Added custodian account trade support (#3978)

* Added custodian account trade support

* UI updates

* Improved UI spacing and field sizes + Fixed input validation

* Reset error message when opening trade modal

* Better error handing + test + surface error in trade modal in UI

* Add delete confirmation modal

* Fixed duplicate ID in site nav

* Replace jQuery.ajax with fetch for onTradeSubmit

* Added support for minimumTradeQty to trading pairs

* Fixed LocalBTCPayServerClient after previous refactoring

* Handling dust amounts + minor API change

* Replaced jQuery with Fetch API + UX improvements + more TODOs

* Moved namespace because Rider was unhappy

* Major UI improvements when swapping or changing assets, fixed bugs in min trade qty, fixed initial qty after an asset change etc

* Commented out code for easier debugging

* Fixed missing default values

Co-authored-by: Dennis Reimann <mail@dennisreimann.de>

BTCPayServer.Abstractions/Custodians/Client/AssetQuoteResult.cs

@@ -1,18 +1,19 @@
-namespace BTCPayServer.Abstractions.Custodians;
+namespace BTCPayServer.Abstractions.Custodians.Client;
 
 public class AssetQuoteResult
 {
-    public string FromAsset { get; }
-    
-    public string ToAsset { get; }
-    public decimal Bid { get; }
-    public decimal Ask { get; }
+    public string FromAsset { get; set; }
+    public string ToAsset { get; set; }
+    public decimal Bid { get; set; }
+    public decimal Ask { get; set; }
+
+    public AssetQuoteResult() { }
 
     public AssetQuoteResult(string fromAsset, string toAsset,decimal bid, decimal ask)
     {
-        this.FromAsset = fromAsset;
-        this.ToAsset = toAsset;
-        this.Bid = bid;
-        this.Ask = ask;
+        FromAsset = fromAsset;
+        ToAsset = toAsset;
+        Bid = bid;
+        Ask = ask;
     }
 }

BTCPayServer.Abstractions/Custodians/Client/MarketTradeResult.cs

@@ -1,7 +1,7 @@
 using System.Collections.Generic;
 using BTCPayServer.Client.Models;
 
-namespace BTCPayServer.Abstractions.Custodians;
+namespace BTCPayServer.Abstractions.Custodians.Client;
 
 /**
  * The result of a market trade. Used as a return type for custodians implementing ICanTrade

BTCPayServer.Abstractions/Custodians/Client/WithdrawResult.cs

@@ -2,7 +2,7 @@ using System;
 using System.Collections.Generic;
 using BTCPayServer.Client.Models;
 
-namespace BTCPayServer.Abstractions.Custodians;
+namespace BTCPayServer.Abstractions.Custodians.Client;
 
 public class WithdrawResult
 {

BTCPayServer.Abstractions/Custodians/ICanTrade.cs

@@ -1,6 +1,7 @@
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
+using BTCPayServer.Abstractions.Custodians.Client;
 using BTCPayServer.Client.Models;
 using Newtonsoft.Json.Linq;
 

BTCPayServer.Abstractions/Custodians/ICanWithdraw.cs

@@ -1,5 +1,6 @@
 using System.Threading;
 using System.Threading.Tasks;
+using BTCPayServer.Abstractions.Custodians.Client;
 using Newtonsoft.Json.Linq;
 
 namespace BTCPayServer.Abstractions.Custodians;

BTCPayServer.Client/BTCPayServerClient.CustodianAccounts.cs

@@ -56,9 +56,14 @@ namespace BTCPayServer.Client
             return await HandleResponse<DepositAddressData>(response);
         }
 
-        public virtual async Task<MarketTradeResponseData> TradeMarket(string storeId, string accountId, TradeRequestData request, CancellationToken token = default)
+        public virtual async Task<MarketTradeResponseData> MarketTradeCustodianAccountAsset(string storeId, string accountId, TradeRequestData request, CancellationToken token = default)
         {
-            var response = await _httpClient.SendAsync(CreateHttpRequest($"api/v1/stores/{storeId}/custodian-accounts/{accountId}/trades/market", bodyPayload: request, method: HttpMethod.Post), token);
+            
+            //var response = await _httpClient.SendAsync(CreateHttpRequest("api/v1/users", null, request, HttpMethod.Post), token);
+            //return await HandleResponse<ApplicationUserData>(response);
+            var internalRequest = CreateHttpRequest($"api/v1/stores/{storeId}/custodian-accounts/{accountId}/trades/market", null,
+                    request, HttpMethod.Post);
+            var response = await _httpClient.SendAsync(internalRequest, token);
             return await HandleResponse<MarketTradeResponseData>(response);
         }
 
@@ -73,7 +78,6 @@ namespace BTCPayServer.Client
             var queryPayload = new Dictionary<string, object>();
             queryPayload.Add("fromAsset", fromAsset);
             queryPayload.Add("toAsset", toAsset);
-
             var response = await _httpClient.SendAsync(CreateHttpRequest($"api/v1/stores/{storeId}/custodian-accounts/{accountId}/trades/quote", queryPayload), token);
             return await HandleResponse<TradeQuoteResponseData>(response);
         }

BTCPayServer.Client/Models/AssetPairData.cs

@@ -1,20 +1,31 @@
+using Newtonsoft.Json;
+
 namespace BTCPayServer.Client.Models;
 
+[JsonObject(MemberSerialization.OptIn)]
 public class AssetPairData
 {
     public AssetPairData()
     {
     }
     
-    public AssetPairData(string assetBought, string assetSold)
+    public AssetPairData(string assetBought, string assetSold, decimal minimumTradeQty)
     {
         AssetBought = assetBought;
         AssetSold = assetSold;
+        MinimumTradeQty = minimumTradeQty;
     }
-    
+
+    [JsonProperty]
     public string AssetBought { set; get; }
+
+    [JsonProperty]
     public string AssetSold { set; get; }
 
+    [JsonProperty]
+    public decimal MinimumTradeQty { set; get; }
+
+    
     public override string ToString()
     {
         return AssetBought + "/" + AssetSold;

BTCPayServer.Client/Models/CustodianData.cs

@@ -1,10 +1,12 @@
+using System.Collections.Generic;
+
 namespace BTCPayServer.Client.Models;
 
 public class CustodianData
 {
     public string Code { get; set; }
     public string Name { get; set; }
-    public string[] TradableAssetPairs { get; set; }
+    public Dictionary<string, AssetPairData> TradableAssetPairs { get; set; }
     public string[] WithdrawablePaymentMethods { get; set; }
     public string[] DepositablePaymentMethods { get; set; }
     

BTCPayServer.Tests/GreenfieldAPITests.cs

@@ -2859,13 +2859,13 @@ namespace BTCPayServer.Tests
             
             // Test: Trade, unauth
             var tradeRequest = new TradeRequestData {FromAsset = MockCustodian.TradeFromAsset, ToAsset = MockCustodian.TradeToAsset, Qty = MockCustodian.TradeQtyBought.ToString(CultureInfo.InvariantCulture)};
-            await AssertHttpError(401, async () => await unauthClient.TradeMarket(storeId, accountId, tradeRequest));
+            await AssertHttpError(401, async () => await unauthClient.MarketTradeCustodianAccountAsset(storeId, accountId, tradeRequest));
             
             // Test: Trade, auth, but wrong permission
-            await AssertHttpError(403, async () => await managerClient.TradeMarket(storeId, accountId, tradeRequest));
+            await AssertHttpError(403, async () => await managerClient.MarketTradeCustodianAccountAsset(storeId, accountId, tradeRequest));
             
             // Test: Trade, correct permission, correct assets, correct amount
-            var newTradeResult = await tradeClient.TradeMarket(storeId, accountId, tradeRequest);
+            var newTradeResult = await tradeClient.MarketTradeCustodianAccountAsset(storeId, accountId, tradeRequest);
             Assert.NotNull(newTradeResult);
             Assert.Equal(accountId, newTradeResult.AccountId);
             Assert.Equal(mockCustodian.Code, newTradeResult.CustodianCode);
@@ -2886,23 +2886,27 @@ namespace BTCPayServer.Tests
             
             // Test: GetTradeQuote, SATS
             var satsTradeRequest = new TradeRequestData {FromAsset = MockCustodian.TradeFromAsset, ToAsset = "SATS", Qty = MockCustodian.TradeQtyBought.ToString(CultureInfo.InvariantCulture)};
-            await AssertApiError(400, "use-asset-synonym", async () => await tradeClient.TradeMarket(storeId, accountId, satsTradeRequest));
+            await AssertApiError(400, "use-asset-synonym", async () => await tradeClient.MarketTradeCustodianAccountAsset(storeId, accountId, satsTradeRequest));
             
             // TODO Test: Trade with percentage qty
             
+            // Test: Trade with wrong decimal format (example: JavaScript scientific format)
+            var wrongQtyTradeRequest = new TradeRequestData {FromAsset = MockCustodian.TradeFromAsset, ToAsset = MockCustodian.TradeToAsset, Qty = "6.1e-7"};
+            await AssertApiError(400,"bad-qty-format", async () => await tradeClient.MarketTradeCustodianAccountAsset(storeId, accountId, wrongQtyTradeRequest));
+            
             // Test: Trade, wrong assets method
             var wrongAssetsTradeRequest = new TradeRequestData {FromAsset = "WRONG", ToAsset = MockCustodian.TradeToAsset, Qty = MockCustodian.TradeQtyBought.ToString(CultureInfo.InvariantCulture)};
-            await AssertHttpError(WrongTradingPairException.HttpCode, async () => await tradeClient.TradeMarket(storeId, accountId, wrongAssetsTradeRequest));
+            await AssertHttpError(WrongTradingPairException.HttpCode, async () => await tradeClient.MarketTradeCustodianAccountAsset(storeId, accountId, wrongAssetsTradeRequest));
 
