/*
 * 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/>.
 */

#define _DEFAULT_SOURCE
//#include <dnode.h>
#include "os.h"

#include "tglobal.h"
#include "taoserror.h"
#include "taosmsg.h"
#include "tcache.h"
#include "query.h"
#include "trpc.h"
#include "tsdb.h"
#include "vnode.h"
#include "vnodeInt.h"
#include "tqueue.h"

static int32_t (*vnodeProcessReadMsgFp[TSDB_MSG_TYPE_MAX])(SVnodeObj *pVnode, SReadMsg *pReadMsg);
static int32_t  vnodeProcessQueryMsg(SVnodeObj *pVnode, SReadMsg *pReadMsg);
static int32_t  vnodeProcessFetchMsg(SVnodeObj *pVnode, SReadMsg *pReadMsg);
static int32_t  vnodeNotifyCurrentQhandle(void* handle, void* qhandle, int32_t vgId);

void vnodeInitReadFp(void) {
  vnodeProcessReadMsgFp[TSDB_MSG_TYPE_QUERY] = vnodeProcessQueryMsg;
  vnodeProcessReadMsgFp[TSDB_MSG_TYPE_FETCH] = vnodeProcessFetchMsg;
}

int32_t vnodeProcessRead(void *param, SReadMsg *pReadMsg) {
  SVnodeObj *pVnode = (SVnodeObj *)param;
  int msgType = pReadMsg->rpcMsg.msgType;

  if (vnodeProcessReadMsgFp[msgType] == NULL) {
    vDebug("vgId:%d, msgType:%s not processed, no handle", pVnode->vgId, taosMsg[msgType]);
    return TSDB_CODE_VND_MSG_NOT_PROCESSED;
  }

  if (pVnode->status != TAOS_VN_STATUS_READY) {
    vDebug("vgId:%d, msgType:%s not processed, vnode status is %d", pVnode->vgId, taosMsg[msgType], pVnode->status);
    return TSDB_CODE_APP_NOT_READY; 
  }

  // tsdb may be in reset state  
  if (pVnode->tsdb == NULL) return TSDB_CODE_APP_NOT_READY;
  if (pVnode->status == TAOS_VN_STATUS_CLOSING)
    return TSDB_CODE_APP_NOT_READY;

  // TODO: Later, let slave to support query
  if (pVnode->syncCfg.replica > 1 && pVnode->role != TAOS_SYNC_ROLE_MASTER) {
    vDebug("vgId:%d, msgType:%s not processed, replica:%d role:%d", pVnode->vgId, taosMsg[msgType], pVnode->syncCfg.replica, pVnode->role);
    return TSDB_CODE_APP_NOT_READY;
  }

  return (*vnodeProcessReadMsgFp[msgType])(pVnode, pReadMsg);
}

static void vnodePutItemIntoReadQueue(SVnodeObj *pVnode, void **qhandle) {
  SReadMsg *pRead = (SReadMsg *)taosAllocateQitem(sizeof(SReadMsg));
  pRead->rpcMsg.msgType = TSDB_MSG_TYPE_QUERY;
  pRead->pCont = qhandle;
  pRead->contLen = 0;
  pRead->rpcMsg.handle = NULL;

  atomic_add_fetch_32(&pVnode->refCount, 1);

  vDebug("QInfo:%p add to vread queue for exec query, msg:%p", *qhandle, pRead);
  taosWriteQitem(pVnode->rqueue, TAOS_QTYPE_QUERY, pRead);
}

static int32_t vnodeDumpQueryResult(SRspRet *pRet, void* pVnode, void** handle, bool* freeHandle) {
  bool continueExec = false;

  int32_t code = TSDB_CODE_SUCCESS;
  if ((code = qDumpRetrieveResult(*handle, (SRetrieveTableRsp **)&pRet->rsp, &pRet->len, &continueExec)) == TSDB_CODE_SUCCESS) {
    if (continueExec) {
      *freeHandle = false;
      vnodePutItemIntoReadQueue(pVnode, handle);
      pRet->qhandle = *handle;
    } else {
      *freeHandle = true;
      vDebug("QInfo:%p exec completed, free handle:%d", *handle, *freeHandle);
    }
  } else {
    SRetrieveTableRsp *pRsp = (SRetrieveTableRsp *)rpcMallocCont(sizeof(SRetrieveTableRsp));
    memset(pRsp, 0, sizeof(SRetrieveTableRsp));
    pRsp->completed = true;

    pRet->rsp = pRsp;
    pRet->len = sizeof(SRetrieveTableRsp);
    *freeHandle = true;
  }

  return code;
}

static void vnodeBuildNoResultQueryRsp(SRspRet* pRet) {
  pRet->rsp = (SRetrieveTableRsp *)rpcMallocCont(sizeof(SRetrieveTableRsp));
  pRet->len = sizeof(SRetrieveTableRsp);

  memset(pRet->rsp, 0, sizeof(SRetrieveTableRsp));
  SRetrieveTableRsp* pRsp = pRet->rsp;

  pRsp->completed = true;
}

static int32_t vnodeProcessQueryMsg(SVnodeObj *pVnode, SReadMsg *pReadMsg) {
  void    *pCont = pReadMsg->pCont;
  int32_t  contLen = pReadMsg->contLen;
  SRspRet *pRet = &pReadMsg->rspRet;

