Create blink lightning invoices (BTC, or stablesats) using BTCPay Server

BTCPayServer.Lightning.sln

@@ -31,6 +31,10 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "misc", "misc", "{216059DB-7
 		src\Build\Common.csproj = src\Build\Common.csproj
 	EndProjectSection
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BTCPayServer.Lightning.Blink", "src\BTCPayServer.Lightning.Blink\BTCPayServer.Lightning.Blink.csproj", "{DD000D73-3AD5-465E-9AA9-64802CC88BF3}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BlinkTest", "BlinkTest\BlinkTest.csproj", "{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -149,6 +153,30 @@ Global
 		{B024DBD2-FCF4-4C48-9EBE-09AA7AAF36FB}.Release|x64.Build.0 = Release|Any CPU
 		{B024DBD2-FCF4-4C48-9EBE-09AA7AAF36FB}.Release|x86.ActiveCfg = Release|Any CPU
 		{B024DBD2-FCF4-4C48-9EBE-09AA7AAF36FB}.Release|x86.Build.0 = Release|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Debug|x64.Build.0 = Debug|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Debug|x86.Build.0 = Debug|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Release|Any CPU.Build.0 = Release|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Release|x64.ActiveCfg = Release|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Release|x64.Build.0 = Release|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Release|x86.ActiveCfg = Release|Any CPU
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3}.Release|x86.Build.0 = Release|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Debug|x64.Build.0 = Debug|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Debug|x86.Build.0 = Debug|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Release|Any CPU.Build.0 = Release|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Release|x64.ActiveCfg = Release|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Release|x64.Build.0 = Release|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Release|x86.ActiveCfg = Release|Any CPU
+		{4D375E18-F7FF-4A6D-9994-EE1D0C3C05C3}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -162,6 +190,7 @@ Global
 		{542D3F73-7067-4873-89EF-FA0345E32C04} = {5BA1A1B2-2713-4CF4-9B63-087531598797}
 		{4057015B-9D8A-411A-B7C2-3342D9F53BD0} = {5BA1A1B2-2713-4CF4-9B63-087531598797}
 		{B024DBD2-FCF4-4C48-9EBE-09AA7AAF36FB} = {5BA1A1B2-2713-4CF4-9B63-087531598797}
+		{DD000D73-3AD5-465E-9AA9-64802CC88BF3} = {5BA1A1B2-2713-4CF4-9B63-087531598797}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {5E91C820-C650-4ACA-B064-05ECE0A74CE8}

BlinkTest/BlinkTest.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\src\BTCPayServer.Lightning.Blink\BTCPayServer.Lightning.Blink.csproj" />
+  </ItemGroup>
+</Project>

BlinkTest/Program.cs

@@ -0,0 +1,38 @@
+using System.Text.Json;
+
+using BTCPayServer.Lightning.Blink;
+using BTCPayServer.Lightning.Blink.Utilities;
+
+Uri apiUri = new Uri("https://api.blink.sv/graphql");
+// put your blink API key here
+string apiKey = "";
+
+// To include your stablesats in your total balance as converted to sats
+// var blinkApiClient = new BlinkApiClient(apiUri, apiKey, true);
+var blinkApiClient = new BlinkApiClient(apiUri, apiKey, false);
+
+var defaultWallet = await blinkApiClient.GetDefaultWallet(CancellationToken.None);
+Console.WriteLine(defaultWallet.Id);
+
+var totalBalance = await blinkApiClient.GetBalance(CancellationToken.None);
+Console.WriteLine(totalBalance.OffchainBalance.Local);
+
+var createIncoiceResponse = await blinkApiClient.CreateLnInvoice(
+    CancellationToken.None,
+    100L,
+    TimeSpan.FromMinutes(10),
+    "a memo to remember");
+
+string jsonResponse = JsonSerializer.Serialize(createIncoiceResponse, new JsonSerializerOptions { WriteIndented = true });
+Console.WriteLine(jsonResponse);
+
+var btcRate = await blinkApiClient.getBtcRate(CancellationToken.None);
+
+var convertedToSats = RateConversions.convertCentsToSats(createIncoiceResponse.Amount, btcRate);
+var deviation = (createIncoiceResponse.AmountReceived - convertedToSats) / createIncoiceResponse.AmountReceived * 100;
+
+Console.WriteLine($"Invoice created with {createIncoiceResponse.Amount.MilliSatoshi} {defaultWallet.WalletCurrency}");
+Console.WriteLine($"Conversion rate is {btcRate.Base} / 10^{btcRate.Offset}");
+Console.WriteLine($"My own conversion: {convertedToSats} sats");
+Console.WriteLine($"Received sats: {createIncoiceResponse.AmountReceived.MilliSatoshi}");
+Console.WriteLine($"Deviation: %{deviation}");

