refactor: move project under backend

backend/app/src/watchers/btcWatcher.js

@@ -0,0 +1,103 @@
+const { readDb, writeDb } = require('../storage');
+const { getBitcoinRpcUrls, createRoundRobinPicker } = require('../utils/rpc');
+
+const BTC_NETWORK = 'btc:mainnet';
+
+async function callRpc(url, method, params = []) {
+  const body = JSON.stringify({
+    jsonrpc: '1.0',
+    id: 'capay',
+    method,
+    params
+  });
+
+  const response = await fetch(url, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body
+  });
+
+  if (!response.ok) {
+    throw new Error(`rpc ${method} failed (${response.status})`);
+  }
+
+  const payload = await response.json();
+  if (payload.error) {
+    const message = payload.error.message || JSON.stringify(payload.error);
+    throw new Error(`rpc ${method} error: ${message}`);
+  }
+
+  return payload.result;
+}
+
+function startBtcWatcher({ notifyMerchant }) {
+  const rpcUrls = getBitcoinRpcUrls();
+  if (!rpcUrls.length) {
+    console.warn('[btcWatcher] No Bitcoin 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 === BTC_NETWORK && tx.status === 'pending');
+      if (pending.length === 0) {
+        running = false;
+        return;
+      }
+
+      const rpcUrl = pickRpcUrl();
+      const now = new Date().toISOString();
+      const confirmedEvents = [];
+
+      for (const tx of pending.slice(0, maxPerCycle)) {
+        try {
+          const result = await callRpc(rpcUrl, 'getrawtransaction', [tx.txHash, true]);
+          const confirmations = Number(result?.confirmations || 0);
+
+          tx.confirmations = confirmations;
+          tx.lastCheckedAt = now;
+          tx.updatedAt = now;
+
+          if (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 });
+            }
+          }
+        } catch (error) {
+          tx.lastCheckedAt = now;
+          console.warn('[btcWatcher] rpc error', tx.txHash, error.message);
+        }
+      }
+
+      await writeDb(db);
+
+      for (const event of confirmedEvents) {
+        await notifyMerchant(event.order, event.tx);
+      }
+    } catch (error) {
+      console.error('[btcWatcher] poll error', error.message);
+    } finally {
+      running = false;
+    }
+  }
+
+  poll();
+  setInterval(poll, pollInterval);
+  console.log(`[btcWatcher] started with interval ${pollInterval}ms`);
+}
+
+module.exports = { startBtcWatcher };