Adding optional Blockstream esplora backend support.

backend/mempool-config.sample.json

@@ -19,5 +19,7 @@
   "BITCOIN_NODE_PORT": 8332,
   "BITCOIN_NODE_USER": "",
   "BITCOIN_NODE_PASS": "",
+  "BACKEND_API": "bitcoind",
+  "ESPLORA_API_URL": "https://www.blockstream.info/api",
   "TX_PER_SECOND_SPAN_SECONDS": 150
 }

backend/package.json

@@ -9,6 +9,7 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
+    "axios": "^0.19.0",
     "bitcoin": "^3.0.1",
     "compression": "^1.7.3",
     "express": "^4.16.3",

backend/src/api/bitcoin/bitcoin-api-abstract-factory.ts

@@ -0,0 +1,10 @@
+import { IMempoolInfo, ITransaction, IBlock } from '../../interfaces';
+
+export interface AbstractBitcoinApi {
+  getMempoolInfo(): Promise<IMempoolInfo>;
+  getRawMempool(): Promise<ITransaction['txid'][]>;
+  getRawTransaction(txId: string): Promise<ITransaction>;
+  getBlockCount(): Promise<number>;
+  getBlock(hash: string): Promise<IBlock>;
+  getBlockHash(height: number): Promise<string>;
+}

backend/src/api/bitcoin/bitcoin-api-factory.ts

@@ -0,0 +1,16 @@
+const config = require('../../../mempool-config.json');
+import { AbstractBitcoinApi } from './bitcoin-api-abstract-factory';
+import BitcoindApi from './bitcoind-api';
+import EsploraApi from './esplora-api';
+
+function factory(): AbstractBitcoinApi {
+  switch (config.BACKEND_API) {
+    case 'esplora':
+      return new EsploraApi();
+    case 'bitcoind':
+    default:
+      return new BitcoindApi();
+  }
+}
+
+export default factory();

backend/src/api/bitcoin/bitcoind-api.ts

@@ -1,8 +1,9 @@
-const config = require('../../mempool-config.json');
+const config = require('../../../mempool-config.json');
 import * as bitcoin from 'bitcoin';
-import { ITransaction, IMempoolInfo, IBlock } from '../interfaces';
+import { ITransaction, IMempoolInfo, IBlock } from '../../interfaces';
+import { AbstractBitcoinApi } from './bitcoin-api-abstract-factory';
 
-class BitcoinApi {
+class BitcoindApi implements AbstractBitcoinApi {
   client: any;
 
   constructor() {
@@ -81,4 +82,4 @@ class BitcoinApi {
   }
 }
 
-export default new BitcoinApi();
+export default BitcoindApi;

backend/src/api/bitcoin/esplora-api.ts

@@ -0,0 +1,99 @@
+const config = require('../../../mempool-config.json');
+import { ITransaction, IMempoolInfo, IBlock } from '../../interfaces';
+import { AbstractBitcoinApi } from './bitcoin-api-abstract-factory';
+import axios, { AxiosResponse } from 'axios';
+
+class EsploraApi implements AbstractBitcoinApi {
+  client: any;
+
+  constructor() {
+    this.client = axios.create({
+      baseURL: config.ESPLORA_API_URL,
+      timeout: 15000,
+    });
+  }
+
+  getMempoolInfo(): Promise<IMempoolInfo> {
+    return new Promise(async (resolve, reject) => {
+      try {
+        const response: AxiosResponse = await this.client.get('/mempool');
+        resolve({
+          size: response.data.count,
+          bytes: response.data.vsize,
+        });
+      } catch (error) {
+        reject(error);
+      }
+    });
+  }
+
+  getRawMempool(): Promise<ITransaction['txid'][]> {
+    return new Promise(async (resolve, reject) => {
+      try {
+        const response: AxiosResponse = await this.client.get('/mempool/txids');
+        resolve(response.data);
+      } catch (error) {
+        reject(error);
+      }
+    });
+  }
+
+  getRawTransaction(txId: string): Promise<ITransaction> {
+    return new Promise(async (resolve, reject) => {
+      try {
+        const response: AxiosResponse = await this.client.get('/tx/' + txId);
+
+        response.data.vsize = response.data.size;
+        response.data.size = response.data.weight;
+        response.data.fee = response.data.fee / 100000000;
+
+        resolve(response.data);
+      } catch (error) {
+        reject(error);
+      }
+    });
+  }
+
+  getBlockCount(): Promise<number> {
+    return new Promise(async (resolve, reject) => {
+      try {
+        const response: AxiosResponse = await this.client.get('/blocks/tip/height');
+        resolve(response.data);
+      } catch (error) {
+        reject(error);
+      }
+    });
+  }
+
+  getBlock(hash: string): Promise<IBlock> {
+    return new Promise(async (resolve, reject) => {
+      try {
+        const blockInfo: AxiosResponse = await this.client.get('/block/' + hash);
+        const blockTxs: AxiosResponse = await this.client.get('/block/' + hash + '/txids');
+
+        const block = blockInfo.data;
+        block.hash = hash;
+        block.nTx = block.tx_count;
+        block.time = block.timestamp;
+        block.tx = blockTxs.data;
+
+        resolve(block);
+      } catch (error) {
+        reject(error);
+      }
+    });
+  }
+
+  getBlockHash(height: number): Promise<string> {
+    return new Promise(async (resolve, reject) => {
+      try {
+        const response: AxiosResponse = await this.client.get('/block-height/' + height);
+        resolve(response.data);
+      } catch (error) {
+        reject(error);
+      }
+    });
+  }
+}
+
+export default EsploraApi;

