Initial capay platform scaffold

app/src/watchers/evmWatcher.js

@@ -0,0 +1,76 @@
+const { JsonRpcProvider } = require('ethers');
+const { readDb, writeDb } = require('../storage');
+const { getEthereumRpcUrls, createRoundRobinPicker } = require('../utils/rpc');
+
+function startEvmWatcher({ notifyMerchant }) {
+  const rpcUrls = getEthereumRpcUrls();
+  if (!rpcUrls.length) {
+    console.warn('[evmWatcher] No Ethereum RPC URLs configured. Skipping watcher.');
+    return;
+  }
+
+  const pollInterval = Number(process.env.TX_POLL_INTERVAL_MS || 180000);
+  const maxPerCycle = Number(process.env.MAX_TX_CHECK_PER_CYCLE || 20);
+  const minConfirmations = Number(process.env.MIN_CONFIRMATIONS || 1);
+  const pickRpcUrl = createRoundRobinPicker(rpcUrls);
+
+  let running = false;
+
+  async function poll() {
+    if (running) return;
+    running = true;
+    try {
+      const db = await readDb();
+      const pending = db.txs.filter((tx) => tx.network === 'evm:ethereum' && tx.status === 'pending');
+      if (pending.length === 0) {
+        running = false;
+        return;
+      }
+
+      const rpcUrl = pickRpcUrl();
+      const provider = new JsonRpcProvider(rpcUrl);
+      const latestBlock = await provider.getBlockNumber();
+      const now = new Date().toISOString();
+      const confirmedEvents = [];
+
+      for (const tx of pending.slice(0, maxPerCycle)) {
+        const receipt = await provider.getTransactionReceipt(tx.txHash);
+        tx.lastCheckedAt = now;
+
+        if (!receipt) continue;
+
+        const confirmations = latestBlock - receipt.blockNumber + 1;
+        tx.confirmations = confirmations;
+        tx.updatedAt = now;
+
+        if (receipt.status === 1 && confirmations >= minConfirmations) {
+          tx.status = 'confirmed';
+          const order = db.orders.find((item) => item.id === tx.orderId);
+          if (order) {
+            order.status = 'paid';
+            order.updatedAt = now;
+            confirmedEvents.push({ order, tx });
+          }
+        } else if (receipt.status === 0) {
+          tx.status = 'failed';
+        }
+      }
+
+      await writeDb(db);
+
+      for (const event of confirmedEvents) {
+        await notifyMerchant(event.order, event.tx);
+      }
+    } catch (error) {
+      console.error('[evmWatcher] poll error', error.message);
+    } finally {
+      running = false;
+    }
+  }
+
+  poll();
+  setInterval(poll, pollInterval);
+  console.log(`[evmWatcher] started with interval ${pollInterval}ms`);
+}
+
+module.exports = { startEvmWatcher };