/*
 * 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 "builtinsimpl.h"
#include "tpercentile.h"
#include "querynodes.h"
#include "taggfunction.h"
#include "tdatablock.h"

typedef struct SSumRes {
  union {
    int64_t  isum;
    uint64_t usum;
    double   dsum;
  };
} SSumRes;

typedef struct SAvgRes {
  double  result;
  SSumRes sum;
  int64_t count;
} SAvgRes;

typedef struct STopBotRes {
  int32_t num;
} STopBotRes;

typedef struct SStddevRes {
  double  result;
  int64_t count;
  union  {double  quadraticDSum; int64_t quadraticISum;};
  union  {double  dsum; int64_t isum;};
} SStddevRes;

typedef struct SPercentileInfo {
  double      result;
  tMemBucket *pMemBucket;
  int32_t     stage;
  double      minval;
  double      maxval;
  int64_t     numOfElems;
} SPercentileInfo;

typedef struct SDiffInfo {
  bool  hasPrev;
  bool  includeNull;
  bool  ignoreNegative;
  bool  firstOutput;
  union { int64_t i64; double d64;} prev;
} SDiffInfo;

#define SET_VAL(_info, numOfElem, res)  \
  do {                                  \
    if ((numOfElem) <= 0) {             \
      break;                            \
    }                                   \
    (_info)->numOfRes = (res);          \
  } while (0)

#define GET_TS_LIST(x)    ((TSKEY*)((x)->ptsList))
#define GET_TS_DATA(x, y) (GET_TS_LIST(x)[(y)])

#define DO_UPDATE_TAG_COLUMNS_WITHOUT_TS(ctx)                      \
  do {                                                             \
    for (int32_t _i = 0; _i < (ctx)->tagInfo.numOfTagCols; ++_i) { \
      SqlFunctionCtx *__ctx = (ctx)->tagInfo.pTagCtxList[_i];      \
      __ctx->fpSet.process(__ctx);                                 \
    }                                                              \
  } while (0);

#define DO_UPDATE_SUBSID_RES(ctx, ts)                                 \
  do {                                                                \
    for (int32_t _i = 0; _i < (ctx)->subsidiaryRes.numOfCols; ++_i) { \
      SqlFunctionCtx *__ctx = (ctx)->subsidiaryRes.pCtx[_i];          \
      if (__ctx->functionId == FUNCTION_TS_DUMMY) {                   \
        __ctx->tag.i = (ts);                                          \
        __ctx->tag.nType = TSDB_DATA_TYPE_BIGINT;                     \
      }                                                               \
      __ctx->fpSet.process(__ctx);                                    \
    }                                                                 \
  } while (0)

#define UPDATE_DATA(ctx, left, right, num, sign, _ts) \
  do {                                                \
    if (((left) < (right)) ^ (sign)) {                \
      (left) = (right);                               \
      DO_UPDATE_SUBSID_RES(ctx, _ts);                 \
      (num) += 1;                                     \
    }                                                 \
  } while (0)

#define LOOPCHECK_N(val, _col, ctx, _t, _nrow, _start, sign, num)        \
  do {                                                                   \
    _t *d = (_t *)((_col)->pData);                                       \
    for (int32_t i = (_start); i < (_nrow) + (_start); ++i) {            \
      if (((_col)->hasNull) && colDataIsNull_f((_col)->nullbitmap, i)) { \
        continue;                                                        \
      }                                                                  \
      TSKEY ts = (ctx)->ptsList != NULL ? GET_TS_DATA(ctx, i) : 0;       \
      UPDATE_DATA(ctx, val, d[i], num, sign, ts);                        \
    }                                                                    \
  } while (0)


bool functionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo) {
  if (pResultInfo->initialized) {
    return false;
  }

  if (pCtx->pOutput != NULL) {
    memset(pCtx->pOutput, 0, (size_t)pCtx->resDataInfo.bytes);
  }

  initResultRowEntry(pResultInfo, pCtx->resDataInfo.interBufSize);
  return true;
}

void functionFinalize(SqlFunctionCtx *pCtx) {
  SResultRowEntryInfo* pResInfo = GET_RES_INFO(pCtx);

  cleanupResultRowEntry(pResInfo);
  pResInfo->isNullRes = (pResInfo->numOfRes == 0)? 1:0;
}