             // Test: wrong account ID
-            await AssertHttpError(404, async () => await tradeClient.TradeMarket(storeId, "WRONG-ACCOUNT-ID", tradeRequest));
+            await AssertHttpError(404, async () => await tradeClient.MarketTradeCustodianAccountAsset(storeId, "WRONG-ACCOUNT-ID", tradeRequest));
             
             // Test: wrong store ID
-            await AssertHttpError(403, async () => await tradeClient.TradeMarket("WRONG-STORE-ID", accountId, tradeRequest));
+            await AssertHttpError(403, async () => await tradeClient.MarketTradeCustodianAccountAsset("WRONG-STORE-ID", accountId, tradeRequest));
             
             // Test: Trade, correct assets, wrong amount
-            var wrongQtyTradeRequest = new TradeRequestData {FromAsset = MockCustodian.TradeFromAsset, ToAsset = MockCustodian.TradeToAsset, Qty = "0.01"};
-            await AssertApiError(400, "insufficient-funds", async () => await tradeClient.TradeMarket(storeId, accountId, wrongQtyTradeRequest));
+            var insufficientFundsTradeRequest = new TradeRequestData {FromAsset = MockCustodian.TradeFromAsset, ToAsset = MockCustodian.TradeToAsset, Qty = "0.01"};
+            await AssertApiError(400, "insufficient-funds", async () => await tradeClient.MarketTradeCustodianAccountAsset(storeId, accountId, insufficientFundsTradeRequest));
 
 
             // Test: GetTradeQuote, unauth

BTCPayServer.Tests/MockCustodian/MockCustodian.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using BTCPayServer.Abstractions.Custodians;
+using BTCPayServer.Abstractions.Custodians.Client;
 using BTCPayServer.Abstractions.Form;
 using BTCPayServer.Client.Models;
 using Newtonsoft.Json.Linq;
@@ -76,7 +77,7 @@ public class MockCustodian : ICustodian, ICanDeposit, ICanTrade, ICanWithdraw
     public List<AssetPairData> GetTradableAssetPairs()
     {
         var r = new List<AssetPairData>();
-        r.Add(new AssetPairData("BTC", "EUR"));
+        r.Add(new AssetPairData("BTC", "EUR", (decimal) 0.0001));
         return r;
     }
 

BTCPayServer/Components/MainNav/Default.cshtml

@@ -109,7 +109,7 @@
                                         </li>
                                     }
                                     <li class="nav-item">
-                                        <a asp-area="" asp-controller="UICustodianAccounts" asp-action="CreateCustodianAccount" asp-route-storeId="@Model.Store.Id" class="nav-link js-scroll-trigger @ViewData.IsActivePage(CustodianAccountsNavPages.Create)" id="StoreNav-CreateApp">
+                                        <a asp-area="" asp-controller="UICustodianAccounts" asp-action="CreateCustodianAccount" asp-route-storeId="@Model.Store.Id" class="nav-link js-scroll-trigger @ViewData.IsActivePage(CustodianAccountsNavPages.Create)" id="StoreNav-CreateCustodianAccount">
                                             <vc:icon symbol="new"/>
                                             <span>Add Custodian</span>
                                             <span class="badge bg-warning ms-1" style="font-size:10px;">Experimental</span>

BTCPayServer/Controllers/GreenField/GreenfieldCustodianAccountController.cs

@@ -6,6 +6,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using BTCPayServer.Abstractions.Constants;
 using BTCPayServer.Abstractions.Custodians;
+using BTCPayServer.Abstractions.Custodians.Client;
 using BTCPayServer.Abstractions.Extensions;
 using BTCPayServer.Abstractions.Form;
 using BTCPayServer.Client;
@@ -231,7 +232,7 @@ namespace BTCPayServer.Controllers.Greenfield
         [HttpPost("~/api/v1/stores/{storeId}/custodian-accounts/{accountId}/trades/market")]
         [Authorize(Policy = Policies.CanTradeCustodianAccount,
             AuthenticationSchemes = AuthenticationSchemes.Greenfield)]
-        public async Task<IActionResult> TradeMarket(string storeId, string accountId,
+        public async Task<IActionResult> MarketTradeCustodianAccountAsset(string storeId, string accountId,
             TradeRequestData request, CancellationToken cancellationToken = default)
         {
             // TODO add SATS check everywhere. We cannot change to 'BTC' ourselves because the qty / price would be different too.
@@ -246,29 +247,38 @@ namespace BTCPayServer.Controllers.Greenfield
 
             if (custodian is ICanTrade tradableCustodian)
             {
-                decimal Qty;
-                if (request.Qty.EndsWith("%", StringComparison.InvariantCultureIgnoreCase))
+                bool isPercentage = request.Qty.EndsWith("%", StringComparison.InvariantCultureIgnoreCase);
+                string qtyString = isPercentage ? request.Qty.Substring(0, request.Qty.Length - 1) : request.Qty;
+                bool canParseQty = Decimal.TryParse(qtyString, out decimal qty);
+                if (!canParseQty)
                 {
-                    // Qty is a percentage of current holdings
-                    var percentage = Decimal.Parse( request.Qty.Substring(0, request.Qty.Length - 1), CultureInfo.InvariantCulture);
+                    return this.CreateAPIError(400, "bad-qty-format",
+                        $"Quantity should be a number or a number ending with '%' for percentages.");
+                }
+
+                if (isPercentage)
+                {
+                    // Percentage of current holdings => calculate the amount
                     var config = custodianAccount.GetBlob();
                     var balances = custodian.GetAssetBalancesAsync(config, cancellationToken).Result;
                     var fromAssetBalance = balances[request.FromAsset];
                     var priceQuote =
                         await tradableCustodian.GetQuoteForAssetAsync(request.FromAsset, request.ToAsset, config, cancellationToken);
-                    Qty = fromAssetBalance / priceQuote.Ask * percentage / 100;
-                }
-                else
-                {
-                    // Qty is an exact amount
-                    Qty = Decimal.Parse(request.Qty, CultureInfo.InvariantCulture);
-                    
+                    qty = fromAssetBalance / priceQuote.Ask * qty / 100;
                 }
 
-                var result = await tradableCustodian.TradeMarketAsync(request.FromAsset, request.ToAsset, Qty,
+                try
+                {
+                    var result = await tradableCustodian.TradeMarketAsync(request.FromAsset, request.ToAsset, qty,
                         custodianAccount.GetBlob(), cancellationToken);
 
-                return Ok(ToModel(result, accountId, custodianAccount.CustodianCode));
+                    return Ok(ToModel(result, accountId, custodianAccount.CustodianCode));
+                }
+                catch (CustodianApiException e)
+                {
+                    return this.CreateAPIError(e.HttpStatus,  e.Code,
+                        e.Message);
+                }
             }
 
             return this.CreateAPIError(400, "market-trade-not-supported",

BTCPayServer/Controllers/GreenField/GreenfieldCustodianController.cs

@@ -40,12 +40,12 @@ namespace BTCPayServer.Controllers.Greenfield
             if (custodian is ICanTrade tradableCustodian)
             {
                 var tradableAssetPairs = tradableCustodian.GetTradableAssetPairs();
-                var tradableAssetPairStrings = new string[tradableAssetPairs.Count];
-                for (int i = 0; i < tradableAssetPairs.Count; i++)
+                var tradableAssetPairsDict = new Dictionary<string, AssetPairData>(tradableAssetPairs.Count);
+                foreach (var tradableAssetPair in tradableAssetPairs)
                 {
-                    tradableAssetPairStrings[i] = tradableAssetPairs[i].ToString();
+                    tradableAssetPairsDict.Add(tradableAssetPair.ToString(), tradableAssetPair);
                 }
-                result.TradableAssetPairs = tradableAssetPairStrings;
+                result.TradableAssetPairs = tradableAssetPairsDict;
             }
 
             if (custodian is ICanDeposit depositableCustodian)

BTCPayServer/Controllers/GreenField/LocalBTCPayServerClient.cs

@@ -90,7 +90,8 @@ namespace BTCPayServer.Controllers.Greenfield
             else
             {
                 context.User =
-                    new ClaimsPrincipal(new ClaimsIdentity(new List<Claim>()
+                    new ClaimsPrincipal(new ClaimsIdentity(
+                        new List<Claim>()
                         {
                             new(_identityOptions.CurrentValue.ClaimsIdentity.RoleClaimType, Roles.ServerAdmin)
                         },
@@ -204,7 +205,7 @@ namespace BTCPayServer.Controllers.Greenfield
             public Task<AuthorizationResult> AuthorizeAsync(ClaimsPrincipal user, object resource, string policyName)
             {
                 return AuthorizeAsync(user, resource,
-                    new List<IAuthorizationRequirement>(new[] {new PolicyRequirement(policyName)}));
+                    new List<IAuthorizationRequirement>(new[] { new PolicyRequirement(policyName) }));
             }
         }
 
@@ -214,6 +215,14 @@ namespace BTCPayServer.Controllers.Greenfield
             throw new NotSupportedException("This method is not supported by the LocalBTCPayServerClient.");
         }
 