  SQueryTableMsg* pQueryTableMsg = (SQueryTableMsg*) pCont;
  memset(pRet, 0, sizeof(SRspRet));

  // qHandle needs to be freed correctly
  if (pReadMsg->rpcMsg.code == TSDB_CODE_RPC_NETWORK_UNAVAIL) {
    SRetrieveTableMsg* killQueryMsg = (SRetrieveTableMsg*) pReadMsg->pCont;
    killQueryMsg->free = htons(killQueryMsg->free);
    killQueryMsg->qhandle = htobe64(killQueryMsg->qhandle);

    vWarn("QInfo:%p connection %p broken, kill query", (void*) killQueryMsg->qhandle, pReadMsg->rpcMsg.handle);
    assert(pReadMsg->rpcMsg.contLen > 0 && killQueryMsg->free == 1);

    void** qhandle = qAcquireQInfo(pVnode->qMgmt, (uint64_t) killQueryMsg->qhandle);
    if (qhandle == NULL || *qhandle == NULL) {
      vWarn("QInfo:%p invalid qhandle, no matched query handle, conn:%p", (void*) killQueryMsg->qhandle, pReadMsg->rpcMsg.handle);
    } else {
      assert(*qhandle == (void*) killQueryMsg->qhandle);

      qKillQuery(*qhandle);
      qReleaseQInfo(pVnode->qMgmt, (void**) &qhandle, true);
    }

    return TSDB_CODE_TSC_QUERY_CANCELLED;
  }

  int32_t code = TSDB_CODE_SUCCESS;
  void**  handle = NULL;

  if (contLen != 0) {
    qinfo_t pQInfo = NULL;
    code = qCreateQueryInfo(pVnode->tsdb, pVnode->vgId, pQueryTableMsg, &pQInfo);

    SQueryTableRsp *pRsp = (SQueryTableRsp *) rpcMallocCont(sizeof(SQueryTableRsp));
    pRsp->code    = code;
    pRsp->qhandle = 0;

    pRet->len = sizeof(SQueryTableRsp);
    pRet->rsp = pRsp;
    int32_t vgId = pVnode->vgId;

    // current connect is broken
    if (code == TSDB_CODE_SUCCESS) {
      handle = qRegisterQInfo(pVnode->qMgmt, (uint64_t) pQInfo);
      if (handle == NULL) {  // failed to register qhandle, todo add error test case
        vError("vgId:%d QInfo:%p register qhandle failed, return to app, code:%s", pVnode->vgId, (void *)pQInfo,
               tstrerror(pRsp->code));
        pRsp->code = TSDB_CODE_QRY_INVALID_QHANDLE;
        qDestroyQueryInfo(pQInfo);  // destroy it directly
      } else {
        assert(*handle == pQInfo);
        pRsp->qhandle = htobe64((uint64_t) pQInfo);
      }

      if (handle != NULL && vnodeNotifyCurrentQhandle(pReadMsg->rpcMsg.handle, *handle, pVnode->vgId) != TSDB_CODE_SUCCESS) {
        vError("vgId:%d, QInfo:%p, query discarded since link is broken, %p", pVnode->vgId, *handle, pReadMsg->rpcMsg.handle);
        pRsp->code = TSDB_CODE_RPC_NETWORK_UNAVAIL;
        qReleaseQInfo(pVnode->qMgmt, (void**) &handle, true);
        return pRsp->code;
      }
    } else {
      assert(pQInfo == NULL);
    }

    if (handle != NULL) {
      vDebug("vgId:%d, QInfo:%p, dnode query msg disposed, create qhandle and returns to app", vgId, *handle);
      vnodePutItemIntoReadQueue(pVnode, handle);
    }
  } else {
    assert(pCont != NULL);
    void** qhandle = (void**) pCont;

    vDebug("vgId:%d, QInfo:%p, dnode continues to exec query", pVnode->vgId, *qhandle);

    bool freehandle = false;
    bool buildRes = qTableQuery(*qhandle); // do execute query

    // build query rsp, the retrieve request has reached here already
    if (buildRes) {
      // update the connection info according to the retrieve connection
      pReadMsg->rpcMsg.handle = qGetResultRetrieveMsg(*qhandle);
      assert(pReadMsg->rpcMsg.handle != NULL);

      vDebug("vgId:%d, QInfo:%p, start to build retrieval rsp after query paused, %p", pVnode->vgId, *qhandle,
             pReadMsg->rpcMsg.handle);

