1 files changed, 200 insertions, 0 deletions
diff --git a/apps/files_versions/lib/Expiration.php b/apps/files_versions/lib/Expiration.php
new file mode 100644
index 00000000000..1e04d93379f
--- /dev/null
+++ b/apps/files_versions/lib/Expiration.php
@@ -0,0 +1,200 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OCA\Files_Versions;
+
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\IConfig;
+use Psr\Log\LoggerInterface;
+
+class Expiration {
+
+	// how long do we keep files a version if no other value is defined in the config file (unit: days)
+	public const NO_OBLIGATION = -1;
+
+	/** @var string */
+	private $retentionObligation;
+
+	/** @var int */
+	private $minAge;
+
+	/** @var int */
+	private $maxAge;
+
+	/** @var bool */
+	private $canPurgeToSaveSpace;
+
+	public function __construct(
+		IConfig $config,
+		private ITimeFactory $timeFactory,
+		private LoggerInterface $logger,
+	) {
+		$this->retentionObligation = $config->getSystemValue('versions_retention_obligation', 'auto');
+
+		if ($this->retentionObligation !== 'disabled') {
+			$this->parseRetentionObligation();
+		}
+	}
+
+	/**
+	 * Is versions expiration enabled
+	 * @return bool
+	 */
+	public function isEnabled(): bool {
+		return $this->retentionObligation !== 'disabled';
+	}
+
+	/**
+	 * Is default expiration active
+	 */
+	public function shouldAutoExpire(): bool {
+		return $this->minAge === self::NO_OBLIGATION
+				|| $this->maxAge === self::NO_OBLIGATION;
+	}
+
+	/**
+	 * Check if given timestamp in expiration range
+	 * @param int $timestamp
+	 * @param bool $quotaExceeded
+	 * @return bool
+	 */
+	public function isExpired(int $timestamp, bool $quotaExceeded = false): bool {
+		// No expiration if disabled
+		if (!$this->isEnabled()) {
+			return false;
+		}
+
+		// Purge to save space (if allowed)
+		if ($quotaExceeded && $this->canPurgeToSaveSpace) {
+			return true;
+		}
+
+		$time = $this->timeFactory->getTime();
+		// Never expire dates in future e.g. misconfiguration or negative time
+		// adjustment
+		if ($time < $timestamp) {
+			return false;
+		}
+
+		// Purge as too old
+		if ($this->maxAge !== self::NO_OBLIGATION) {
+			$maxTimestamp = $time - ($this->maxAge * 86400);
+			$isOlderThanMax = $timestamp < $maxTimestamp;
+		} else {
+			$isOlderThanMax = false;
+		}
+
+		if ($this->minAge !== self::NO_OBLIGATION) {
+			// older than Min obligation and we are running out of quota?
+			$minTimestamp = $time - ($this->minAge * 86400);
+			$isMinReached = ($timestamp < $minTimestamp) && $quotaExceeded;
+		} else {
+			$isMinReached = false;
+		}
+
+		return $isOlderThanMax || $isMinReached;
+	}
+
+	/**
+	 * Get minimal retention obligation as a timestamp
+	 *
+	 * @return int|false
+	 */
+	public function getMinAgeAsTimestamp() {
+		$minAge = false;
+		if ($this->isEnabled() && $this->minAge !== self::NO_OBLIGATION) {
+			$time = $this->timeFactory->getTime();
+			$minAge = $time - ($this->minAge * 86400);
+		}
+		return $minAge;
+	}
+
+	/**
+	 * Get maximal retention obligation as a timestamp
+	 *
+	 * @return int|false
+	 */
+	public function getMaxAgeAsTimestamp() {
+		$maxAge = false;
+		if ($this->isEnabled() && $this->maxAge !== self::NO_OBLIGATION) {
+			$time = $this->timeFactory->getTime();
+			$maxAge = $time - ($this->maxAge * 86400);
+		}
+		return $maxAge;
+	}
+
+	/**
+	 * Read versions_retention_obligation, validate it
+	 * and set private members accordingly
+	 */
+	private function parseRetentionObligation(): void {
+		$splitValues = explode(',', $this->retentionObligation);
+		if (!isset($splitValues[0])) {
+			$minValue = 'auto';
+		} else {
+			$minValue = trim($splitValues[0]);
+		}
+
+		if (!isset($splitValues[1])) {
+			$maxValue = 'auto';
+		} else {
+			$maxValue = trim($splitValues[1]);
+		}
+
+		$isValid = true;
+		// Validate
+		if (!ctype_digit($minValue) && $minValue !== 'auto') {
+			$isValid = false;
+			$this->logger->warning(
+				$minValue . ' is not a valid value for minimal versions retention obligation. Check versions_retention_obligation in your config.php. Falling back to auto.',
+				['app' => 'files_versions']
+			);
+		}
+
+		if (!ctype_digit($maxValue) && $maxValue !== 'auto') {
+			$isValid = false;
+			$this->logger->warning(
+				$maxValue . ' is not a valid value for maximal versions retention obligation. Check versions_retention_obligation in your config.php. Falling back to auto.',
+				['app' => 'files_versions']
+			);
+		}
+
+		if (!$isValid) {
+			$minValue = 'auto';
+			$maxValue = 'auto';
+		}
+
+
+		if ($minValue === 'auto' && $maxValue === 'auto') {
+			// Default: Delete anytime if space needed
+			$this->minAge = self::NO_OBLIGATION;
+			$this->maxAge = self::NO_OBLIGATION;
+			$this->canPurgeToSaveSpace = true;
+		} elseif ($minValue !== 'auto' && $maxValue === 'auto') {
+			// Keep for X days but delete anytime if space needed
+			$this->minAge = (int)$minValue;
+			$this->maxAge = self::NO_OBLIGATION;
+			$this->canPurgeToSaveSpace = true;
+		} elseif ($minValue === 'auto' && $maxValue !== 'auto') {
+			// Delete anytime if space needed, Delete all older than max automatically
+			$this->minAge = self::NO_OBLIGATION;
+			$this->maxAge = (int)$maxValue;
+			$this->canPurgeToSaveSpace = true;
+		} elseif ($minValue !== 'auto' && $maxValue !== 'auto') {
+			// Delete all older than max OR older than min if space needed
+
+			// Max < Min as per https://github.com/owncloud/core/issues/16301
+			if ($maxValue < $minValue) {
+				$maxValue = $minValue;
+			}
+
+			$this->minAge = (int)$minValue;
+			$this->maxAge = (int)$maxValue;
+			$this->canPurgeToSaveSpace = false;
+		}
+	}
+}