Merge pull request #1 from xx-labs/chain/get-successful-transfers

chain: get transfer receipt

.gitignore

+# env
+**/.env
+
+# node modules
+**/node_modules
+
 # IDE
 .idea
-
-# Packages
-*/node_modules
+.vscode
 
 # Local network
 localnet/db
 localnet/chain.log
+
+# macos
+**/.DS_Store
+
+# logs
+**/logs
\ No newline at end of file

transfers/.eslintrc.json

+{
+    "env": {
+        "browser": true,
+        "commonjs": true,
+        "es2021": true
+    },
+    "extends": [
+        "airbnb-base"
+    ],
+    "parserOptions": {
+        "ecmaVersion": "latest"
+    },
+    "rules": {
+    }
+}

transfers/index.js

+const { ApiPromise, WsProvider } = require('@polkadot/api');
+require('dotenv').config();
+
+/**
+ *
+ * @param {number} ms miliseconds
+ * @returns
+ */
+async function wait(ms) {
+  return new Promise((resolve) => {
+    setTimeout(resolve, ms);
+  });
+}
+
+/**
+ * Connect to xxNetwork Public Node thorugh a websocket
+ * @return {Promise} chain api
+ */
+async function connect() {
+  const provider = new WsProvider(process.env.WS_CHAIN);
+  const api = await ApiPromise.create({
+    provider,
+  });
+  await api.isReady;
+  return api;
+}
+
+/**
+ * Check if node is in sync
+ * @param {Promise} api
+ * @returns {boolean}
+ */
+async function checkSynching(api) {
+  const health = await api.rpc.system.health();
+  return health.isSyncing.toHuman();
+}
+
+/**
+ * Get api of synchronized xxNetwork Public Node
+ * @returns {Promise} chain api
+ */
+async function getAPI() {
+  // Connect to the node
+  const api = await connect();
+
+  // Wait for node to be synced
+  const isSyncing = await checkSynching(api);
+  if (isSyncing) {
+    api.disconnect();
+    console.log('Node is not synced! Waiting 5 seconds...');
+    await wait(5000);
+    return getAPI();
+  }
+  return api;
+}
+
+/**
+ * Get all transfers in the latest finalized block
+ * @param {Object} blockEvents list of events
+ * @returns {Object} list of transfers
+ */
+function getTransfers(blockEvents) {
+  const transfers = blockEvents
+    .filter((record) => (record.event.section === 'balances' && record.event.method === 'Transfer'))
+    .map(({ event: { data } }) => ({
+      from: data[0].toHuman(),
+      to: data[1].toHuman(),
+      amount: data[2].toHuman(),
+    }));
+  return transfers;
+}
+
+/**
+ * Get receipt of successful transfer sent/received by a specified address
+ * @param {Promise} api chain api
+ * @param {string} address xx network address
+ * @param {boolean} sender true if address is the sender
+ * @returns {Promise}
+ */
+async function getReceipt(api, address, sender) {
+  console.log('Starting finalized blocks listener...');
+
+  return new Promise((reject, resolve) => {
+    api.rpc.chain.subscribeFinalizedHeads(async (header) => {
+      // Get block number
+      const blockNumber = header.number.toNumber();
+      console.log(blockNumber);
+
+      // Get block hash
+      const blockHash = await api.rpc.chain.getBlockHash(blockNumber);
+
+      // Get block events
+      const blockEvents = await api.query.system.events.at(blockHash);
+      const transfers = getTransfers(blockEvents);
+      let transfer;
+      if (sender) {
+        transfer = transfers.filter((tx) => (tx.from === address));
+      } else {
+        transfer = transfers.filter((tx) => (tx.to === address));
+      }
+      if (transfer.length) {
+        console.log(`Found Transfer in block #${blockNumber} ${sender ? 'from' : 'to'} Address: `, transfer);
+        resolve();
+      }
+    });
+  });
+}
+
+/**
+ * Listen to all new finalized blocks after making sure node is in sync
+ * and get receipt of latest committed transfer sent/received by input address
+ */
+async function main() {
+  const api = await getAPI();
+
+  // Insert address of which you want to get a receipt
+  const Alice = '6a6XHUGV5mu33rX1vn3iivxxUR4hwoUapsuECGyHpPzfaNtt';
+  // const Bob = '6YXN1Q6Lx3u8tr2WVr5myb3zNa3pVG5FL3ku8uqckR5RoA21';
+
+  // Define if that address is the sender or recipient of the transfer
+  const sender = true;
+
+  // Subscribe to new finalized blocks
+  await getReceipt(api, Alice, sender);
+}
+
+main().catch((err) => console.error(err)).finally(() => process.exit());

transfers/package.json

+{
+  "name": "get-transfers",
+  "version": "1.0.0",
+  "description": "synchronize with chain and analyze the successful transfers of addresses through the node interfaces",
+  "main": "index.js",
+  "license": "MIT",
+  "scripts": {
+    "start": "node index.js"
+  },
+  "devDependencies": {
+    "eslint": "^8.12.0",
+    "eslint-config-airbnb-base": "^15.0.0",
+    "eslint-plugin-import": "^2.25.4"
+  },
+  "dependencies": {
+    "@polkadot/api": "^7.14.3",
+    "dotenv": "^16.0.0"
+  }
+}