/**
 * //selma
 */


package SSF.OS.BGP4;


import java.io.*;
import java.util.*;
import SSF.OS.BGP4.Comm.*;
import SSF.OS.BGP4.Path.*;
import SSF.OS.BGP4.Util.*;


// ===== class SSF.OS.BGP4.History =========================================== //

public class History extends Attribute {

  // ......................... constants ........................... //
     
  /** The AS path attribute type code. */
  public static final int TYPECODE = 10;
     
  /** The name of the attribute as a string. */
  public static final String name = "History";
     
  /** The name of the path attribute as a DML attribute. */
  public static final String dmlname = "History";
     
  /** The name of the NHI form of the path attribute as a DML attribute. */
  public static final String nhidmlname = "History";
    
    //..................member data..................................//

    Vector history; //of PathChageEvents

    public History(){
	super();
	history=new Vector();
    }

    public History(PathChangeEvent pce){
	super();
	history=new Vector();
        history.add(pce);
    }

    // ----- opt ------------------------------------------------------------- //
    /* See description in Attribute parent class. */
    public final boolean opt() { return true; }
    
    // ----- trans ----------------------------------------------------------- //
    /* See description in Attribute parent class. */
    public final boolean trans() { return true; }
    
    // ----- partial --------------------------------------------------------- //
    /* See description in Attribute parent class. */
    public final boolean partial() { return false; }


    public Attribute copy() {
	History cpHistory=new History();
	PathChangeEvent pce=null;
	for (int i=0; i<history.size(); i++){
            pce=(PathChangeEvent)history.elementAt(i);
	    cpHistory.history.add(pce.copyPCE());
	}
	return cpHistory;
    }


  // ----- bytecount ------------------------------------------------------- //
    /**
   * Returns the number of octets (bytes) needed to represent this AS path
   * attribute in an update message.  The number is the sum of the two octets
   * needed for the attribute type (which contains attribute flags and the
   * attribute type code), the one or two octets needed for the attribute
   * length, and the variable number of octets needed for the attribute value.
   *
   * @return the number of octets (bytes) needed to represent this History
   *         attribute in an update message
   */
    public int bytecount() {
    int octets = 2; // 2 octets for the attribute type

    for (int i=0; i<history.size(); i++) {
      octets += (((PathChangeEvent)history.elementAt(i)).bytecount());
    }
    if (octets > 255) { // 1 or 2 octets for the attribute length field
      octets += 2;
    } else {
      octets++;
    }
    return octets;
  }

    
    public String printHistory(){
	String s="";
	PathChangeEvent pce=null;
	for (int i=0; i<history.size(); i++){
            pce=(PathChangeEvent)history.elementAt(i);
	    s+=pce.printPCE();
	}
	//System.out.println();
	return s;
    }

    // ----- equals ---------------------------------------------------------- //
   public boolean equals(Attribute attrib) {
    if (attrib == null || !(attrib instanceof History)) {
      return false;
    }
    History hst = (History)attrib;
    if (history.size() !=hst.history.size()) {
      return false;
    }
    for (int i=0; i<history.size(); i++) {
      if (!((PathChangeEvent)history.get(i)).equals((PathChangeEvent)hst.history.get(i))) {
        return false;
      }
    }
    return true;
  }

    
    //------------------------------------------------------------------------//
    public PathChangeEvent updateHistory(RouteInfo prvs, RouteInfo info, String as_nh){
	boolean cycle=false;
	boolean added=false;
	 //rte is the update whose history will be used 

	  PathChangeEvent pce=new PathChangeEvent(); 
	  History hst=null;
	  if (prvs==null && info!=null)
	      pce=pce.computePCE(null,info.route(),as_nh);
	  else  pce=pce.computePCE(prvs.route(),info.route(),as_nh);
	
	 return pce;
	 
    }
//------------------------------------------------------------------------//
    public boolean checkCycle(Route rte, PathChangeEvent pce, int minth){
	//to deal with transient oscillations we added minth=2 as mine alg
		int count=0;
	
	if (rte!=null) {
	    History hst=(History)rte.pas[History.TYPECODE];
	    if (hst==null) return false;
	    else {
	
		for (int i=0; i< hst.history.size(); i++){
		    PathChangeEvent pe=(PathChangeEvent)hst.history.elementAt(i);
		    if (pce.equalforCycle(pe)) {
			count++;
				
			if (count>(2*minth)){
			  
			    return true;
			}
		    }
		  
		}
	    }
	}

	return false;
    }

//------------------------------------------------------------------------//
    public void addHistory(PathChangeEvent pce, Route rte,  RouteInfo info){
	//add pce to rte's history and set info's history to the resulting history
	if (pce!=null){
	    //extract history of rte; the update
	    History    hst=null;
	    if (rte!=null){
		hst=(History)rte.pas[History.TYPECODE];
	    }
	    if (rte!=null){
		if (hst!=null){
		    hst.history.add(pce);
		    info.route().pas[History.TYPECODE]=(History)hst.copy();
		}
		else {
		    hst=new History(pce);
		    info.route().pas[History.TYPECODE]=hst;
		}
	    }
	    else { 
                if (info.route().epsilon){
                    //old route was better, right now it is epsilon, and 
                    //due to link failure rte=null, therefore no carried hst avail.(=empty)
		    //that is why it should be set to
                    hst=new History(pce);
		    info.route().pas[History.TYPECODE]=hst; 
		    //System.out.println("after adding pce, history of newrt="+hst.printHistory());
		}
	    }
	    if (hst!=null)
		; 
	    
	}
    }
    
} // end class