<?php
// $Id$

/**
 * @file
 * Database interface code for MySQL database servers.
 */

/**
 * @ingroup database
 * @{
 */

// Include functions shared between mysql and mysqli.
require_once './includes/database.mysql-common.inc';

/**
 * Report database status.
 */
function db_status_report($phase) {
  $t = get_t();

  $version = db_version();

  $form['mysql'] = array(
    'title' => $t('MySQL database'),
    'value' => ($phase == 'runtime') ? l($version, 'admin/reports/status/sql') : $version,
  );

  if (version_compare($version, DRUPAL_MINIMUM_MYSQL) < 0) {
    $form['mysql']['severity'] = REQUIREMENT_ERROR;
    $form['mysql']['description'] = $t('Your MySQL Server is too old. Drupal requires at least MySQL %version.', array('%version' => DRUPAL_MINIMUM_MYSQL));
  }

  return $form;
}

/**
 * Returns the version of the database server currently in use.
 *
 * @return Database server version
 */
function db_version() {
  list($version) = explode('-', mysql_get_server_info());
  return $version;
}

/**
 * Initialize a database connection.
 */
function db_connect($url) {
  $url = parse_url($url);

  // Check if MySQL support is present in PHP
  if (!function_exists('mysql_connect')) {
    _db_error_page('Unable to use the MySQL database because the MySQL extension for PHP is not installed. Check your <code>php.ini</code> to see how you can enable it.');
  }

  // Decode url-encoded information in the db connection string
  $url['user'] = urldecode($url['user']);
  // Test if database url has a password.
  if (isset($url['pass'])) {
    $url['pass'] = urldecode($url['pass']);
  }
  else {
    $url['pass'] = '';
  }
  $url['host'] = urldecode($url['host']);
  $url['path'] = urldecode($url['path']);

  // Allow for non-standard MySQL port.
  if (isset($url['port'])) {
    $url['host'] = $url['host'] .':'. $url['port'];
  }

  // - TRUE makes mysql_connect() always open a new link, even if
  //   mysql_connect() was called before with the same parameters.
  //   This is important if you are using two databases on the same
  //   server.
  // - 2 means CLIENT_FOUND_ROWS: return the number of found
  //   (matched) rows, not the number of affected rows.
  $connection = @mysql_connect($url['host'], $url['user'], $url['pass'], TRUE, 2);
  if (!$connection || !mysql_select_db(substr($url['path'], 1))) {
    // Show error screen otherwise
    _db_error_page(mysql_error());
  }

  /* On MySQL 4.1 and later, force UTF-8 */
  if (version_compare(mysql_get_server_info(), '4.1.0', '>=')) {
    mysql_query('SET NAMES "utf8"', $connection);
  }
  return $connection;
}

/**
 * Helper function for db_query().
 */
function _db_query($query, $debug = 0) {
  global $active_db, $queries, $user;

  if (variable_get('dev_query', 0)) {
    list($usec, $sec) = explode(' ', microtime());
    $timer = (float)$usec + (float)$sec;
    // If devel.module query logging is enabled, prepend a comment with the username and calling function
    // to the SQL string. This is useful when running mysql's SHOW PROCESSLIST to learn what exact
    // code is issueing the slow query.
    $bt = debug_backtrace();
    // t() may not be available yet so we don't wrap 'Anonymous'.
    $name = $user->uid ? $user->name : variable_get('anonymous', 'Anonymous');
    // str_replace() to prevent SQL injection via username or anonymous name.
    $name = str_replace(array('*', '/'), '', $name);
    $query = '/* '. $name .' : '. $bt[2]['function'] .' */ '. $query;
  }

