Add longTermFeeRate websocket endpoint (#1262)

* feat: add longTermFeeRate websocket endpoint

* chore: regenerate blockbook-api.ts with longTermFeeRate

api/types.go

@@ -620,3 +620,8 @@ type Eip1559Fees struct {
 	PriorityFeeTrend           string      `json:"priorityFeeTrend,omitempty" ts_type:"'up' | 'down'"`
 	BaseFeeTrend               string      `json:"baseFeeTrend,omitempty" ts_type:"'up' | 'down'"`
 }
+
+type LongTermFeeRate struct {
+	FeePerUnit string `json:"feePerUnit" ts_doc:"Long term fee rate (in sat/kByte)."`
+	Blocks     uint64 `json:"blocks" ts_doc:"Amount of blocks used for the long term fee rate estimation."`
+}

bchain/basechain.go

@@ -39,6 +39,11 @@ func (b *BaseChain) GetMempoolEntry(txid string) (*MempoolEntry, error) {
 	return nil, errors.New("GetMempoolEntry: not supported")
 }
 
+// LongTermFeeRate returns smallest fee rate from historic blocks.
+func (b *BaseChain) LongTermFeeRate() (*LongTermFeeRate, error) {
+	return nil, errors.New("not supported")
+}
+
 // EthereumTypeGetBalance is not supported
 func (b *BaseChain) EthereumTypeGetBalance(addrDesc AddressDescriptor) (*big.Int, error) {
 	return nil, errors.New("not supported")

bchain/coins/blockchain.go

@@ -297,6 +297,11 @@ func (c *blockChainWithMetrics) EstimateFee(blocks int) (v big.Int, err error) {
 	return c.b.EstimateFee(blocks)
 }
 
+func (c *blockChainWithMetrics) LongTermFeeRate() (v *bchain.LongTermFeeRate, err error) {
+	defer func(s time.Time) { c.observeRPCLatency("LongTermFeeRate", s, err) }(time.Now())
+	return c.b.LongTermFeeRate()
+}
+
 func (c *blockChainWithMetrics) SendRawTransaction(tx string) (v string, err error) {
 	defer func(s time.Time) { c.observeRPCLatency("SendRawTransaction", s, err) }(time.Now())
 	return c.b.SendRawTransaction(tx)

bchain/coins/btc/bitcoinrpc.go

@@ -873,6 +873,21 @@ func (b *BitcoinRPC) EstimateFee(blocks int) (big.Int, error) {
 	return r, nil
 }
 
+// LongTermFeeRate returns smallest fee rate from historic blocks.
+func (b *BitcoinRPC) LongTermFeeRate() (*bchain.LongTermFeeRate, error) {
+	blocks := 1008 // ~7 days of blocks, highest number estimatesmartfee supports
+	glog.V(1).Info("rpc: estimatesmartfee (long term fee rate) - ", blocks)
+	// Going for the ECONOMICAL mode, to get the lowest fee rate
+	feePerUnit, err := b.blockchainEstimateSmartFee(blocks, false)
+	if err != nil {
+		return nil, err
+	}
+	return &bchain.LongTermFeeRate{
+		Blocks:     uint64(blocks),
+		FeePerUnit: feePerUnit,
+	}, nil
+}
+
 // SendRawTransaction sends raw transaction
 func (b *BitcoinRPC) SendRawTransaction(tx string) (string, error) {
 	glog.V(1).Info("rpc: sendrawtransaction")

bchain/types.go

@@ -211,6 +211,12 @@ type ChainInfo struct {
 	Consensus        interface{} `json:"consensus,omitempty" ts_doc:"Additional consensus details, structure depends on chain."`
 }
 
+// LongTermFeeRate gets information about the fee rate over longer period of time.
+type LongTermFeeRate struct {
+	FeePerUnit big.Int `json:"feePerUnit" ts_doc:"Long term fee rate (in sat/kByte)."`
+	Blocks     uint64  `json:"blocks" ts_doc:"Amount of blocks used for the long term fee rate estimation."`
+}
+
 // RPCError defines rpc error returned by backend
 type RPCError struct {
 	Code    int    `json:"code" ts_doc:"Error code returned by the backend RPC."`
@@ -324,6 +330,7 @@ type BlockChain interface {
 	GetTransactionSpecific(tx *Tx) (json.RawMessage, error)
 	EstimateSmartFee(blocks int, conservative bool) (big.Int, error)
 	EstimateFee(blocks int) (big.Int, error)
+	LongTermFeeRate() (*LongTermFeeRate, error)
 	SendRawTransaction(tx string) (string, error)
 	GetMempoolEntry(txid string) (*MempoolEntry, error)
 	GetContractInfo(contractDesc AddressDescriptor) (*ContractInfo, error)

