<?php

/**

 * @file

 * Database interface code for SQLite embedded database engine.

 */

/**

 * @addtogroup database

 * @{

 */

include_once DRUPAL_ROOT . '/includes/database/prefetch.inc';

/**

 * Specific SQLite implementation of DatabaseConnection.

 */

class DatabaseConnection_sqlite extends DatabaseConnection {

  /**

   * Whether this database connection supports savepoints.

   *

   * Version of sqlite lower then 3.6.8 can't use savepoints.

   * See http://www.sqlite.org/releaselog/3_6_8.html

   *

   * @var boolean

   */

  protected $savepointSupport = FALSE;

  /**

   * Whether or not the active transaction (if any) will be rolled back.

   *

   * @var boolean

   */

  protected $willRollback;

  /**

   * All databases attached to the current database. This is used to allow

   * prefixes to be safely handled without locking the table

   *

   * @var array

   */

  protected $attachedDatabases = array();

  /**

   * Whether or not a table has been dropped this request: the destructor will

   * only try to get rid of unnecessary databases if there is potential of them

   * being empty.

   *

   * This variable is set to public because DatabaseSchema_sqlite needs to

   * access it. However, it should not be manually set.

   *

   * @var boolean

   */

  var $tableDropped = FALSE;

  public function __construct(array $connection_options = array()) {

    // We don't need a specific PDOStatement class here, we simulate it below.

    $this->statementClass = NULL;

    // This driver defaults to transaction support, except if explicitly passed FALSE.

    $this->transactionSupport = $this->transactionalDDLSupport = !isset($connection_options['transactions']) || $connection_options['transactions'] !== FALSE;

    $this->connectionOptions = $connection_options;

    // Allow PDO options to be overridden.

    $connection_options += array(

      'pdo' => array(),

    );

    $connection_options['pdo'] += array(

      // Convert numeric values to strings when fetching.

      PDO::ATTR_STRINGIFY_FETCHES => TRUE,

    );

    parent::__construct('sqlite:' . $connection_options['database'], '', '', $connection_options['pdo']);

    // Attach one database for each registered prefix.

    $prefixes = $this->prefixes;

    foreach ($prefixes as $table => &$prefix) {

      // Empty prefix means query the main database -- no need to attach anything.

      if (!empty($prefix)) {

        // Only attach the database once.

        if (!isset($this->attachedDatabases[$prefix])) {

          $this->attachedDatabases[$prefix] = $prefix;

          $this->query('ATTACH DATABASE :database AS :prefix', array(':database' => $connection_options['database'] . '-' . $prefix, ':prefix' => $prefix));

        }

        // Add a ., so queries become prefix.table, which is proper syntax for

        // querying an attached database.

        $prefix .= '.';

      }

    }

    // Regenerate the prefixes replacement table.

    $this->setPrefix($prefixes);

    // Detect support for SAVEPOINT.

    $version = $this->query('SELECT sqlite_version()')->fetchField();

    $this->savepointSupport = (version_compare($version, '3.6.8') >= 0);

    // Create functions needed by SQLite.

    $this->sqliteCreateFunction('if', array($this, 'sqlFunctionIf'));

    $this->sqliteCreateFunction('greatest', array($this, 'sqlFunctionGreatest'));

    $this->sqliteCreateFunction('pow', 'pow', 2);

    $this->sqliteCreateFunction('length', 'strlen', 1);

    $this->sqliteCreateFunction('md5', 'md5', 1);

    $this->sqliteCreateFunction('concat', array($this, 'sqlFunctionConcat'));

    $this->sqliteCreateFunction('substring', array($this, 'sqlFunctionSubstring'), 3);

    $this->sqliteCreateFunction('substring_index', array($this, 'sqlFunctionSubstringIndex'), 3);

    $this->sqliteCreateFunction('rand', array($this, 'sqlFunctionRand'));

    // Execute sqlite init_commands.

    if (isset($connection_options['init_commands'])) {

      $this->exec(implode('; ', $connection_options['init_commands']));

    }

  }

  /**

   * Destructor for the SQLite connection.

   *

   * We prune empty databases on destruct, but only if tables have been

   * dropped. This is especially needed when running the test suite, which

   * creates and destroy databases several times in a row.

   */

  public function __destruct() {

    if ($this->tableDropped && !empty($this->attachedDatabases)) {

      foreach ($this->attachedDatabases as $prefix) {

        // Check if the database is now empty, ignore the internal SQLite tables.

        try {

          $count = $this->query('SELECT COUNT(*) FROM ' . $prefix . '.sqlite_master WHERE type = :type AND name NOT LIKE :pattern', array(':type' => 'table', ':pattern' => 'sqlite_%'))->fetchField();

          // We can prune the database file if it doesn't have any tables.

          if ($count == 0) {

            // Detach the database.