EFuncDataRequired countDataRequired(SFunctionNode* pFunc, STimeWindow* pTimeWindow) {
  SNode* pParam = nodesListGetNode(pFunc->pParameterList, 0);
  if (QUERY_NODE_COLUMN == nodeType(pParam) && PRIMARYKEY_TIMESTAMP_COL_ID == ((SColumnNode*)pParam)->colId) {
    return FUNC_DATA_REQUIRED_NOT_LOAD;
  }
  return FUNC_DATA_REQUIRED_STATIS_LOAD;
}

bool getCountFuncEnv(SFunctionNode* UNUSED_PARAM(pFunc), SFuncExecEnv* pEnv) {
  pEnv->calcMemSize = sizeof(int64_t);
  return true;
}

/*
 * count function does need the finalize, if data is missing, the default value, which is 0, is used
 * count function does not use the pCtx->interResBuf to keep the intermediate buffer
 */
int32_t countFunction(SqlFunctionCtx *pCtx) {
  int32_t numOfElem = 0;

  /*
   * 1. column data missing (schema modified) causes pInputCol->hasNull == true. pInput->colDataAggIsSet == true;
   * 2. for general non-primary key columns, pInputCol->hasNull may be true or false, pInput->colDataAggIsSet == true;
   * 3. for primary key column, pInputCol->hasNull always be false, pInput->colDataAggIsSet == false;
   */
  SInputColumnInfoData* pInput = &pCtx->input;
  SColumnInfoData* pInputCol = pInput->pData[0];
  if (pInput->colDataAggIsSet && pInput->totalRows == pInput->numOfRows) {
    numOfElem = pInput->numOfRows - pInput->pColumnDataAgg[0]->numOfNull;
    ASSERT(numOfElem >= 0);
  } else {
    if (pInputCol->hasNull) {
      for (int32_t i = pInput->startRowIndex; i < pInput->startRowIndex + pInput->numOfRows; ++i) {
        if (colDataIsNull(pInputCol, pInput->totalRows, i, NULL)) {
          continue;
        }
        numOfElem += 1;
      }
    } else {
      //when counting on the primary time stamp column and no statistics data is presented, use the size value directly.
      numOfElem = pInput->numOfRows;
    }
  }

  SResultRowEntryInfo* pResInfo = GET_RES_INFO(pCtx);
  char* buf = GET_ROWCELL_INTERBUF(pResInfo);
  *((int64_t *)buf) += numOfElem;

  SET_VAL(pResInfo, numOfElem, 1);
  return TSDB_CODE_SUCCESS;
}

#define LIST_ADD_N(_res, _col, _start, _rows, _t, numOfElem)             \
  do {                                                                   \
    _t *d = (_t *)(_col->pData);                                         \
    for (int32_t i = (_start); i < (_rows) + (_start); ++i) {            \
      if (((_col)->hasNull) && colDataIsNull_f((_col)->nullbitmap, i)) { \
        continue;                                                        \
      };                                                                 \
      (_res) += (d)[i];                                                  \
      (numOfElem)++;                                                     \
    }                                                                    \
  } while (0)

int32_t sumFunction(SqlFunctionCtx *pCtx) {
  int32_t numOfElem = 0;

  // Only the pre-computing information loaded and actual data does not loaded
  SInputColumnInfoData* pInput = &pCtx->input;
  SColumnDataAgg *pAgg = pInput->pColumnDataAgg[0];
  int32_t type = pInput->pData[0]->info.type;

  SSumRes* pSumRes = GET_ROWCELL_INTERBUF(GET_RES_INFO(pCtx));

  if (pInput->colDataAggIsSet) {
    numOfElem = pInput->numOfRows - pAgg->numOfNull;
    ASSERT(numOfElem >= 0);

    if (IS_SIGNED_NUMERIC_TYPE(type)) {
      pSumRes->isum += pAgg->sum;
    } else if (IS_UNSIGNED_NUMERIC_TYPE(type)) {
      pSumRes->usum += pAgg->sum;
    } else if (IS_FLOAT_TYPE(type)) {
      pSumRes->dsum += GET_DOUBLE_VAL((const char*)&(pAgg->sum));
    }
  } else {  // computing based on the true data block
    SColumnInfoData* pCol = pInput->pData[0];

