${escapeHtml(title)}

${escapeHtml(JSON.stringify(payload, null, 2))}

`; } function sendJson(req, res, title, payload, status = 200) { if (wantsHtml(req.get('accept'))) { res.status(status).type('html').send(renderJsonPage(title, payload)); return; } res.status(status).json(payload); } async function openDatabase() { if (!databasePromise) { databasePromise = initSqlJs({ locateFile: () => wasmPath, }).then((SQL) => { const bytes = fs.readFileSync(databasePath); return new SQL.Database(new Uint8Array(bytes)); }); } return databasePromise; } async function queryRows(sql, params = []) { const database = await openDatabase(); const statement = database.prepare(sql); const rows = []; try { statement.bind(params); while (statement.step()) { rows.push(statement.getAsObject()); } return rows; } finally { statement.free(); } } async function writeRows(sql, params = []) { const database = await openDatabase(); database.run(sql, params); fs.writeFileSync(databasePath, database.export()); } function readFormString(value) { return typeof value === 'string' ? value.trim() : ''; } function readFormNumber(value) { if (typeof value !== 'string') { return NaN; } return Number(value); } app.get('/', (req, res) => { res.type('html').send(fs.readFileSync(indexPath, 'utf8')); }); app.get('/api/books', async (req, res, next) => { try { const books = await queryRows(` select id, title, author, year, rating from books order by rating desc, year desc `); sendJson(req, res, 'Books', { books, source: 'data/books.sqlite' }); } catch (error) { next(error); } }); app.post('/api/books', async (req, res, next) => { try { const body = req.body ?? {}; const title = readFormString(body.title); const author = readFormString(body.author); const year = readFormNumber(body.year); const rating = readFormNumber(body.rating); if ( !title || !author || !Number.isInteger(year) || year < 0 || !Number.isFinite(rating) || rating < 0 || rating > 5 ) { sendJson( req, res, 'Invalid Book', { error: 'Provide a title, author, non-negative year, and rating from 0 to 5.', }, 400, ); return; } await writeRows( ` insert into books (title, author, year, rating) values (?, ?, ?, ?) `, [title, author, year, rating], ); const [book] = await queryRows(` select id, title, author, year, rating from books where id = last_insert_rowid() `); if (wantsHtml(req.get('accept'))) { res.redirect(303, '/api/books'); return; } sendJson(req, res, 'Book Created', { book }, 201); } catch (error) { next(error); } }); app.get('/api/books/:id', async (req, res, next) => { try { const [book] = await queryRows( ` select id, title, author, year, rating from books where id = ? `, [Number(req.params.id)], ); if (!book) { sendJson(req, res, 'Book Not Found', { error: 'Book not found' }, 404); return; } sendJson(req, res, book.title, { book }); } catch (error) { next(error); } }); app.get('/api/stats', async (req, res, next) => { try { const [stats] = await queryRows(` select count(*) as count, round(avg(rating), 2) as averageRating, min(year) as earliestYear, max(year) as latestYear from books `); sendJson(req, res, 'Stats', { stats }); } catch (error) { next(error); } }); app.use((error, req, res, _next) => { sendJson( req, res, 'Server Error', { error: error instanceof Error ? error.message : String(error) }, 500, ); }); app.use((req, res) => { sendJson(req, res, 'Not Found', { error: 'Not Found', path: req.path }, 404); }); app.listen(port, () => { console.log(`Express + SQLite server running on port ${port}`); });