1 files changed, 69 insertions, 0 deletions
diff --git a/apps/files_external/lib/Config/SimpleSubstitutionTrait.php b/apps/files_external/lib/Config/SimpleSubstitutionTrait.php
new file mode 100644
index 00000000000..85a76054fa8
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+++ b/apps/files_external/lib/Config/SimpleSubstitutionTrait.php
@@ -0,0 +1,69 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\Files_External\Config;
+
+/**
+ * Trait SimpleSubstitutionTrait
+ *
+ * @package OCA\Files_External\Config
+ * @since 16.0.0
+ */
+trait SimpleSubstitutionTrait {
+	/**
+	 * @var string the placeholder without $ prefix
+	 * @since 16.0.0
+	 */
+	protected $placeholder;
+
+	/** @var string */
+	protected $sanitizedPlaceholder;
+
+	/**
+	 * @param mixed $optionValue
+	 * @param string $replacement
+	 * @return mixed
+	 * @since 16.0.0
+	 */
+	private function processInput($optionValue, string $replacement) {
+		$this->checkPlaceholder();
+		if (is_array($optionValue)) {
+			foreach ($optionValue as &$value) {
+				$value = $this->substituteIfString($value, $replacement);
+			}
+		} else {
+			$optionValue = $this->substituteIfString($optionValue, $replacement);
+		}
+		return $optionValue;
+	}
+
+	/**
+	 * @throws \RuntimeException
+	 */
+	protected function checkPlaceholder(): void {
+		$this->sanitizedPlaceholder = trim(strtolower($this->placeholder));
+		if (!(bool)\preg_match('/^[a-z0-9]*$/', $this->sanitizedPlaceholder)) {
+			throw new \RuntimeException(sprintf(
+				'Invalid placeholder %s, only [a-z0-9] are allowed', $this->sanitizedPlaceholder
+			));
+		}
+		if ($this->sanitizedPlaceholder === '') {
+			throw new \RuntimeException('Invalid empty placeholder');
+		}
+	}
+
+	/**
+	 * @param mixed $value
+	 * @param string $replacement
+	 * @return mixed
+	 */
+	protected function substituteIfString($value, string $replacement) {
+		if (is_string($value)) {
+			return str_ireplace('$' . $this->sanitizedPlaceholder, $replacement, $value);
+		}
+		return $value;
+	}
+}