Added State machine to save the current state of the tumbling session

Breeze/src/Breeze.TumbleBit.Client/Controllers/TumbleBitController.cs

@@ -43,7 +43,7 @@ namespace Breeze.TumbleBit.Controllers
             }
             catch (Exception e)
             {                
-                return ErrorHelpers.BuildErrorResponse(HttpStatusCode.BadRequest, $"An error occured connecting to the tumbler.", e.ToString());
+                return ErrorHelpers.BuildErrorResponse(HttpStatusCode.BadRequest, $"An error occured connecting to the tumbler with uri {request.ServerAddress}.", e.ToString());
             }
         }
 
@@ -68,7 +68,7 @@ namespace Breeze.TumbleBit.Controllers
             }
             catch (Exception e)
             {
-                return ErrorHelpers.BuildErrorResponse(HttpStatusCode.BadRequest, $"An error occured connecting to the tumbler.", e.ToString());
+                return ErrorHelpers.BuildErrorResponse(HttpStatusCode.BadRequest, "An error occured starting tumbling session.", e.ToString());
             }
         }
     }

Breeze/src/Breeze.TumbleBit.Client/IStateMachine.cs

+namespace Breeze.TumbleBit.Client
+{
+    public interface IStateMachine
+    {
+        /// <summary>
+        /// Saves the state of the current tumbling session.
+        /// </summary>
+        void Save();
+
+        /// <summary>
+        /// Loads the state of the current tumbling session.
+        /// </summary>
+        /// <returns></returns>
+        IStateMachine Load();
+
+        /// <summary>
+        /// Deletes the state of the current tumbling session..
+        /// </summary>
+        void Delete();
+    }
+}

Breeze/src/Breeze.TumbleBit.Client/ITumbleBitManager.cs

 using System;
-using System.Collections.Generic;
-using System.Text;
 using System.Threading.Tasks;
 using NBitcoin;
 using NTumbleBit.ClassicTumbler;
@@ -27,5 +25,15 @@ namespace Breeze.TumbleBit.Client
         /// <param name="height">The height of the block in the blockchain.</param>
         /// <param name="block">The block.</param>
         void ProcessBlock(int height, Block block);
+
+        /// <summary>
+        /// Pauses the tumbling.
+        /// </summary>
+        void PauseTumbling();
+
+        /// <summary>
+        /// Finishes the tumbling and clean up all saved data.
+        /// </summary>
+        void FinishTumbling();
     }
 }

Breeze/src/Breeze.TumbleBit.Client/Models/SignVoucherRequest.cs

 using NBitcoin;
 using NTumbleBit.ClassicTumbler;
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
 
 namespace Breeze.TumbleBit.Models
 {

Breeze/src/Breeze.TumbleBit.Client/Models/TumblerEscrowKeyResponse.cs

 using NBitcoin;
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
 
 namespace Breeze.TumbleBit.Models
 {

Breeze/src/Breeze.TumbleBit.Client/TumbleBitFeature.cs

 using System;
+using System.Collections.Generic;
 using Breeze.TumbleBit.Client;
 using Breeze.TumbleBit.Controllers;
 using Stratis.Bitcoin.Builder.Feature;
 using Microsoft.Extensions.DependencyInjection;
 using Stratis.Bitcoin.Builder;
-using Stratis.Bitcoin.Logging;
-using Microsoft.Extensions.Logging;
-using Serilog;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
+using Stratis.Bitcoin.Wallet.JsonConverters;
 
 namespace Breeze.TumbleBit
 {
     public class TumbleBitFeature : FullNodeFeature
     {       
-        public TumbleBitFeature()
-        {
-        }
-
         public override void Start()
         {
         }
@@ -35,6 +32,13 @@ namespace Breeze.TumbleBit
                 .AddFeature<TumbleBitFeature>()
                 .FeatureServices(services =>
                     {
+                        JsonConvert.DefaultSettings = () => new JsonSerializerSettings
+                        {
+                            Formatting = Formatting.Indented,                            
+                            ContractResolver = new CamelCasePropertyNamesContractResolver(),
+                            Converters = new List<JsonConverter> { new NetworkConverter() }
+                        };
+
                         services.AddSingleton<ITumbleBitManager, TumbleBitManager> ();
                         services.AddSingleton<TumbleBitController>();
                     });

Breeze/src/Breeze.TumbleBit.Client/TumbleBitManager.cs

@@ -4,7 +4,6 @@ using Microsoft.Extensions.Logging;
 using NBitcoin;
 using NTumbleBit.ClassicTumbler;
 using Stratis.Bitcoin;
-using Stratis.Bitcoin.Logging;
 using Stratis.Bitcoin.Wallet;
 
 namespace Breeze.TumbleBit.Client
@@ -16,11 +15,13 @@ namespace Breeze.TumbleBit.Client
     public class TumbleBitManager : ITumbleBitManager
     {
         private ITumblerService tumblerService;
-
-        private IWalletManager walletManager;
+        private readonly IWalletManager walletManager;
         private readonly ILogger logger;
         private readonly Signals signals;
         private readonly ConcurrentChain chain;
+        private readonly Network network;
+        private TumblingState tumblingState;
+        private IDisposable blockReceiver;
         
         private ClassicTumblerParameters TumblerParameters { get; set; }
 
@@ -29,7 +30,11 @@ namespace Breeze.TumbleBit.Client
             this.walletManager = walletManager;
             this.chain = chain;
             this.signals = signals;
+            this.network = network;
             this.logger = loggerFactory.CreateLogger(this.GetType().FullName);
+
+            // load the persisted tumbling state 
+            this.tumblingState = TumblingState.LoadState();
         }
 
