Add BIP-329 wallet label import (#7457)

diff --git a/BTCPayServer.Tests/FastTests.cs b/BTCPayServer.Tests/FastTests.cs
index b6086d3..8664943 100644
--- a/BTCPayServer.Tests/FastTests.cs
+++ b/BTCPayServer.Tests/FastTests.cs
@@ -29,6 +29,7 @@ using BTCPayServer.Services.Fees;
 using BTCPayServer.Services.Invoices;
 using BTCPayServer.Services.Rates;
 using BTCPayServer.Services.Wallets;
+using BTCPayServer.Services.Wallets.Import;
 using BTCPayServer.Validation;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Configuration.Memory;
@@ -226,6 +227,39 @@ namespace BTCPayServer.Tests
             Assert.False(blob.ReceiptOptions.Enabled);
         }
 
+        [Fact]
+        public async Task CanParseBip329LabelsImport()
+        {
+            var network = Network.RegTest;
+            var txId = "aecb52b892f5e12454b3ee1ad554ffe28c1cca35ffdfaa441c74a30cf7a279f0";
+            var address = new Key().PubKey.GetAddress(ScriptPubKeyType.Segwit, network).ToString();
+            var mainnetAddress = new Key().PubKey.GetAddress(ScriptPubKeyType.Segwit, Network.Main).ToString();
+            var input =
+                $"{{\"type\":\"tx\",\"ref\":\"{txId.ToUpperInvariant()}\",\"label\":\" fee reimbursement \"}}\n" +
+                $"{{\"type\":\"addr\",\"ref\":\"{address}\",\"label\":\"donations\"}}\n" +
+                $"{{\"type\":\"output\",\"ref\":\"{txId}:1\",\"label\":\"change\"}}\n" +
+                "\n" +
+                $"{{\"type\":\"tx\",\"ref\":\"{txId.ToUpperInvariant()}\",\"label\":\" fee reimbursement \"}}\n" +
+                $"{{\"type\":\"addr\",\"ref\":\"{mainnetAddress}\",\"label\":\"wrong network\"}}\n" +
+                $"{{\"type\":\"xpub\",\"ref\":\"xpub-ref\",\"label\":\"unsupported type\"}}\n" +
+                $"{{\"type\":\"tx\",\"ref\":\"not-a-txid\",\"label\":\"bad ref\"}}\n" +
+                $"{{\"type\":\"tx\",\"ref\":\"{txId}\",\"label\":\"\"}}\n" +
+                $"{{\"type\":\"tx\",\"ref\":\"{txId}\"}}\n" +
+                $"{{\"type\":\"tx\",\"ref\":\"{txId}\",\"label\":{{}}}}\n" +
+                $"{{\"type\":\"tx\",\"ref\":[1],\"label\":\"array ref\"}}\n" +
+                $"{{\"type\":5,\"ref\":\"{txId}\",\"label\":\"numeric type\"}}\n" +
+                "not json\n";
+
+            var result = await Bip329Import.Parse(new StringReader(input), network);
+
+            Assert.Equal(3, result.Labels.Count);
+            // duplicate line deduped, invalid lines skipped, blank line ignored
+            Assert.Equal(9, result.SkippedLines);
+            Assert.Contains(result.Labels, l => l is { ObjectType: WalletObjectData.Types.Tx, Label: "fee reimbursement" } && l.ObjectId == txId);
+            Assert.Contains(result.Labels, l => l is { ObjectType: WalletObjectData.Types.Address, Label: "donations" } && l.ObjectId == address);
+            Assert.Contains(result.Labels, l => l is { ObjectType: WalletObjectData.Types.Utxo, Label: "change" } && l.ObjectId == OutPoint.Parse($"{txId}-1").ToString());
+        }
+
         [Fact]
         public void CanParsePaymentMethodId()
         {
diff --git a/BTCPayServer.Tests/WalletTests.cs b/BTCPayServer.Tests/WalletTests.cs
index a57aecb..36ed976 100644
--- a/BTCPayServer.Tests/WalletTests.cs
+++ b/BTCPayServer.Tests/WalletTests.cs
@@ -778,11 +778,38 @@ public class WalletTests(ITestOutputHelper helper) : UnitTestBase(helper)
         });
 
