class DatabaseTasks

abstract class DatabaseTasks {
    
    /**
     * Structure that describes each task to run.
     *
     * @var array
     *
     * Each value of the tasks array is an associative array defining the function
     * to call (optional) and any arguments to be passed to the function.
     */
    protected $tasks = array(
        array(
            'function' => 'checkEngineVersion',
            'arguments' => array(),
        ),
        array(
            'arguments' => array(
                'CREATE TABLE {drupal_install_test} (id int NULL)',
                'Drupal can use CREATE TABLE database commands.',
                'Failed to <strong>CREATE</strong> a test table on your database server with the command %query. The server reports the following message: %error.<p>Are you sure the configured username has the necessary permissions to create tables in the database?</p>',
                TRUE,
            ),
        ),
        array(
            'arguments' => array(
                'INSERT INTO {drupal_install_test} (id) VALUES (1)',
                'Drupal can use INSERT database commands.',
                'Failed to <strong>INSERT</strong> a value into a test table on your database server. We tried inserting a value with the command %query and the server reported the following error: %error.',
            ),
        ),
        array(
            'arguments' => array(
                'UPDATE {drupal_install_test} SET id = 2',
                'Drupal can use UPDATE database commands.',
                'Failed to <strong>UPDATE</strong> a value in a test table on your database server. We tried updating a value with the command %query and the server reported the following error: %error.',
            ),
        ),
        array(
            'arguments' => array(
                'DELETE FROM {drupal_install_test}',
                'Drupal can use DELETE database commands.',
                'Failed to <strong>DELETE</strong> a value from a test table on your database server. We tried deleting a value with the command %query and the server reported the following error: %error.',
            ),
        ),
        array(
            'arguments' => array(
                'DROP TABLE {drupal_install_test}',
                'Drupal can use DROP TABLE database commands.',
                'Failed to <strong>DROP</strong> a test table from your database server. We tried dropping a table with the command %query and the server reported the following error %error.',
            ),
        ),
    );
    
    /**
     * Results from tasks.
     *
     * @var array
     */
    protected $results = array();
    
    /**
     * Ensure the PDO driver is supported by the version of PHP in use.
     */
    protected function hasPdoDriver() {
        return in_array($this->pdoDriver, PDO::getAvailableDrivers());
    }
    
    /**
     * Assert test as failed.
     */
    protected function fail($message) {
        $this->results[$message] = FALSE;
    }
    
    /**
     * Assert test as a pass.
     */
    protected function pass($message) {
        $this->results[$message] = TRUE;
    }
    
    /**
     * Check whether Drupal is installable on the database.
     */
    public function installable() {
        return $this->hasPdoDriver() && empty($this->error);
    }
    
    /**
     * Return the human-readable name of the driver.
     */
    public abstract function name();
    
    /**
     * Return the minimum required version of the engine.
     *
     * @return
     *   A version string. If not NULL, it will be checked against the version
     *   reported by the Database engine using version_compare().
     */
    public function minimumVersion() {
        return NULL;
    }
    
    /**
     * Run database tasks and tests to see if Drupal can run on the database.
     */
    public function runTasks() {
        // We need to establish a connection before we can run tests.
        if ($this->connect()) {
            foreach ($this->tasks as $task) {
                if (!isset($task['function'])) {
                    $task['function'] = 'runTestQuery';
                }
                if (method_exists($this, $task['function'])) {
                    // Returning false is fatal. No other tasks can run.
                    if (FALSE === call_user_func_array(array(
                        $this,
                        $task['function'],
                    ), $task['arguments'])) {
                        break;
                    }
                }
                else {
                    throw new DatabaseTaskException(st("Failed to run all tasks against the database server. The task %task wasn't found.", array(
                        '%task' => $task['function'],
                    )));
                }
            }
        }
        // Check for failed results and compile message
        $message = '';
        foreach ($this->results as $result => $success) {
            if (!$success) {
                $message .= '<p class="error">' . $result . '</p>';
            }
        }
        if (!empty($message)) {
            $message = 'Resolve all issues below to continue the installation. For help configuring your database server, see the <a href="http://drupal.org/getting-started/install">installation handbook</a>, or contact your hosting provider.' . $message;
            throw new DatabaseTaskException($message);
        }
    }
    
    /**
     * Check if we can connect to the database.
     */
    protected function connect() {
        try {
            // This doesn't actually test the connection.
            db_set_active();
            // Now actually do a check.
            Database::getConnection();
            $this->pass('Drupal can CONNECT to the database ok.');
        } catch (Exception $e) {
            $this->fail(st('Failed to connect to your database server. The server reports the following message: %error.<ul><li>Is the database server running?</li><li>Does the database exist, and have you entered the correct database name?</li><li>Have you entered the correct username and password?</li><li>Have you entered the correct database hostname?</li></ul>', array(
                '%error' => $e->getMessage(),
            )));
            return FALSE;
        }
        return TRUE;
    }
    