            $this->query('DETACH DATABASE :schema', array(':schema' => $prefix));

            // Destroy the database file.

            unlink($this->connectionOptions['database'] . '-' . $prefix);

          }

        }

        catch (Exception $e) {

          // Ignore the exception and continue. There is nothing we can do here

          // to report the error or fail safe.

        }

      }

    }

  }

  /**

   * SQLite compatibility implementation for the IF() SQL function.

   */

  public function sqlFunctionIf($condition, $expr1, $expr2 = NULL) {

    return $condition ? $expr1 : $expr2;

  }

  /**

   * SQLite compatibility implementation for the GREATEST() SQL function.

   */

  public function sqlFunctionGreatest() {

    $args = func_get_args();

    foreach ($args as $k => $v) {

      if (!isset($v)) {

        unset($args);

      }

    }

    if (count($args)) {

      return max($args);

    }

    else {

      return NULL;

    }

  }

  /**

   * SQLite compatibility implementation for the CONCAT() SQL function.

   */

  public function sqlFunctionConcat() {

    $args = func_get_args();

    return implode('', $args);

  }

  /**

   * SQLite compatibility implementation for the SUBSTRING() SQL function.

   */

  public function sqlFunctionSubstring($string, $from, $length) {

    return substr($string, $from - 1, $length);

  }

  /**

   * SQLite compatibility implementation for the SUBSTRING_INDEX() SQL function.

   */

  public function sqlFunctionSubstringIndex($string, $delimiter, $count) {

    // If string is empty, simply return an empty string.

    if (empty($string)) {

      return '';

    }

    $end = 0;

    for ($i = 0; $i < $count; $i++) {

      $end = strpos($string, $delimiter, $end + 1);

      if ($end === FALSE) {

        $end = strlen($string);

      }

    }

    return substr($string, 0, $end);

  }

  /**

   * SQLite compatibility implementation for the RAND() SQL function.

   */

  public function sqlFunctionRand($seed = NULL) {

    if (isset($seed)) {

      mt_srand($seed);

    }

    return mt_rand() / mt_getrandmax();

  }

  /**

   * SQLite-specific implementation of DatabaseConnection::prepare().

   *

   * We don't use prepared statements at all at this stage. We just create

   * a DatabaseStatement_sqlite object, that will create a PDOStatement

   * using the semi-private PDOPrepare() method below.

   */

  public function prepare($query, $options = array()) {

    return new DatabaseStatement_sqlite($this, $query, $options);

  }

  /**

   * NEVER CALL THIS FUNCTION: YOU MIGHT DEADLOCK YOUR PHP PROCESS.

   *

   * This is a wrapper around the parent PDO::prepare method. However, as

   * the PDO SQLite driver only closes SELECT statements when the PDOStatement

   * destructor is called and SQLite does not allow data change (INSERT,

   * UPDATE etc) on a table which has open SELECT statements, you should never

   * call this function and keep a PDOStatement object alive as that can lead

   * to a deadlock. This really, really should be private, but as

   * DatabaseStatement_sqlite needs to call it, we have no other choice but to

   * expose this function to the world.

   */

  public function PDOPrepare($query, array $options = array()) {

    return parent::prepare($query, $options);

  }

  public function queryRange($query, $from, $count, array $args = array(), array $options = array()) {

    return $this->query($query . ' LIMIT ' . (int) $from . ', ' . (int) $count, $args, $options);

  }

  public function queryTemporary($query, array $args = array(), array $options = array()) {

    // Generate a new temporary table name and protect it from prefixing.

    // SQLite requires that temporary tables to be non-qualified.

    $tablename = $this->generateTemporaryTableName();

    $prefixes = $this->prefixes;

    $prefixes[$tablename] = '';

    $this->setPrefix($prefixes);

    $this->query('CREATE TEMPORARY TABLE ' . $tablename . ' AS ' . $query, $args, $options);

    return $tablename;

  }

  public function driver() {

    return 'sqlite';

  }

  public function databaseType() {

    return 'sqlite';

  }

  public function mapConditionOperator($operator) {

    // We don't want to override any of the defaults.

    static $specials = array(

      'LIKE' => array('postfix' => " ESCAPE '\\'"),

      'NOT LIKE' => array('postfix' => " ESCAPE '\\'"),

    );

    return isset($specials[$operator]) ? $specials[$operator] : NULL;

  }

  public function prepareQuery($query) {

    return $this->prepare($this->prefixTables($query));

  }

  public function nextId($existing_id = 0) {

    $transaction = $this->startTransaction();

    // We can safely use literal queries here instead of the slower query

    // builder because if a given database breaks here then it can simply

    // override nextId. However, this is unlikely as we deal with short strings

    // and integers and no known databases require special handling for those

    // simple cases. If another transaction wants to write the same row, it will

    // wait until this transaction commits.

