Better handle when log_type isn't file and give explanation

lib/Controller/LogController.php

@@ -25,7 +25,6 @@
 use OCA\LogReader\Log\SearchFilter;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http\JSONResponse;
-use OCP\AppFramework\Http\TemplateResponse;
 use OCP\IConfig;
 use OCP\IRequest;
 
@@ -53,11 +52,33 @@ public function __construct($appName,
 	 * @param int $count
 	 * @param int $offset
 	 * @param string $levels
-	 * @return TemplateResponse
+	 * @return JSONResponse
 	 */
-	public function get($count = 50, $offset = 0, $levels = '11111') {
-		$iterator = $this->logIteratorFactory->getLogIterator($levels);
-		return $this->responseFromIterator($iterator, $count, $offset);
+	public function get($count = 50, $offset = 0, $levels = '11111'): JSONResponse {
+		$logType = $this->config->getSystemValue('log_type', 'file');
+		if ($logType === 'file') { // we only support web access when `log_type` is set to `file` (the default)
+			$iterator = $this->logIteratorFactory->getLogIterator($levels);
+			return $this->responseFromIterator($iterator, $count, $offset);
+		} else { // A log_type other than `file` seems to be configured so:
+			//     * Generate a dummy entry so we don't error out
+			//     * Use the dummy entry to inform the admin to look elsewhere and/or correct their configuration
+			$dummyLine["id"] = uniqid();
+			$dummyLine["reqid"] = "00000000000000000000"; // irrelevant
+			$dummyLine["level"] = 1; // INFO
+			$dummyLine["time"] = date(DATE_ATOM, time());
+			$dummyLine["remoteAddr"] = "0.0.0.0";
+			$dummyLine["user"] = "---";
+			$dummyLine["app"] = "Logreader";
+			$dummyLine["method"] = "---";
+			$dummyLine["url"] = "---";
+			$dummyLine["message"] =
+				'File-based logging must be enabled to access logs from the Web UI. Your `log_type` is currently '
+				. 'set to: [' . $logType . ']. If you feel this is an error, please verify `log_type` in your '
+				. 'config.php and check the Nextcloud Administration Manual. This is not an actual log entry.';
+			$dummyLine["userAgent"] = "---";
+			$dummyLine["version"] = "---";
+			return new JSONResponse(['data' => $dummyLine, 'remain' => false]);
+		}
 	}
 
 
@@ -91,6 +112,12 @@ public function poll(string $lastReqId, string $levels = '11111'): JSONResponse
 		$cycles = 0;
 		$maxCycles = 20;
 
+		$logType = $this->config->getSystemValue('log_type', 'file');
+		if ($logType !== 'file') { // we only support access when `log_type` is set to `file` (the default)
+			// TODO: Don't even attempt polling in the front-end
+			sleep(20);
+			return new JSONResponse([]);
+		}
 		$lastItem = $this->getLastItem($levels);
 		while ($lastItem === null || $lastItem['reqId'] === $lastReqId) {
 			sleep(1);
@@ -128,11 +155,11 @@ public function poll(string $lastReqId, string $levels = '11111'): JSONResponse
 	 * @param int $count
 	 * @param int $offset
 	 * @param string $levels
-	 * @return TemplateResponse
+	 * @return JSONResponse
 	 *
 	 * @NoCSRFRequired
 	 */
-	public function search($query = '', $count = 50, $offset = 0, $levels = '11111') {
+	public function search($query = '', $count = 50, $offset = 0, $levels = '11111'): JSONResponse {
 		$iterator = $this->logIteratorFactory->getLogIterator($levels);
 		$iterator = new \LimitIterator($iterator, 0, 100000); // limit the number of message we search to avoid huge search times
 		$iterator->rewind();
@@ -193,7 +220,7 @@ public function setLevels(string $levels): int {
 		return $minLevel;
 	}
 
-	protected function responseFromIterator(\Iterator $iterator, $count, $offset) {
+	protected function responseFromIterator(\Iterator $iterator, $count, $offset): JSONResponse {
 		$iterator->rewind();
 		for ($i = 0; $i < $offset; $i++) {
 			$iterator->next();