+
+        public override async Task<MarketTradeResponseData> MarketTradeCustodianAccountAsset(string storeId, string accountId,
+            TradeRequestData request, CancellationToken cancellationToken = default)
+        {
+            return GetFromActionResult<MarketTradeResponseData>(
+                await GetController<GreenfieldCustodianAccountController>().MarketTradeCustodianAccountAsset(storeId, accountId, request, cancellationToken));
+        }
+
         public override async Task<StoreWebhookData> CreateWebhook(string storeId, CreateStoreWebhookRequest create,
             CancellationToken token = default)
         {
@@ -460,8 +469,8 @@ namespace BTCPayServer.Controllers.Greenfield
             return result switch
             {
                 JsonResult jsonResult => (T)jsonResult.Value,
-                OkObjectResult {Value: T res} => res,
-                OkObjectResult {Value: JValue res} => res.Value<T>(),
+                OkObjectResult { Value: T res } => res,
+                OkObjectResult { Value: JValue res } => res.Value<T>(),
                 _ => default
             };
         }
@@ -470,9 +479,11 @@ namespace BTCPayServer.Controllers.Greenfield
         {
             switch (result)
             {
-                case UnprocessableEntityObjectResult {Value: List<GreenfieldValidationError> validationErrors}:
+                case UnprocessableEntityObjectResult { Value: List<GreenfieldValidationError> validationErrors }:
                     throw new GreenfieldValidationException(validationErrors.ToArray());
-                case BadRequestObjectResult {Value: GreenfieldAPIError error}:
+                case BadRequestObjectResult { Value: GreenfieldAPIError error }:
+                    throw new GreenfieldAPIException(400, error);
+                case ObjectResult { Value: GreenfieldAPIError error }:
                     throw new GreenfieldAPIException(400, error);
                 case NotFoundResult _:
                     throw new GreenfieldAPIException(404, new GreenfieldAPIError("not-found", ""));
@@ -1085,7 +1096,7 @@ namespace BTCPayServer.Controllers.Greenfield
         }
 
         public override async Task<PointOfSaleAppData> CreatePointOfSaleApp(
-           string storeId,
+            string storeId,
             CreatePointOfSaleAppRequest request, CancellationToken token = default)
         {
             return GetFromActionResult<PointOfSaleAppData>(

BTCPayServer/Controllers/UICustodianAccountsController.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using System.Threading.Tasks;
 using BTCPayServer.Abstractions.Constants;
@@ -7,6 +8,8 @@ using BTCPayServer.Abstractions.Custodians;
 using BTCPayServer.Abstractions.Extensions;
 using BTCPayServer.Abstractions.Form;
 using BTCPayServer.Client;
+using BTCPayServer.Client.Models;
+using BTCPayServer.Controllers.Greenfield;
 using BTCPayServer.Data;
 using BTCPayServer.Filters;
 using BTCPayServer.Models.CustodianAccountViewModels;
@@ -26,30 +29,32 @@ namespace BTCPayServer.Controllers
     [ExperimentalRouteAttribute]
     public class UICustodianAccountsController : Controller
     {
+        private readonly IEnumerable<ICustodian> _custodianRegistry;
+        private readonly UserManager<ApplicationUser> _userManager;
+        private readonly CustodianAccountRepository _custodianAccountRepository;
+        private readonly CurrencyNameTable _currencyNameTable;
+        private readonly BTCPayServerClient _btcPayServerClient;
+
         public UICustodianAccountsController(
             CurrencyNameTable currencyNameTable,
             UserManager<ApplicationUser> userManager,
             CustodianAccountRepository custodianAccountRepository,
-            IEnumerable<ICustodian> custodianRegistry
+            IEnumerable<ICustodian> custodianRegistry,
+            BTCPayServerClient btcPayServerClient
         )
         {
             _currencyNameTable = currencyNameTable ?? throw new ArgumentNullException(nameof(currencyNameTable));
             _userManager = userManager;
             _custodianAccountRepository = custodianAccountRepository;
             _custodianRegistry = custodianRegistry;
+            _btcPayServerClient = btcPayServerClient;
         }
 
-        private readonly IEnumerable<ICustodian> _custodianRegistry;
-        private readonly UserManager<ApplicationUser> _userManager;
-        private readonly CustodianAccountRepository _custodianAccountRepository;
-        private readonly CurrencyNameTable _currencyNameTable;
-
         public string CreatedCustodianAccountId { get; set; }
 
         [HttpGet("/stores/{storeId}/custodian-accounts/{accountId}")]
         public async Task<IActionResult> ViewCustodianAccount(string storeId, string accountId)
         {
-            var vm = new ViewCustodianAccountViewModel();
             var custodianAccount = await _custodianAccountRepository.FindById(storeId, accountId);
 
             if (custodianAccount == null)
@@ -62,14 +67,34 @@ namespace BTCPayServer.Controllers
                 return NotFound();
             }
 
+            var vm = new ViewCustodianAccountViewModel();
             vm.Custodian = custodian;
             vm.CustodianAccount = custodianAccount;
+
+            return View(vm);
+        }
+
+        [HttpGet("/stores/{storeId}/custodian-accounts/{accountId}.json")]
+        public async Task<IActionResult> ViewCustodianAccountAjax(string storeId, string accountId)
+        {
+            var vm = new ViewCustodianAccountBalancesViewModel();
+            var custodianAccount = await _custodianAccountRepository.FindById(storeId, accountId);
+
+            if (custodianAccount == null)
+                return NotFound();
+
+            var custodian = _custodianRegistry.GetCustodianByCode(custodianAccount.CustodianCode);
+            if (custodian == null)
+            {
+                // TODO The custodian account is broken. The custodian is no longer available. Maybe delete the custodian account?
+                return NotFound();
+            }
+
             var store = GetCurrentStore();
-            var storeBlob = BTCPayServer.Data.StoreDataExtensions.GetStoreBlob(store);
+            var storeBlob = StoreDataExtensions.GetStoreBlob(store);
             var defaultCurrency = storeBlob.DefaultCurrency;
-            vm.DefaultCurrency = defaultCurrency;
-
-
+            vm.DustThresholdInFiat = 1;
+            vm.StoreDefaultFiat = defaultCurrency;
             try
             {
                 var assetBalances = new Dictionary<string, AssetBalanceInfo>();
@@ -81,11 +106,15 @@ namespace BTCPayServer.Controllers
                     var asset = pair.Key;
 
                     assetBalances.Add(asset,
-                        new AssetBalanceInfo { Asset = asset, Qty = pair.Value }
+                        new AssetBalanceInfo
+                        {
+                            Asset = asset,
+                            Qty = pair.Value,
+                            FormattedQty = pair.Value.ToString(CultureInfo.InvariantCulture)
+                        }
                     );
                 }
 
-
                 if (custodian is ICanTrade tradingCustodian)
                 {
                     var config = custodianAccount.GetBlob();
@@ -95,10 +124,20 @@ namespace BTCPayServer.Controllers
                     {
                         var asset = pair.Key;
                         var assetBalance = assetBalances[asset];
+                        var tradableAssetPairsList =
+                            tradableAssetPairs.Where(o => o.AssetBought == asset || o.AssetSold == asset).ToList();
+                        var tradableAssetPairsDict = new Dictionary<string, AssetPairData>(tradableAssetPairsList.Count);
+                        foreach (var assetPair in tradableAssetPairsList)
+                        {
+                            tradableAssetPairsDict.Add(assetPair.ToString(), assetPair);
+                        }
+                        assetBalance.TradableAssetPairs = tradableAssetPairsDict;
 
                         if (asset.Equals(defaultCurrency))
                         {
-                            assetBalance.FormattedFiatValue = _currencyNameTable.DisplayFormatCurrency(pair.Value.Qty, defaultCurrency);
+                            assetBalance.FormattedFiatValue =
+                                _currencyNameTable.DisplayFormatCurrency(pair.Value.Qty, defaultCurrency);
+                            assetBalance.FiatValue = pair.Value.Qty;
                         }
                         else
                         {
@@ -108,11 +147,14 @@ namespace BTCPayServer.Controllers
                                     config, default);
                                 assetBalance.Bid = quote.Bid;
                                 assetBalance.Ask = quote.Ask;
-                                assetBalance.FiatAsset = defaultCurrency;
-                                assetBalance.FormattedBid = _currencyNameTable.DisplayFormatCurrency(quote.Bid, quote.FromAsset);
-                                assetBalance.FormattedAsk = _currencyNameTable.DisplayFormatCurrency(quote.Ask, quote.FromAsset);
-                                assetBalance.FormattedFiatValue = _currencyNameTable.DisplayFormatCurrency(pair.Value.Qty * quote.Bid, pair.Value.FiatAsset);
-                                assetBalance.TradableAssetPairs = tradableAssetPairs.Where(o => o.AssetBought == asset || o.AssetSold == asset);
+                                assetBalance.FormattedBid =
+                                    _currencyNameTable.DisplayFormatCurrency(quote.Bid, quote.FromAsset);
+                                assetBalance.FormattedAsk =
+                                    _currencyNameTable.DisplayFormatCurrency(quote.Ask, quote.FromAsset);
+                                assetBalance.FormattedFiatValue =
+                                    _currencyNameTable.DisplayFormatCurrency(pair.Value.Qty * quote.Bid,
+                                        defaultCurrency);
+                                assetBalance.FiatValue = pair.Value.Qty * quote.Bid;
                             }
                             catch (WrongTradingPairException)
                             {
@@ -136,8 +178,10 @@ namespace BTCPayServer.Controllers
                     }
                 }
 
+                vm.CanDeposit = false;
                 if (custodian is ICanDeposit depositableCustodian)
                 {
+                    vm.CanDeposit = true;
                     var depositablePaymentMethods = depositableCustodian.GetDepositablePaymentMethods();
                     foreach (var depositablePaymentMethod in depositablePaymentMethods)
                     {
@@ -154,10 +198,10 @@ namespace BTCPayServer.Controllers
             }
             catch (Exception e)
             {
-                vm.GetAssetBalanceException = e;
+                vm.AssetBalanceExceptionMessage = e.Message;
             }
 
