{{/* Base DDL template with common structure */}}
{{- define "ddl_header" -}}
-- DDL Operation: {{.Operation}}
-- Schema: {{.Schema}}
-- Object: {{.ObjectName}}
{{- end -}}

{{- define "ddl_footer" -}}
-- End of {{.Operation}}
{{- end -}}

{{/* Base ALTER TABLE structure */}}
{{- define "alter_table_base" -}}
ALTER TABLE {{.SchemaName}}.{{.TableName}}
  {{block "alter_operation" .}}{{end}};
{{- end -}}

{{/* Common existence check pattern */}}
{{- define "exists_check" -}}
DO $$
BEGIN
    IF NOT EXISTS (
        {{block "exists_query" .}}{{end}}
    ) THEN
        {{block "create_statement" .}}{{end}}
    END IF;
END;
$$;
{{- end -}}

{{/* Common drop pattern */}}
{{- define "drop_if_exists" -}}
{{block "drop_type" .}}{{end}} IF EXISTS {{.SchemaName}}.{{.ObjectName}};
{{- end -}}