    $stmt = $this->query('UPDATE {sequences} SET value = GREATEST(value, :existing_id) + 1', array(

      ':existing_id' => $existing_id,

    ));

    if (!$stmt->rowCount()) {

      $this->query('INSERT INTO {sequences} (value) VALUES (:existing_id + 1)', array(

        ':existing_id' => $existing_id,

      ));

    }

    // The transaction gets committed when the transaction object gets destroyed

    // because it gets out of scope.

    return $this->query('SELECT value FROM {sequences}')->fetchField();

  }

  public function rollback($savepoint_name = 'drupal_transaction') {

    if ($this->savepointSupport) {

      return parent::rollBack($savepoint_name);

    }

    if (!$this->inTransaction()) {

      throw new DatabaseTransactionNoActiveException();

    }

    // A previous rollback to an earlier savepoint may mean that the savepoint

    // in question has already been rolled back.

    if (!in_array($savepoint_name, $this->transactionLayers)) {

      return;

    }

    // We need to find the point we're rolling back to, all other savepoints

    // before are no longer needed.

    while ($savepoint = array_pop($this->transactionLayers)) {

      if ($savepoint == $savepoint_name) {

        // Mark whole stack of transactions as needed roll back.

        $this->willRollback = TRUE;

        // If it is the last the transaction in the stack, then it is not a

        // savepoint, it is the transaction itself so we will need to roll back

        // the transaction rather than a savepoint.

        if (empty($this->transactionLayers)) {

          break;

        }

        return;

      }

    }

    if ($this->supportsTransactions()) {

      PDO::rollBack();

    }

  }

  public function pushTransaction($name) {

    if ($this->savepointSupport) {

      return parent::pushTransaction($name);

    }

    if (!$this->supportsTransactions()) {

      return;

    }

    if (isset($this->transactionLayers[$name])) {

      throw new DatabaseTransactionNameNonUniqueException($name . " is already in use.");

    }

    if (!$this->inTransaction()) {

      PDO::beginTransaction();

    }

    $this->transactionLayers[$name] = $name;

  }

  public function popTransaction($name) {

    if ($this->savepointSupport) {

      return parent::popTransaction($name);

    }

    if (!$this->supportsTransactions()) {

      return;

    }

    if (!$this->inTransaction()) {

      throw new DatabaseTransactionNoActiveException();

    }

    // Commit everything since SAVEPOINT $name.

    while($savepoint = array_pop($this->transactionLayers)) {

      if ($savepoint != $name) continue;

      // If there are no more layers left then we should commit or rollback.

      if (empty($this->transactionLayers)) {

        // If there was any rollback() we should roll back whole transaction.

        if ($this->willRollback) {

          $this->willRollback = FALSE;

          PDO::rollBack();

        }

        elseif (!PDO::commit()) {

          throw new DatabaseTransactionCommitFailedException();

        }

      }

      else {

        break;

      }

    }

  }

  public function utf8mb4IsActive() {

    return TRUE;

  }

  public function utf8mb4IsSupported() {

    return TRUE;

  }

}

/**

 * Specific SQLite implementation of DatabaseConnection.

 *

 * See DatabaseConnection_sqlite::PDOPrepare() for reasons why we must prefetch

 * the data instead of using PDOStatement.

 *

 * @see DatabaseConnection_sqlite::PDOPrepare()

 */

class DatabaseStatement_sqlite extends DatabaseStatementPrefetch implements Iterator, DatabaseStatementInterface {

  /**

   * SQLite specific implementation of getStatement().

   *

   * The PDO SQLite layer doesn't replace numeric placeholders in queries

   * correctly, and this makes numeric expressions (such as COUNT(*) >= :count)

   * fail. We replace numeric placeholders in the query ourselves to work

   * around this bug.

   *

   * See http://bugs.php.net/bug.php?id=45259 for more details.

   */

  protected function getStatement($query, &$args = array()) {

    if (count($args)) {

      // Check if $args is a simple numeric array.

      if (range(0, count($args) - 1) === array_keys($args)) {

        // In that case, we have unnamed placeholders.

        $count = 0;

        $new_args = array();

        foreach ($args as $value) {

          if (is_float($value) || is_int($value)) {

            if (is_float($value)) {

              // Force the conversion to float so as not to loose precision

              // in the automatic cast.

              $value = sprintf('%F', $value);

            }

            $query = substr_replace($query, $value, strpos($query, '?'), 1);

          }