namespace Implab.Diagnostics {
    struct OperationContext {
        readonly LogicalOperation m_initial;
        public readonly static OperationContext EMPTY = new OperationContext(LogicalOperation.EMPTY, false);
        LogicalOperation m_current;
        readonly bool m_ownership;

        public OperationContext(LogicalOperation operation, bool ownership) {
            Safe.ArgumentNotNull(operation, "operation");

            m_initial = operation;
            m_current = operation;
            m_ownership = ownership;
        }

        public LogicalOperation CurrentOperation {
            get { return m_current; }
        }

        public void BeginLogicalOperation(string name) {
            m_current = new LogicalOperation(name, m_current);
        }

        public LogicalOperation DetachLogicalOperation() {
            var detached = m_current;
            if (m_current != LogicalOperation.EMPTY) {
                if (m_current != m_initial)
                    m_current = m_current.Parent;
                else if (m_ownership)
                    m_current = LogicalOperation.EMPTY;
                else
                    detached = LogicalOperation.EMPTY;
            }
            TraceLog.TraceWarning("EndLogicalOperation can't be applied in the current context");
            return detached;
        }

        public void EndLogicalOperation() {
            if (m_current != m_initial) {
                m_current = m_current.Parent;
            } else if (m_current != null && m_ownership) {
                m_current = null;
            } else {
                TraceLog.TraceWarning("EndLogicalOperation can't be applied in the current context");
            }
        }
    }
}