  $result = mysql_query($query, $active_db);

  if (variable_get('dev_query', 0)) {
    $query = $bt[2]['function'] ."\n". $query;
    list($usec, $sec) = explode(' ', microtime());
    $stop = (float)$usec + (float)$sec;
    $diff = $stop - $timer;
    $queries[] = array($query, $diff);
  }

  if ($debug) {
    print '<p>query: '. $query .'<br />error:'. mysql_error($active_db) .'</p>';
  }

  if (!mysql_errno($active_db)) {
    return $result;
  }
  else {
    // Indicate to drupal_error_handler that this is a database error.
    ${DB_ERROR} = TRUE;
    trigger_error(check_plain(mysql_error($active_db) ."\nquery: ". $query), E_USER_WARNING);
    return FALSE;
  }
}

/**
 * Fetch one result row from the previous query as an object.
 *
 * @param $result
 *   A database query result resource, as returned from db_query().
 * @return
 *   An object representing the next row of the result, or FALSE. The attributes
 *   of this object are the table fields selected by the query.
 */
function db_fetch_object($result) {
  if ($result) {
    return mysql_fetch_object($result);
  }
}

/**
 * Fetch one result row from the previous query as an array.
 *
 * @param $result
 *   A database query result resource, as returned from db_query().
 * @return
 *   An associative array representing the next row of the result, or FALSE.
 *   The keys of this object are the names of the table fields selected by the
 *   query, and the values are the field values for this result row.
 */
function db_fetch_array($result) {
  if ($result) {
    return mysql_fetch_array($result, MYSQL_ASSOC);
  }
}

/**
 * Return an individual result field from the previous query.
 *
 * Only use this function if exactly one field is being selected; otherwise,
 * use db_fetch_object() or db_fetch_array().
 *
 * @param $result
 *   A database query result resource, as returned from db_query().
 * @return
 *   The resulting field or FALSE.
 */
function db_result($result) {
  if ($result && mysql_num_rows($result) > 0) {
    // The mysql_fetch_row function has an optional second parameter $row
    // but that can't be used for compatibility with Oracle, DB2, etc.
    $array = mysql_fetch_row($result);
    return $array[0];
  }
  return FALSE;
}

/**
 * Determine whether the previous query caused an error.
 */
function db_error() {
  global $active_db;
  return mysql_errno($active_db);
}

/**
 * Determine the number of rows changed by the preceding query.
 */
function db_affected_rows() {
  global $active_db;
  return mysql_affected_rows($active_db);
}

/**
 * Runs a limited-range query in the active database.
 *
 * Use this as a substitute for db_query() when a subset of the query is to be
 * returned.
 * User-supplied arguments to the query should be passed in as separate parameters
 * so that they can be properly escaped to avoid SQL injection attacks.
 *
 * @param $query
 *   A string containing an SQL query.
 * @param ...
 *   A variable number of arguments which are substituted into the query
 *   using printf() syntax. The query arguments can be enclosed in one
 *   array instead.
 *   Valid %-modifiers are: %s, %d, %f, %b (binary data, do not enclose
 *   in '') and %%.
 *
 *   NOTE: using this syntax will cast NULL and FALSE values to decimal 0,
 *   and TRUE values to decimal 1.
 *
 * @param $from
 *   The first result row to return.
 * @param $count
 *   The maximum number of result rows to return.
 * @return
 *   A database query result resource, or FALSE if the query was not executed
 *   correctly.
 */
function db_query_range($query) {
  $args = func_get_args();
  $count = array_pop($args);
  $from = array_pop($args);
  array_shift($args);

  $query = db_prefix_tables($query);
  if (isset($args[0]) and is_array($args[0])) { // 'All arguments in one array' syntax
    $args = $args[0];
  }
  _db_query_callback($args, TRUE);
  $query = preg_replace_callback(DB_QUERY_REGEXP, '_db_query_callback', $query);
  $query .= ' LIMIT '. (int)$from .', '. (int)$count;
  return _db_query($query);
}

