Add description for registerID and add exists fn

Author: y21

backend/SessionIDManager.js

@@ -2,6 +2,7 @@ const {
  randomBytes
 } = require("crypto");
 /**
+ * Registers a session ID
  * 
  * @param {object} database The database object (must have a run method - recommended sql client: sqlite)
  * @param {string} username The username (does not need to be escaped)
@@ -28,11 +29,55 @@ exports.registerID = (database, username, session, expires) => {
  }).catch(error => {
  if (error.toString().includes("no such table: sessionids")) {
  database.run("CREATE TABLE sessionids (`username` TEXT, `sessionid` TEXT, `expires` TEXT)").catch(reject);
- reject({ toString: () => "Table was not present at execution. It has been created now." });
+ reject({
+ toString: () => "Table was not present at execution. It has been created now."
+ });
  } else console.log(error);
  });
  } catch (e) {
  reject(e);
  }
  });
 }
+
+/**
+ * Checks if a session ID exists
+ * 
+ * @param {object} database The database object (must have a run method - recommended sql client: sqlite)
+ * @param {object} data An object with both a type property (search keyword, either: session, username or expiresAt) and a value property
+ * @returns {promise<boolean|object>} Whether the session ID exists or not (or an object with error information)
+ */
+exports.exists = (database, data) => {
+ return new Promise((resolve, reject) => {
+ try {
+ switch (data.type) {
+ case "session":
+ database.prepare("SELECT * FROM sessionids WHERE sessionid = ?").then(prepare => {
+ prepare.get([data.value]).then(result => {
+ if (typeof result === "undefined") resolve(false);
+ else resolve(true);
+ });
+ }).catch(reject);
+ break;
+ case "username":
+ database.prepare("SELECT * FROM sessionids WHERE username = ?").then(prepare => {
+ prepare.get([data.value]).then(result => {
+ if (typeof result === "undefined") resolve(false);
+ else resolve(true);
+ });
+ }).catch(reject);
+ break;
+ case "expiresAt":
+ database.prepare("SELECT * FROM sessionids WHERE expires = ?").then(prepare => {
+ prepare.get([data.value]).then(result => {
+ if (typeof result === "undefined") resolve(false);
+ else resolve(true);
+ });
+ }).catch(reject);
+ break;
+ }
+ } catch (e) {
+ reject(e)
+ }
+ });
+}