-            return View(vm);
+            return Ok(vm);
         }
 
         [HttpGet("/stores/{storeId}/custodian-accounts/{accountId}/edit")]
@@ -173,6 +217,7 @@ namespace BTCPayServer.Controllers
                 // TODO The custodian account is broken. The custodian is no longer available. Maybe delete the custodian account?
                 return NotFound();
             }
+
             var configForm = await custodian.GetConfigForm(custodianAccount.GetBlob(), "en-US");
 
             var vm = new EditCustodianAccountViewModel();
@@ -198,6 +243,7 @@ namespace BTCPayServer.Controllers
                 // TODO The custodian account is broken. The custodian is no longer available. Maybe delete the custodian account?
                 return NotFound();
             }
+
             var configForm = await custodian.GetConfigForm(custodianAccount.GetBlob(), locale);
 
             var newData = new JObject();
@@ -255,12 +301,16 @@ namespace BTCPayServer.Controllers
                 ModelState.AddModelError(nameof(vm.SelectedCustodian), "Invalid Custodian");
                 return View(vm);
             }
+
             if (string.IsNullOrEmpty(vm.Name))
             {
                 vm.Name = custodian.Name;
             }
 
-            var custodianAccountData = new CustodianAccountData { CustodianCode = vm.SelectedCustodian, StoreId = vm.StoreId, Name = custodian.Name };
+            var custodianAccountData = new CustodianAccountData
+            {
+                CustodianCode = vm.SelectedCustodian, StoreId = vm.StoreId, Name = custodian.Name
+            };
 
 
             var configData = new JObject();
@@ -287,8 +337,7 @@ namespace BTCPayServer.Controllers
             return View(vm);
         }
 
-
-        [HttpGet("/stores/{storeId}/custodian-accounts/{accountId}/delete")]
+        [HttpPost("/stores/{storeId}/custodian-accounts/{accountId}/delete")]
         public async Task<IActionResult> DeleteCustodianAccount(string storeId, string accountId)
         {
             var custodianAccount = await _custodianAccountRepository.FindById(storeId, accountId);
@@ -301,7 +350,7 @@ namespace BTCPayServer.Controllers
             if (isDeleted)
             {
                 TempData[WellKnownTempData.SuccessMessage] = "Custodian account deleted";
-                return RedirectToAction("Dashboard", "UIStores", new { storeId });
+                return RedirectToAction(nameof(UIStoresController.Dashboard), "UIStores", new { storeId });
             }
 
             TempData[WellKnownTempData.ErrorMessage] = "Could not delete custodian account";
@@ -335,6 +384,98 @@ namespace BTCPayServer.Controllers
             return filteredData;
         }
 
+        [HttpGet("/stores/{storeId}/custodian-accounts/{accountId}/trade/prepare")]
+        public async Task<IActionResult> GetTradePrepareAjax(string storeId, string accountId,
+            [FromQuery] string assetToTrade, [FromQuery] string assetToTradeInto)
+        {
+            if (string.IsNullOrEmpty(assetToTrade) || string.IsNullOrEmpty(assetToTradeInto))
+            {
+                return BadRequest();
+            }
+
+            TradePrepareViewModel vm = new();
+            var custodianAccount = await _custodianAccountRepository.FindById(storeId, accountId);
+
+            if (custodianAccount == null)
+                return NotFound();
+
+            var custodian = _custodianRegistry.GetCustodianByCode(custodianAccount.CustodianCode);
+            if (custodian == null)
+            {
+                // TODO The custodian account is broken. The custodian is no longer available. Maybe delete the custodian account?
+                return NotFound();
+            }
+
+            var store = GetCurrentStore();
+            var storeBlob = BTCPayServer.Data.StoreDataExtensions.GetStoreBlob(store);
+            var defaultCurrency = storeBlob.DefaultCurrency;
+
+            try
+            {
+                var assetBalancesData =
+                    await custodian.GetAssetBalancesAsync(custodianAccount.GetBlob(), cancellationToken: default);
+
+                if (custodian is ICanTrade tradingCustodian)
+                {
+                    var config = custodianAccount.GetBlob();
+
+                    foreach (var pair in assetBalancesData)
+                    {
+                        var oneAsset = pair.Key;
+                        if (assetToTrade.Equals(oneAsset))
+                        {
+                            vm.MaxQtyToTrade = pair.Value;
+                            //vm.FormattedMaxQtyToTrade = pair.Value;
+
+                            if (assetToTrade.Equals(assetToTradeInto))
+                            {
+                                // We cannot trade the asset for itself
+                                return BadRequest();
+                            }
+
+                            try
+                            {
+                                var quote = await tradingCustodian.GetQuoteForAssetAsync(assetToTrade, assetToTradeInto,
+                                    config, default);
+                                
+                                // TODO Ask is normally a higher number than Bid!! Let's check this!! Maybe a Unit Test?
+                                vm.Ask = quote.Ask;
+                                vm.Bid = quote.Bid;
+                                vm.FromAsset = quote.FromAsset;
+                                vm.ToAsset = quote.ToAsset;
+                            }
+                            catch (WrongTradingPairException)
+                            {
+                                // Cannot trade this asset, just ignore
+                            }
+                        }
+                    }
+                }
+            }
+            catch (Exception e)
+            {
+                return BadRequest();
+            }
+
+            return Ok(vm);
+        }
+
+        [HttpPost("/stores/{storeId}/custodian-accounts/{accountId}/trade")]
+        public async Task<IActionResult> Trade(string storeId, string accountId,
+            [FromBody] TradeRequestData request)
+        {
+            try
+            {
+                var result = await _btcPayServerClient.MarketTradeCustodianAccountAsset(storeId, accountId, request);
+                return Ok(result);
+            }
+            catch (GreenfieldAPIException e)
+            {
+                var result = new ObjectResult(e.APIError) { StatusCode = e.HttpCode };
+                return result;
+            }
+        }
+
         private StoreData GetCurrentStore() => HttpContext.GetStoreData();
     }
 }

BTCPayServer/Models/CustodianAccountViewModels/AssetBalanceInfo.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using BTCPayServer.Client.Models;
 
@@ -11,9 +10,10 @@ public class AssetBalanceInfo
     public decimal? Bid { get; set; }
     public decimal? Ask { get; set; }
     public decimal Qty { get; set; }
-    public string FiatAsset { get; set; }
+    public string FormattedQty { get; set; }
     public string FormattedFiatValue { get; set; }
-    public IEnumerable<AssetPairData> TradableAssetPairs { get; set; }
+    public decimal FiatValue { get; set; }
+    public Dictionary<string, AssetPairData> TradableAssetPairs { get; set; }
     public bool CanWithdraw { get; set; }
     public bool CanDeposit { get; set; }
     public string FormattedBid { get; set; }

BTCPayServer/Models/CustodianAccountViewModels/TradePrepareViewModel.cs

@@ -0,0 +1,9 @@
+using BTCPayServer.Abstractions.Custodians.Client;
+
+namespace BTCPayServer.Models.CustodianAccountViewModels;
+
+public class TradePrepareViewModel : AssetQuoteResult
+{
+    public decimal MaxQtyToTrade { get; set; }
+    
+}

BTCPayServer/Models/CustodianAccountViewModels/ViewCustodianAccountBalancesViewModel.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+
+namespace BTCPayServer.Models.CustodianAccountViewModels
+{
+    public class ViewCustodianAccountBalancesViewModel
+    {
+        public Dictionary<string,AssetBalanceInfo> AssetBalances { get; set; }
+        public string AssetBalanceExceptionMessage { get; set; }
+        
+        public string StoreDefaultFiat { get; set; }
+        public decimal DustThresholdInFiat { get; set; }
+        public bool CanDeposit { get; set; }
+    }
+}

BTCPayServer/Models/CustodianAccountViewModels/ViewCustodianAccountViewModel.cs

@@ -1,5 +1,3 @@
-using System;
-using System.Collections.Generic;
 using BTCPayServer.Abstractions.Custodians;
 using BTCPayServer.Data;
 
@@ -9,8 +7,6 @@ namespace BTCPayServer.Models.CustodianAccountViewModels
     {
         public ICustodian Custodian { get; set; }
         public CustodianAccountData CustodianAccount { get; set; }
-        public Dictionary<string,AssetBalanceInfo> AssetBalances { get; set; }
-        public Exception GetAssetBalanceException { get; set; }
-        public string DefaultCurrency { get; set; }
+
     }
 }

BTCPayServer/Views/Shared/_Form.cshtml

@@ -3,7 +3,7 @@
 @foreach (var fieldset in Model.Fieldsets)
 {
     <fieldset>
-        <legend>@fieldset.Label</legend>
+        <legend class="h3 mt-4 mb-3">@fieldset.Label</legend>
         @foreach (var field in fieldset.Fields)
         {
 @if ("text".Equals(field.Type))
@@ -22,7 +22,7 @@
             </label>
         }
 
-        <input class="form-control @(@field.IsValid() ? "" : "is-invalid")" id="@field.Name" type="text" required="@field.Required" name="@field.Name" value="@field.Value" aria-describedby="HelpText@field.Name"/>
+        <input class="form-control @(field.IsValid() ? "" : "is-invalid")" id="@field.Name" type="text" required="@field.Required" name="@field.Name" value="@field.Value" aria-describedby="HelpText@field.Name"/>
         <small id="HelpText@field.Name" class="form-text text-muted">
             @field.HelpText
         </small>

BTCPayServer/Views/UICustodianAccounts/CreateCustodianAccount.cshtml

@@ -16,8 +16,10 @@
 <div class="row">
     <div class="col-xl-8 col-xxl-constrain">
         <form asp-action="CreateCustodianAccount">
-            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
-            
+            @if (!ViewContext.ModelState.IsValid)
+            {
+                <div asp-validation-summary="ModelOnly" class="text-danger"></div>
+            }
             @if (!string.IsNullOrEmpty(Model.SelectedCustodian))
             {
                 <partial name="_FormTopMessages" model="Model.ConfigForm" />

