MDL-64994 analytics: Add a simple semantic version check method

This method is to be used for checking that a compatible version of the
moodlemlbackend package is installed on the server. The package is
expected to use the semantic versioning scheme (semver.org).

lib/mlbackend/python/classes/processor.php

@@ -395,4 +395,39 @@ class processor implements  \core_analytics\classifier, \core_analytics\regresso
         // This is not ideal, but there is no read access to moodle filesystem files.
         return $file->copy_content_to_temp('core_analytics');
     }
+
+    /**
+     * Check that the given package version can be used and return the error status.
+     *
+     * When evaluating the version, we assume the sematic versioning scheme as described at
+     * https://semver.org/.
+     *
+     * @param string $actual The actual Python package version
+     * @param string $required The required version of the package
+     * @return int -1 = actual version is too low, 1 = actual version too high, 0 = actual version is ok
+     */
+    public static function check_pip_package_version($actual, $required = self::REQUIRED_PIP_PACKAGE_VERSION) {
+
+        if (empty($actual)) {
+            return -1;
+        }
+
+        if (version_compare($actual, $required, '<')) {
+            return -1;
+        }
+
+        $parts = explode('.', $required);
+        $requiredapiver = reset($parts);
+
+        $parts = explode('.', $actual);
+        $actualapiver = reset($parts);
+
+        if ($requiredapiver > 0 || $actualapiver > 1) {
+            if (version_compare($actual, $requiredapiver + 1, '>=')) {
+                return 1;
+            }
+        }
+
+        return 0;
+    }
 }