backend/src/api/blocks.ts

@@ -1,5 +1,5 @@
 const config = require('../../mempool-config.json');
-import bitcoinApi from './bitcoin-api-wrapper';
+import bitcoinApi from './bitcoin/bitcoin-api-factory';
 import { DB } from '../database';
 import { IBlock, ITransaction } from '../interfaces';
 import memPool from './mempool';
@@ -56,7 +56,7 @@ class Blocks {
           block = storedBlock;
         } else {
           const blockHash = await bitcoinApi.getBlockHash(this.currentBlockHeight);
-          block = await bitcoinApi.getBlock(blockHash, 1);
+          block = await bitcoinApi.getBlock(blockHash);
 
           const coinbase = await memPool.getRawTransaction(block.tx[0], true);
           if (coinbase && coinbase.totalOut) {
@@ -74,6 +74,7 @@ class Blocks {
               transactions.push(mempool[block.tx[i]]);
               found++;
             } else {
+              console.log(`Fetching block tx ${i} of ${block.tx.length}`);
               const tx = await memPool.getRawTransaction(block.tx[i]);
               if (tx) {
                 transactions.push(tx);

backend/src/api/mempool.ts

@@ -1,5 +1,5 @@
 const config = require('../../mempool-config.json');
-import bitcoinApi from './bitcoin-api-wrapper';
+import bitcoinApi from './bitcoin/bitcoin-api-factory';
 import { ITransaction, IMempoolInfo, IMempool } from '../interfaces';
 
 class Mempool {
@@ -52,32 +52,40 @@ class Mempool {
   public async getRawTransaction(txId: string, isCoinbase = false): Promise<ITransaction | false> {
     try {
       const transaction = await bitcoinApi.getRawTransaction(txId);
-      let totalIn = 0;
-      if (!isCoinbase) {
-        for (let i = 0; i < transaction.vin.length; i++) {
-          try {
-            const result = await bitcoinApi.getRawTransaction(transaction.vin[i].txid);
-            transaction.vin[i]['value'] = result.vout[transaction.vin[i].vout].value;
-            totalIn += result.vout[transaction.vin[i].vout].value;
-          } catch (err) {
-            console.log('Locating historical tx error');
-          }
-        }
-      }
+
       let totalOut = 0;
       transaction.vout.forEach((output) => totalOut += output.value);
 
-      if (totalIn > totalOut) {
-        transaction.fee = parseFloat((totalIn - totalOut).toFixed(8));
+      if (config.BACKEND_API === 'esplora') {
         transaction.feePerWeightUnit = (transaction.fee * 100000000) / (transaction.vsize * 4) || 0;
         transaction.feePerVsize = (transaction.fee * 100000000) / (transaction.vsize) || 0;
-      } else if (!isCoinbase) {
-        transaction.fee = 0;
-        transaction.feePerVsize = 0;
-        transaction.feePerWeightUnit = 0;
-        console.log('Minus fee error!');
+        transaction.totalOut = totalOut / 100000000;
+      } else {
+        let totalIn = 0;
+        if (!isCoinbase) {
+          for (let i = 0; i < transaction.vin.length; i++) {
+            try {
+              const result = await bitcoinApi.getRawTransaction(transaction.vin[i].txid);
+              transaction.vin[i]['value'] = result.vout[transaction.vin[i].vout].value;
+              totalIn += result.vout[transaction.vin[i].vout].value;
+            } catch (err) {
+              console.log('Locating historical tx error');
+            }
+          }
+        }
+
+        if (totalIn > totalOut) {
+          transaction.fee = parseFloat((totalIn - totalOut).toFixed(8));
+          transaction.feePerWeightUnit = (transaction.fee * 100000000) / (transaction.vsize * 4) || 0;
+          transaction.feePerVsize = (transaction.fee * 100000000) / (transaction.vsize) || 0;
+        } else if (!isCoinbase) {
+          transaction.fee = 0;
+          transaction.feePerVsize = 0;
+          transaction.feePerWeightUnit = 0;
+          console.log('Minus fee error!');
+        }
+        transaction.totalOut = totalOut;
       }
-      transaction.totalOut = totalOut;
       return transaction;
     } catch (e) {
       console.log(txId + ' not found');

backend/src/index.ts

@@ -6,7 +6,7 @@ import * as http from 'http';
 import * as https from 'https';
 import * as WebSocket from 'ws';
 
-import bitcoinApi from './api/bitcoin-api-wrapper';
+import bitcoinApi from './api/bitcoin/bitcoin-api-factory';
 import diskCache from './api/disk-cache';
 import memPool from './api/mempool';
 import blocks from './api/blocks';
@@ -55,7 +55,7 @@ class MempoolSpace {
         port: 8999
     };
     this.server.listen(opts, () => {
-      console.log(`Server started on ${opts.host}:${opts.port})`);
+      console.log(`Server started on ${opts.host}:${opts.port}`);
     });
   }
 

backend/src/interfaces.ts

@@ -1,10 +1,10 @@
 export interface IMempoolInfo {
   size: number;
   bytes: number;
-  usage: number;
-  maxmempool: number;
-  mempoolminfee: number;
-  minrelaytxfee: number;
+  usage?: number;
+  maxmempool?: number;
+  mempoolminfee?: number;
+  minrelaytxfee?: number;
 }
 
 export interface ITransaction {

frontend/src/app/blockchain-blocks/blockchain-blocks.component.ts

@@ -22,6 +22,9 @@ export class BlockchainBlocksComponent implements OnInit, OnDestroy {
   ngOnInit() {
     this.blocksSubscription = this.memPoolService.blocks$
       .subscribe((block) => {
+        if (this.blocks.some((b) => b.height === block.height)) {
+          return;
+        }
         this.blocks.unshift(block);
         this.blocks = this.blocks.slice(0, 8);
       });