         await s.InWalletTransactions().AssertHasLabels(targetLabel);
+
+        // Import BIP-329 labels from the transactions page toolbar (#6663)
+        var walletId = new WalletId(s.StoreId, "BTC");
+        const string toolbarLabel = "bip329-toolbar";
+        var toolbarTxId = transactions[1].TransactionHash.ToString();
+        var toolbarFile = Path.Combine(Path.GetTempPath(), $"bip329-{Guid.NewGuid():N}.jsonl");
+        await File.WriteAllTextAsync(toolbarFile, $"{{\"type\":\"tx\",\"ref\":\"{toolbarTxId}\",\"label\":\"{toolbarLabel}\"}}\n");
+        await s.Page.SetInputFilesAsync("#Dropdowns .wallet-labels__import-file", toolbarFile);
+        await s.Page.WaitForURLAsync(s.ServerUri + $"wallets/{walletId}/labels");
+        await s.FindAlertMessage(partialText: "Imported 1 label(s).");
+        var toolbarTx = await client.GetOnChainWalletTransaction(s.StoreId, "BTC", toolbarTxId);
+        Assert.Contains(toolbarLabel, toolbarTx.Labels.Keys);
+
+        await s.GoToWalletTransactions(s.WalletId);
         // The label dropdown exposes a "Manage Labels" link that navigates to the wallet labels page (#7252)
         await s.SearchFilters.LabelSelectorToggle.ClickAsync();
         await s.Page.ClickAsync("#LabelSelectorMenu a:has-text('Manage Labels')");
-        var walletId = new WalletId(s.StoreId , "BTC");
         await s.Page.WaitForURLAsync(s.ServerUri + $"wallets/{walletId}/labels");
+
+        // Import BIP-329 labels from the wallet labels page (#6663)
+        const string importedLabel = "bip329-imported";
+        var importedTxId = transactions[0].TransactionHash.ToString();
+        var importFile = Path.Combine(Path.GetTempPath(), $"bip329-{Guid.NewGuid():N}.jsonl");
+        await File.WriteAllTextAsync(importFile,
+            $"{{\"type\":\"tx\",\"ref\":\"{importedTxId}\",\"label\":\"{importedLabel}\"}}\n" +
+            "not json\n");
+        await s.Page.SetInputFilesAsync(".wallet-labels__import-file", importFile);
+        await s.Page.ClickAsync(".wallet-labels__import-button");
+        await s.FindAlertMessage(partialText: "Imported 1 label(s), skipped 1 line(s).");
+        Assert.True(await s.Page.Locator($".transaction-label:has-text('{importedLabel}')").IsVisibleAsync());
+        var importedTx = await client.GetOnChainWalletTransaction(s.StoreId, "BTC", importedTxId);
+        Assert.Contains(importedLabel, importedTx.Labels.Keys);
     }
 
     [Fact]
diff --git a/BTCPayServer/Plugins/Wallets/Controllers/UIWalletsController.cs b/BTCPayServer/Plugins/Wallets/Controllers/UIWalletsController.cs
index 6f5564f..395d55c 100644
--- a/BTCPayServer/Plugins/Wallets/Controllers/UIWalletsController.cs
+++ b/BTCPayServer/Plugins/Wallets/Controllers/UIWalletsController.cs
@@ -3,6 +3,7 @@ using System;
 using System.Collections.Generic;
 using System.Data.Common;
 using System.Globalization;
+using System.IO;
 using System.Linq;
 using System.Net.Mime;
 using System.Text;
@@ -33,6 +34,7 @@ using BTCPayServer.Services.Rates;
 using BTCPayServer.Services.Stores;
 using BTCPayServer.Services.Wallets;
 using BTCPayServer.Services.Wallets.Export;
+using BTCPayServer.Services.Wallets.Import;
 using BTCPayServer.Plugins.Wallets;
 using Dapper;
 using Microsoft.AspNetCore.Authorization;
@@ -2274,6 +2276,46 @@ namespace BTCPayServer.Controllers
             return RedirectToAction(nameof(WalletLabels), new { walletId });
         }
 
