/*
 * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
 *
 * This program is free software: you can use, redistribute, and/or modify
 * it under the terms of the GNU Affero General Public License, version 3
 * or later ("AGPL"), as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include "syncAppendEntriesReply.h"
#include "syncIndexMgr.h"
#include "syncInt.h"
#include "syncRaftLog.h"
#include "syncRaftStore.h"
#include "syncUtil.h"
#include "syncVoteMgr.h"

// TLA+ Spec
// HandleAppendEntriesResponse(i, j, m) ==
//    /\ m.mterm = currentTerm[i]
//    /\ \/ /\ m.msuccess \* successful
//          /\ nextIndex'  = [nextIndex  EXCEPT ![i][j] = m.mmatchIndex + 1]
//          /\ matchIndex' = [matchIndex EXCEPT ![i][j] = m.mmatchIndex]
//       \/ /\ \lnot m.msuccess \* not successful
//          /\ nextIndex' = [nextIndex EXCEPT ![i][j] =
//                               Max({nextIndex[i][j] - 1, 1})]
//          /\ UNCHANGED <<matchIndex>>
//    /\ Discard(m)
//    /\ UNCHANGED <<serverVars, candidateVars, logVars, elections>>
//
int32_t syncNodeOnAppendEntriesReplyCb(SSyncNode* ths, SyncAppendEntriesReply* pMsg) {
  int32_t ret = 0;
  syncAppendEntriesReplyLog2("==syncNodeOnAppendEntriesReplyCb==", pMsg);

  if (pMsg->term < ths->pRaftStore->currentTerm) {
    sTrace("DropStaleResponse, receive term:%lu, current term:%lu", pMsg->term, ths->pRaftStore->currentTerm);
    return ret;
  }

  // no need this code, because if I receive reply.term, then I must have sent for that term.
  //  if (pMsg->term > ths->pRaftStore->currentTerm) {
  //    syncNodeUpdateTerm(ths, pMsg->term);
  //  }

  assert(pMsg->term == ths->pRaftStore->currentTerm);

  if (pMsg->success) {
    // nextIndex = reply.matchIndex + 1
    syncIndexMgrSetIndex(ths->pNextIndex, &(pMsg->srcId), pMsg->matchIndex + 1);

    // matchIndex = reply.matchIndex
    syncIndexMgrSetIndex(ths->pMatchIndex, &(pMsg->srcId), pMsg->matchIndex);

    // maybe commit
    syncNodeMaybeAdvanceCommitIndex(ths);

  } else {
    SyncIndex nextIndex = syncIndexMgrGetIndex(ths->pNextIndex, &(pMsg->srcId));
    if (nextIndex > SYNC_INDEX_BEGIN) {
      --nextIndex;
    } else {
      nextIndex = SYNC_INDEX_BEGIN;
    }
    syncIndexMgrSetIndex(ths->pNextIndex, &(pMsg->srcId), nextIndex);
  }

  return ret;
}