BTCPayServer/Views/UICustodianAccounts/EditCustodianAccount.cshtml

@@ -1,5 +1,6 @@
 @using BTCPayServer.Views.Apps
 @using BTCPayServer.Abstractions.Extensions
+@using BTCPayServer.Abstractions.Models
 @model BTCPayServer.Models.CustodianAccountViewModels.EditCustodianAccountViewModel
 @{
     ViewData.SetActivePage(AppsNavPages.Update, "Edit custodian account");
@@ -15,9 +16,11 @@
 
 <div class="row">
     <div class="col-xl-8 col-xxl-constrain">
-        <form asp-action="EditCustodianAccount">
-            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
-            
+        <form asp-action="EditCustodianAccount" class="mb-5">
+            @if (!ViewContext.ModelState.IsValid)
+            {
+                <div asp-validation-summary="ModelOnly" class="text-danger"></div>
+            }
             <partial name="_FormTopMessages" model="Model.ConfigForm"/>
 
             <div class="form-group">
@@ -32,5 +35,10 @@
                 <input type="submit" value="Continue" class="btn btn-primary" id="Save"/>
             </div>
         </form>
+        <a asp-action="DeleteCustodianAccount" asp-route-storeId="@Model.CustodianAccount.StoreId" asp-route-accountId="@Model.CustodianAccount.Id" class="btn btn-outline-danger" role="button" id="DeleteCustodianAccountConfig" data-bs-toggle="modal" data-bs-target="#ConfirmModal" data-description="The custodian account <strong>@Model.CustodianAccount.Name</strong> will be permanently deleted." data-confirm-input="DELETE">
+            <span class="fa fa-trash"></span> Delete this custodian account
+        </a>
     </div>
 </div>
+
+<partial name="_Confirm" model="@(new ConfirmModel("Delete custodian account", "The custodian account will be permanently deleted.", "Delete"))" />

BTCPayServer/Views/UICustodianAccounts/ViewCustodianAccount.cshtml

@@ -10,180 +10,338 @@
     <partial name="_ValidationScriptsPartial"/>
 }
 
+<style>
+    .trade-qty label{display: block; }
+</style>
 
-<partial name="_StatusMessage"/>
-
-<div class="sticky-header-setup"></div>
-<div class="sticky-header d-sm-flex align-items-center justify-content-between">
-    <h2 class="mb-0">
-        @ViewData["Title"]
-    </h2>
-    <div class="d-flex gap-3 mt-3 mt-sm-0">
-        <a asp-action="EditCustodianAccount" asp-route-storeId="@Model.CustodianAccount.StoreId" asp-route-accountId="@Model.CustodianAccount.Id" class="btn btn-primary mt-3 mt-sm-0" role="button" id="EditCustodianAccountConfig">
-            <span class="fa fa-gear"></span> Configure
-        </a>
-        <a asp-action="DeleteCustodianAccount" asp-route-storeId="@Model.CustodianAccount.StoreId" asp-route-accountId="@Model.CustodianAccount.Id" class="btn btn-danger mt-3 mt-sm-0" role="button" id="DeleteCustodianAccountConfig">
-            <span class="fa fa-trash"></span> Delete
-        </a>
-        <!--
-        <button type="submit" class="btn btn-primary order-sm-1" id="SaveSettings">Save</button>
-        <a class="btn btn-secondary" id="ViewApp" target="app_" href="/apps/MQ2sCVsmQ95JBZ4aZDtoSwMAnBY/pos">View</a>
-        -->
+<div id="custodianAccountView" v-cloak>
+    <div class="sticky-header-setup"></div>
+    <div class="sticky-header d-flex flex-wrap gap-3 align-items-center justify-content-between">
+        <h2 class="mb-0">
+            @ViewData["Title"]
+        </h2>
+        <div class="d-flex flex-wrap gap-3">
+            <a class="btn btn-primary" role="button" v-if="account && account.canDeposit" v-on:click="openDepositModal()" href="#">
+                <span class="fa fa-download"></span> Deposit
+            </a>
+            <a asp-action="EditCustodianAccount" asp-route-storeId="@Model.CustodianAccount.StoreId" asp-route-accountId="@Model.CustodianAccount.Id" class="btn btn-primary" role="button" id="EditCustodianAccountConfig">
+                <span class="fa fa-gear"></span> Configure
+            </a>
+            <!--
+            <button type="submit" class="btn btn-primary order-sm-1" id="SaveSettings">Save</button>
+            <a class="btn btn-secondary" id="ViewApp" target="app_" href="/apps/MQ2sCVsmQ95JBZ4aZDtoSwMAnBY/pos">View</a>
+            -->
+        </div>
     </div>
 
-</div>
+    <partial name="_StatusMessage"/>
 
-<div class="row">
-    <div class="col-xl-12">
+    <div class="row">
+        <div class="col-xl-12">
+            <div v-if="!account" class="loading d-flex justify-content-center p-3">
+                <div class="spinner-border text-light" role="status">
+                    <span class="visually-hidden">Loading...</span>
+                </div>
+            </div>
 
-        @if (@Model.GetAssetBalanceException != null)
-        {
-            <p class="alert alert-danger">
-                @Model.GetAssetBalanceException.Message
-            </p>
-        }
+            <div v-if="account">
+                <p class="alert alert-danger" v-if="account.assetBalanceExceptionMessage">
+                    {{ account.assetBalanceExceptionMessage }}
+                </p>
 
-        <h2>Balances</h2>
-        <div class="table-responsive">
-            <table class="table table-hover table-responsive-md">
-                <thead>
-                <tr>
-                    <th>Asset</th>
-                    <th class="text-end">Balance</th>
-                    <th class="text-end">Unit Price (Bid)</th>
-                    <th class="text-end">Unit Price (Ask)</th>
-                    <th class="text-end">Fiat Value</th>
-                    <th class="text-end">Actions</th>
-                </tr>
-                </thead>
-                <tbody>
-                @if (Model.AssetBalances != null && Model.AssetBalances.Count > 0)
-                {
-                    @foreach (var pair in Model.AssetBalances.OrderBy(key => key.Key))
-                    {
+                <h2>Balances</h2>
+                
+                <div class="form-check">
+                  <input class="form-check-input" type="checkbox" v-model="hideDustAmounts" id="flexCheckDefault">
+                  <label class="form-check-label" for="flexCheckDefault" >
+                      Hide holdings worth less than {{ account.dustThresholdInFiat }} {{ account.storeDefaultFiat }}.
+                  </label>
+                </div>
+                
+                
+                <div class="table-responsive">
+                    <table class="table table-hover table-responsive-md">
+                        <thead>
                         <tr>
-                            <td>@pair.Key</td>
+                            <th>Asset</th>
+                            <th class="text-end">Balance</th>
+                            <th class="text-end">Unit Price (Bid)</th>
+                            <th class="text-end">Unit Price (Ask)</th>
+                            <th class="text-end">Fiat Value</th>
+                            <th class="text-end">Actions</th>
+                        </tr>
+                        </thead>
+                        <tbody>
+                        <tr v-for="row in sortedAssetRows" :key="row.asset">
+                            <td>{{ row.asset }}</td>
                             <!-- TODO format as number? How? -->
-                            <th class="text-end">@pair.Value.Qty</th>
+                            <th class="text-end">{{ row.formattedQty }}</th>
                             <th class="text-end">
-                                @pair.Value.FormattedBid
+                                {{ row.formattedBid }}
                             </th>
                             <th class="text-end">
-                                @pair.Value.FormattedAsk
+                                {{ row.formattedAsk }}
                             </th>
                             <th class="text-end">
-                                @(pair.Value.FormattedFiatValue)
+                                {{ row.formattedFiatValue }}
                             </th>
                             <th class="text-end">
-                                @if (pair.Value.TradableAssetPairs != null)
-                                {
-                                    <a data-bs-toggle="modal" data-bs-target="#tradeModal" href="#">Trade</a>
-                                }
-                                @if (pair.Value.CanDeposit)
-                                {
-                                    <a data-bs-toggle="modal" data-bs-target="#depositModal" href="#">Deposit</a>
-                                }
-                                @if (pair.Value.CanWithdraw)
-                                {
-                                    <a data-bs-toggle="modal" data-bs-target="#withdrawModal" href="#">Withdraw</a>
-                                }
+                                <a v-if="row.tradableAssetPairs" v-on:click="openTradeModal(row)" href="#">Trade</a>
+                                <a v-if="row.canDeposit" v-on:click="openDepositModal(row)" href="#">Deposit</a>
+                                <a v-if="row.canWithdraw" v-on:click="openWithdrawModal(row)" href="#">Withdraw</a>
                             </th>
                         </tr>
+                        <tr v-if="account.assetBalances.length === 0">
+                            <td colspan="999" class="text-center">No assets are stored with this custodian (yet).</td>
+                        </tr>
+                        <tr v-if="account.assetBalanceExceptionMessage !== null">
+                            <td colspan="999" class="text-center">An error occured while loading assets and balances.</td>
+                        </tr>
+                        </tbody>
+                    </table>
+                </div>
+
+
+                <h2>Features</h2>
+                <p>The @Model?.Custodian.Name custodian supports:</p>
+                <ul>
+                    <li>Viewing asset account</li>
+                    @if (Model?.Custodian is ICanTrade)
+                    {
+                        <li>Trading</li>
                     }
-                }
-                else if (Model.GetAssetBalanceException == null)
-                {
-                    <tr>
-                        <td colspan="999" class="text-center">No assets are stored with this custodian (yet).</td>
-                    </tr>
-                }
-                else
-                {
-                    <tr>
-                        <td colspan="999" class="text-center">An error occured while loading assets and balances.</td>
-                    </tr>
-                }
-                </tbody>
-            </table>
+                    @if (Model?.Custodian is ICanDeposit)
+                    {
+                        <li>Depositing (Greenfield API only, for now)</li>
+                    }
+                    @if (Model?.Custodian is ICanWithdraw)
+                    {
+                        <li>Withdrawing (Greenfield API only, for now)</li>
+                    }
+                </ul>
+            </div>
         </div>
-
-
-        <h2>Features</h2>
-        <p>The @Model.Custodian.Name custodian supports:</p>
-        <ul>
-            <li>Viewing asset balances</li>
-            @if (Model.Custodian is ICanTrade)
-            {
-                <li>Trading (Greenfield API only, for now)</li>
-            }
-            @if (Model.Custodian is ICanDeposit)
-            {
-                <li>Depositing (Greenfield API only, for now)</li>
-            }
-            @if (Model.Custodian is ICanWithdraw)
-            {
-                <li>Withdrawing (Greenfield API only, for now)</li>
-            }
-        </ul>
-
-
     </div>
-</div>
 