+        const int MaxLabelImportSize = 1_000_000;
+        [HttpPost("{walletId}/labels/import")]
+        [Authorize(Policy = WalletPolicies.CanManageWalletTransactions, AuthenticationSchemes = AuthenticationSchemes.Cookie)]
+        public async Task<IActionResult> ImportWalletLabels(
+            [ModelBinder(typeof(WalletIdModelBinder))]
+            WalletId walletId, IFormFile? file)
+        {
+            if (file is null || file.Length == 0)
+            {
+                TempData[WellKnownTempData.ErrorMessage] = StringLocalizer["Please select a BIP-329 file to import."].Value;
+                return RedirectToAction(nameof(WalletLabels), new { walletId });
+            }
+
+            if (file.Length > MaxLabelImportSize)
+            {
+                TempData[WellKnownTempData.ErrorMessage] = StringLocalizer["The import file is too big (1 MB maximum)."].Value;
+                return RedirectToAction(nameof(WalletLabels), new { walletId });
+            }
+
+            var network = handlers.GetBitcoinHandler(walletId.CryptoCode).Network;
+            using var reader = new StreamReader(file.OpenReadStream());
+            var import = await Bip329Import.Parse(reader, network.NBitcoinNetwork);
+            if (import.Labels.Count == 0)
+            {
+                TempData[WellKnownTempData.ErrorMessage] = StringLocalizer["No labels could be imported from this file. Expected BIP-329 format: one JSON object per line."].Value;
+                return RedirectToAction(nameof(WalletLabels), new { walletId });
+            }
+
+            var reqs = import.Labels
+                .GroupBy(l => (l.ObjectType, l.ObjectId))
+                .Select(g => (new WalletObjectId(walletId, g.Key.ObjectType, g.Key.ObjectId), g.Select(l => l.Label).ToArray()))
+                .ToArray();
+            await WalletRepository.AddWalletObjectLabels(reqs);
+
+            TempData[WellKnownTempData.SuccessMessage] = import.SkippedLines == 0
+                ? StringLocalizer["Imported {0} label(s).", import.Labels.Count].Value
+                : StringLocalizer["Imported {0} label(s), skipped {1} line(s).", import.Labels.Count, import.SkippedLines].Value;
+            return RedirectToAction(nameof(WalletLabels), new { walletId });
+        }
+
         private string? GetImage(BTCPayNetwork network)
         {
             var pmi = PaymentTypes.CHAIN.GetPaymentMethodId(network.CryptoCode);
diff --git a/BTCPayServer/Plugins/Wallets/Views/UIWallets/WalletLabels.cshtml b/BTCPayServer/Plugins/Wallets/Views/UIWallets/WalletLabels.cshtml
index 68b1a03..196c129 100644
--- a/BTCPayServer/Plugins/Wallets/Views/UIWallets/WalletLabels.cshtml
+++ b/BTCPayServer/Plugins/Wallets/Views/UIWallets/WalletLabels.cshtml
@@ -40,6 +40,12 @@
 
 <partial name="_StatusMessage" />
 
+<form method="post" enctype="multipart/form-data" asp-action="ImportWalletLabels" asp-route-walletId="@Model.WalletId"
+      class="wallet-labels__import d-flex flex-wrap align-items-center gap-2 mb-4" permission="@WalletPolicies.CanManageWalletTransactions">
+    <input type="file" name="file" class="form-control wallet-labels__import-file w-auto" accept=".jsonl,.json,.txt" required />
+    <button type="submit" class="btn btn-secondary wallet-labels__import-button" text-translate="true">Import BIP-329 labels</button>
+</form>
+
 @if (Model.Labels.Any())
 {
     <div class="table-responsive-md">
diff --git a/BTCPayServer/Plugins/Wallets/Views/UIWallets/WalletTransactions.cshtml b/BTCPayServer/Plugins/Wallets/Views/UIWallets/WalletTransactions.cshtml
index a1d10b8..a17817b 100644
--- a/BTCPayServer/Plugins/Wallets/Views/UIWallets/WalletTransactions.cshtml
+++ b/BTCPayServer/Plugins/Wallets/Views/UIWallets/WalletTransactions.cshtml
@@ -165,6 +165,14 @@
 
         // the actions div marks the end of the list table
         observer.observe($actions);
+
+        delegate('click', '.wallet-labels__import-button', event => {
+            event.target.closest('form').querySelector('.wallet-labels__import-file').click()
+        })
+        delegate('change', '.wallet-labels__import-file', event => {
+            if (event.target.files.length > 0)
+                event.target.closest('form').submit()
+        })
     </script>
 }
 