src/BTCPayServer.Lightning.Blink/BTCPayServer.Lightning.Blink.csproj

@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="GraphQL.Client.Serializer.Newtonsoft" Version="6.0.2" />
+    <PackageReference Include="GraphQL.Client" Version="6.0.2" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\BTCPayServer.Lightning.Common\BTCPayServer.Lightning.Common.csproj" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Remove="Models\" />
+    <None Remove="Models\Responses\" />
+    <None Remove="Utilities\" />
+  </ItemGroup>
+  <ItemGroup>
+    <Folder Include="Models\" />
+    <Folder Include="Models\Responses\" />
+    <Folder Include="Utilities\" />
+  </ItemGroup>
+</Project>

src/BTCPayServer.Lightning.Blink/BlinkApiClient.cs

@@ -0,0 +1,234 @@
+using GraphQL;
+using GraphQL.Client.Http;
+using GraphQL.Client.Serializer.Newtonsoft;
+
+using BTCPayServer.Lightning.Blink.Models.Responses;
+using BTCPayServer.Lightning.Blink.Models;
+using BTCPayServer.Lightning.Blink.Utilities;
+
+namespace BTCPayServer.Lightning.Blink;
+
+public class BlinkApiClient
+{
+    private Uri _baseUri;
+    private string _apiKey;
+    private bool _includeStablesats;
+
+    public BlinkApiClient(Uri baseUri, string apiKey, bool includeStablesats = false)
+    {
+        _baseUri = baseUri;
+        _apiKey = apiKey;
+        _includeStablesats = includeStablesats;
+    }
+
+    public async Task<BlinkWallet> GetDefaultWallet(CancellationToken cancellationToken)
+    {
+        string query = @"
+            query GetDefaultWallet {
+                me {
+                    defaultAccount {
+                        defaultWalletId
+                        wallets {
+                            balance
+                            id
+                            walletCurrency
+                        }
+                    }
+                }
+            }";
+
+        var defaultWalletRequest = new GraphQLRequest
+        {
+            Query = query,
+            OperationName = "GetDefaultWallet"
+        };
+
+        var response = await getGraphQLHttpClient().SendQueryAsync<GetDefaultWalletIdResponse>(defaultWalletRequest, cancellationToken);
+        string defaultWalletId = response.Data.Me.DefaultAccount.DefaultWalletId;
+        var defaultWallet = response.Data.Me.DefaultAccount.Wallets.Find((w) => w.Id == defaultWalletId);
+
+        if (defaultWallet == null)
+        {
+            throw new Exception(string.Format("Could not find wallet information for wallet id {0}", defaultWalletId));
+        }
+
+        return new BlinkWallet
+        {
+            Id = defaultWallet.Id,
+            Balance = defaultWallet.Balance,
+            WalletCurrency = defaultWallet.WalletCurrency
+        };
+    }
+
+    public async Task<PriceInfo> getBtcRate(CancellationToken cancellationToken)
+    {
+        string query = @"
+            query RealtimePrice($currency: DisplayCurrency) {
+              realtimePrice(currency: $currency) {
+                btcSatPrice {
+                  base,
+                  offset
+                }
+              }
+            }";
+
+        var getBtcRateRequest = new GraphQLRequest
+        {
+            Query = query,
+            Variables = new
+            {
+                input = new
+                {
+                    currency = "USD"
+                }
+            }
+        };
+
+        var response = await getGraphQLHttpClient().SendQueryAsync<GetBtcRateResponse>(getBtcRateRequest, cancellationToken);
+
+        return response.Data.RealtimePrice.BtcSatPrice;
+    }
+
+    public async Task<LightningNodeBalance> GetBalance(CancellationToken cancellationToken)
+    {
+        string realtimePriceQuery = _includeStablesats
+            ? @"realtimePrice {
+                    btcSatPrice {
+                      base
+                      offset
+                    }
+                    denominatorCurrency
+                  }"
+            : "";
+
+        string query = $@"
+            query GetWalletBalances {{
+                me {{
+                    defaultAccount {{
+                      defaultWalletId,
+                      wallets {{
+                        balance
+                        id
+                        walletCurrency
+                      }}
