/*
 * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.controller.cluster.raft.messages;

import com.google.common.annotations.VisibleForTesting;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import org.opendaylight.controller.cluster.raft.RaftVersions;

/**
 * Reply for the AppendEntries message.
 */
public final class AppendEntriesReply extends AbstractRaftRPC {
    private static final long serialVersionUID = -7487547356392536683L;

    // true if follower contained entry matching
    // prevLogIndex and prevLogTerm
    private final boolean success;

    // The index of the last entry in the followers log
    // This will be used to set the matchIndex for the follower on the
    // Leader
    private final long logLastIndex;

    private final long logLastTerm;

    // The followerId - this will be used to figure out which follower is
    // responding
    private final String followerId;

    private final short payloadVersion;

    private final short raftVersion;

    private final boolean forceInstallSnapshot;

    private final boolean needsLeaderAddress;

    private final short recipientRaftVersion;

    @VisibleForTesting
    public AppendEntriesReply(final String followerId, final long term, final boolean success, final long logLastIndex,
            final long logLastTerm, final short payloadVersion) {
        this(followerId, term, success, logLastIndex, logLastTerm, payloadVersion, false, false,
                RaftVersions.CURRENT_VERSION);
    }

    public AppendEntriesReply(final String followerId, final long term, final boolean success, final long logLastIndex,
            final long logLastTerm, final short payloadVersion, final boolean forceInstallSnapshot,
            final boolean needsLeaderAddress, final short recipientRaftVersion) {
        this(followerId, term, success, logLastIndex, logLastTerm, payloadVersion, forceInstallSnapshot,
                needsLeaderAddress, RaftVersions.CURRENT_VERSION, recipientRaftVersion);
    }

    private AppendEntriesReply(final String followerId, final long term, final boolean success, final long logLastIndex,
            final long logLastTerm, final short payloadVersion, final boolean forceInstallSnapshot,
            final boolean needsLeaderAddress, final short raftVersion, final short recipientRaftVersion) {
        super(term);
        this.followerId = followerId;
        this.success = success;
        this.logLastIndex = logLastIndex;
        this.logLastTerm = logLastTerm;
        this.payloadVersion = payloadVersion;
        this.forceInstallSnapshot = forceInstallSnapshot;
        this.raftVersion = raftVersion;
        this.needsLeaderAddress = needsLeaderAddress;
        this.recipientRaftVersion = recipientRaftVersion;
    }

    public boolean isSuccess() {
        return success;
    }

    public long getLogLastIndex() {
        return logLastIndex;
    }

    public long getLogLastTerm() {
        return logLastTerm;
    }

    public String getFollowerId() {
        return followerId;
    }

    public short getPayloadVersion() {
        return payloadVersion;
    }

    public short getRaftVersion() {
        return raftVersion;
    }

    public boolean isForceInstallSnapshot() {
        return forceInstallSnapshot;
    }

    public boolean isNeedsLeaderAddress() {
        return needsLeaderAddress;
    }

    @Override
    public String toString() {
        return "AppendEntriesReply [term=" + getTerm() + ", success=" + success + ", followerId=" + followerId
                + ", logLastIndex=" + logLastIndex + ", logLastTerm=" + logLastTerm + ", forceInstallSnapshot="
                + forceInstallSnapshot + ", needsLeaderAddress=" + needsLeaderAddress
                + ", payloadVersion=" + payloadVersion + ", raftVersion=" + raftVersion
                + ", recipientRaftVersion=" + recipientRaftVersion + "]";
    }

    @Override
    Object writeReplace() {
        return recipientRaftVersion >= RaftVersions.FLUORINE_VERSION ? new Proxy2(this) : new Proxy(this);
    }

    /**
     * Fluorine version that adds the needsLeaderAddress flag.
     */
    private static class Proxy2 implements Externalizable {
        private static final long serialVersionUID = 1L;

        private AppendEntriesReply appendEntriesReply;

        // checkstyle flags the public modifier as redundant which really doesn't make sense since it clearly isn't
        // redundant. It is explicitly needed for Java serialization to be able to create instances via reflection.
        @SuppressWarnings("checkstyle:RedundantModifier")
        public Proxy2() {
        }

        Proxy2(final AppendEntriesReply appendEntriesReply) {
            this.appendEntriesReply = appendEntriesReply;
        }

        @Override
        public void writeExternal(final ObjectOutput out) throws IOException {
            out.writeShort(appendEntriesReply.raftVersion);
            out.writeLong(appendEntriesReply.getTerm());
            out.writeObject(appendEntriesReply.followerId);
            out.writeBoolean(appendEntriesReply.success);
            out.writeLong(appendEntriesReply.logLastIndex);
            out.writeLong(appendEntriesReply.logLastTerm);
            out.writeShort(appendEntriesReply.payloadVersion);
            out.writeBoolean(appendEntriesReply.forceInstallSnapshot);
            out.writeBoolean(appendEntriesReply.needsLeaderAddress);
        }

        @Override
        public void readExternal(final ObjectInput in) throws IOException, ClassNotFoundException {
            short raftVersion = in.readShort();
            long term = in.readLong();
            String followerId = (String) in.readObject();
            boolean success = in.readBoolean();
            long logLastIndex = in.readLong();
            long logLastTerm = in.readLong();
            short payloadVersion = in.readShort();
            boolean forceInstallSnapshot = in.readBoolean();
            boolean needsLeaderAddress = in.readBoolean();

            appendEntriesReply = new AppendEntriesReply(followerId, term, success, logLastIndex, logLastTerm,
                    payloadVersion, forceInstallSnapshot, needsLeaderAddress, raftVersion,
                    RaftVersions.CURRENT_VERSION);
        }

        private Object readResolve() {
            return appendEntriesReply;
        }
    }

    /**
     * Pre-Fluorine version.
     */
    @Deprecated
    private static class Proxy implements Externalizable {
        private static final long serialVersionUID = 1L;

        private AppendEntriesReply appendEntriesReply;

        // checkstyle flags the public modifier as redundant which really doesn't make sense since it clearly isn't
        // redundant. It is explicitly needed for Java serialization to be able to create instances via reflection.
        @SuppressWarnings("checkstyle:RedundantModifier")
        public Proxy() {
        }

        Proxy(final AppendEntriesReply appendEntriesReply) {
            this.appendEntriesReply = appendEntriesReply;
        }

        @Override
        public void writeExternal(final ObjectOutput out) throws IOException {
            out.writeShort(appendEntriesReply.raftVersion);
            out.writeLong(appendEntriesReply.getTerm());
            out.writeObject(appendEntriesReply.followerId);
            out.writeBoolean(appendEntriesReply.success);
            out.writeLong(appendEntriesReply.logLastIndex);
            out.writeLong(appendEntriesReply.logLastTerm);
            out.writeShort(appendEntriesReply.payloadVersion);
            out.writeBoolean(appendEntriesReply.forceInstallSnapshot);
        }

        @Override
        public void readExternal(final ObjectInput in) throws IOException, ClassNotFoundException {
            short raftVersion = in.readShort();
            long term = in.readLong();
            String followerId = (String) in.readObject();
            boolean success = in.readBoolean();
            long logLastIndex = in.readLong();
            long logLastTerm = in.readLong();
            short payloadVersion = in.readShort();
            boolean forceInstallSnapshot = in.readBoolean();

            appendEntriesReply = new AppendEntriesReply(followerId, term, success, logLastIndex, logLastTerm,
                    payloadVersion, forceInstallSnapshot, false, raftVersion, RaftVersions.CURRENT_VERSION);
        }

        private Object readResolve() {
            return appendEntriesReply;
        }
    }
}