blockbook-api.ts

@@ -745,6 +745,12 @@ export interface WsEstimateFeeRes {
     feeLimit?: string;
     eip1559?: Eip1559Fees;
 }
+export interface WsLongTermFeeRateRes {
+    /** Long term fee rate (in sat/kByte). */
+    feePerUnit: string;
+    /** Amount of blocks used for the long term fee rate estimation. */
+    blocks: number;
+}
 export interface WsSendTransactionReq {
     /** Hex-encoded transaction data to broadcast. */
     hex: string;

build/tools/typescriptify/typescriptify.go

@@ -54,6 +54,7 @@ func main() {
 	t.Add(server.WsTransactionSpecificReq{})
 	t.Add(server.WsEstimateFeeReq{})
 	t.Add(server.WsEstimateFeeRes{})
+	t.Add(server.WsLongTermFeeRateRes{})
 	t.Add(server.WsSendTransactionReq{})
 	t.Add(server.WsSubscribeAddressesReq{})
 	t.Add(server.WsSubscribeFiatRatesReq{})

server/websocket.go

@@ -369,6 +369,9 @@ var requestHandlers = map[string]func(*WebsocketServer, *websocketChannel, *WsRe
 	"estimateFee": func(s *WebsocketServer, c *websocketChannel, req *WsReq) (rv interface{}, err error) {
 		return s.estimateFee(req.Params)
 	},
+	"longTermFeeRate": func(s *WebsocketServer, c *websocketChannel, req *WsReq) (rv interface{}, err error) {
+		return s.longTermFeeRate()
+	},
 	"sendTransaction": func(s *WebsocketServer, c *websocketChannel, req *WsReq) (rv interface{}, err error) {
 		r := WsSendTransactionReq{}
 		err = json.Unmarshal(req.Params, &r)
@@ -737,6 +740,17 @@ func (s *WebsocketServer) estimateFee(params []byte) (interface{}, error) {
 	return res, nil
 }
 
+func (s *WebsocketServer) longTermFeeRate() (res interface{}, err error) {
+	feeRate, err := s.chain.LongTermFeeRate()
+	if err != nil {
+		return nil, err
+	}
+	return WsLongTermFeeRateRes{
+		FeePerUnit: feeRate.FeePerUnit.String(),
+		Blocks:     feeRate.Blocks,
+	}, nil
+}
+
 func (s *WebsocketServer) sendTransaction(tx string) (res resultSendTransaction, err error) {
 	txid, err := s.chain.SendRawTransaction(tx)
 	if err != nil {

server/ws_types.go

@@ -133,6 +133,12 @@ type WsEstimateFeeRes struct {
 	Eip1559    *api.Eip1559Fees `json:"eip1559,omitempty"`
 }
 
+// WsLongTermFeeRateRes is returned in response to a long term fee rate request.
+type WsLongTermFeeRateRes struct {
+	FeePerUnit string `json:"feePerUnit" ts_doc:"Long term fee rate (in sat/kByte)."`
+	Blocks     uint64 `json:"blocks" ts_doc:"Amount of blocks used for the long term fee rate estimation."`
+}
+
 // WsSendTransactionReq is used to broadcast a transaction to the network.
 type WsSendTransactionReq struct {
 	Hex string `json:"hex" ts_doc:"Hex-encoded transaction data to broadcast."`

static/test-websocket.html

@@ -289,6 +289,19 @@
                 }
             }
 
+            function longTermFeeRate() {
+                try {
+                    const method = 'longTermFeeRate';
+                    send(method, {}, function (result) {
+                        document.getElementById('longTermFeeRateResult').innerText = JSON.stringify(
+                            result,
+                        ).replace(/,/g, ', ');
+                    });
+                } catch (e) {
+                    document.getElementById('longTermFeeRateResult').innerText = e;
+                }
+            }
+
             function sendTransaction() {
                 var hex = document.getElementById('sendTransactionHex').value.trim();
                 const method = 'sendTransaction';
@@ -892,6 +905,20 @@
             <div class="row">
                 <div class="col" id="estimateFeeResult"></div>
             </div>
+            <div class="row">
+                <div class="col">
+                    <input
+                        class="btn btn-secondary"
+                        type="button"
+                        value="longTermFeeRate"
+                        onclick="longTermFeeRate()"
+                    />
+                </div>
+                <div class="col"></div>
+            </div>
+            <div class="row">
+                <div class="col" id="longTermFeeRateResult"></div>
+            </div>
             <div class="row">
                 <div class="col">
                     <input