    int32_t start     = pInput->startRowIndex;
    int32_t numOfRows = pInput->numOfRows;

    if (IS_SIGNED_NUMERIC_TYPE(type) || type == TSDB_DATA_TYPE_BOOL) {
      if (type == TSDB_DATA_TYPE_TINYINT || type == TSDB_DATA_TYPE_BOOL) {
        LIST_ADD_N(pSumRes->isum, pCol, start, numOfRows, int8_t, numOfElem);
      } else if (type == TSDB_DATA_TYPE_SMALLINT) {
        LIST_ADD_N(pSumRes->isum, pCol, start, numOfRows, int16_t, numOfElem);
      } else if (type == TSDB_DATA_TYPE_INT) {
        LIST_ADD_N(pSumRes->isum, pCol, start, numOfRows, int32_t, numOfElem);
      } else if (type == TSDB_DATA_TYPE_BIGINT) {
        LIST_ADD_N(pSumRes->isum, pCol, start, numOfRows, int64_t, numOfElem);
      }
    } else if (IS_UNSIGNED_NUMERIC_TYPE(type)) {
      if (type == TSDB_DATA_TYPE_UTINYINT) {
        LIST_ADD_N(pSumRes->usum, pCol, start, numOfRows, uint8_t, numOfElem);
      } else if (type == TSDB_DATA_TYPE_USMALLINT) {
        LIST_ADD_N(pSumRes->usum, pCol, start, numOfRows, uint16_t, numOfElem);
      } else if (type == TSDB_DATA_TYPE_UINT) {
        LIST_ADD_N(pSumRes->usum, pCol, start, numOfRows, uint32_t, numOfElem);
      } else if (type == TSDB_DATA_TYPE_UBIGINT) {
        LIST_ADD_N(pSumRes->usum, pCol, start, numOfRows, uint64_t, numOfElem);
      }
    } else if (type == TSDB_DATA_TYPE_DOUBLE) {
      LIST_ADD_N(pSumRes->dsum, pCol, start, numOfRows, double, numOfElem);
    } else if (type == TSDB_DATA_TYPE_FLOAT) {
      LIST_ADD_N(pSumRes->dsum, pCol, start, numOfRows, float, numOfElem);
    }
  }

  // data in the check operation are all null, not output
  SET_VAL(GET_RES_INFO(pCtx), numOfElem, 1);
  return TSDB_CODE_SUCCESS;
}

bool getSumFuncEnv(SFunctionNode* UNUSED_PARAM(pFunc), SFuncExecEnv* pEnv) {
  pEnv->calcMemSize = sizeof(SSumRes);
  return true;
}

bool getAvgFuncEnv(SFunctionNode* UNUSED_PARAM(pFunc), SFuncExecEnv* pEnv) {
  pEnv->calcMemSize = sizeof(double);
  return true;
}

bool avgFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo) {
  if (!functionSetup(pCtx, pResultInfo)) {
    return false;
  }

  SAvgRes* pRes = GET_ROWCELL_INTERBUF(pResultInfo);
  memset(pRes, 0, sizeof(SAvgRes));
  return true;
}

int32_t avgFunction(SqlFunctionCtx* pCtx) {
  int32_t numOfElem = 0;

  // Only the pre-computing information loaded and actual data does not loaded
  SInputColumnInfoData* pInput = &pCtx->input;
  int32_t               type = pInput->pData[0]->info.type;

  SAvgRes* pAvgRes = GET_ROWCELL_INTERBUF(GET_RES_INFO(pCtx));