 
-<div class="modal" tabindex="-1" role="dialog" id="withdrawModal">
-    <div class="modal-dialog" role="document">
-        <div class="modal-content">
-            <div class="modal-header">
-                <h5 class="modal-title">Withdraw</h5>
-                <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close">
-                    <vc:icon symbol="close"/>
-                </button>
+    <div class="modal" tabindex="-1" role="dialog" id="withdrawModal">
+        <div class="modal-dialog" role="document">
+            <div class="modal-content">
+                <div class="modal-header">
+                    <h5 class="modal-title">Withdraw</h5>
+                    <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close">
+                        <vc:icon symbol="close"/>
+                    </button>
+                </div>
+                <div class="modal-body">
+                    <p>Withdrawals are coming soon, but if you need this today, you can use our <a rel="noopener noreferrer" href="https://docs.btcpayserver.org/API/Greenfield/v1/" target="_blank">Greenfield API "Withdraw to store wallet" endpoint</a> to execute a withdrawal.</p>
+                </div>
+                <div class="modal-footer">
+                    <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
+                </div>
             </div>
-            <div class="modal-body">
-                <p>Withdrawals are coming soon, but if you need this today, you can use our <a rel="noopener noreferrer" href="https://docs.btcpayserver.org/API/Greenfield/v1/" target="_blank">Greenfield API "Withdraw to store wallet" endpoint</a> to execute a withdrawal.</p>
-            </div>
-            <div class="modal-footer">
-                <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
+        </div>
+    </div>
+
+    <div class="modal" tabindex="-1" role="dialog" id="depositModal">
+        <div class="modal-dialog" role="document">
+            <div class="modal-content">
+                <div class="modal-header">
+                    <h5 class="modal-title">Deposit</h5>
+                    <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close">
+                        <vc:icon symbol="close"/>
+                    </button>
+                </div>
+                <div class="modal-body">
+                    <p>Deposits are coming soon, but if you need this today, you can use our <a rel="noopener noreferrer" href="https://docs.btcpayserver.org/API/Greenfield/v1/" target="_blank">Greenfield API "Get a deposit address for custodian" endpoint</a> to get a deposit address to send your assets to.</p>
+                </div>
+                <div class="modal-footer">
+                    <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
+                </div>
             </div>
         </div>
     </div>
+
+    <div class="modal" tabindex="-1" role="dialog" id="tradeModal" :data-bs-keyboard="!trade.isExecuting">
+        <div class="modal-dialog" role="document">
+            <form class="modal-content" v-on:submit="onTradeSubmit" method="post" asp-action="Trade" asp-route-accountId="@Model?.CustodianAccount?.Id" asp-route-storeId="@Model?.CustodianAccount?.StoreId">
+                <div class="modal-header">
+                    <h5 class="modal-title">Trade {{ trade.qty }} {{ trade.assetToTrade }} into {{ trade.assetToTradeInto }}</h5>
+                    <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close" v-if="!trade.isExecuting">
+                        <vc:icon symbol="close"/>
+                    </button>
+                </div>
+                <div class="modal-body">
+                    <div class="loading d-flex justify-content-center p-3" v-if="trade.isExecuting">
+                        <div class="spinner-border text-light" role="status">
+                            <span class="visually-hidden">Loading...</span>
+                        </div>
+                    </div>
+
+                    <div v-if="!trade.isExecuting && trade.results === null">
+                        <p v-if="trade.errorMsg" class="alert alert-danger">{{ trade.errorMsg }}</p>
+
+                        <div class="row mb-2 trade-qty">
+                            <div class="col-side">  
+                                <label class="form-label">
+                                    Convert
+                                    <div class="input-group has-validation">
+                                    <!--
+                                    getMinQtyToTrade() = {{ getMinQtyToTrade(this.trade.assetToTradeInto, this.trade.assetToTrade) }}
+                                    <br/>
+                                    Max Qty to Trade = {{ trade.maxQtyToTrade }}
+                                    -->
+                                        <input name="Qty" type="number" min="0" step="any" :max="trade.maxQtyToTrade" :min="getMinQtyToTrade()" class="form-control qty" v-bind:class="{ 'is-invalid': trade.qty < getMinQtyToTrade() || trade.qty > trade.maxQtyToTrade }" v-model="trade.qty"/>
+                                        <select name="FromAsset" v-model="trade.assetToTrade" class="form-control">
+                                            <option v-for="option in availableAssetsToTrade" v-bind:value="option">
+                                                {{ option }}
+                                            </option>
+                                        </select>
+                                    </div>
+                                </label>
+                            </div>
+                            <div class="col-center text-center">
+                                &nbsp;
+                                <br/>
+                                <button v-if="canSwapTradeAssets()" type="button" class="btn btn-secondary btn-square" v-on:click="swapTradeAssets()" aria-label="Swap assets">
+                                    <i class="fa fa-arrows-h" aria-hidden="true"></i>
+                                </button>
+                            </div>
+                            <div class="col-side">
+                                <label class="form-label">
+                                    Into
+                                    <div class="input-group">
+                                        <input disabled="disabled" type="number" class="form-control qty" v-model="tradeQtyToReceive"/>
+                                        <select name="ToAsset" v-model="trade.assetToTradeInto" class="form-control">
+                                            <option v-for="option in availableAssetsToTradeInto" v-bind:value="option">
+                                                {{ option }}
+                                            </option>
+                                        </select>
+                                    </div>
+                                </label>
+                            </div>
+                        </div>
+                        <div>
+                            <div class="btn-group" role="group" aria-label="Set qty to a percentage of holdings">
+                                <button v-on:click="setTradeQtyPercent(10)" class="btn btn-secondary" type="button">10%</button>
+                                <button v-on:click="setTradeQtyPercent(25)" class="btn btn-secondary" type="button">25%</button>
+                                <button v-on:click="setTradeQtyPercent(50)" class="btn btn-secondary" type="button">50%</button>
+                                <button v-on:click="setTradeQtyPercent(75)" class="btn btn-secondary" type="button">75%</button>
+                                <button v-on:click="setTradeQtyPercent(90)" class="btn btn-secondary" type="button">90%</button>
+                                <button v-on:click="setTradeQtyPercent(100)" class="btn btn-secondary" type="button">100%</button>
+                            </div>
+                        </div>
+
+                        <p v-if="trade.price">
+                            <br/>
+                            1 {{ trade.assetToTradeInto }} = {{ trade.price }} {{ trade.assetToTrade }}
+                            <br/>
+                            1 {{ trade.assetToTrade }} = {{ 1 / trade.price }} {{ trade.assetToTradeInto }}
+                        </p>
+                        <p v-if="canExecuteTrade">
+                            After the trade
+                            {{ trade.maxQtyToTrade - trade.qty }} {{ trade.assetToTrade }} will remain in your account.
+                        </p>
+                        
+                        <!--
+                        <p>
+                            trade.priceForPair = {{ trade.priceForPair }}
+                        </p>
+                        <table>
+                            <thead>
+                            <tr>
+                                <th>From</th>
+                                <th>To</th>
+                                <th>Min Qty to Trade</th>
+                                <th>Price</th>
+                            </tr>
+                            </thead>
+                            <tbody>
+                            <tr>
+                                <td>EUR</td>
+                                <td>BTC</td>
+                                <td>{{getMinQtyToTrade('EUR', 'BTC')}}</td>
+                                <td>{{trade.priceForPair['EUR/BTC']}}</td>
+                            </tr>
+                            <tr>
+                                <td>BTC</td>
+                                <td>EUR</td>
+                                <td>{{getMinQtyToTrade('BTC', 'EUR')}}</td>
+                                <td>{{trade.priceForPair['BTC/EUR']}}</td>
+                            </tr>
+                            <tr>
+                                <td>EUR</td>
+                                <td>LTC</td>
+                                <td>{{getMinQtyToTrade('EUR', 'LTC')}}</td>
+                                <td>{{trade.priceForPair['EUR/LTC']}}</td>
+                            </tr>
+                            <tr>
+                                <td>LTC</td>
+                                <td>EUR</td>
+                                <td>{{getMinQtyToTrade('LTC', 'EUR')}}</td>
+                                <td>{{trade.priceForPair['LTC/EUR']}}</td>
+                            </tr>
+                            <tr>
+                                <td>BTC</td>
+                                <td>LTC</td>
+                                <td>{{getMinQtyToTrade('BTC', 'LTC')}}</td>
+                                <td>{{trade.priceForPair['BTC/LTC']}}</td>
+                            </tr>
+                            <tr>
+                                <td>LTC</td>
+                                <td>BTC</td>
+                                <td>{{getMinQtyToTrade('LTC', 'BTC')}}</td>
+                                <td>{{trade.priceForPair['LTC/BTC']}}</td>
+                            </tr>
+                            </tbody>
+                        </table>
+                        -->
+                        <small class="form-text text-muted">Final results may vary due to trading fees and slippage.</small>
+                    </div>
+                    <div v-if="trade.results !== null">
+                        <p class="alert alert-success">Successfully traded {{ trade.results.fromAsset}} into {{ trade.results.toAsset}}.</p>
+                        <table class="table table-striped">
+                            <thead>
+                            <tr>
+                                <th colspan="2">Asset</th>
+                                <th>Comment</th>
+                            </tr>
+                            </thead>
+                            <tbody>
+                            <tr v-for="entry in trade.results.ledgerEntries">
+                                <td class="text-end" v-bind:class="{ 'text-success': entry.qty > 0, 'text-danger': entry.qty < 0 }"><span v-if="entry.qty > 0">+</span>{{ entry.qty }}</td>
+                                <td v-bind:class="{ 'text-success': entry.qty > 0, 'text-danger': entry.qty < 0 }">{{ entry.asset }}</td>
+                                <td v-bind:class="{ 'text-success': entry.qty > 0, 'text-danger': entry.qty < 0 }">
+                                    <span v-if="entry.type !== 'Trade'">{{ entry.type}}</span>
+                                </td>
+                            </tr>
+                            </tbody>
+                        </table>
+                        <p>Trade ID: {{ trade.results.tradeId }}</p>
+                    </div>
+                </div>
+                <div class="modal-footer" v-if="!trade.isExecuting">
+                    
+                    <div class="modal-footer-left">
+                        <span v-if="trade.isUpdating">
+                            Updating quote...
+                        </span>
+                    </div>
+                    
+                    <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">
+                        <span v-if="trade.results">Close</span>
+                        <span v-if="!trade.results">Cancel</span>
+                    </button>
+                    <button v-if="canExecuteTrade" type="submit" class="btn btn-primary">Execute</button>
+                </div>
+            </form>
+        </div>
+    </div>
 </div>
 
