feat: implement variables mapper (#1034)

Author: devsergiy

v2/pkg/astnormalization/variables_mapper.go

@@ -0,0 +1,31 @@
+package astnormalization
+
+import (
+	"github.com/wundergraph/graphql-go-tools/v2/pkg/ast"
+	"github.com/wundergraph/graphql-go-tools/v2/pkg/astvisitor"
+	"github.com/wundergraph/graphql-go-tools/v2/pkg/operationreport"
+)
+
+type VariablesMapper struct {
+	walker                  *astvisitor.Walker
+	variablesMappingVisitor *variablesMappingVisitor
+}
+
+func NewVariablesMapper() *VariablesMapper {
+	walker := astvisitor.NewDefaultWalker()
+	mapper := remapVariables(&walker)
+
+	return &VariablesMapper{
+		walker:                  &walker,
+		variablesMappingVisitor: mapper,
+	}
+}
+
+func (v *VariablesMapper) NormalizeOperation(operation, definition *ast.Document, report *operationreport.Report) map[string]string {
+	v.walker.Walk(operation, definition, report)
+	if report.HasErrors() {
+		return nil
+	}
+
+	return v.variablesMappingVisitor.mapping
+}