package org.jgroups.protocols.pbcast;

import org.jgroups.*;
import org.jgroups.logging.Log;
import org.jgroups.util.Digest;
import org.jgroups.util.MergeId;

import java.util.Collection;
import java.util.Map;
import java.util.Vector;


public abstract class GmsImpl {
    protected final GMS    gms;
    protected final Merger merger;
    protected final Log    log;
    volatile boolean       leaving=false;


    protected GmsImpl(GMS gms) {
        this.gms=gms;
        merger=gms.merger;
        log=gms.getLog();
    }

    public abstract void      join(Address mbr, boolean useFlushIfPresent);
    public abstract void      joinWithStateTransfer(Address local_addr,boolean useFlushIfPresent);
    
    public abstract void      leave(Address mbr);

    public void               handleJoinResponse(JoinRsp join_rsp) {}
    public void               handleLeaveResponse() {}

    public void               suspect(Address mbr)   {}
    public void               unsuspect(Address mbr) {}

    public void               merge(Map<Address,View> views)                               {} // only processed by coord
    public void               handleMergeRequest(Address sender, MergeId merge_id, Collection<? extends Address> mbrs)  {} // only processed by coords
    public void               handleMergeResponse(MergeData data, MergeId merge_id) {} // only processed by coords
    public void               handleMergeView(MergeData data, MergeId merge_id)     {} // only processed by coords
    public void               handleMergeCancelled(MergeId merge_id)                {} // only processed by coords
    public void               handleDigestResponse(Address sender, Digest digest)   {} // only processed by coords

    public void               handleMembershipChange(Collection<Request> requests)  {}
    public void               handleViewChange(View new_view, Digest digest)        {}

    public void               init() throws Exception {leaving=false;}
    public void               start() throws Exception {leaving=false;}
    public void               stop() {leaving=true;}



    protected void sendMergeRejectedResponse(Address sender, MergeId merge_id) {
        Message msg=new Message(sender, null, null);
        msg.setFlag(Message.OOB);
        GMS.GmsHeader hdr=new GMS.GmsHeader(GMS.GmsHeader.MERGE_RSP);
        hdr.merge_rejected=true;
        hdr.merge_id=merge_id;
        msg.putHeader(gms.getId(), hdr);
        if(log.isDebugEnabled()) log.debug("merge response=" + hdr);
        gms.getDownProtocol().down(new Event(Event.MSG, msg));
    }


    protected void wrongMethod(String method_name) {
        if(log.isWarnEnabled())
            log.warn(method_name + "() should not be invoked on an instance of " + getClass().getName());
    }



    /**
       Returns potential coordinator based on lexicographic ordering of member addresses. Another
       approach would be to keep track of the primary partition and return the first member if we
       are the primary partition.
     */
    protected boolean iWouldBeCoordinator(Vector<Address> new_mbrs) {
        Membership tmp_mbrs=gms.members.copy();
        tmp_mbrs.merge(new_mbrs, null);
        tmp_mbrs.sort();
        return !(tmp_mbrs.size() <= 0 || gms.local_addr == null) && gms.local_addr.equals(tmp_mbrs.elementAt(0));
    }


    public static class Request {
        static final int JOIN    = 1;
        static final int LEAVE   = 2;
        static final int SUSPECT = 3;
        static final int MERGE   = 4;        
        static final int JOIN_WITH_STATE_TRANSFER    = 6;


        int               type=-1;
        Address           mbr;
        boolean           suspected;
        Map<Address,View> views; // different view on MERGE
        boolean           useFlushIfPresent;


        Request(int type, Address mbr, boolean suspected) {
            this.type=type;
            this.mbr=mbr;
            this.suspected=suspected;
        }

        Request(int type, Address mbr, boolean suspected, Map<Address,View> views, boolean useFlushPresent) {
            this(type, mbr, suspected);
            this.views=views;
            this.useFlushIfPresent=useFlushPresent;
        }
        
        Request(int type, Address mbr, boolean suspected, Map<Address,View> views) {
        	this(type, mbr, suspected, views, true);
        }

        public int getType() {
            return type;
        }

        public String toString() {
            switch(type) {
                case JOIN:    return "JOIN(" + mbr + ")";
                case JOIN_WITH_STATE_TRANSFER:    return "JOIN_WITH_STATE_TRANSFER(" + mbr + ")";
                case LEAVE:   return "LEAVE(" + mbr + ", " + suspected + ")";
                case SUSPECT: return "SUSPECT(" + mbr + ")";
                case MERGE:   return "MERGE(" + views.size() + " views)";               
            }
            return "<invalid (type=" + type + ")";
        }

        /**
         * Specifies whether this request can be processed with other request simultaneously
         */
        public boolean canBeProcessedTogether(Request other) {
            if(other == null)
                return false;
            int other_type=other.type;
            return (type == JOIN || type == LEAVE || type == SUSPECT) &&
                    (other_type == JOIN || other_type == LEAVE || other_type == SUSPECT);
        }
    }

}