class Tasks

abstract class Tasks {
    
    /**
     * The name of the PDO driver this database type requires.
     *
     * @var string
     */
    protected $pdoDriver;
    
    /**
     * 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 = [
        [
            'function' => 'checkEngineVersion',
            'arguments' => [],
        ],
        [
            'arguments' => [
                'CREATE TABLE {drupal_install_test} (id int NOT NULL PRIMARY KEY)',
                '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,
            ],
        ],
        [
            'arguments' => [
                '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.',
            ],
        ],
        [
            'arguments' => [
                '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.',
            ],
        ],
        [
            'arguments' => [
                '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.',
            ],
        ],
        [
            'arguments' => [
                '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 = [
        'fail' => [],
        'pass' => [],
    ];
    
    /**
     * 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['fail'][] = $message;
    }
    
    /**
     * Assert test as a pass.
     */
    protected function pass($message) {
        $this->results['pass'][] = $message;
    }
    
    /**
     * 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.
     *
     * @return array
     *   A list of error messages.
     */
    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([
                        $this,
                        $task['function'],
                    ], $task['arguments'])) {
                        break;
                    }
                }
                else {
                    $this->fail(t("Failed to run all tasks against the database server. The task %task wasn't found.", [
                        '%task' => $task['function'],
                    ]));
                }
            }
        }
        return $this->results['fail'];
    }
    
    /**
     * Checks engine version requirements for the status report.
     *
     * This method is called during runtime and update requirements checks.
     *
     * @return \Drupal\Core\StringTranslation\TranslatableMarkup[]
     *   A list of error messages.
     */
    public final function engineVersionRequirementsCheck() {
        $this->checkEngineVersion();
        return $this->results['fail'];
    }
    
    /**
     * Check if we can connect to the database.
     */
    protected function connect() {
        try {
            // This doesn't actually test the connection.
            Database::setActiveConnection();
            // Now actually do a check.
            Database::getConnection();
            $this->pass('Drupal can CONNECT to the database ok.');
        } catch (\Exception $e) {
            $this->fail(t('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 and port number?</li></ul>', [
                '%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, $fatal = FALSE) {
        try {
            Database::getConnection()->query($query);
            $this->pass(t($pass));
        } catch (\Exception $e) {
            $this->fail(t($fail, [
                '%query' => $query,
                '%error' => $e->getMessage(),
                '%name' => $this->name(),
            ]));
            return !$fatal;
        }
    }
    
    /**
     * Check the engine version.
     */
    protected function checkEngineVersion() {
        // Ensure that the database server has the right version.
        if ($this->minimumVersion() && version_compare(Database::getConnection()->version(), $this->minimumVersion(), '<')) {
            $this->fail(t("The database server version %version is less than the minimum required version %minimum_version.", [
                '%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(array $database) {
        // Use reflection to determine the driver name.
        // @todo https:///www.drupal.org/node/3123240 Provide a better way to get
        //   the driver name.
        $reflection = new \ReflectionClass($this);
        $dir_parts = explode(DIRECTORY_SEPARATOR, dirname(dirname($reflection->getFileName())));
        $driver = array_pop($dir_parts);
        $form['database'] = [
            '#type' => 'textfield',
            '#title' => t('Database name'),
            '#default_value' => empty($database['database']) ? '' : $database['database'],
            '#size' => 45,
            '#required' => TRUE,
            '#states' => [
                'required' => [
                    ':input[name=driver]' => [
                        'value' => $driver,
                    ],
                ],
            ],
        ];
        $form['username'] = [
            '#type' => 'textfield',
            '#title' => t('Database username'),
            '#default_value' => empty($database['username']) ? '' : $database['username'],
            '#size' => 45,
            '#required' => TRUE,
            '#states' => [
                'required' => [
                    ':input[name=driver]' => [
                        'value' => $driver,
                    ],
                ],
            ],
        ];
        $form['password'] = [
            '#type' => 'password',
            '#title' => t('Database password'),
            '#default_value' => empty($database['password']) ? '' : $database['password'],
            '#required' => FALSE,
            '#size' => 45,
        ];
        $form['advanced_options'] = [
            '#type' => 'details',
            '#title' => t('Advanced options'),
            '#weight' => 10,
        ];
        global $install_state;
        // @todo https://www.drupal.org/project/drupal/issues/3110839 remove PHP 7.4
        //   work around and add a better message for the migrate UI.
        $profile = $install_state['parameters']['profile'] ?? NULL;
        $db_prefix = $profile == 'standard' ? 'drupal_' : $profile . '_';
        $form['advanced_options']['prefix'] = [
            '#type' => 'textfield',
            '#title' => t('Table name prefix'),
            '#default_value' => empty($database['prefix']) ? '' : $database['prefix'],
            '#size' => 45,
            '#description' => t('If more than one application will be sharing this database, a unique table name prefix – such as %prefix – will prevent collisions.', [
                '%prefix' => $db_prefix,
            ]),
            '#weight' => 10,
        ];
        $form['advanced_options']['host'] = [
            '#type' => 'textfield',
            '#title' => t('Host'),
            '#default_value' => empty($database['host']) ? 'localhost' : $database['host'],
            '#size' => 45,
            // Hostnames can be 255 characters long.
'#maxlength' => 255,
            '#required' => TRUE,
        ];
        $form['advanced_options']['port'] = [
            '#type' => 'number',
            '#title' => t('Port number'),
            '#default_value' => empty($database['port']) ? '' : $database['port'],
            '#min' => 0,
            '#max' => 65535,
        ];
        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) {
        $errors = [];
        // Verify the table prefix.
        if (!empty($database['prefix']) && is_string($database['prefix']) && !preg_match('/^[A-Za-z0-9_.]+$/', $database['prefix'])) {
            $errors[$database['driver'] . '][prefix'] = t('The database table prefix you have entered, %prefix, is invalid. The table prefix can only contain alphanumeric characters, periods, or underscores.', [
                '%prefix' => $database['prefix'],
            ]);
        }
        return $errors;
    }

}