tapdb: add SparseBlockHeight helper function

Author: Roasbeef

tapdb/sqlutils.go

@@ -1,6 +1,7 @@
 package tapdb
 
 import (
+	"bytes"
 	"context"
 	"database/sql"
 	"encoding/binary"
@@ -14,7 +15,9 @@ import (
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightninglabs/taproot-assets/fn"
 	"github.com/lightninglabs/taproot-assets/internal/test"
+	"github.com/lightninglabs/taproot-assets/proof"
 	"github.com/lightninglabs/taproot-assets/tapdb/sqlc"
+	lfn "github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/stretchr/testify/require"
 	"golang.org/x/exp/constraints"
 )
@@ -94,6 +97,25 @@ func sqlStr(s string) sql.NullString {
 	}
 }
 
+// SparseDecodeBlockHeight sparse decodes a proof to extract the block height.
+func SparseDecodeBlockHeight(rawProof []byte) (lfn.Option[uint32], error) {
+	var blockHeightVal uint32
+	err := proof.SparseDecode(
+		bytes.NewReader(rawProof),
+		proof.BlockHeightRecord(&blockHeightVal),
+	)
+	if err != nil {
+		return lfn.None[uint32](), fmt.Errorf("unable to "+
+			"sparse decode proof: %w", err)
+	}
+
+	if blockHeightVal == 0 {
+		return lfn.None[uint32](), nil
+	}
+
+	return lfn.Some(blockHeightVal), nil
+}
+
 // extractSqlInt64 turns a NullInt64 into a numerical type. This can be useful
 // when reading directly from the database, as this function handles extracting
 // the inner value from the "option"-like struct.