feat(btc): add witness utils

Co-authored-by: Gaze <dev@gaze.network>

pkg/btcutils/witness.go

@@ -0,0 +1,59 @@
+package btcutils
+
+import (
+	"encoding/hex"
+	"strings"
+
+	"github.com/btcsuite/btcd/wire"
+	"github.com/cockroachdb/errors"
+)
+
+const (
+	witnessSeparator = " "
+)
+
+// WitnessToHex formats the passed witness stack as a slice of hex-encoded strings.
+func WitnessToHex(witness wire.TxWitness) []string {
+	if len(witness) == 0 {
+		return nil
+	}
+
+	result := make([]string, 0, len(witness))
+	for _, wit := range witness {
+		result = append(result, hex.EncodeToString(wit))
+	}
+
+	return result
+}
+
+// WitnessToString formats the passed witness stack as a space-separated string of hex-encoded strings.
+func WitnessToString(witness wire.TxWitness) string {
+	w := WitnessToHex(witness)
+	if w == nil {
+		return ""
+	}
+	return strings.Join(w, witnessSeparator)
+}
+
+// WitnessFromHex parses the passed slice of hex-encoded strings into a witness stack.
+func WitnessFromHex(witnesses []string) (wire.TxWitness, error) {
+	if len(witnesses) == 0 {
+		return nil, nil
+	}
+
+	result := make(wire.TxWitness, 0, len(witnesses))
+	for _, wit := range witnesses {
+		decoded, err := hex.DecodeString(wit)
+		if err != nil {
+			return nil, errors.WithStack(err)
+		}
+		result = append(result, decoded)
+	}
+
+	return result, nil
+}
+
+// WitnessFromString parses the passed space-separated string of hex-encoded strings into a witness stack.
+func WitnessFromString(witnesses string) (wire.TxWitness, error) {
+	return WitnessFromHex(strings.Split(witnesses, witnessSeparator))
+}