class mod_labnbook_session to store and query LnN info

classes/session.php

+<?php
+
+/**
+ * @license http://www.gnu.org/licenses/gpl-3.0.html  GNU GPL v3
+ */
+
+/* @var $DB moodle_database */
+
+/**
+ * Queries on LabNbook info for the current user.
+ */
+class mod_labnbook_session
+{
+    private static $singleton;
+
+    /**
+     * @var string
+     */
+    private $url;
+
+    /**
+     * @var string
+     */
+    private $secret;
+
+    /**
+     * @var int
+     */
+    private $userId;
+
+    /**
+     * @var array
+     */
+    private $missions = [];
+
+    private $identifyByCasAuth = true;
+
+    private $identifyByStudentNumber = true;
+
+    private $autoCreateUser = true;
+
+    public static function load() {
+        if (empty(self::$singleton)) {
+            self::$singleton = new self;
+        }
+        return self::$singleton;
+    }
+
+    public function __construct() {
+        global $CFG, $USER;
+        $this->url = rtrim($CFG->labnbook_url, '/');
+        $this->secret = $CFG->labnbook_key;
+        $this->userId = $this->fetchUserId($USER->id);
+    }
+
+    /**
+     * Search the LabNbook user ID in the cache (object attribute),
+     *  then in the user session,
+     *  then the DB,
+     *  then through the LabNbook REST API (first GET, then PUT).
+     *
+     * @return int
+     */
+    public function getUserId() {
+        if (!isset($this->userId)) {
+            $this->userId = $this->fetchUserId();
+        }
+        return $this->userId;
+    }
+
+    public function getMissions() {
+        if (!isset($this->missions)) {
+            $this->missions = $this->fetchMissions();
+        }
+        return $this->missions;
+    }
+
+    /**
+     * @global moodle_database $DB
+     * @global object $SESSION
+     * @global object $USER
+     * @param boolean $force
+     * @return int
+     */
+    protected function fetchUserId($force = false) {
+        global $DB, $SESSION, $USER;
+        if ($force || !isset($SESSION->labnbook_userid)) {
+            $userId = $DB->get_field("mod_labnbook_user", "labnbook_userid", ['userid' => $USER->id]);
+            if (!$userId && $this->identifyByStudentNumber && $USER->idnumber) {
+                $userId = $this->fetch('GET', "/user/identify", null, ['idnumber' => $USER->idnumber]);
+            }
+            if (!$userId && $this->identifyByCasAuth && $USER->auth === 'cas') {
+                $userId = $this->fetch('GET', "/user/identify", null, ['username' => $USER->username]);
+            }
+            if (!$userId && $this->autoCreateUser) {
+                $user = array_filter(
+                    (array) $USER,
+                    function($k) {
+                        $want = ['username', 'firstname', 'lastname', 'email'];
+                        return in_array($k, $want);
+                    },
+                    ARRAY_FILTER_USE_KEY
+                );
+                /**
+                 * @todo Add the boolean attribute 'teacher', true if user has editing rights in the current course.
+                 */
+                $userId = $this->fetch('PUT', "/user/create", null, $user);
+            }
+            $SESSION->labnbook_userid = (int) $userId;
+        }
+        return $SESSION->labnbook_userid;
+    }
+
+    /**
+     * @global object $SESSION
+     * @param boolean $force
+     * @return array assoc: ID => name
+     */
+    protected function fetchMissions($force = false) {
+        global $SESSION;
+        if ($force || !isset($SESSION->labnbook_missions)) {
+            $userId = $this->getUserId();
+            if ($userId) {
+                $SESSION->labnbook_missions = $this->fetch('GET', "/teacher/{$userId}/mission/list", []);
+            } else {
+                $SESSION->labnbook_missions = [];
+            }
+        }
+        return $SESSION->labnbook_missions;
+    }
+
+    /**
+     * Query the LabNbook API.
+     *
+     * @param string $urlPath
+     * @param mixed $defaultValue
+     * @param array $payload
+     * @return mixed
+     */
+    protected function fetch($verb, $urlPath, $defaultValue = null, $payload = []) {
+        $payload['key'] = $this->secret;
+        $curl = curl_init();
+        curl_setopt_array($curl, [
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_CUSTOMREQUEST, $verb,
+            CURLOPT_URL => $this->url . "/api/index.php" . $urlPath,
+            CURLOPT_HTTPHEADER, ['Content-Type:application/json', 'Accept:application/json'],
+            CURLOPT_POSTFIELDS => json_encode($payload),
+        ]);
+        $response = curl_exec($curl);
+        $responseCode = curl_getinfo($curl, CURLINFO_RESPONSE_CODE);
+        if ($response === false || $responseCode != 200) {
+            // log the error?
+            // See curl_error($curl);
+            curl_close($curl);
+            return $defaultValue;
+        }
+        curl_close($curl);
+        return json_encode($response);
+    }
+}