feat: add gRPC method to estimate fee

lib/chain/ChainClient.ts

@@ -107,7 +107,7 @@ class ChainClient extends BaseClient implements ChainClientInterface {
     const feeResponse = await this.rpcClient.call<number>('estimatefee', numberBlocks);
     const feePerKb = feeResponse * 100000000;
 
-    return Math.ceil(feePerKb / 1000);
+    return Math.round(feePerKb / 1000);
   }
 
   public generate = (blocks: number): Promise<string[]> => {

lib/grpc/GrpcServer.ts

@@ -1,12 +1,12 @@
 import fs from 'fs';
+import assert from 'assert';
 import { pki, md } from 'node-forge';
 import grpc, { Server } from 'grpc';
-import Logger from '../Logger';
 import Errors from './Errors';
+import Logger from '../Logger';
 import GrpcService from './GrpcService';
 import Service from '../service/Service';
 import { BoltzService } from '../proto/boltzrpc_grpc_pb';
-import assert from 'assert';
 
 type GrpcConfig = {
   host: string,
@@ -27,6 +27,7 @@ class GrpcServer {
       getBalance: grpcService.getBalance,
       newAddress: grpcService.newAddress,
       getTransaction: grpcService.getTransaction,
+      getFeeEstimation: grpcService.getFeeEstimation,
       broadcastTransaction: grpcService.broadcastTransaction,
       listenOnAddress: grpcService.listenOnAddress,
       subscribeTransactions: grpcService.subscribeTransactions,

lib/grpc/GrpcService.ts

@@ -48,6 +48,14 @@ class GrpcService {
     }
   }
 
+  public getFeeEstimation: grpc.handleUnaryCall<boltzrpc.GetFeeEstimationRequest, boltzrpc.GetFeeEstimationResponse> = async (call, callback) => {
+    try {
+      callback(null, await this.service.getFeeEstimation(call.request.toObject()));
+    } catch (error) {
+      callback(error, null);
+    }
+  }
+
   public broadcastTransaction: grpc.handleUnaryCall<boltzrpc.BroadcastTransactionRequest,
   boltzrpc.BroadcastTransactionResponse> = async (call, callback) => {