From aefb81b7f0869101c6f5ecb98acbe6e107e10f5d Mon Sep 17 00:00:00 2001
From: Umar Bolatov <bolatovumar@gmail.com>
Date: Fri, 9 Jul 2021 21:04:01 -0700
Subject: [PATCH] Add "skip" and "limit" params for onchain txs API endpoint
 (#2688)

Discussed here: https://github.com/btcpayserver/btcpayserver/discussions/2667
---
 .../StoreOnChainWalletsController.cs          | 20 ++++++++++++-------
 ...agger.template.stores-wallet.on-chain.json | 20 ++++++++++++++++++-
 2 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/BTCPayServer/Controllers/GreenField/StoreOnChainWalletsController.cs b/BTCPayServer/Controllers/GreenField/StoreOnChainWalletsController.cs
index 07241870a..6e05f307d 100644
--- a/BTCPayServer/Controllers/GreenField/StoreOnChainWalletsController.cs
+++ b/BTCPayServer/Controllers/GreenField/StoreOnChainWalletsController.cs
@@ -1,3 +1,4 @@
+#nullable enable
 using System;
 using System.Collections.Generic;
 using System.Globalization;
@@ -156,8 +157,13 @@ namespace BTCPayServer.Controllers.GreenField
 
         [Authorize(Policy = Policies.CanModifyStoreSettings, AuthenticationSchemes = AuthenticationSchemes.Greenfield)]
         [HttpGet("~/api/v1/stores/{storeId}/payment-methods/onchain/{cryptoCode}/wallet/transactions")]
-        public async Task<IActionResult> ShowOnChainWalletTransactions(string storeId, string cryptoCode,
-            [FromQuery]TransactionStatus[] statusFilter = null)
+        public async Task<IActionResult> ShowOnChainWalletTransactions(
+            string storeId, 
+            string cryptoCode,
+            [FromQuery] TransactionStatus[]? statusFilter = null,
+            [FromQuery] int skip = 0,
+            [FromQuery] int limit = int.MaxValue
+        )
         {
             if (IsInvalidWalletRequest(cryptoCode, out BTCPayNetwork network,
                 out DerivationSchemeSettings derivationScheme, out IActionResult actionResult)) return actionResult;
@@ -183,7 +189,7 @@ namespace BTCPayServer.Controllers.GreenField
                 filteredFlatList.AddRange(txs.ReplacedTransactions.Transactions);
             }
 
-            var result = filteredFlatList.Select(information =>
+            var result = filteredFlatList.Skip(skip).Take(limit).Select(information =>
             {
                 walletTransactionsInfoAsync.TryGetValue(information.TransactionId.ToString(), out var transactionInfo);
                 return ToModel(transactionInfo, information, wallet);
@@ -297,7 +303,7 @@ namespace BTCPayServer.Controllers.GreenField
                     subtractFeesOutputsCount.Add(index);
                 }
 
-                BitcoinUrlBuilder bip21 = null;
+                BitcoinUrlBuilder? bip21 = null;
                 var amount = destination.Amount;
                 if (amount.GetValueOrDefault(0) <= 0)
                 {
@@ -542,15 +548,15 @@ namespace BTCPayServer.Controllers.GreenField
             return paymentMethod;
         }
 
-        private OnChainWalletTransactionData ToModel(WalletTransactionInfo walletTransactionsInfoAsync,
+        private OnChainWalletTransactionData ToModel(WalletTransactionInfo? walletTransactionsInfoAsync,
             TransactionInformation tx,
             BTCPayWallet wallet)
         {
             return new OnChainWalletTransactionData()
             {
                 TransactionHash = tx.TransactionId,
-                Comment = walletTransactionsInfoAsync?.Comment?? string.Empty,
-                Labels = walletTransactionsInfoAsync?.Labels?? new Dictionary<string, LabelData>(),
+                Comment = walletTransactionsInfoAsync?.Comment ?? string.Empty,
+                Labels = walletTransactionsInfoAsync?.Labels ?? new Dictionary<string, LabelData>(),
                 Amount = tx.BalanceChange.GetValue(wallet.Network),
                 BlockHash = tx.BlockHash,
                 BlockHeight = tx.Height,
diff --git a/BTCPayServer/wwwroot/swagger/v1/swagger.template.stores-wallet.on-chain.json b/BTCPayServer/wwwroot/swagger/v1/swagger.template.stores-wallet.on-chain.json
index 4a357c639..f6eb4ee91 100644
--- a/BTCPayServer/wwwroot/swagger/v1/swagger.template.stores-wallet.on-chain.json
+++ b/BTCPayServer/wwwroot/swagger/v1/swagger.template.stores-wallet.on-chain.json
@@ -263,13 +263,31 @@
                         "name": "statusFilter",
                         "in": "query",
                         "required": false,
-                        "description": "statuses to filter the transactions with",
+                        "description": "Statuses to filter the transactions with",
                         "schema": {
                             "type": "array",
                             "items": {
                                 "$ref": "#/components/schemas/TransactionStatus"
                             }
                         }
+                    },
+                    {
+                        "name": "skip",
+                        "in": "query",
+                        "required": false,
+                        "description": "Number of transactions to skip from the start",
+                        "schema": {
+                            "type": "integer"
+                        }
+                    },
+                    {
+                        "name": "limit",
+                        "in": "query",
+                        "required": false,
+                        "description": "Maximum number of transactions to return",
+                        "schema": {
+                            "type": "integer"
+                        }
                     }
                 ],
                 "description": "Get store on-chain wallet transactions",