baculum: Add offset parameter to messages endpoint

gui/baculum/protected/API/Pages/API/Messages.php

@@ -35,12 +35,17 @@ class Messages extends BaculumAPIServer {
 	public function get() {
 		$misc = $this->getModule('misc');
 		$limit = $this->Request->contains('limit') ? intval($this->Request['limit']) : 0;
+		$offset = $this->Request->contains('offset') && $misc->isValidInteger($this->Request['offset']) ? (int)$this->Request['offset'] : 0;
 
 		$cmd = ['messages'];
 		$result = $this->getModule('bconsole')->bconsoleCommand($this->director, $cmd, null, true);
 		$output = $result->output;
 		if ($result->exitcode == 0) {
-			$output = $limit > 0 ? array_slice($output, -$limit) : $output;
+			if ($limit > 0 && $offset <= 0) {
+				$output =  array_slice($output, -$limit);
+			} elseif ($limit > 0 && $offset > 0) {
+				$output = array_slice($output, -$offset, $limit);
+			}
 		}
 		$this->output = $output;
 		$this->error = $result->exitcode > 0 ? GenericError::ERROR_WRONG_EXITCODE : GenericError::ERROR_NO_ERRORS;

gui/baculum/protected/API/openapi_baculum.json

@@ -5558,16 +5558,28 @@
 						}
 					}
 				},
-				"parameters": [{
-					"name": "limit",
-					"in": "query",
-					"description": "Set messages log Limit.",
-					"required": false,
-					"default": 0,
-					"schema": {
-						"type": "integer"
+				"parameters": [
+					{
+						"name": "limit",
+						"in": "query",
+						"description": "Set messages log Limit. It is applyed from the end, not from the beginning. Ex. for msg1, msg2, msg3, msg4 and limit=2 it displays msg3 and msg4.",
+						"required": false,
+						"default": 0,
+						"schema": {
+							"type": "integer"
+						}
+					},
+					{
+						"name": "offset",
+						"in": "query",
+						"description": "Messages' offset must be used together with limit. It is applyed from the end, not from the beginning. Ex. for msg1, msg2, msg3, msg4 and offset=3 limit=2 it displays msg2 and msg3.",
+						"required": false,
+						"default": 0,
+						"schema": {
+							"type": "integer"
+						}
 					}
-				}]
+				]
 			}
 		},
 		"/api/v2/directors/{director_name}/status": {