API: Add experimental Json API

in preparation for external healthchecks and the
admin backend. We define a couple test routes:

- / List all routes
- /ping Replies pong for online-checks
- /stats Get high-level bot statistics
- /most-recent-drop Returns the most recent entry from dropHistories

The last two routes require a valid apikey header.
All routes are prefixed by /api/v1

api/jsonApi.js

@@ -0,0 +1,89 @@
+require("dotenv").config();
+const express = require('express');
+const bodyParser = require('body-parser');
+const { Card, User, DropHistory, Character, Group } = require("../models");
+const { Op } = require('sequelize');
+
+const ACCESS_TOKEN = process.env.API_ACCESS_TOKEN;
+const app = express();
+const router = express.Router();
+
+const PREFIX = '/api/v1';
+
+app.use(bodyParser.json());
+
+function isAuthorized(req, res) {
+  const providedToken = req.headers['apikey'];
+  if (providedToken !== ACCESS_TOKEN) {
+    res.status(401).json({ error: 'Unauthorized' });
+    return false;
+  }
+
+  return true;
+}
+
+router.get('/', (req, res) => {
+  const routes = router.stack
+    .filter(layer => layer.route) // Filter out non-routes
+    .map(layer => {
+      return {
+        route: PREFIX + layer.route.path,
+        methods: layer.route.methods
+      };
+    });
+
+  res.json({ routes: routes });
+});
+
+router.get('/ping', (req, res) => {
+  res.json({ status: 'Pong' });
+});
+
+router.get('/stats', async (req, res) => {
+  
+  if(!isAuthorized(req, res)){return;}
+
+  res.json({ 
+    users: await User.count(),
+    cards: await Card.count({where: { burned: { [Op.eq]: false }}}),
+    burned: await Card.count({where: { burned: { [Op.eq]: true }}}),
+    drops: await DropHistory.count(),
+    groups: await Group.count({where: { enabled: { [Op.eq]: true }}}),
+    characters: await Character.count({where: { enabled: { [Op.eq]: true }}}),
+    uptime: app.client.uptime
+  });
+});
+
+router.get('/most-recent-drop', async (req, res) => {
+  
+  if(!isAuthorized(req, res)){return;}
+
+  try {
+    const mostRecentDrop = await DropHistory.findOne({
+      order: [['createdAt', 'DESC']]
+    });
+
+    if (!mostRecentDrop) {
+      return res.status(404).send('No drops found');
+    }
+
+   const dropData = JSON.parse(mostRecentDrop.dropData);
+
+   const cards = await Promise.all(Object.keys(dropData).map(async key => {
+     const cardData = dropData[key]?.cardData;
+     if(!cardData) {return};
+     const card = JSON.parse(cardData);
+     return { identifier: card.identifier, quality: card.quality, character: await Character.findByPk(card.characterId) };
+   }));
+   
+   let response = { dropper: await User.findByPk(dropData.dropper), cards: cards.filter(Boolean)};
+  
+   res.json(response);
+ } catch (error) {
+   console.error(error);
+   res.status(500).send('Error fetching most recent drop');
+ }
+}).needsAuth= true;
+
+app.use(PREFIX, router);
+module.exports = app;