  // computing based on the true data block
  SColumnInfoData* pCol = pInput->pData[0];

  int32_t start = pInput->startRowIndex;
  int32_t numOfRows = pInput->numOfRows;

  switch (type) {
    case TSDB_DATA_TYPE_TINYINT: {
        int8_t* plist = (int8_t*)pCol->pData;
        for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
          if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
            continue;
          }

          numOfElem += 1;
          pAvgRes->count += 1;
          pAvgRes->sum.isum += plist[i];
        }

        break;
      }

      case TSDB_DATA_TYPE_SMALLINT: {
      int16_t* plist = (int16_t*)pCol->pData;
      for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
        if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        numOfElem += 1;
        pAvgRes->count += 1;
        pAvgRes->sum.isum += plist[i];
      }
      break;
    }

    case TSDB_DATA_TYPE_INT: {
      int32_t* plist = (int32_t*)pCol->pData;
      for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
        if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        numOfElem += 1;
        pAvgRes->count += 1;
        pAvgRes->sum.isum += plist[i];
      }

      break;
    }

    case TSDB_DATA_TYPE_BIGINT: {
      int64_t* plist = (int64_t*)pCol->pData;
      for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
        if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        numOfElem += 1;
        pAvgRes->count += 1;
        pAvgRes->sum.isum += plist[i];
      }
      break;
    }

    case TSDB_DATA_TYPE_FLOAT: {
      float* plist = (float*)pCol->pData;
      for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
        if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        numOfElem += 1;
        pAvgRes->count += 1;
        pAvgRes->sum.dsum += plist[i];
      }
      break;
    }

    case TSDB_DATA_TYPE_DOUBLE: {
      double* plist = (double*)pCol->pData;
      for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
        if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        numOfElem += 1;
        pAvgRes->count += 1;
        pAvgRes->sum.dsum += plist[i];
      }
      break;
    }

    default:
      break;
  }

  // data in the check operation are all null, not output
  SET_VAL(GET_RES_INFO(pCtx), numOfElem, 1);
  return TSDB_CODE_SUCCESS;
}

void avgFinalize(SqlFunctionCtx* pCtx) {
  functionFinalize(pCtx);

  SInputColumnInfoData* pInput = &pCtx->input;
  int32_t type = pInput->pData[0]->info.type;
  SAvgRes* pAvgRes = GET_ROWCELL_INTERBUF(GET_RES_INFO(pCtx));
  if (IS_INTEGER_TYPE(type)) {
    pAvgRes->result = pAvgRes->sum.isum / ((double) pAvgRes->count);
  } else {
    pAvgRes->result = pAvgRes->sum.dsum / ((double) pAvgRes->count);
  }
}

EFuncDataRequired statisDataRequired(SFunctionNode* pFunc, STimeWindow* pTimeWindow){
  return FUNC_DATA_REQUIRED_STATIS_LOAD;
}

bool maxFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo) {
  if (!functionSetup(pCtx, pResultInfo)) {
    return false;
  }

  char* buf = GET_ROWCELL_INTERBUF(pResultInfo);
  switch (pCtx->resDataInfo.type) {
    case TSDB_DATA_TYPE_INT:
      *((int32_t *)buf) = INT32_MIN;
      break;
    case TSDB_DATA_TYPE_UINT:
      *((uint32_t *)buf) = 0;
      break;
    case TSDB_DATA_TYPE_FLOAT:
      *((float *)buf) = -FLT_MAX;
      break;
    case TSDB_DATA_TYPE_DOUBLE:
    SET_DOUBLE_VAL(((double *)buf), -DBL_MAX);
      break;
    case TSDB_DATA_TYPE_BIGINT:
      *((int64_t *)buf) = INT64_MIN;
      break;
    case TSDB_DATA_TYPE_UBIGINT:
      *((uint64_t *)buf) = 0;
      break;
    case TSDB_DATA_TYPE_SMALLINT:
      *((int16_t *)buf) = INT16_MIN;
      break;
    case TSDB_DATA_TYPE_USMALLINT:
      *((uint16_t *)buf) = 0;
      break;
    case TSDB_DATA_TYPE_TINYINT:
      *((int8_t *)buf) = INT8_MIN;
      break;
    case TSDB_DATA_TYPE_UTINYINT:
      *((uint8_t *)buf) = 0;
      break;
    case TSDB_DATA_TYPE_BOOL:
      *((int8_t*)buf) = 0;
      break;
    default:
      assert(0);
  }
  return true;
}

bool minFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo) {
  if (!functionSetup(pCtx, pResultInfo)) {
    return false;  // not initialized since it has been initialized
  }

