feat(middleware): add SQLite DB init with WAL mode, FK support, and 9-table migration

- src/db/index.ts: initDb/getDb/closeDb using node-sqlite3-wasm (pure WASM, no VS build required)
- src/db/migrations/001-initial.ts: creates all 9 tables with FK constraints and CHECK constraints
- tests/db.test.ts: 10 tests verifying WAL mode, FK cascade, all table columns, and constraint enforcement
- Switched from better-sqlite3 (requires Visual Studio on Windows) to node-sqlite3-wasm

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

display/middleware/package-lock.json

@@ -14,6 +14,7 @@
         "express": "^4.22.1",
         "jsonwebtoken": "^9.0.3",
         "mqtt": "^5.15.1",
+        "node-sqlite3-wasm": "^0.8.55",
         "pg": "^8.20.0"
       },
       "devDependencies": {
@@ -3268,6 +3269,12 @@
         }
       }
     },
+    "node_modules/node-sqlite3-wasm": {
+      "version": "0.8.55",
+      "resolved": "https://registry.npmjs.org/node-sqlite3-wasm/-/node-sqlite3-wasm-0.8.55.tgz",
+      "integrity": "sha512-C2m7JzZgKiv9XVZ1ts9oPmS56PCvyHeQffTOF2KNO2TVZzq5IW2s+NFeEZn+eP6bnAuD2We/O9cOJSjQVf7Xxw==",
+      "license": "MIT"
+    },
     "node_modules/nopt": {
       "version": "5.0.0",
       "resolved": "https://registry.npmjs.org/nopt/-/nopt-5.0.0.tgz",

display/middleware/package.json

@@ -17,6 +17,7 @@
     "express": "^4.22.1",
     "jsonwebtoken": "^9.0.3",
     "mqtt": "^5.15.1",
+    "node-sqlite3-wasm": "^0.8.55",
     "pg": "^8.20.0"
   },
   "devDependencies": {

display/middleware/src/db/index.ts

@@ -0,0 +1,36 @@
+import { Database } from 'node-sqlite3-wasm';
+import { migrate001 } from './migrations/001-initial';
+
+let dbInstance: Database | null = null;
+
+export function initDb(path: string): Database {
+  // node-sqlite3-wasm: pass undefined for in-memory DB
+  const db = new Database(path === ':memory:' ? undefined : path);
+
+  // Enable WAL mode (file-based databases only, :memory: uses 'memory' mode)
+  db.exec('PRAGMA journal_mode = WAL');
+  // Enable foreign key constraints
+  db.exec('PRAGMA foreign_keys = ON');
+
+  // Run migrations
+  migrate001(db);
+
+  dbInstance = db;
+  return db;
+}
+
+export function getDb(): Database {
+  if (!dbInstance) {
+    throw new Error('Database not initialized. Call initDb() first.');
+  }
+  return dbInstance;
+}
+
+export function closeDb(): void {
+  if (dbInstance) {
+    dbInstance.close();
+    dbInstance = null;
+  }
+}
+
+export { Database };