+                    }}
+                }}
+                {realtimePriceQuery}
+            }}";
+
+        var balancesRequest = new GraphQLRequest
+        {
+            Query = query,
+            OperationName = "GetWalletBalances"
+        };
+
+        var response = await getGraphQLHttpClient().SendQueryAsync<GetWalletBalancesResponse>(balancesRequest, cancellationToken);
+        var responseData = response.Data;
+
+        long totalBalanceSats = responseData.Me.DefaultAccount.Wallets.Sum(wallet =>
+        {
+            if (wallet.WalletCurrency == "USD")
+            {
+                var realtimePrice = responseData.RealtimePrice;
+
+                if (_includeStablesats
+                        && realtimePrice != null
+                        && realtimePrice.BtcSatPrice != null
+                        && realtimePrice.DenominatorCurrency == "USD")
+                {
+                    return RateConversions.convertCentsToSats(wallet.Balance, realtimePrice.BtcSatPrice);
+                }
+
+                return 0;
+            } else
+            {
+                return wallet.Balance;
+            }
+        });
+
+        var offchain = new OffchainBalance
+        {
+            Local = new LightMoney(totalBalanceSats, LightMoneyUnit.MilliSatoshi)
+        };
+
+        return new LightningNodeBalance(null, offchain);
+    }
+
+    public async Task<LightningInvoice> CreateLnInvoice(CancellationToken cancellationToken, long amount, TimeSpan expiresIn, string? memo = null)
+    {
+        var wallet = await this.GetDefaultWallet(cancellationToken);
+
+        string apiCall = wallet.WalletCurrency == "USD" ? "lnUsdInvoiceCreate" : "LnInvoiceCreate";
+
+        string query = $@"
+            mutation {apiCall}($input: {apiCall.Capitalize()}Input!) {{
+              {apiCall}(input: $input) {{
+                invoice {{
+                  paymentRequest
+                  paymentHash
+                  paymentSecret
+                  satoshis
+                }}
+                errors {{
+                  message
+                }}
+              }}
+            }}";
+
+        var createLnInvoiceRequest = new GraphQLRequest
+        {
+            Query = query,
+            OperationName = apiCall,
+            Variables = new
+            {
+                input = new
+                {
+                    amount,
+                    walletId = wallet.Id,
+                    expiresIn,
+                    memo
+                }
+            }
+        };
+
+        var response = await getGraphQLHttpClient().SendMutationAsync<LnInvoiceCreateResponse>(createLnInvoiceRequest, cancellationToken);
+        var graphQlErrors = response.Errors;
+
+        if (graphQlErrors != null && graphQlErrors.Length > 0)
+        {
+            var messages = string.Join(", ", graphQlErrors.Select(e => e.Message));
+            throw new Exception($"An error occured with invoice creation query: {messages}");
+        }
+
+        var invoiceData = response.Data.LnInvoiceCreate != null
+            ? response.Data.LnInvoiceCreate
+            : response.Data.LnUsdInvoiceCreate;
+
+        if (invoiceData.Errors.Count > 0)
+        {
+            var messages = string.Join(", ", invoiceData.Errors.Select(e => e.Message));
+            throw new Exception($"An error occured with invoice creation: {messages}");
+        }
+
+        return new LightningInvoice
+        {
+            Amount = amount,
+            PaymentHash = invoiceData.Invoice.PaymentHash,
+            ExpiresAt = DateTimeOffset.UtcNow.Add(expiresIn),
+            AmountReceived = invoiceData.Invoice.Satoshis,
+            Status = LightningInvoiceStatus.Unpaid,
+            BOLT11 = invoiceData.Invoice.PaymentRequest,
+            Preimage = invoiceData.Invoice.PaymentSecret
+        };
+    }
+
+    private GraphQLHttpClient getGraphQLHttpClient() {
+        var graphQLClient = new GraphQLHttpClient(_baseUri, new NewtonsoftJsonSerializer());
+
+        graphQLClient.HttpClient.DefaultRequestHeaders.Clear();
+        graphQLClient.HttpClient.DefaultRequestHeaders.Add("X-API-KEY", _apiKey);
+        graphQLClient.HttpClient.DefaultRequestHeaders.Add("User-Agent", "BTCPayServer.Lightning.BlinkApiClient");
+
+        return graphQLClient;
+    }
+}