  char* buf = GET_ROWCELL_INTERBUF(pResultInfo);
  switch (pCtx->resDataInfo.type) {
    case TSDB_DATA_TYPE_TINYINT:
      *((int8_t *)buf) = INT8_MAX;
      break;
    case TSDB_DATA_TYPE_UTINYINT:
      *(uint8_t *) buf = UINT8_MAX;
      break;
    case TSDB_DATA_TYPE_SMALLINT:
      *((int16_t *)buf) = INT16_MAX;
      break;
    case TSDB_DATA_TYPE_USMALLINT:
      *((uint16_t *)buf) = UINT16_MAX;
      break;
    case TSDB_DATA_TYPE_INT:
      *((int32_t *)buf) = INT32_MAX;
      break;
    case TSDB_DATA_TYPE_UINT:
      *((uint32_t *)buf) = UINT32_MAX;
      break;
    case TSDB_DATA_TYPE_BIGINT:
      *((int64_t *)buf) = INT64_MAX;
      break;
    case TSDB_DATA_TYPE_UBIGINT:
      *((uint64_t *)buf) = UINT64_MAX;
      break;
    case TSDB_DATA_TYPE_FLOAT:
      *((float *)buf) = FLT_MAX;
      break;
    case TSDB_DATA_TYPE_DOUBLE:
      SET_DOUBLE_VAL(((double *)buf), DBL_MAX);
      break;
    case TSDB_DATA_TYPE_BOOL:
      *((int8_t*)buf) = 1;
      break;
    default:
      assert(0);
  }

  return true;
}

bool getMinmaxFuncEnv(SFunctionNode* UNUSED_PARAM(pFunc), SFuncExecEnv* pEnv) {
  pEnv->calcMemSize = sizeof(int64_t);
  return true;
}


int32_t doMinMaxHelper(SqlFunctionCtx *pCtx, int32_t isMinFunc) {
  int32_t numOfElems = 0;

  SInputColumnInfoData* pInput = &pCtx->input;
  SColumnDataAgg *pAgg = pInput->pColumnDataAgg[0];

  SColumnInfoData* pCol = pInput->pData[0];
  int32_t type = pCol->info.type;

  SResultRowEntryInfo* pResInfo = GET_RES_INFO(pCtx);
  char* buf = GET_ROWCELL_INTERBUF(pResInfo);

  // data in current data block are qualified to the query
  if (pInput->colDataAggIsSet) {
    numOfElems = pInput->numOfRows - pAgg->numOfNull;
    ASSERT(pInput->numOfRows == pInput->totalRows && numOfElems >= 0);

    if (numOfElems == 0) {
      return numOfElems;
    }

    void*   tval = NULL;
    int16_t index = 0;

    if (isMinFunc) {
      tval  = &pInput->pColumnDataAgg[0]->min;
      index = pInput->pColumnDataAgg[0]->minIndex;
    } else {
      tval  = &pInput->pColumnDataAgg[0]->max;
      index = pInput->pColumnDataAgg[0]->maxIndex;
    }

    // the index is the original position, not the relative position
    TSKEY key = (pCtx->ptsList != NULL)? pCtx->ptsList[index]:TSKEY_INITIAL_VAL;

    if (IS_SIGNED_NUMERIC_TYPE(type)) {
      int64_t prev = 0;
      GET_TYPED_DATA(prev, int64_t, type, buf);

      int64_t val = GET_INT64_VAL(tval);
      if ((prev < val) ^ isMinFunc) {
        *(int64_t*) buf = val;
        for (int32_t i = 0; i < (pCtx)->subsidiaryRes.numOfCols; ++i) {
          SqlFunctionCtx* __ctx = pCtx->subsidiaryRes.pCtx[i];
          if (__ctx->functionId == FUNCTION_TS_DUMMY) {  // TODO refactor
            __ctx->tag.i = key;
            __ctx->tag.nType = TSDB_DATA_TYPE_BIGINT;
          }