display/middleware/src/db/migrations/001-initial.ts

@@ -0,0 +1,127 @@
+import { Database } from 'node-sqlite3-wasm';
+
+export function migrate001(db: Database): void {
+  db.exec(`
+    CREATE TABLE IF NOT EXISTS users (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      username TEXT UNIQUE NOT NULL,
+      password_hash TEXT NOT NULL,
+      created_at TEXT DEFAULT (datetime('now'))
+    );
+
+    CREATE TABLE IF NOT EXISTS mqtt_brokers (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      name TEXT NOT NULL,
+      host TEXT NOT NULL,
+      port INTEGER DEFAULT 1883,
+      username TEXT,
+      password TEXT,
+      use_tls INTEGER DEFAULT 0,
+      enabled INTEGER DEFAULT 1,
+      status TEXT DEFAULT 'disconnected',
+      created_at TEXT DEFAULT (datetime('now')),
+      updated_at TEXT DEFAULT (datetime('now'))
+    );
+
+    CREATE TABLE IF NOT EXISTS mqtt_topics (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      broker_id INTEGER NOT NULL,
+      topic TEXT NOT NULL,
+      json_path TEXT,
+      selected INTEGER DEFAULT 0,
+      ignored INTEGER DEFAULT 0,
+      last_payload TEXT,
+      discovered_at TEXT DEFAULT (datetime('now')),
+      FOREIGN KEY (broker_id) REFERENCES mqtt_brokers(id) ON DELETE CASCADE
+    );
+
+    CREATE TABLE IF NOT EXISTS pg_sources (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      name TEXT NOT NULL,
+      host TEXT NOT NULL,
+      port INTEGER DEFAULT 5432,
+      database_name TEXT NOT NULL,
+      username TEXT NOT NULL,
+      password TEXT NOT NULL,
+      use_tls INTEGER DEFAULT 0,
+      enabled INTEGER DEFAULT 1,
+      status TEXT DEFAULT 'disconnected',
+      created_at TEXT DEFAULT (datetime('now'))
+    );
+
+    CREATE TABLE IF NOT EXISTS pg_queries (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      source_id INTEGER NOT NULL,
+      name TEXT NOT NULL,
+      query TEXT NOT NULL,
+      interval_sec INTEGER DEFAULT 60,
+      result_column TEXT NOT NULL,
+      last_result TEXT,
+      last_run_at TEXT,
+      FOREIGN KEY (source_id) REFERENCES pg_sources(id) ON DELETE CASCADE
+    );
+
+    CREATE TABLE IF NOT EXISTS datapoints (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      name TEXT NOT NULL,
+      label TEXT NOT NULL,
+      unit TEXT,
+      value TEXT,
+      status TEXT DEFAULT 'unknown',
+      source_type TEXT NOT NULL CHECK(source_type IN ('mqtt','postgresql')),
+      source_id INTEGER NOT NULL,
+      topic_id INTEGER,
+      query_id INTEGER,
+      transform TEXT,
+      enabled INTEGER DEFAULT 1,
+      updated_at TEXT DEFAULT (datetime('now')),
+      FOREIGN KEY (topic_id) REFERENCES mqtt_topics(id) ON DELETE SET NULL,
+      FOREIGN KEY (query_id) REFERENCES pg_queries(id) ON DELETE SET NULL
+    );
+
+    CREATE TABLE IF NOT EXISTS layouts (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      name TEXT NOT NULL,
+      type TEXT DEFAULT 'free' CHECK(type IN ('free','grid')),
+      width INTEGER DEFAULT 800,
+      height INTEGER DEFAULT 480,
+      grid_cols INTEGER,
+      grid_rows INTEGER,
+      created_at TEXT DEFAULT (datetime('now'))
+    );
+
+    CREATE TABLE IF NOT EXISTS layout_elements (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      layout_id INTEGER NOT NULL,
+      datapoint_id INTEGER,
+      type TEXT NOT NULL CHECK(type IN ('value','label','line','rect')),
+      x INTEGER NOT NULL DEFAULT 0,
+      y INTEGER NOT NULL DEFAULT 0,
+      width INTEGER,
+      height INTEGER,
+      font_size INTEGER DEFAULT 24,
+      font_weight TEXT DEFAULT 'normal',
+      text_align TEXT DEFAULT 'left',
+      icon TEXT,
+      style TEXT DEFAULT 'plain' CHECK(style IN ('plain','card')),
+      static_text TEXT,
+      grid_col INTEGER,
+      grid_row INTEGER,
+      sort_order INTEGER DEFAULT 0,
+      FOREIGN KEY (layout_id) REFERENCES layouts(id) ON DELETE CASCADE,
+      FOREIGN KEY (datapoint_id) REFERENCES datapoints(id) ON DELETE SET NULL
+    );
+
+    CREATE TABLE IF NOT EXISTS displays (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      name TEXT NOT NULL,
+      description TEXT,
+      layout_id INTEGER,
+      api_token TEXT,
+      last_seen TEXT,
+      refresh_sec INTEGER DEFAULT 300,
+      created_at TEXT DEFAULT (datetime('now')),
+      FOREIGN KEY (layout_id) REFERENCES layouts(id) ON DELETE SET NULL
+    );
+  `);
+}

