From d4c83ebb419bc7b39f5e3a351cf7e8c8ccf07f54 Mon Sep 17 00:00:00 2001
From: Ruslan <emkil.russel@gmail.com>
Date: Tue, 14 Jun 2022 11:44:44 +0300
Subject: [PATCH] Unsubscribe from the remote storage (#25)

* unsubscribe from remote storage when cancelling subscription request

* bump library version

* fix request call
---
 SubstrateSdk.podspec                          |  2 +-
 SubstrateSdk/Classes/Network/RPCMethod.swift  |  1 +
 .../Classes/Network/WebSocketEngine.swift     | 35 +++++++++++++++++++
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/SubstrateSdk.podspec b/SubstrateSdk.podspec
index a0c232d..1fb13a5 100644
--- a/SubstrateSdk.podspec
+++ b/SubstrateSdk.podspec
@@ -8,7 +8,7 @@
 
 Pod::Spec.new do |s|
   s.name             = 'SubstrateSdk'
-  s.version          = '1.1.0'
+  s.version          = '1.2.0'
   s.summary          = 'Utility library that implements clients specific logic to interact with substrate based networks'
 
   s.homepage         = 'https://github.com/nova-wallet/substrate-sdk-ios'
diff --git a/SubstrateSdk/Classes/Network/RPCMethod.swift b/SubstrateSdk/Classes/Network/RPCMethod.swift
index 4371e99..9422f83 100644
--- a/SubstrateSdk/Classes/Network/RPCMethod.swift
+++ b/SubstrateSdk/Classes/Network/RPCMethod.swift
@@ -2,6 +2,7 @@ import Foundation
 
 public enum RPCMethod {
     public static let storageSubscribe = "state_subscribeStorage"
+    public static let storageUnsubscribe = "state_unsubscribeStorage"
     public static let chain = "system_chain"
     public static let getStorage = "state_getStorage"
     public static let getStorageKeysPaged = "state_getKeysPaged"
diff --git a/SubstrateSdk/Classes/Network/WebSocketEngine.swift b/SubstrateSdk/Classes/Network/WebSocketEngine.swift
index 6fa8be6..da14a12 100644
--- a/SubstrateSdk/Classes/Network/WebSocketEngine.swift
+++ b/SubstrateSdk/Classes/Network/WebSocketEngine.swift
@@ -443,6 +443,41 @@ extension WebSocketEngine {
                 error: JSONRPCEngineError.clientCancelled
             )
         }
+
+        // check whether there is subscription for this id and send unsubscribe request
+
+        if let subscription = subscriptions[identifier], let remoteId = subscription.remoteId {
+            unsubscribe(for: remoteId)
+        }
+
+        subscriptions[identifier] = nil
+    }
+
+    func unsubscribe(for remoteId: String) {
+        pendingSubscriptionResponses[remoteId] = nil
+
+        do {
+            let request = try prepareRequest(
+                method: RPCMethod.storageUnsubscribe,
+                params: [remoteId],
+                options: JSONRPCOptions()
+            ) { [weak self] (result: (Result<Bool, Error>)) in
+                self?.provideUnsubscriptionResult(result, remoteId: remoteId)
+            }
+
+            updateConnectionForRequest(request)
+        } catch {
+            logger?.error("(\(chainName):\(selectedURL)) Failed to create unsubscription request: \(error)")
+        }
+    }
+
+    func provideUnsubscriptionResult(_ result: (Result<Bool, Error>), remoteId: String) {
+        switch result {
+        case let .success(isSuccess):
+            logger?.debug("(\(chainName):\(selectedURL)) Unsubscription request completed \(remoteId): \(isSuccess)")
+        case let .failure(error):
+            logger?.error("(\(chainName):\(selectedURL)) Unsubscription request failed \(remoteId): \(error)")
+        }
     }
 
     func completeRequestForRemoteId(_ identifier: UInt16, data: Data) {