feat: add collections (#484)

closes #418

server/routes/collection.ts

@@ -0,0 +1,27 @@
+import { Router } from 'express';
+import TheMovieDb from '../api/themoviedb';
+import Media from '../entity/Media';
+import { mapCollection } from '../models/Collection';
+
+const collectionRoutes = Router();
+
+collectionRoutes.get<{ id: string }>('/:id', async (req, res, next) => {
+  const tmdb = new TheMovieDb();
+
+  try {
+    const collection = await tmdb.getCollection({
+      collectionId: Number(req.params.id),
+      language: req.query.language as string,
+    });
+
+    const media = await Media.getRelatedMedia(
+      collection.parts.map((part) => part.id)
+    );
+
+    return res.status(200).json(mapCollection(collection, media));
+  } catch (e) {
+    return next({ status: 404, message: 'Collection does not exist' });
+  }
+});
+
+export default collectionRoutes;