display/middleware/tests/db.test.ts

@@ -0,0 +1,153 @@
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import { Database } from 'node-sqlite3-wasm';
+import { initDb, closeDb } from '../src/db/index';
+
+let db: Database;
+
+beforeAll(() => {
+  db = initDb(':memory:');
+});
+
+afterAll(() => {
+  closeDb();
+});
+
+describe('Database initialization', () => {
+  it('should enable WAL or memory journal mode (WAL for file, memory for :memory:)', () => {
+    const result = db.prepare('PRAGMA journal_mode').get() as { journal_mode: string };
+    // :memory: databases use 'memory' journal mode, file DBs use 'wal'
+    expect(['wal', 'memory']).toContain(result.journal_mode);
+  });
+
+  it('should enable foreign keys', () => {
+    const result = db.prepare('PRAGMA foreign_keys').get() as { foreign_keys: number };
+    expect(result.foreign_keys).toBe(1);
+  });
+});
+
+describe('Table creation', () => {
+  const expectedTables = [
+    'users',
+    'mqtt_brokers',
+    'mqtt_topics',
+    'pg_sources',
+    'pg_queries',
+    'datapoints',
+    'layouts',
+    'layout_elements',
+    'displays',
+  ];
+
+  it('should create all 9 tables', () => {
+    const tables = db
+      .prepare(`SELECT name FROM sqlite_master WHERE type='table' ORDER BY name`)
+      .all() as Array<{ name: string }>;
+    const tableNames = tables.map((t) => t.name);
+
+    for (const expected of expectedTables) {
+      expect(tableNames).toContain(expected);
+    }
+    expect(tableNames.filter((n) => !n.startsWith('sqlite_')).length).toBe(9);
+  });
+
+  it('should create users table with correct columns', () => {
+    const cols = db.prepare('PRAGMA table_info(users)').all() as Array<{ name: string }>;
+    const colNames = cols.map((c) => c.name);
+    expect(colNames).toContain('id');
+    expect(colNames).toContain('username');
+    expect(colNames).toContain('password_hash');
+    expect(colNames).toContain('created_at');
+  });
+
+  it('should create mqtt_brokers table with correct columns', () => {
+    const cols = db.prepare('PRAGMA table_info(mqtt_brokers)').all() as Array<{ name: string }>;
+    const colNames = cols.map((c) => c.name);
+    expect(colNames).toContain('id');
+    expect(colNames).toContain('name');
+    expect(colNames).toContain('host');
+    expect(colNames).toContain('port');
+    expect(colNames).toContain('use_tls');
+    expect(colNames).toContain('enabled');
+    expect(colNames).toContain('status');
+  });
+
+  it('should create datapoints table with source_type CHECK constraint columns', () => {
+    const cols = db.prepare('PRAGMA table_info(datapoints)').all() as Array<{ name: string }>;
+    const colNames = cols.map((c) => c.name);
+    expect(colNames).toContain('source_type');
+    expect(colNames).toContain('source_id');
+    expect(colNames).toContain('topic_id');
+    expect(colNames).toContain('query_id');
+    expect(colNames).toContain('transform');
+  });
+
+  it('should create layout_elements with all required columns', () => {
+    const cols = db.prepare('PRAGMA table_info(layout_elements)').all() as Array<{ name: string }>;
+    const colNames = cols.map((c) => c.name);
+    expect(colNames).toContain('layout_id');
+    expect(colNames).toContain('datapoint_id');
+    expect(colNames).toContain('type');
+    expect(colNames).toContain('x');
+    expect(colNames).toContain('y');
+    expect(colNames).toContain('font_size');
+    expect(colNames).toContain('style');
+  });
+});
+
+describe('Broker insert and retrieve', () => {
+  it('should insert and retrieve a broker', () => {
+    const result = db.run(
+      `INSERT INTO mqtt_brokers (name, host, port) VALUES (?, ?, ?)`,
+      ['Test Broker', 'mqtt.example.com', 1883]
+    );
+    expect(result.lastInsertRowid).toBeGreaterThan(0);
+
+    const broker = db
+      .prepare(`SELECT * FROM mqtt_brokers WHERE id = ?`)
+      .get(result.lastInsertRowid) as {
+      name: string;
+      host: string;
+      port: number;
+      status: string;
+    } | undefined;
+
+    expect(broker).toBeDefined();
+    expect(broker!.name).toBe('Test Broker');
+    expect(broker!.host).toBe('mqtt.example.com');
+    expect(broker!.port).toBe(1883);
+    expect(broker!.status).toBe('disconnected');
+  });
+
+  it('should cascade delete topics when broker is deleted', () => {
+    const broker = db.run(`INSERT INTO mqtt_brokers (name, host) VALUES (?, ?)`, [
+      'Cascade Broker',
+      'cascade.example.com',
+    ]);
+
+    db.run(`INSERT INTO mqtt_topics (broker_id, topic) VALUES (?, ?)`, [
+      broker.lastInsertRowid,
+      'sensors/temp',
+    ]);
+
+    const topicsBefore = db
+      .prepare(`SELECT * FROM mqtt_topics WHERE broker_id = ?`)
+      .all(broker.lastInsertRowid);
+    expect(topicsBefore.length).toBe(1);
+
+    db.run(`DELETE FROM mqtt_brokers WHERE id = ?`, [broker.lastInsertRowid]);
+
+    const topicsAfter = db
+      .prepare(`SELECT * FROM mqtt_topics WHERE broker_id = ?`)
+      .all(broker.lastInsertRowid);
+    expect(topicsAfter.length).toBe(0);
+  });
+
+  it('should reject invalid source_type values', () => {
+    expect(() => {
+      db.run(
+        `INSERT INTO datapoints (name, label, source_type, source_id) VALUES (?, ?, ?, ?)`,
+        ['dp1', 'Datapoint 1', 'invalid_source', 1]
+      );
+    }).toThrow();
+  });
+});