refactor backend and persist stock campaign queue

backend/db.js

@@ -0,0 +1,72 @@
+const { Pool } = require('pg');
+const { DATABASE_URL } = require('./config');
+
+const pool = new Pool({
+    connectionString: DATABASE_URL
+});
+
+const initDB = async () => {
+    try {
+        await pool.query(`
+            CREATE TABLE IF NOT EXISTS orders (
+                id SERIAL PRIMARY KEY,
+                cliente_nome VARCHAR(255),
+                data_pedido VARCHAR(50),
+                valor_pedido NUMERIC(10, 2),
+                produto_id VARCHAR(100),
+                produto_descricao TEXT,
+                quantidade INTEGER,
+                valor_unitario NUMERIC(10, 5),
+                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+            );
+        `);
+
+        await pool.query(`ALTER TABLE orders ADD COLUMN IF NOT EXISTS pedido_id VARCHAR(100);`).catch(() => {});
+        await pool.query(`ALTER TABLE orders ADD COLUMN IF NOT EXISTS cliente_fone VARCHAR(50);`).catch(() => {});
+
+        await pool.query(`CREATE UNIQUE INDEX IF NOT EXISTS unique_order_product ON orders (pedido_id, produto_id);`).catch(err => {
+            console.error('Notice: Could not create unique index (might already exist or there are duplicates):', err.message);
+        });
+
+        await pool.query(`
+            CREATE TABLE IF NOT EXISTS stock (
+                produto_id VARCHAR(100) PRIMARY KEY,
+                nome TEXT,
+                saldo INTEGER DEFAULT 0,
+                delta_estoque INTEGER DEFAULT 0,
+                updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+            );
+        `);
+
+        await pool.query(`
+            CREATE TABLE IF NOT EXISTS stock_campaign_queue (
+                id SERIAL PRIMARY KEY,
+                base_product_name TEXT NOT NULL,
+                produto_id VARCHAR(100) NOT NULL,
+                nome TEXT NOT NULL,
+                saldo INTEGER DEFAULT 0,
+                delta_estoque INTEGER DEFAULT 0,
+                status VARCHAR(20) DEFAULT 'pending',
+                attempts INTEGER DEFAULT 0,
+                last_error TEXT,
+                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+                updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+                sent_at TIMESTAMP
+            );
+        `);
+
+        await pool.query(`CREATE INDEX IF NOT EXISTS idx_stock_campaign_queue_status ON stock_campaign_queue (status);`);
+        await pool.query(`CREATE INDEX IF NOT EXISTS idx_orders_cliente_fone ON orders (cliente_fone);`);
+        await pool.query(`CREATE INDEX IF NOT EXISTS idx_orders_produto_id ON orders (produto_id);`);
+
+        console.log('Database initialized successfully.');
+    } catch (err) {
+        console.error('Failed to initialize database:', err);
+        throw err;
+    }
+};
+
+module.exports = {
+    pool,
+    initDB
+};