug(1, "Failed to reconnect to db");
  }
  return zmDbConnected;
}

void zmDbClose() {
  std::lock_guard<std::mutex> lck(db_mutex);
  if (zmDbConnected) {
    Debug(1, "Closing database. Connection id was %lu", db_thread_id);
    mysql_close(&dbconn);
    // mysql_init() call implicitly mysql_library_init() but
    // mysql_close() does not call mysql_library_end()
    mysql_library_end();
    zmDbConnected = false;
  }
}

MYSQL_RES *zmDbFetch(const std::string &query) {
  std::lock_guard<std::mutex> lck(db_mutex);
  if (!zmDbConnected && !zmDbConnect()) {
    Error("Not connected.");
    return nullptr;
  }


  int rc = mysql_query(&dbconn, query.c_str());
  if (rc) {
    std::string reason = mysql_error(&dbconn); // store for later because it will get clobbered by second attempt
    Debug(1, "Can't run query: %s rc:%d, reason:%s", query.c_str(), rc, reason.c_str());
    if (mysql_ping(&dbconn) and zmDbReconnect()) {
      rc = mysql_query(&dbconn, query.c_str());
    }
    if (rc) {
      Error("Can't run query: %s rc:%d, reason:%s", query.c_str(), rc, reason.c_str());
      return nullptr;
    }
  }
  MYSQL_RES *result = mysql_store_result(&dbconn);
  if (!result) {
    Error("Can't use query result: %s for query %s", mysql_error(&dbconn), query.c_str());
  }
  return result;
}

zmDbRow *zmDbFetchOne(const std::string &query) {
  zmDbRow *row = new zmDbRow();
  if (row->fetch(query)) {
    return row;
  }
  delete row;
  return nullptr;
}

MYSQL_RES *zmDbRow::fetch(const std::string &query) {
  result_set = zmDbFetch(query);
  if (!result_set) return result_set;

  int n_rows = mysql_num_rows(result_set);
  if (n_rows != 1) {
    Error("Bogus number of lines return from query, %d returned for query %s.", n_rows, query.c_str());
    mysql_free_result(result_set);
    result_set = nullptr;
    return result_set;
  }

  row = mysql_fetch_row(result_set);
  if (!row) {
    mysql_free_result(result_set);
    result_set = nullptr;
    Error("Error getting row from query %s. Error is %s", query.c_str(), mysql_error(&dbconn));
  }
  return result_set;
}

/* performs SQL queries.  Will repeat if error is LOCK_WAIT_TIMEOUT
 * We assume that in general our SQL is properly formed, so errors will
 * be due to external factors.
 */

int zmDbDo(const std::string &query) {
  std::lock_guard<std::mutex> lck(db_mutex);
  if (!zmDbConnected and !zmDbConnect())
    return 0;
  int rc;
  Logger *logger = Logger::fetch();
  Logger::Level oldLevel = logger->databaseLevel();
  logger->databaseLevel(Logger::NOLOG);

  while ((rc = mysql_query(&dbconn, query.c_str())) and !zm_terminate) {
    std::string reason = mysql_error(&dbconn);
    Debug(1, "Failed running sql query %s, thread_id: %lu, %d %s", query.c_str(), db_thread_id, rc, reason.c_str());

    if (mysql_ping(&dbconn)) {
      // Was a connection error
      while (!zmDbReconnect() and !zm_terminate) {
        // If we failed. Sleeping 1 sec may be way too much.
        sleep(1);
      }
      if (zm_terminate) return 0;
    } else {
      // Not a connection error
      Error("Can't run query %s: %d %s", query.c_str(), rc, reason.c_str());
      if (mysql_errno(&dbconn) != ER_LOCK_WAIT_TIMEOUT) {
        return rc;
      }
    } // end if !connected
  }

  Debug(1, "Success running sql query %s, thread_id: %lu", query.c_str(), db_thread_id);
  logger->databaseLevel(oldLevel);
  return 1;
}

int zmDbDoInsert(const std::string &query) {
  std::lock_guard<std::mutex> lck(db_mutex);
  if (!zmDbConnected and !zmDbConnect())
    return 0;
  int rc;
  while ((rc = mysql_query(&dbconn, query.c_str())) and !zm_terminate) {
    std::string reason = mysql_error(&dbconn);
    if (mysql_ping(&dbconn)) {
      if (!zmDbReconnect()) sleep(1);
    } else {
      Error("Can't run query %s: %d %s", query.c_str(), rc, reason.c_str());
      if ((mysql_errno(&dbconn) != ER_LOCK_WAIT_TIMEOUT))
        return 0;
    }
  }
  // Might not be an int... FIXME
  int id = mysql_insert_id(&dbconn);
  Debug(2, "Success running sql insert %s. Resulting id is %d", query.c_str(), id);
  return id;
}

int zmDbDoUpdate(const std::string &query) {
  std::lock_guard<std::mutex> lck(db_mutex);
  if (!zmDbConnected and !zmDbConnect())
    return 0;
  int rc;
  while ( (rc = mysql_query(&dbconn, query.c_str())) and !zm_terminate) {
    if (mysql_ping(&dbconn)) {
      if (!zmDbReconnect()) sleep(1);
    } else {
      Error("Can't run query %s: %s", query.c_str(), mysql_error(&dbconn));
      if ( (mysql_errno(&dbconn) != ER_LOCK_WAIT_TIMEOUT) )
        return -rc;
    }
  }
  int affected = mysql_affected_rows(&dbconn);
  Debug(2, "Success running sql update %s. Rows modified %d", query.c_str(), affected);
  return affected;
}

zmDbRow::~zmDbRow() {
  if (result_set) {
    mysql_free_result(result_set);
    result_set = nullptr;
  }
  row = nullptr;
}

zmDbQueue::zmDbQueue() :
  mTerminate(false) {
  mThread = std::thread(&zmDbQueue::process, this);
}

zmDbQueue::~zmDbQueue() {
  stop();
}

void zmDbQueue::stop() {
  {
    std::unique_lock<std::mutex> lock(mMutex);

    mTerminate = true;
  }
  mCondition.notify_all();

  if (mThread.joinable()) mThread.join();
}

void zmDbQueue::process() {
  std::unique_lock<std::mutex> lock(mMutex);

  while (!mTerminate and !zm_terminate) {
    if (mQueue.empty()) {
      mCondition.wait(lock);
    }
    while (!mQueue.empty()) {
      if (mQueue.size() > 40) {
        Logger *log = Logger::fetch();
        Logger::Level db_level = log->databaseLevel();
        log->databaseLevel(Logger::NOLOG);
        Warning("db queue size has grown larger %zu than 40 entries", mQueue.size());
        log->databaseLevel(db_level);
      }
      std::string sql = mQueue.front();
      mQueue.pop();
      // My idea for leaving the locking around each sql statement is to allow
      // other db writers to get a chance
      lock.unlock();
      zmDbDo(sql);
      lock.lock();
    }
  }
}  // end void zmDbQueue::process()

void zmDbQueue::push(std::string &&sql) {
  {
    std::unique_lock<std::mutex> lock(mMutex);
    if (mTerminate) return;
    mQueue.push(std::move(sql));
  }
  mCondition.notify_all();
}

std::string zmDbEscapeString(const std::string& to_escape) {
  // According to docs, size of safer_whatever must be 2 * length + 1
  // due to unicode conversions + null terminator.
  std::string escaped((to_escape.length() * 2) + 1, '\0');


  size_t escaped_len = mysql_real_escape_string(&dbconn, &escaped[0], to_escape.c_str(), to_escape.length());
  escaped.resize(escaped_len);

  return escaped;
}
