feat: add local memory tracker to calculate stock deltas

src/controllers/webhook.controller.ts

@@ -1,6 +1,8 @@
 import { Request, Response } from 'express';
 import { sendToN8n } from '../services/n8n.service';
 import axios from 'axios';
+import fs from 'fs';
+import path from 'path';
 
 export const handleTinyOrderUpdate = async (req: Request, res: Response): Promise<void> => {
   try {
@@ -156,12 +158,53 @@ export const handleTinyStockUpdate = async (req: Request, res: Response): Promis
             return;
         }
 
-        console.log('Received stock webhook from Tiny. Forwarding to n8n...');
+        console.log('Received stock webhook from Tiny. Calculating delta...');
         let payload = req.body || {};
         if (payload && typeof payload.dados === 'string') {
             try { payload.dados = JSON.parse(payload.dados); } catch (e) {}
         }
         
+        // --- SMART MEMORY LOGIC ---
+        const memoryFile = path.join(process.cwd(), 'stock_memory.json');
+        let memory: Record<string, number> = {};
+        
+        // Load memory if it exists
+        if (fs.existsSync(memoryFile)) {
+            try {
+                memory = JSON.parse(fs.readFileSync(memoryFile, 'utf-8'));
+            } catch (e) {
+                console.error("Failed to parse stock_memory.json, starting fresh.");
+            }
+        }
+
+        const dados = payload.dados || {};
+        const idProduto = String(dados.idProduto || dados.id || "");
+        const novoSaldo = Number(dados.saldo || 0);
+
+        let deltaEstoque = 0;
+        
+        if (idProduto) {
+            const estoqueAntigo = memory[idProduto];
+            
+            if (estoqueAntigo !== undefined) {
+                // We know what it was before, calculate the difference
+                deltaEstoque = novoSaldo - estoqueAntigo;
+            } else {
+                // First time seeing this product. Default delta to 0 so we don't alert on initial load.
+                deltaEstoque = 0; 
+            }
+
+            // Save the new balance to memory
+            memory[idProduto] = novoSaldo;
+            fs.writeFileSync(memoryFile, JSON.stringify(memory, null, 2));
+            
+            console.log(`[Stock Tracker] Product ${idProduto}: Old=${estoqueAntigo ?? 'None'} -> New=${novoSaldo}. Delta=${deltaEstoque > 0 ? '+' : ''}${deltaEstoque}`);
+        }
+
+        // Inject the delta into the payload so n8n can easily read it
+        if (!payload.dados) payload.dados = {};
+        payload.dados.delta_estoque = deltaEstoque;
+        
         await sendToN8n(payload, targetUrl);
     } catch (error) {
         console.error('Error handling Tiny stock webhook:', error);