Add Feedback domain module: public submission flow, admin CRUD, reporting (#7)

Co-authored-by: Patrick Müller <mail@pmueller.me>
Reviewed-on: #7
Co-authored-by: Patrick Mueller <patrick@mueller-patrick.tech>
Co-committed-by: Patrick Mueller <patrick@mueller-patrick.tech>

src/models/feedback/admin/songs.admin.service.ts

@@ -0,0 +1,56 @@
+import {NachklangFeedbackDB} from '../Feedback.db';
+
+export const addSong = async (eventId: number, title: string, composer: string | null): Promise<number> => {
+	let conn = await NachklangFeedbackDB.getConnection();
+	try {
+		await conn.beginTransaction();
+		const posRows = await conn.query('SELECT COALESCE(MAX(position), -1) + 1 as next_position FROM songs WHERE event_id = ?', [eventId]);
+		const position = posRows[0].next_position;
+		const res = await conn.query(
+			'INSERT INTO songs (event_id, title, composer, position) VALUES (?,?,?,?) RETURNING song_id',
+			[eventId, title, composer, position]
+		);
+		await conn.commit();
+		return res[0].song_id;
+	} catch (err) {
+		await conn.rollback();
+		throw err;
+	} finally {
+		await conn.end();
+	}
+};
+
+export const updateSong = async (songId: number, title: string, composer: string | null): Promise<boolean> => {
+	let conn = await NachklangFeedbackDB.getConnection();
+	try {
+		await conn.beginTransaction();
+		const res = await conn.query('UPDATE songs SET title = ?, composer = ? WHERE song_id = ?', [title, composer, songId]);
+		await conn.commit();
+		return res.affectedRows > 0;
+	} catch (err) {
+		await conn.rollback();
+		throw err;
+	} finally {
+		await conn.end();
+	}
+};
+
+/**
+ * Removes a song. submission_answers rows referencing it keep their
+ * song_title_snapshot (song_id is set to NULL via ON DELETE SET NULL) -
+ * past answers still say what song was rated, even after the song is gone.
+ */
+export const deleteSong = async (songId: number): Promise<boolean> => {
+	let conn = await NachklangFeedbackDB.getConnection();
+	try {
+		await conn.beginTransaction();
+		const res = await conn.query('DELETE FROM songs WHERE song_id = ?', [songId]);
+		await conn.commit();
+		return res.affectedRows > 0;
+	} catch (err) {
+		await conn.rollback();
+		throw err;
+	} finally {
+		await conn.end();
+	}
+};