          __ctx->fpSet.process(__ctx);
        }
      }
    } else if (IS_UNSIGNED_NUMERIC_TYPE(type)) {
      uint64_t prev = 0;
      GET_TYPED_DATA(prev, uint64_t, type, buf);

      uint64_t val = GET_UINT64_VAL(tval);
      if ((prev < val) ^ isMinFunc) {
        *(uint64_t*) buf = val;
        for (int32_t i = 0; i < (pCtx)->subsidiaryRes.numOfCols; ++i) {
          SqlFunctionCtx* __ctx = pCtx->subsidiaryRes.pCtx[i];
          if (__ctx->functionId == FUNCTION_TS_DUMMY) {  // TODO refactor
            __ctx->tag.i = key;
            __ctx->tag.nType = TSDB_DATA_TYPE_BIGINT;
          }

          __ctx->fpSet.process(__ctx);
        }
      }
    } else if (type == TSDB_DATA_TYPE_DOUBLE) {
      double  val = GET_DOUBLE_VAL(tval);
      UPDATE_DATA(pCtx, *(double*) buf, val, numOfElems, isMinFunc, key);
    } else if (type == TSDB_DATA_TYPE_FLOAT) {
      double val = GET_DOUBLE_VAL(tval);
      UPDATE_DATA(pCtx, *(float*) buf, val, numOfElems, isMinFunc, key);
    }

    return numOfElems;
  }

  int32_t start = pInput->startRowIndex;
  int32_t numOfRows = pInput->numOfRows;

  if (IS_SIGNED_NUMERIC_TYPE(type) || type == TSDB_DATA_TYPE_BOOL) {
    if (type == TSDB_DATA_TYPE_TINYINT || type == TSDB_DATA_TYPE_BOOL) {
      LOOPCHECK_N(*(int8_t*)buf, pCol, pCtx, int8_t, numOfRows, start, isMinFunc, numOfElems);
    } else if (type == TSDB_DATA_TYPE_SMALLINT) {
      LOOPCHECK_N(*(int16_t*) buf, pCol, pCtx, int16_t, numOfRows, start, isMinFunc, numOfElems);
    } else if (type == TSDB_DATA_TYPE_INT) {
      int32_t *pData = (int32_t*)pCol->pData;
      int32_t *val = (int32_t*) buf;

      for (int32_t i = start; i < start + numOfRows; ++i) {
        if ((pCol->hasNull) && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        if ((*val < pData[i]) ^ isMinFunc) {
          *val = pData[i];
          TSKEY ts = (pCtx->ptsList != NULL)? GET_TS_DATA(pCtx, i) : 0;
          DO_UPDATE_SUBSID_RES(pCtx, ts);
        }

        numOfElems += 1;
      }

#if defined(_DEBUG_VIEW)
      qDebug("max value updated:%d", *retVal);
#endif
    } else if (type == TSDB_DATA_TYPE_BIGINT) {
      LOOPCHECK_N(*(int64_t*) buf, pCol, pCtx, int64_t, numOfRows, start, isMinFunc, numOfElems);
    }
  } else if (IS_UNSIGNED_NUMERIC_TYPE(type)) {
    if (type == TSDB_DATA_TYPE_UTINYINT) {
      LOOPCHECK_N(*(uint8_t*) buf, pCol, pCtx, uint8_t, numOfRows, start, isMinFunc, numOfElems);
    } else if (type == TSDB_DATA_TYPE_USMALLINT) {
      LOOPCHECK_N(*(uint16_t*) buf, pCol, pCtx, uint16_t, numOfRows, start, isMinFunc, numOfElems);
    } else if (type == TSDB_DATA_TYPE_UINT) {
      LOOPCHECK_N(*(uint32_t*) buf, pCol, pCtx, uint32_t, numOfRows, start, isMinFunc, numOfElems);
    } else if (type == TSDB_DATA_TYPE_UBIGINT) {
      LOOPCHECK_N(*(uint64_t*) buf, pCol, pCtx, uint64_t, numOfRows, start, isMinFunc, numOfElems);
    }
  } else if (type == TSDB_DATA_TYPE_DOUBLE) {
    LOOPCHECK_N(*(double*) buf, pCol, pCtx, double, numOfRows, start, isMinFunc, numOfElems);
  } else if (type == TSDB_DATA_TYPE_FLOAT) {
    LOOPCHECK_N(*(float*) buf, pCol, pCtx, float, numOfRows, start, isMinFunc, numOfElems);
  }