-<div class="modal" tabindex="-1" role="dialog" id="depositModal">
-    <div class="modal-dialog" role="document">
-        <div class="modal-content">
-            <div class="modal-header">
-                <h5 class="modal-title">Deposit</h5>
-                <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close">
-                    <vc:icon symbol="close"/>
-                </button>
-            </div>
-            <div class="modal-body">
-                <p>Deposits are coming soon, but if you need this today, you can use our <a rel="noopener noreferrer" href="https://docs.btcpayserver.org/API/Greenfield/v1/" target="_blank">Greenfield API "Get a deposit address for custodian" endpoint</a> to get a deposit address to send your assets to.</p>
-            </div>
-            <div class="modal-footer">
-                <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
-            </div>
-        </div>
-    </div>
-</div>
-
-<div class="modal" tabindex="-1" role="dialog" id="tradeModal">
-    <div class="modal-dialog" role="document">
-        <div class="modal-content">
-            <div class="modal-header">
-                <h5 class="modal-title">Trade</h5>
-                <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close">
-                    <vc:icon symbol="close"/>
-                </button>
-            </div>
-            <div class="modal-body">
-                <p>Trades are coming soon, but if you need this today, you can use our <a rel="noopener noreferrer" href="https://docs.btcpayserver.org/API/Greenfield/v1/" target="_blank"> Greenfield API "Trade one asset for another" endpoint</a> to convert an asset to another via a market order.</p>
-            </div>
-            <div class="modal-footer">
-                <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
-            </div>
-        </div>
-    </div>
-</div>
+<script src="~/vendor/vuejs/vue.min.js" asp-append-version="true"></script>
+<script type="text/javascript">
+var ajaxBalanceUrl = "@Url.Action("ViewCustodianAccountAjax", "UICustodianAccounts", new { storeId = Model?.CustodianAccount.StoreId, accountId = Model?.CustodianAccount.Id })";
+var ajaxTradePrepareUrl = "@Url.Action("GetTradePrepareAjax", "UICustodianAccounts", new { storeId = Model?.CustodianAccount.StoreId, accountId = Model?.CustodianAccount.Id })";
+</script>
+<script src="~/js/custodian-account.js" asp-append-version="true"></script>

