refactor(types): add SignedHeaderFromContext (#2370)

ref:
evstack/ev-abci#101 (comment)

Author: julienrbrt

block/manager.go

@@ -849,19 +849,13 @@ func (m *Manager) execCreateBlock(_ context.Context, height uint64, lastSignatur
 	return header, blockData, nil
 }
 
-type headerContextKey struct{}
-
-// HeaderContextKey is used to store the header in the context.
-// This is useful if the execution client needs to access the header during transaction execution.
-var HeaderContextKey = headerContextKey{}
-
 func (m *Manager) execApplyBlock(ctx context.Context, lastState types.State, header *types.SignedHeader, data *types.Data) (types.State, error) {
 	rawTxs := make([][]byte, len(data.Txs))
 	for i := range data.Txs {
 		rawTxs[i] = data.Txs[i]
 	}
 
-	ctx = context.WithValue(ctx, HeaderContextKey, header)
+	ctx = context.WithValue(ctx, types.SignedHeaderContextKey, header)
 	newStateRoot, _, err := m.exec.ExecuteTxs(ctx, rawTxs, header.Height(), header.Time(), lastState.AppHash)
 	if err != nil {
 		return types.State{}, fmt.Errorf("failed to execute transactions: %w", err)

types/signed_header.go

@@ -2,12 +2,28 @@ package types
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"fmt"
 
 	"github.com/celestiaorg/go-header"
 )
 
+type signedHeaderContextKey struct{}
+
+// SignedHeaderContextKey is used to store the signed header in the context.
+// This is useful if the execution client needs to access the signed header during transaction execution.
+var SignedHeaderContextKey = signedHeaderContextKey{}
+
+func SignedHeaderFromContext(ctx context.Context) (*SignedHeader, bool) {
+	sh, ok := ctx.Value(SignedHeaderContextKey).(*SignedHeader)
+	if !ok {
+		return nil, false
+	}
+
+	return sh, true
+}
+
 var (
 	// ErrLastHeaderHashMismatch is returned when the last header hash doesn't match.
 	ErrLastHeaderHashMismatch = errors.New("last header hash mismatch")