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

        LogicalOperation m_initial;
        LogicalOperation m_current;
        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 {
                    TraceLog.TraceWarning("DetachLogicalOperation can't be applied in the current context");
                    detached = LogicalOperation.EMPTY;
                }
            } else {
                TraceLog.TraceWarning("DetachLogicalOperation can't be applied in the current context");
            }

            return detached;
        }

        public LogicalOperation EndLogicalOperation() {
            var current = m_current;
            if (m_current != LogicalOperation.EMPTY && (m_current != m_initial || m_ownership)) {
                m_current = m_current.Parent;
                if (current == m_initial) {
                    // we have complete the owned operation
                    m_initial = m_current;
                    m_ownership = false;
                }
            } else {
                TraceLog.TraceWarning("EndLogicalOperation can't be applied in the current context");
            }
            return current;
        }

        public void Leave() {

            if ((m_ownership && m_current != LogicalOperation.EMPTY) || (!m_ownership && m_current != m_initial) )
                TraceLog.TraceWarning("Trying to leave unfinished logical operation {0}", m_current.Name);
        }
    }
}