Reverse swaps

Author: kaloudis

mobile/swaps.go

@@ -1,13 +1,16 @@
 package lndmobile
 
 import (
+	"bytes"
 	"encoding/hex"
 	"fmt"
+	"io/ioutil"
+	"net/http"
 
+	"github.com/BoltzExchange/boltz-client/boltz"
 	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/decred/dcrd/dcrec/secp256k1/v4"
-	"github.com/BoltzExchange/boltz-client/boltz"
 )
 
 func leaf(script string) txscript.TapLeaf {
@@ -38,7 +41,7 @@ func CreateClaimTransaction(endpoint string, id string, claimLeaf string, refund
 	if err != nil {
 		return fmt.Errorf("Error decoding service public key hex: %s", err)
 	}
-    
+
 	// Parse the public key
 	servicePubKeyFormatted, err := secp256k1.ParsePubKey(servicePubKeyBytes)
 	if err != nil {
@@ -61,4 +64,126 @@ func CreateClaimTransaction(endpoint string, id string, claimLeaf string, refund
 	}
 
 	return nil
-}
+}
+
+func CreateReverseClaimTransaction(endpoint string, id string, claimLeaf string, refundLeaf string, privateKey string, servicePubKey string, preimageHex string, transactionHex string, lockupAddress string, destinationAddress string, feeRate int32, isTestnet bool) error {
+	var toCurrency = boltz.CurrencyBtc
+	var network *boltz.Network
+	if isTestnet {
+		network = boltz.TestNet
+	} else {
+		network = boltz.MainNet
+	}
+
+	boltzApi := &boltz.Api{URL: endpoint}
+
+	// Decode the hex string to bytes
+	privKeyBytes, err := hex.DecodeString(privateKey)
+	if err != nil {
+		fmt.Printf("Failed to decode hex string: %v", err)
+	}
+
+	// Create the private key using btcec
+	keys, _ := btcec.PrivKeyFromBytes(privKeyBytes)
+
+	// Decode the hex string to bytes
+	servicePubKeyBytes, err := hex.DecodeString(servicePubKey)
+	if err != nil {
+		return fmt.Errorf("Error decoding service public key hex: %s", err)
+	}
+
+	// Parse the public key
+	servicePubKeyFormatted, err := secp256k1.ParsePubKey(servicePubKeyBytes)
+	if err != nil {
+		return fmt.Errorf("Error parsing service public key %s", err)
+	}
+
+	swapTree := &boltz.SwapTree{
+		ClaimLeaf:  leaf(claimLeaf),
+		RefundLeaf: leaf(refundLeaf),
+	}
+
+	if err := swapTree.Init(false, false, keys, servicePubKeyFormatted); err != nil {
+		return fmt.Errorf("Error initializing swap tree %s", err)
+	}
+
+	lockupTransaction, err := boltz.NewTxFromHex(toCurrency, transactionHex, nil)
+	if err != nil {
+		return fmt.Errorf("Error constructing lockup tx %s", err)
+	}
+
+	vout, _, err := lockupTransaction.FindVout(network, lockupAddress)
+	if err != nil {
+		return fmt.Errorf("Error finding vout %s", err)
+	}
+
+	preimage, err := hex.DecodeString(preimageHex)
+	if err != nil {
+		return fmt.Errorf("Error decoding preimage hex string: %w", err)
+	}
+
+	satPerVbyte := float64(feeRate)
+	claimTransaction, _, err := boltz.ConstructTransaction(
+		network,
+		boltz.CurrencyBtc,
+		[]boltz.OutputDetails{
+			{
+				SwapId:            id,
+				SwapType:          boltz.ReverseSwap,
+				Address:           destinationAddress,
+				LockupTransaction: lockupTransaction,
+				Vout:              vout,
+				Preimage:          preimage,
+				PrivateKey:        keys,
+				SwapTree:          swapTree,
+				Cooperative:       true,
+			},
+		},
+		satPerVbyte,
+		boltzApi,
+	)
+	if err != nil {
+		return fmt.Errorf("could not create claim transaction: %w", err)
+	}
+
+	txHex, err := claimTransaction.Serialize()
+	if err != nil {
+		return fmt.Errorf("could not serialize claim transaction: %w", err)
+	}
+
+	var broadcastUrl string
+	if isTestnet {
+		broadcastUrl = "https://mempool.space/testnet/api/tx"
+	} else {
+		broadcastUrl = "https://mempool.space/api/tx"
+	}
+
+	// Create HTTP request
+	req, err := http.NewRequest("POST", broadcastUrl, bytes.NewBufferString(txHex))
+	if err != nil {
+		return fmt.Errorf("failed to create HTTP request: %v", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	// Execute HTTP request
+	client := &http.Client{}
+	resp, err := client.Do(req)
+	if err != nil {
+		return fmt.Errorf("failed to send HTTP request: %v", err)
+	}
+	defer resp.Body.Close()
+
+	// Read response
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("failed to read response body: %v", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("non-200 response: %d, body: %s", resp.StatusCode, string(body))
+	}
+
+	fmt.Printf("Transaction broadcasted successfully: %s\n", string(body))
+
+	return nil
+}