    /**
     * Run SQL tests to ensure the database can execute commands with the current user.
     */
    protected function runTestQuery($query, $pass, $fail, $fatal = FALSE) {
        try {
            db_query($query);
            $this->pass(st($pass));
        } catch (Exception $e) {
            $this->fail(st($fail, array(
                '%query' => $query,
                '%error' => $e->getMessage(),
                '%name' => $this->name(),
            )));
            return !$fatal;
        }
    }
    
    /**
     * Check the engine version.
     */
    protected function checkEngineVersion() {
        if ($this->minimumVersion() && version_compare(Database::getConnection()->version(), $this->minimumVersion(), '<')) {
            $this->fail(st("The database version %version is less than the minimum required version %minimum_version.", array(
                '%version' => Database::getConnection()->version(),
                '%minimum_version' => $this->minimumVersion(),
            )));
        }
    }
    
    /**
     * Return driver specific configuration options.
     *
     * @param $database
     *  An array of driver specific configuration options.
     *
     * @return
     *   The options form array.
     */
    public function getFormOptions($database) {
        $form['database'] = array(
            '#type' => 'textfield',
            '#title' => st('Database name'),
            '#default_value' => empty($database['database']) ? '' : $database['database'],
            '#size' => 45,
            '#required' => TRUE,
            '#description' => st('The name of the database your @drupal data will be stored in. It must exist on your server before @drupal can be installed.', array(
                '@drupal' => drupal_install_profile_distribution_name(),
            )),
        );
        $form['username'] = array(
            '#type' => 'textfield',
            '#title' => st('Database username'),
            '#default_value' => empty($database['username']) ? '' : $database['username'],
            '#required' => TRUE,
            '#size' => 45,
        );
        $form['password'] = array(
            '#type' => 'password',
            '#title' => st('Database password'),
            '#default_value' => empty($database['password']) ? '' : $database['password'],
            '#required' => FALSE,
            '#size' => 45,
        );
        $form['advanced_options'] = array(
            '#type' => 'fieldset',
            '#title' => st('Advanced options'),
            '#collapsible' => TRUE,
            '#collapsed' => TRUE,
            '#description' => st("These options are only necessary for some sites. If you're not sure what you should enter here, leave the default settings or check with your hosting provider."),
            '#weight' => 10,
        );
        $profile = drupal_get_profile();
        $db_prefix = $profile == 'standard' ? 'drupal_' : $profile . '_';
        $form['advanced_options']['db_prefix'] = array(
            '#type' => 'textfield',
            '#title' => st('Table prefix'),
            '#default_value' => '',
            '#size' => 45,
            '#description' => st('If more than one application will be sharing this database, enter a table prefix such as %prefix for your @drupal site here.', array(
                '@drupal' => drupal_install_profile_distribution_name(),
                '%prefix' => $db_prefix,
            )),
            '#weight' => 10,
        );
        $form['advanced_options']['host'] = array(
            '#type' => 'textfield',
            '#title' => st('Database host'),
            '#default_value' => empty($database['host']) ? 'localhost' : $database['host'],
            '#size' => 45,
            // Hostnames can be 255 characters long.
'#maxlength' => 255,
            '#required' => TRUE,
            '#description' => st('If your database is located on a different server, change this.'),
        );
        $form['advanced_options']['port'] = array(
            '#type' => 'textfield',
            '#title' => st('Database port'),
            '#default_value' => empty($database['port']) ? '' : $database['port'],
            '#size' => 45,
            // The maximum port number is 65536, 5 digits.
'#maxlength' => 5,
            '#description' => st('If your database server is listening to a non-standard port, enter its number.'),
        );
        return $form;
    }
    
    /**
     * Validates driver specific configuration settings.
     *
     * Checks to ensure correct basic database settings and that a proper
     * connection to the database can be established.
     *
     * @param $database
     *   An array of driver specific configuration options.
     *
     * @return
     *   An array of driver configuration errors, keyed by form element name.
     */
    public function validateDatabaseSettings($database) {
        $errors = array();
        // Verify the table prefix.
        if (!empty($database['prefix']) && is_string($database['prefix']) && !preg_match('/^[A-Za-z0-9_.]+$/', $database['prefix'])) {
            $errors[$database['driver'] . '][advanced_options][db_prefix'] = st('The database table prefix you have entered, %prefix, is invalid. The table prefix can only contain alphanumeric characters, periods, or underscores.', array(
                '%prefix' => $database['prefix'],
            ));
        }
        // Verify the database port.
        if (!empty($database['port']) && !is_numeric($database['port'])) {
            $errors[$database['driver'] . '][advanced_options][port'] = st('Database port must be a number.');
        }
        return $errors;
    }

}