Introduce BackendService for managing external storage backends

Backends are registered to the BackendService through new data
structures:

Backends are concrete classes, deriving from
\OCA\Files_External\Lib\Backend\Backend. During construction, the
various configuration parameters of the Backend can be set, in a design
similar to Symfony Console.

DefinitionParameter stores a parameter configuration for an external
storage: name of parameter, human-readable name, type of parameter
(text, password, hidden, checkbox), flags (optional or not).

Storages in the StoragesController now get their parameters validated
server-side (fixes a TODO).

1 files changed, 86 insertions, 0 deletions

diff --git a/apps/files_external/lib/dependencytrait.php b/apps/files_external/lib/dependencytrait.php
new file mode 100644
index 00000000000..116421eab14
--- /dev/null
+++ b/apps/files_external/lib/dependencytrait.php
@@ -0,0 +1,86 @@
+<?php
+/**
+ * @author Robin McCorkell <rmccorkell@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\Files_External\Lib;
+
+use \OCA\Files_External\Lib\MissingDependency;
+
+/**
+ * Trait for objects that have dependencies for use
+ */
+trait DependencyTrait {
+
+	/** @var callable|null dependency check */
+	private $dependencyCheck = null;
+
+	/**
+	 * @return bool
+	 */
+	public function hasDependencies() {
+		return !is_null($this->dependencyCheck);
+	}
+
+	/**
+	 * @param callable $dependencyCheck
+	 * @return self
+	 */
+	public function setDependencyCheck(callable $dependencyCheck) {
+		$this->dependencyCheck = $dependencyCheck;
+		return $this;
+	}
+
+	/**
+	 * Check if object is valid for use
+	 *
+	 * @return MissingDependency[] Unsatisfied dependencies
+	 */
+	public function checkDependencies() {
+		$ret = [];
+
+		if ($this->hasDependencies()) {
+			$result = call_user_func($this->dependencyCheck);
+			if ($result !== true) {
+				if (!is_array($result)) {
+					$result = [$result];
+				}
+				foreach ($result as $key => $value) {
+					if (!($value instanceof MissingDependency)) {
+						$module = null;
+						$message = null;
+						if (is_numeric($key)) {
+							$module = $value;
+						} else {
+							$module = $key;
+							$message = $value;
+						}
+						$value = new MissingDependency($module, $this);
+						$value->setMessage($message);
+					}
+					$ret[] = $value;
+				}
+			}
+		}
+
+		return $ret;
+	}
+
+}
+