      // set the real rsp error code
      pReadMsg->rpcMsg.code = vnodeDumpQueryResult(&pReadMsg->rspRet, pVnode, qhandle, &freehandle);

      // NOTE: set return code to be TSDB_CODE_QRY_HAS_RSP to notify dnode to return msg to client
      code = TSDB_CODE_QRY_HAS_RSP;
    } else {
      freehandle = qQueryCompleted(*qhandle);
    }

    // NOTE: if the qhandle is not put into vread queue or query is completed, free the qhandle.
    // If the building of result is not required, simply free it. Otherwise, mandatorily free the qhandle
    if (freehandle || (!buildRes)) {
      qReleaseQInfo(pVnode->qMgmt, (void **)&qhandle, freehandle);
    }
  }

  return code;
}

static int32_t vnodeProcessFetchMsg(SVnodeObj *pVnode, SReadMsg *pReadMsg) {
  void *   pCont = pReadMsg->pCont;
  SRspRet *pRet = &pReadMsg->rspRet;

  SRetrieveTableMsg *pRetrieve = pCont;
  pRetrieve->free = htons(pRetrieve->free);
  pRetrieve->qhandle = htobe64(pRetrieve->qhandle);

  vDebug("vgId:%d, QInfo:%p, retrieve msg is disposed, free:%d, conn:%p", pVnode->vgId, (void*) pRetrieve->qhandle, pRetrieve->free, pReadMsg->rpcMsg.handle);

  memset(pRet, 0, sizeof(SRspRet));

  int32_t code = TSDB_CODE_SUCCESS;
  void** handle = qAcquireQInfo(pVnode->qMgmt, pRetrieve->qhandle);
  if (handle == NULL || (*handle) != (void*) pRetrieve->qhandle) {
    code = TSDB_CODE_QRY_INVALID_QHANDLE;
    vDebug("vgId:%d, invalid qhandle in retrieving result, QInfo:%p", pVnode->vgId, (void*) pRetrieve->qhandle);
    
    vnodeBuildNoResultQueryRsp(pRet);
    return code;
  }

  if (pRetrieve->free == 1) {
    vWarn("vgId:%d, QInfo:%p, retrieve msg received to kill query and free qhandle", pVnode->vgId, *handle);
    qKillQuery(*handle);
    qReleaseQInfo(pVnode->qMgmt, (void**) &handle, true);

    vnodeBuildNoResultQueryRsp(pRet);
    code = TSDB_CODE_TSC_QUERY_CANCELLED;
    return code;
  }

  // register the qhandle to connect to quit query immediate if connection is broken
  if (vnodeNotifyCurrentQhandle(pReadMsg->rpcMsg.handle, *handle, pVnode->vgId) != TSDB_CODE_SUCCESS) {
    vError("vgId:%d, QInfo:%p, retrieve discarded since link is broken, %p", pVnode->vgId, *handle, pReadMsg->rpcMsg.handle);
    code = TSDB_CODE_RPC_NETWORK_UNAVAIL;
    qReleaseQInfo(pVnode->qMgmt, (void**) &handle, true);
    return code;
  }

  bool freeHandle = true;
  bool buildRes   = false;

  code = qRetrieveQueryResultInfo(*handle, &buildRes, pReadMsg->rpcMsg.handle);
  if (code != TSDB_CODE_SUCCESS) {
    //TODO handle malloc failure
    pRet->rsp = (SRetrieveTableRsp *)rpcMallocCont(sizeof(SRetrieveTableRsp));
    pRet->len = sizeof(SRetrieveTableRsp);
    memset(pRet->rsp, 0, sizeof(SRetrieveTableRsp));
    freeHandle = true;
  } else { // result is not ready, return immediately
    if (!buildRes) {
      qReleaseQInfo(pVnode->qMgmt, (void**) &handle, false);
      return TSDB_CODE_QRY_NOT_READY;
    }

    code = vnodeDumpQueryResult(pRet, pVnode, handle, &freeHandle);
  }

  // If qhandle is not added into vread queue, the query should be completed already or paused with error.
  // Here free qhandle immediately
  if (freeHandle) {
    qReleaseQInfo(pVnode->qMgmt, (void**) &handle, true);
  }

  return code;
}

// notify connection(handle) that current qhandle is created, if current connection from
// client is broken, the query needs to be killed immediately.
int32_t vnodeNotifyCurrentQhandle(void* handle, void* qhandle, int32_t vgId) {
  SRetrieveTableMsg* killQueryMsg = rpcMallocCont(sizeof(SRetrieveTableMsg));
  killQueryMsg->qhandle = htobe64((uint64_t) qhandle);
  killQueryMsg->free = htons(1);
  killQueryMsg->header.vgId = htonl(vgId);
  killQueryMsg->header.contLen = htonl(sizeof(SRetrieveTableMsg));

  vDebug("QInfo:%p register qhandle to connect:%p", qhandle, handle);
  return rpcReportProgress(handle, (char*) killQueryMsg, sizeof(SRetrieveTableMsg));
}
