R – How to avoid long switch ..need help refactoring

i needed help refactoring the following class,

Following is a class Operation with variety of Operations in switch :
i want to avoid the switch statement.I read few articles on using polymorphism and state pattern .but when i refactor the classes i dont get access to many variables,properties
Im confused on whether to use operation as abstract class or to implement an interface.
Just wanted to know which type of refactoring will help in this case
polymorphism or state pattern?
And when to use them?

public class Operation
    {
        public enum OperationType
        {
            add,
            update,
            delete,
            retrieve
        }
        public enum OperationStatus
        {
            Success,
            NotStarted,
            Error,
            Fail,
            InProcess,
            Free
        }

    // raise this event when operation completes
    public delegate void OperationNotifier(Operation operation);
    public event OperationNotifier OperationEvent=null;           

    private OperationStatus _status=OperationStatus.Free;
    public OperationStatus Status
    {
        get { return _status; }
        set { _status = value; }
    }      


    private string _fileName = null;

    public string FileName
    {
        get { return _fileName; }
        set { _fileName = value; }
    }

    private string _opnid = null;

    public string OperationId
    {
        get { return _opnid; }
        set { _opnid = value; }
    }

    private OperationType _type;
    public OperationType Type
    {
        get { return _type; }
        set { _type = value; }
    }

   public void performOperation(OperationType type, string parameters)
    {  

        switch (type)
        {
            case OperationType.add:
                _status = addOperation(parameters);                   
                break;
            case OperationType.update:
               _status = updateOperation(parameters);
                break;
            case OperationType.delete:
                _status = deleteOperation(parameters);
                break;
            case OperationType.retrieve:
                _status = retrieveOperation(parameters);
                break;
            default:
                break;
        }
        if (OperationEvent != null)
            OperationEvent(this);           
       // return true;
    }


    public OperationStatus addOperation(string parameters)
    {           
        DateTime start = DateTime.Now;
         //Do SOMETHING BIG
        TimeSpan timeTaken = DateTime.Now - start;
        System.Diagnostics.Debug.WriteLine("addOperation:-" + _opnid + "-" + _fileName + "--" + timeTaken.Milliseconds); 
        return OperationStatus.Success;

        }
...other operations here....

Calling code is similar to :

  Operation oprnObj;
                Operation.OperationType operationType;

 oprnObj = new Operation();
 oprnObj.FileName = String.Concat("myxmlfile",".xml");
 oprnObj.OperationId = oprnid;
 oprnObj.OperationEvent += new Operation.OperationNotifier(oprnObj_OperationEvent);
 operation="add"; //get From Outside function getOperation()
 operationType = (Operation.OperationType)Enum.Parse(typeof(Operation.OperationType),   operation.ToLower(), true);
 oprnObj.Type = operationType;
 oprnObj.performOperation(operationType, parameters);

References Threads:
Link
Link
..many more.