BTCPayServer/wwwroot/js/custodian-account.js

@@ -0,0 +1,372 @@
+new Vue({
+    el: '#custodianAccountView',
+    data: {
+        account: null,
+        hideDustAmounts: true,
+        modals: {
+            trade: null,
+            withdraw: null,
+            deposit: null
+        },
+        trade: {
+            row: null,
+            results: null,
+            errorMsg: null,
+            isExecuting: false,
+            isUpdating: false,
+            updateTradePriceAbortController: new AbortController(),
+            priceRefresherInterval: null,
+            assetToTrade: null,
+            assetToTradeInto: null,
+            qty: null,
+            maxQtyToTrade: null,
+            price: null,
+            priceForPair: {}
+        }
+    },
+    computed: {
+        tradeQtyToReceive: function () {
+            return this.trade.qty / this.trade.price;
+        },
+        canExecuteTrade: function () {
+            return this.trade.qty >= this.getMinQtyToTrade() && this.trade.price !== null && this.trade.assetToTrade !== null && this.trade.assetToTradeInto !== null && !this.trade.isExecuting && this.trade.results === null;
+        },
+        availableAssetsToTrade: function () {
+            let r = [];
+            let balances = this?.account?.assetBalances;
+            if (balances) {
+                let t = this;
+                let rows = Object.values(balances);
+                rows = rows.filter(function (row) {
+                    return row.fiatValue > t.account.dustThresholdInFiat;
+                });
+
+                for (let i in rows) {
+                    r.push(rows[i].asset);
+                }
+            }
+            return r.sort();
+        },
+        availableAssetsToTradeInto: function () {
+            let r = [];
+            let pairs = this.account?.assetBalances?.[this.trade.assetToTrade]?.tradableAssetPairs;
+            if (pairs) {
+                for (let i in pairs) {
+                    let pair = pairs[i];
+                    if (pair.assetBought === this.trade.assetToTrade) {
+                        r.push(pair.assetSold);
+                    } else if (pair.assetSold === this.trade.assetToTrade) {
+                        r.push(pair.assetBought);
+                    }
+                }
+            }
+            return r.sort();
+        },
+        sortedAssetRows: function () {
+            if (this.account?.assetBalances) {
+                let rows = Object.values(this.account.assetBalances);
+                let t = this;
+
+                if (this.hideDustAmounts) {
+                    rows = rows.filter(function (row) {
+                        return row.fiatValue > t.account.dustThresholdInFiat;
+                    });
+                }
+
+                rows = rows.sort(function (a, b) {
+                    return b.fiatValue - a.fiatValue;
+                });
+
+                return rows;
+            }
+        }
+    },
+    methods: {
+        getMaxQtyToTrade: function (assetToTrade) {
+            let row = this.account?.assetBalances?.[assetToTrade];
+            if (row) {
+                return row.qty;
+            }
+            return null;
+        },
+        getMinQtyToTrade: function (assetToTrade = this.trade.assetToTrade, assetToTradeInto = this.trade.assetToTradeInto) {
+            if (assetToTrade && assetToTradeInto && this.account?.assetBalances) {
+                for (let asset in this.account.assetBalances) {
+                    let row = this.account.assetBalances[asset];
+
+                    let pairCode = assetToTrade + "/" + assetToTradeInto;
+                    let pairCodeReverse = assetToTradeInto + "/" + assetToTrade;
+
+                    let pair = row.tradableAssetPairs?.[pairCode];
+                    let pairReverse = row.tradableAssetPairs?.[pairCodeReverse];
+
+                    if(pair !== null || pairReverse !== null){
+                        if (pair && !pairReverse) {
+                            return pair.minimumTradeQty;
+                        } else if (!pair && pairReverse) {
+                            // TODO price here could not be what we expect it to be...
+                            let price = this.trade.priceForPair?.[pairCode];
+                            if(!price){
+                                return null;
+                            }
+                            // if (reverse) {
+                            //     return price / pairReverse.minimumTradeQty;
+                            // }else {
+                                return price * pairReverse.minimumTradeQty;
+                            // }
+                        }
+                    }
+                }
+            }
+            return 0;
+        },
+        setTradeQtyPercent: function (percent) {
+            this.trade.qty = percent / 100 * this.trade.maxQtyToTrade;
+        },
+        openTradeModal: function (row) {
+            let _this = this;
+            this.trade.row = row;
+            this.trade.results = null;
+            this.trade.errorMsg = null;
+            this.trade.assetToTrade = row.asset;
+            if (row.asset === this.account.storeDefaultFiat) {
+                this.trade.assetToTradeInto = "BTC";
+            } else {
+                this.trade.assetToTradeInto = this.account.storeDefaultFiat;
+            }
+
+            // TODO watch "this.trade.assetToTrade" for changes and if so, set "qty" to max + fill "maxQtyToTrade" and "price"
+
+            this.trade.qty = row.qty;
+            this.trade.maxQtyToTrade = row.qty;
+            this.trade.price = row.bid;
+
+            if (this.modals.trade === null) {
+                this.modals.trade = new window.bootstrap.Modal('#tradeModal');
+
+                // Disable price refreshing when modal closes...
+                const tradeModelElement = document.getElementById('tradeModal')
+                tradeModelElement.addEventListener('hide.bs.modal', event => {
+                    _this.setTradePriceRefresher(false);
+                });
+            }
+
+            this.setTradePriceRefresher(true);
+            this.modals.trade.show();
+        },
+        openWithdrawModal: function (row) {
+            if (this.modals.withdraw === null) {
+                this.modals.withdraw = new window.bootstrap.Modal('#withdrawModal');
+            }
+            this.modals.withdraw.show();
+        },
+        openDepositModal: function (row) {
+            if (this.modals.deposit === null) {
+                this.modals.deposit = new window.bootstrap.Modal('#depositModal');
+            }
+            this.modals.deposit.show();
+        },
+        onTradeSubmit: async function (e) {
+            e.preventDefault();
+
+            const form = e.currentTarget;
+            const url = form.getAttribute('action');
+            const method = form.getAttribute('method');
+
+            this.trade.isExecuting = true;
+
+            // Prevent the modal from closing by clicking outside or via the keyboard
+            this.modals.trade._config.backdrop = 'static';
+            this.modals.trade._config.keyboard = false;
+
+            const _this = this;
+            const token = document.querySelector("input[name='__RequestVerificationToken']").value;
+
+            const response = await fetch(url, {
+                method,
+                headers: {
+                    'Content-Type': 'application/json',
+                    'RequestVerificationToken': token
+                },
+                body: JSON.stringify({
+                    fromAsset: _this.trade.assetToTrade,
+                    toAsset: _this.trade.assetToTradeInto,
+                    qty: _this.trade.qty
+                })
+            });
+
+            let data = null;
+            try {
+                data = await response.json();
+            } catch (e) {
+            }
+
+            if (response.ok) {
+                _this.trade.results = data;
+                _this.trade.errorMsg = null;
+
+                _this.setTradePriceRefresher(false);
+                _this.refreshAccountBalances();
+            } else {
+                _this.trade.errorMsg = data && data.message || "Error";
+            }
+            _this.modals.trade._config.backdrop = true;
+            _this.modals.trade._config.keyboard = true;
+            _this.trade.isExecuting = false;
+        },
+
+        setTradePriceRefresher: function (enabled) {
+            if (enabled) {
+                // Update immediately...
+                this.updateTradePrice();
+
+                // And keep updating every few seconds...
+                let _this = this;
+                this.trade.priceRefresherInterval = setInterval(function () {
+                    _this.updateTradePrice();
+                }, 5000);
+
+            } else {
+                clearInterval(this.trade.priceRefresherInterval);
+            }
+        },
+
+        updateTradePrice: function () {
+            if (!this.trade.assetToTrade || !this.trade.assetToTradeInto) {
+                // We need to know the 2 assets or we cannot do anything...
+                return;
+            }
+
+            if (this.trade.assetToTrade === this.trade.assetToTradeInto) {
+                // The 2 assets must be different
+                this.trade.price = null;
+                return;
+            }
+
+            if (this.trade.isUpdating) {
+                console.log("Previous request is still running. No need to hammer the server.");
+                return;
+            }
+
+            this.trade.isUpdating = true;
+
+            let _this = this;
+            var searchParams = new URLSearchParams(window.location.search);
+            if (this.trade.assetToTrade) {
+                searchParams.set("assetToTrade", this.trade.assetToTrade);
+            }
+            if (this.trade.assetToTradeInto) {
+                searchParams.set("assetToTradeInto", this.trade.assetToTradeInto);
+            }
+            let url = window.ajaxTradePrepareUrl + "?" + searchParams.toString();
+
+            this.trade.updateTradePriceAbortController = new AbortController();
+
+            fetch(url, {
+                    signal: this.trade.updateTradePriceAbortController.signal,
+                    headers: {
+                        'Content-Type': 'application/json'
+                    }
+                }
+            ).then(function (response) {
+                    _this.trade.isUpdating = false;
+
+                    if (response.ok) {
+                        return response.json();
+                    }
+                    // _this.trade.results = data;
+                    // _this.trade.errorMsg = null; }
+                    // Do nothing on error
+                }
+            ).then(function (data) {
+                _this.trade.maxQtyToTrade = data.maxQtyToTrade;
+
+                // By default trade everything
+                if (_this.trade.qty === null) {
+                    _this.trade.qty = _this.trade.maxQtyToTrade;
+                }
+
+                // Cannot trade more than what we have
+                if (data.maxQtyToTrade < _this.trade.qty) {
+                    _this.trade.qty = _this.trade.maxQtyToTrade;
+                }
+                let pair = data.fromAsset+"/"+data.toAsset;
+                let pairReverse = data.toAsset+"/"+data.fromAsset;
+                
+                // TODO Should we use "bid" in some cases? The spread can be huge with some shitcoins.
+                _this.trade.price = data.ask;
+                _this.trade.priceForPair[pair] = data.ask;
+                _this.trade.priceForPair[pairReverse] = 1 / data.ask;
+                
+            }).catch(function (e) {
+                _this.trade.isUpdating = false;
+                if (e instanceof DOMException && e.code === DOMException.ABORT_ERR) {
+                    console.log("User aborted fetch request");
+                } else {
+                    throw e;
+                }
+            });
+        },
+        canSwapTradeAssets: function () {
+            let minQtyToTrade = this.getMinQtyToTrade(this.trade.assetToTradeInto, this.trade.assetToTrade);
+            let assetToTradeIntoHoldings = this.account?.assetBalances?.[this.trade.assetToTradeInto];
+            if (assetToTradeIntoHoldings) {
+                return assetToTradeIntoHoldings.qty >= minQtyToTrade;
+            }
+        },
+        swapTradeAssets: function () {
+            // Swap the 2 assets
+            let tmp = this.trade.assetToTrade;
+            this.trade.assetToTrade = this.trade.assetToTradeInto;
+            this.trade.assetToTradeInto = tmp;
+            this.trade.price = 1 / this.trade.price;
+            
+            this._refreshTradeDataAfterAssetChange();
+        },
+        _refreshTradeDataAfterAssetChange: function(){
+            let maxQtyToTrade = this.getMaxQtyToTrade(this.trade.assetToTrade);
+            this.trade.qty = maxQtyToTrade
+            this.trade.maxQtyToTrade = maxQtyToTrade;
+
+            this.killAjaxIfRunning(this.trade.updateTradePriceAbortController);
+
+            // Update the price asap, so we can continue
+            let _this = this;
+            setTimeout(function () {
+                _this.updateTradePrice();
+            }, 100);
+        },
+        killAjaxIfRunning: function (abortController) {
+            abortController.abort();
+        },
+        refreshAccountBalances: function () {
+            let _this = this;
+            fetch(window.ajaxBalanceUrl).then(function (response) {
+                return response.json();
+            }).then(function (result) {
+                _this.account = result;
+            });
+        }
+    },
+    watch: {
+        'trade.assetToTrade': function(newValue, oldValue){
+            if(newValue === this.trade.assetToTradeInto){
+                // This is the same as swapping the 2 assets
+                this.trade.assetToTradeInto = oldValue;
+                this.trade.price = 1 / this.trade.price;
+                
+                this._refreshTradeDataAfterAssetChange();
+            }
+            if(newValue !== oldValue){
+                // The qty is going to be wrong, so set to 100%
+                this.trade.qty = this.getMaxQtyToTrade(this.trade.assetToTrade);
+            }
+        }
+    },
+    created: function () {
+        this.refreshAccountBalances();
+    },
+    mounted: function () {
+        // Runs when the app is ready
+    }
+});

BTCPayServer/wwwroot/main/site.css

@@ -528,3 +528,23 @@ svg.icon-note {
         margin-right: 0;
     }
 }
+
+#tradeModal .qty{ width: 53%; }
+#tradeModal .btn-square{ padding: 0; width: 2.5rem; height: 2.5rem; }
+
+#tradeModal .trade-qty {
+    display: flex;
+    justify-content: space-between;
+}
+
+#tradeModal .trade-qty .col-center {
+    flex: 0 0 2rem;
+    padding-left: 0;
+    padding-right: 0;
+}
+
+#tradeModal .trade-qty .col-side {
+    flex: 1;
+}
+
+.modal-footer .modal-footer-left{ margin-right: auto; }

BTCPayServer/wwwroot/swagger/v1/swagger.template.custodians.json

@@ -637,19 +637,38 @@
                     },
                     "tradableAssetPairs": {
                         "type": "array",
-                        "description": "A list of tradable asset pairs, or NULL if the custodian cannot trades/convert assets.",
-                        "nullable": true
+                        "description": "A list of tradable asset pair objects, or NULL if the custodian cannot trades/convert assets.",
+                        "nullable": true,
+                        "items": {
+                            "$ref": "#/components/schemas/AssetPairData"
+                        }
                     }
                 },
                 "example": {
                     "code": "kraken",
                     "name": "Kraken",
-                    "tradableAssetPairs": [
-                        "BTC/USD",
-                        "BTC/EUR",
-                        "LTC/USD",
-                        "LTC/EUR"
-                    ],
+                    "tradableAssetPairs": {
+                        "BTC/USD": {
+                            "assetBought": "BTC",
+                            "assetSold": "USD",
+                            "minimumTradeQty": 0.001
+                        },
+                        "BTC/EUR": {
+                            "assetBought": "BTC",
+                            "assetSold": "EUR",
+                            "minimumTradeQty": 0.001
+                        },
+                        "LTC/USD": {
+                            "assetBought": "LTC",
+                            "assetSold": "USD",
+                            "minimumTradeQty": 0.05
+                        },
+                        "LTC/EUR": {
+                            "assetBought": "LTC",
+                            "assetSold": "EUR",
+                            "minimumTradeQty": 0.05
+                        }
+                    },
                     "withdrawablePaymentMethods": [
                         "BTC-OnChain",
                         "LTC-OnChain"
@@ -1023,6 +1042,27 @@
                     "qty": 1.23456
                 }
             },
+            "AssetPairData": {
+                "type": "object",
+                "description": "An asset pair we can trade.",
+                "properties": {
+                    "pair": {
+                        "type": "string",
+                        "description": "The name of the asset pair.",
+                        "nullable": false
+                    },
+                    "minimumTradeQty": {
+                        "type": "number",
+                        "description": "The smallest amount we can buy or sell.",
+                        "nullable": false
+                    }
+                },
+                "example": {
+                    "assetBought": "BTC",
+                    "assetSold": "USD",
+                    "minimumTradeQty": 0.0001
+                }
+            },
             "LedgerEntryType": {
                 "type": "string",
                 "enum": [