         /// <inheritdoc />
@@ -37,34 +42,85 @@ namespace Breeze.TumbleBit.Client
         {
             this.tumblerService = new TumblerService(serverAddress);
             this.TumblerParameters = await this.tumblerService.GetClassicTumblerParametersAsync();
+
+            if (this.TumblerParameters.Network != this.network)
+            {
+                throw new Exception($"The tumbler is on network {this.TumblerParameters.Network} while the wallet is on network {this.network}.");
+            }
+
+            if (this.tumblingState == null)
+            {
+                this.tumblingState = new TumblingState();
+            }
+            
+            // update and save the state
+            this.tumblingState.TumblerParameters = this.TumblerParameters;
+            this.tumblingState.Save();
+
             return this.TumblerParameters;
         }
 
         /// <inheritdoc />
         public Task TumbleAsync(string destinationWalletName)
         {
+            // make sure the tumbler service is initialized
             if (this.TumblerParameters == null || this.tumblerService == null)
             {
                 throw new Exception("Please connect to the tumbler first.");
             }
 
+            // make sure that the user is not trying to resume the process with a different wallet
+            if (!string.IsNullOrEmpty(this.tumblingState.DestinationWalletName) && this.tumblingState.DestinationWalletName != destinationWalletName)
+            {
+                throw new Exception("Please use the same destination wallet until the end of this tumbling session.");
+            }
+
             Wallet destinationWallet = this.walletManager.GetWallet(destinationWalletName);
             if (destinationWallet == null)
             {
                 throw new Exception($"Destination not found. Have you created a wallet with name {destinationWalletName}?");
             }
 
-            // subscribe to receiving blocks and transactions
-            this.signals.Blocks.Subscribe(new BlockObserver(this.chain, this));
+            // update the state and save
+            this.tumblingState.DestinationWalletName = destinationWalletName;
+            this.tumblingState.Save();
+
+            // subscribe to receiving blocks
+            this.blockReceiver = this.signals.Blocks.Subscribe(new BlockObserver(this.chain, this));
 
             return Task.CompletedTask;
         }
 
+        /// <inheritdoc />
+        public void PauseTumbling()
+        {
+            this.logger.LogDebug($"Stopping the tumbling. Current height is {this.chain.Tip.Height}.");
+            this.blockReceiver.Dispose();
+            this.tumblingState.Save();
+        }
+
+        /// <inheritdoc />
+        public void FinishTumbling()
+        {
+            this.logger.LogDebug($"The tumbling process is wrapping up. Current height is {this.chain.Tip.Height}.");
+            this.blockReceiver.Dispose();
+            this.tumblingState.Delete();
+            this.tumblingState = null;
+        }
+
         /// <inheritdoc />
         public void ProcessBlock(int height, Block block)
         {
             // TODO start the state machine 
             this.logger.LogDebug($"Receive block with height {height}");
+
+            // update the block height in the tumbling state
+            if (this.tumblingState.LastBlockReceivedHeight == 0)
+            {
+                this.tumblingState.StartHeight = height;
+            }
+            this.tumblingState.LastBlockReceivedHeight = height;
+            this.tumblingState.Save();
         }
     }
 }

Breeze/src/Breeze.TumbleBit.Client/TumblingState.cs

+using System;
+using System.IO;
+using System.Runtime.InteropServices;
+using Newtonsoft.Json;
+using NTumbleBit.ClassicTumbler;
+
+namespace Breeze.TumbleBit.Client
+{
+    public class TumblingState : IStateMachine
+    {
+        private const string StateFileName = "tumblebit_state.json";
+
+        [JsonProperty("tumblerParameters")]
+        public ClassicTumblerParameters TumblerParameters { get; set; }
+
+        [JsonProperty("tumblerUri")]
+        public Uri TumblerUri { get; set; }
+
+        [JsonProperty("startHeight")]
+        public int StartHeight { get; set; }
+
+        [JsonProperty("lastBlockReceivedHeight")]
+        public int LastBlockReceivedHeight { get; set; }
+
+        [JsonProperty("destinationWalletName")]
+        public string DestinationWalletName { get; set; }
+
+        /// <inheritdoc />
+        public void Save()
+        {
+            File.WriteAllText(GetStateFilePath(), JsonConvert.SerializeObject(this));
+        }
+
+        /// <inheritdoc />
+        public IStateMachine Load()
+        {
+            return LoadState();
+        }
+
+        /// <inheritdoc />
+        public void Delete()
+        {
+            var stateFilePath = GetStateFilePath();
+            File.Delete(stateFilePath);
+        }
+
+        /// <summary>
+        /// Loads the saved state of the tumbling execution to the file system.
+        /// </summary>
+        /// <returns></returns>
+        public static TumblingState LoadState()
+        {
+            var stateFilePath = GetStateFilePath();
+            if (!File.Exists(stateFilePath))
+            {
+                return null;
+            }
+            
+            // load the file from the local system
+            return JsonConvert.DeserializeObject<TumblingState>(File.ReadAllText(stateFilePath));
+        }
+
+        /// <summary>
+        /// Gets the file path of the file containing the state of the tumbling execution.
+        /// </summary>
+        /// <returns></returns>
+        private static string GetStateFilePath()
+        {
+            string defaultFolderPath;
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                defaultFolderPath = $@"{Environment.GetEnvironmentVariable("AppData")}\Breeze\TumbleBit";
+            }
+            else
+            {
+                defaultFolderPath = $"{Environment.GetEnvironmentVariable("HOME")}/.breeze/TumbleBit";
+            }
+
+            // create the directory if it doesn't exist
+            Directory.CreateDirectory(defaultFolderPath);
+            return Path.Combine(defaultFolderPath, StateFileName);
+        }
+    }
+}