server: Add estimateSmartFee method to the XSNService

server/app/com/xsn/explorer/services/XSNService.scala

@@ -50,6 +50,8 @@ trait XSNService {
 
   def isTPoSContract(txid: TransactionId): FutureApplicationResult[Boolean]
 
+  def estimateSmartFee(confirmationsTarget: Int): FutureApplicationResult[JsValue]
+
   def cleanGenesisBlock(block: rpc.Block): rpc.Block = {
     Option(block)
       .filter(_.hash == genesisBlockhash)
@@ -448,6 +450,27 @@ class XSNServiceRPCImpl @Inject() (
         }
   }
 
+  override def estimateSmartFee(confirmationsTarget: Int): FutureApplicationResult[JsValue] = {
+    val body = s"""
+                  |{
+                  |  "jsonrpc": "1.0",
+                  |  "method": "estimatesmartfee",
+                  |  "params": [$confirmationsTarget]
+                  |}
+                  |""".stripMargin
+
+    server
+        .post(body)
+        .map { response =>
+          val maybe = getResult[JsValue](response)
+
+          maybe.getOrElse {
+            logger.warn(s"Unexpected response from XSN Server, status = ${response.status}, response = ${response.body}")
+
+            Bad(XSNUnexpectedResponseError).accumulating
+          }
+        }
+  }
 
   private def mapError(json: JsValue, errorCodeMapper: Map[Int, ApplicationError]): Option[ApplicationError] = {
     val jsonErrorMaybe = (json \ "error")

server/test/com/xsn/explorer/helpers/DummyXSNService.scala

@@ -26,4 +26,5 @@ class DummyXSNService extends XSNService {
   override def getUnspentOutputs(address: Address): FutureApplicationResult[JsValue] = ???
   override def sendRawTransaction(hex: HexString): FutureApplicationResult[String] = ???
   override def isTPoSContract(txid: TransactionId): FutureApplicationResult[Boolean] = ???
+  override def estimateSmartFee(confirmationsTarget: Int): FutureApplicationResult[JsValue] = ???
 }

server/test/com/xsn/explorer/services/XSNServiceRPCImplSpec.scala

@@ -629,6 +629,20 @@ class XSNServiceRPCImplSpec extends WordSpec {
     }
   }
 
+  "estimateSmartFee" should {
+    "return the result" in {
+      val content = """{"feerate":0.00001,"blocks":2}"""
+      val responseBody = createRPCSuccessfulResponse(Json.parse(content))
+      val json = Json.parse(responseBody)
+
+      mockRequest(request, response)(200, json)
+
+      whenReady(service.estimateSmartFee(1)) { result =>
+        result mustEqual Good(Json.parse(content))
+      }
+    }
+  }
+
   private def mockRequest(request: WSRequest, response: WSResponse)(status: Int, body: JsValue) = {
     when(response.status).thenReturn(status)
     when(response.json).thenReturn(body)