/**
 * Runs a SELECT query and stores its results in a temporary table.
 *
 * Use this as a substitute for db_query() when the results need to stored
 * in a temporary table. Temporary tables exist for the duration of the page
 * request.
 * User-supplied arguments to the query should be passed in as separate parameters
 * so that they can be properly escaped to avoid SQL injection attacks.
 *
 * Note that if you need to know how many results were returned, you should do
 * a SELECT COUNT(*) on the temporary table afterwards. db_affected_rows() does
 * not give consistent result across different database types in this case.
 *
 * @param $query
 *   A string containing a normal SELECT SQL query.
 * @param ...
 *   A variable number of arguments which are substituted into the query
 *   using printf() syntax. The query arguments can be enclosed in one
 *   array instead.
 *   Valid %-modifiers are: %s, %d, %f, %b (binary data, do not enclose
 *   in '') and %%.
 *
 *   NOTE: using this syntax will cast NULL and FALSE values to decimal 0,
 *   and TRUE values to decimal 1.
 *
 * @param $table
 *   The name of the temporary table to select into. This name will not be
 *   prefixed as there is no risk of collision.
 * @return
 *   A database query result resource, or FALSE if the query was not executed
 *   correctly.
 */
function db_query_temporary($query) {
  $args = func_get_args();
  $tablename = array_pop($args);
  array_shift($args);

  $query = preg_replace('/^SELECT/i', 'CREATE TEMPORARY TABLE '. $tablename .' Engine=HEAP SELECT', db_prefix_tables($query));
  if (isset($args[0]) and is_array($args[0])) { // 'All arguments in one array' syntax
    $args = $args[0];
  }
  _db_query_callback($args, TRUE);
  $query = preg_replace_callback(DB_QUERY_REGEXP, '_db_query_callback', $query);
  return _db_query($query);
}

/**
 * Returns a properly formatted Binary Large OBject value.
 *
 * @param $data
 *   Data to encode.
 * @return
 *  Encoded data.
 */
function db_encode_blob($data) {
  global $active_db;
  return "'". mysql_real_escape_string($data, $active_db) ."'";
}

/**
 * Returns text from a Binary Large Object value.
 *
 * @param $data
 *   Data to decode.
 * @return
 *  Decoded data.
 */
function db_decode_blob($data) {
  return $data;
}

/**
 * Prepare user input for use in a database query, preventing SQL injection attacks.
 */
function db_escape_string($text) {
  global $active_db;
  return mysql_real_escape_string($text, $active_db);
}

/**
 * Lock a table.
 */
function db_lock_table($table) {
  db_query('LOCK TABLES {'. db_escape_table($table) .'} WRITE');
}

/**
 * Unlock all locked tables.
 */
function db_unlock_tables() {
  db_query('UNLOCK TABLES');
}

/**
 * Check if a table exists.
 */
function db_table_exists($table) {
  return db_fetch_object(db_query("SHOW TABLES LIKE '{". db_escape_table($table) ."}'")) ? TRUE : FALSE;
}

/**
 * Check if a column exists in the given table.
 */
function db_column_exists($table, $column) {
  return db_fetch_object(db_query("SHOW COLUMNS FROM {%s} LIKE '%s'", $table, $column)) ? TRUE : FALSE;
}

/**
 * Wraps the given table.field entry with a DISTINCT(). The wrapper is added to
 * the SELECT list entry of the given query and the resulting query is returned.
 * This function only applies the wrapper if a DISTINCT doesn't already exist in
 * the query.
 *
 * @param $table Table containing the field to set as DISTINCT
 * @param $field Field to set as DISTINCT
 * @param $query Query to apply the wrapper to
 * @return SQL query with the DISTINCT wrapper surrounding the given table.field.
 */
function db_distinct_field($table, $field, $query) {
  $field_to_select = 'DISTINCT('. $table .'.'. $field .')';
  // (?<!text) is a negative look-behind (no need to rewrite queries that already use DISTINCT).
  return preg_replace('/(SELECT.*)(?:'. $table .'\.|\s)(?<!DISTINCT\()(?<!DISTINCT\('. $table .'\.)'. $field .'(.*FROM )/AUsi', '\1 '. $field_to_select .'\2', $query);
}

/**
 * @} End of "ingroup database".
 */