From 9d7bd871e7c92144deb47ad256b459c5e783c030 Mon Sep 17 00:00:00 2001
From: Mikael Lindlof <mikuz.dev@gmail.com>
Date: Tue, 26 May 2020 23:52:23 +0100
Subject: [PATCH] Add type for second getblockfilter param

---
 btcjson/chainsvrcmds.go      | 15 ++++++++++++---
 btcjson/chainsvrcmds_test.go |  4 ++--
 btcjson/helpers.go           |  8 ++++++++
 rpcclient/chain.go           |  6 +++---
 4 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/btcjson/chainsvrcmds.go b/btcjson/chainsvrcmds.go
index 5619248a5b..a9a881d401 100644
--- a/btcjson/chainsvrcmds.go
+++ b/btcjson/chainsvrcmds.go
@@ -163,10 +163,19 @@ func NewGetBlockCountCmd() *GetBlockCountCmd {
 	return &GetBlockCountCmd{}
 }
 
+// FilterTypeName defines the type used in the getblockfilter JSON-RPC command for the
+// filter type field.
+type FilterTypeName string
+
+const (
+	// FilterTypeBasic is the basic filter type defined in BIP0158.
+	FilterTypeBasic FilterTypeName = "basic"
+)
+
 // GetBlockFilterCmd defines the getblockfilter JSON-RPC command.
 type GetBlockFilterCmd struct {
-	BlockHash  string  // The hash of the block
-	FilterType *string // The type name of the filter, default=basic
+	BlockHash  string          // The hash of the block
+	FilterType *FilterTypeName // The type name of the filter, default=basic
 }
 
 // NewGetBlockFilterCmd returns a new instance which can be used to issue a
@@ -174,7 +183,7 @@ type GetBlockFilterCmd struct {
 //
 // The parameters which are pointers indicate they are optional.  Passing nil
 // for optional parameters will use the default value.
-func NewGetBlockFilterCmd(blockHash string, filterType *string) *GetBlockFilterCmd {
+func NewGetBlockFilterCmd(blockHash string, filterType *FilterTypeName) *GetBlockFilterCmd {
 	return &GetBlockFilterCmd{
 		BlockHash:  blockHash,
 		FilterType: filterType,
diff --git a/btcjson/chainsvrcmds_test.go b/btcjson/chainsvrcmds_test.go
index bd759f6c17..8c10867501 100644
--- a/btcjson/chainsvrcmds_test.go
+++ b/btcjson/chainsvrcmds_test.go
@@ -220,10 +220,10 @@ func TestChainSvrCmds(t *testing.T) {
 				return btcjson.NewCmd("getblockfilter", "0000afaf", "basic")
 			},
 			staticCmd: func() interface{} {
-				return btcjson.NewGetBlockFilterCmd("0000afaf", btcjson.String("basic"))
+				return btcjson.NewGetBlockFilterCmd("0000afaf", btcjson.NewFilterTypeName(btcjson.FilterTypeBasic))
 			},
 			marshalled:   `{"jsonrpc":"1.0","method":"getblockfilter","params":["0000afaf","basic"],"id":1}`,
-			unmarshalled: &btcjson.GetBlockFilterCmd{"0000afaf", btcjson.String("basic")},
+			unmarshalled: &btcjson.GetBlockFilterCmd{"0000afaf", btcjson.NewFilterTypeName(btcjson.FilterTypeBasic)},
 		},
 		{
 			name: "getblockhash",
diff --git a/btcjson/helpers.go b/btcjson/helpers.go
index d9b452e7c3..eda26cb885 100644
--- a/btcjson/helpers.go
+++ b/btcjson/helpers.go
@@ -75,3 +75,11 @@ func String(v string) *string {
 	*p = v
 	return p
 }
+
+// NewFilterTypeName is a helper routine that allocates a new FilterTypeName value to store v and
+// returns a pointer to it.  This is useful when assigning optional parameters.
+func NewFilterTypeName(v FilterTypeName) *FilterTypeName {
+	p := new(FilterTypeName)
+	*p = v
+	return p
+}
diff --git a/rpcclient/chain.go b/rpcclient/chain.go
index 84689e271e..dbcc0621e1 100644
--- a/rpcclient/chain.go
+++ b/rpcclient/chain.go
@@ -388,15 +388,15 @@ func (r FutureGetBlockFilterResult) Receive() (*btcjson.GetBlockFilterResult, er
 // returned instance.
 //
 // See GetBlockFilter for the blocking version and more details.
-func (c *Client) GetBlockFilterAsync(blockHash chainhash.Hash, filterType *string) FutureGetBlockFilterResult {
+func (c *Client) GetBlockFilterAsync(blockHash chainhash.Hash, filterType *btcjson.FilterTypeName) FutureGetBlockFilterResult {
 	hash := blockHash.String()
 
 	cmd := btcjson.NewGetBlockFilterCmd(hash, filterType)
 	return c.sendCmd(cmd)
 }
 
-// GetBlockFilter retrieves a BIP 157 content filter for a particular block.
-func (c *Client) GetBlockFilter(blockHash chainhash.Hash, filterType *string) (*btcjson.GetBlockFilterResult, error) {
+// GetBlockFilter retrieves a BIP0157 content filter for a particular block.
+func (c *Client) GetBlockFilter(blockHash chainhash.Hash, filterType *btcjson.FilterTypeName) (*btcjson.GetBlockFilterResult, error) {
 	return c.GetBlockFilterAsync(blockHash, filterType).Receive()
 }