@@ -197,6 +205,11 @@
                 </div>
             </form>
         </div>
+        <form asp-action="ImportWalletLabels" asp-route-walletId="@walletId" method="post" enctype="multipart/form-data"
+              class="wallet-labels__import" permission="@WalletPolicies.CanManageWalletTransactions">
+            <input type="file" name="file" class="wallet-labels__import-file d-none" accept=".jsonl,.json,.txt" aria-hidden="true" tabindex="-1" />
+            <button type="button" class="btn btn-secondary wallet-labels__import-button" text-translate="true">Import BIP-329 labels</button>
+        </form>
     </div>
 </div>
 <partial name="_StatusMessage" />
diff --git a/BTCPayServer/Services/WalletRepository.cs b/BTCPayServer/Services/WalletRepository.cs
index bbc5364..d81b07f 100644
--- a/BTCPayServer/Services/WalletRepository.cs
+++ b/BTCPayServer/Services/WalletRepository.cs
@@ -657,16 +657,24 @@ namespace BTCPayServer.Services
         public async Task AddWalletObjectLabels(WalletObjectId id, params string[] labels)
         {
             ArgumentNullException.ThrowIfNull(id);
-            var objs = new List<WalletObjectData>();
+            await AddWalletObjectLabels(new[] { (id, labels) });
+        }
+
+        public async Task AddWalletObjectLabels((WalletObjectId id, string[] labels)[] reqs)
+        {
+            var objs = new Dictionary<WalletObjectId, WalletObjectData>();
             var links = new List<WalletObjectLinkData>();
-            objs.Add(NewWalletObjectData(id));
-            foreach (var l in labels.Select(l => l.Trim().Truncate(MaxLabelSize)))
+            foreach (var (id, labels) in reqs)
             {
-                var label = CreateLabel(id.WalletId, l);
-                objs.Add(label.ObjectData);
-                links.Add(NewWalletObjectLinkData(label.Id, id));
+                objs.TryAdd(id, NewWalletObjectData(id));
+                foreach (var l in labels.Select(l => l.Trim().Truncate(MaxLabelSize)).Distinct())
+                {
+                    var label = CreateLabel(id.WalletId, l);
+                    objs.TryAdd(label.Id, label.ObjectData);
+                    links.Add(NewWalletObjectLinkData(label.Id, id));
+                }
             }
-            await EnsureCreated(objs, links);
+            await EnsureCreated(objs.Values.ToList(), links);
         }
         public Task AddWalletTransactionAttachment(WalletId walletId, uint256 txId, Attachment attachment)
         {
diff --git a/BTCPayServer/Services/Wallets/Import/Bip329Import.cs b/BTCPayServer/Services/Wallets/Import/Bip329Import.cs
new file mode 100644
index 0000000..5d523c5
--- /dev/null
+++ b/BTCPayServer/Services/Wallets/Import/Bip329Import.cs
@@ -0,0 +1,86 @@
+#nullable enable
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+using BTCPayServer.Data;
+using NBitcoin;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+
+namespace BTCPayServer.Services.Wallets.Import
+{
+    // https://github.com/bitcoin/bips/blob/master/bip-0329.mediawiki
+    public static class Bip329Import
+    {
+        public record ImportedLabel(string ObjectType, string ObjectId, string Label);
+        public record Result(List<ImportedLabel> Labels, int SkippedLines);
+
+        public static async Task<Result> Parse(TextReader reader, Network network)
+        {
+            var labels = new List<ImportedLabel>();
+            var seen = new HashSet<ImportedLabel>();
+            var skipped = 0;
+            while (await reader.ReadLineAsync() is { } line)
+            {
+                line = line.Trim();
+                if (line.Length == 0)
+                    continue;
+                var entry = TryParseLine(line, network);
+                if (entry is null)
+                    skipped++;
+                else if (seen.Add(entry))
+                    labels.Add(entry);
+            }
+            return new Result(labels, skipped);
+        }
+
+        static ImportedLabel? TryParseLine(string line, Network network)
+        {
+            JObject obj;
+            try
+            {
+                obj = JObject.Parse(line);
+            }
+            catch (JsonException)
+            {
+                return null;
+            }
+            var label = GetString(obj, "label")?.Trim();
+            var reference = GetString(obj, "ref");
+            if (string.IsNullOrEmpty(label) || string.IsNullOrEmpty(reference))
+                return null;
+            return GetString(obj, "type") switch
+            {
+                "tx" when uint256.TryParse(reference, out var txId) =>
+                    new ImportedLabel(WalletObjectData.Types.Tx, txId.ToString(), label),
+                "addr" when TryParseAddress(reference, network) is { } address =>
+                    new ImportedLabel(WalletObjectData.Types.Address, address, label),
+                "output" when TryParseOutpoint(reference) is { } outpoint =>
+                    new ImportedLabel(WalletObjectData.Types.Utxo, outpoint, label),
+                _ => null
+            };
+        }
+
+        static string? GetString(JObject obj, string name)
+            => obj[name] is JValue { Type: JTokenType.String, Value: string s } ? s : null;
+
+        static string? TryParseAddress(string str, Network network)
+        {
+            try
+            {
+                return BitcoinAddress.Create(str, network).ToString();
+            }
+            catch (FormatException)
+            {
+                return null;
+            }
+        }
+
+        static string? TryParseOutpoint(string str)
+        {
+            // BIP-329 references outputs as <txid>:<vout>, NBitcoin parses <txid>-<vout>
+            return OutPoint.TryParse(str.Replace(':', '-'), out var outpoint) ? outpoint!.ToString() : null;
+        }
+    }
+}