  return numOfElems;
}

int32_t minFunction(SqlFunctionCtx *pCtx) {
  int32_t numOfElems = doMinMaxHelper(pCtx, 1);
  SET_VAL(GET_RES_INFO(pCtx), numOfElems, 1);
  return TSDB_CODE_SUCCESS;
}

int32_t maxFunction(SqlFunctionCtx *pCtx) {
  int32_t numOfElems = doMinMaxHelper(pCtx, 0);
  SET_VAL(GET_RES_INFO(pCtx), numOfElems, 1);
  return TSDB_CODE_SUCCESS;
}

bool getTopBotFuncEnv(SFunctionNode* pFunc, SFuncExecEnv* pEnv) {
    SColumnNode* pColNode = (SColumnNode*) nodesListGetNode(pFunc->pParameterList, 0);
  int32_t bytes = pColNode->node.resType.bytes;
  SValueNode* pkNode = (SValueNode*) nodesListGetNode(pFunc->pParameterList, 1);
  return true;
}

bool getStddevFuncEnv(SFunctionNode* pFunc, SFuncExecEnv* pEnv) {
  pEnv->calcMemSize = sizeof(SStddevRes);
  return true;
}

bool stddevFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo) {
  if (!functionSetup(pCtx, pResultInfo)) {
    return false;
  }

  SStddevRes* pRes = GET_ROWCELL_INTERBUF(pResultInfo);
  memset(pRes, 0, sizeof(SStddevRes));
  return true;
}

int32_t stddevFunction(SqlFunctionCtx* pCtx) {
  int32_t numOfElem = 0;

  // Only the pre-computing information loaded and actual data does not loaded
  SInputColumnInfoData* pInput = &pCtx->input;
  int32_t               type = pInput->pData[0]->info.type;

  SStddevRes* pStddevRes = GET_ROWCELL_INTERBUF(GET_RES_INFO(pCtx));

  // computing based on the true data block
  SColumnInfoData* pCol = pInput->pData[0];

  int32_t start = pInput->startRowIndex;
  int32_t numOfRows = pInput->numOfRows;

  switch (type) {
    case TSDB_DATA_TYPE_TINYINT: {
        int8_t* plist = (int8_t*)pCol->pData;
        for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
          if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
            continue;
          }

          numOfElem += 1;
          pStddevRes->count += 1;
          pStddevRes->isum += plist[i];
          pStddevRes->quadraticISum += plist[i] * plist[i];
        }

        break;
      }

      case TSDB_DATA_TYPE_SMALLINT: {
      int16_t* plist = (int16_t*)pCol->pData;
      for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
        if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        numOfElem += 1;
        pStddevRes->count += 1;
        pStddevRes->isum += plist[i];
        pStddevRes->quadraticISum += plist[i] * plist[i];
      }
      break;
    }

    case TSDB_DATA_TYPE_INT: {
      int32_t* plist = (int32_t*)pCol->pData;
      for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
        if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        numOfElem += 1;
        pStddevRes->count += 1;
        pStddevRes->isum += plist[i];
        pStddevRes->quadraticISum += plist[i] * plist[i];
      }

      break;
    }

    case TSDB_DATA_TYPE_BIGINT: {
      int64_t* plist = (int64_t*)pCol->pData;
      for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
        if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        numOfElem += 1;
        pStddevRes->count += 1;
        pStddevRes->isum += plist[i];
        pStddevRes->quadraticISum += plist[i] * plist[i];
      }
      break;
    }

    case TSDB_DATA_TYPE_FLOAT: {
      float* plist = (float*)pCol->pData;
      for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
        if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        numOfElem += 1;
        pStddevRes->count += 1;
        pStddevRes->dsum += plist[i];
        pStddevRes->quadraticDSum += plist[i] * plist[i];
      }
      break;
    }

    case TSDB_DATA_TYPE_DOUBLE: {
      double* plist = (double*)pCol->pData;
      for (int32_t i = start; i < numOfRows + pInput->startRowIndex; ++i) {
        if (pCol->hasNull && colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        numOfElem += 1;
        pStddevRes->count += 1;
        pStddevRes->dsum += plist[i];
        pStddevRes->quadraticDSum += plist[i] * plist[i];
      }
      break;
    }

    default:
      break;
  }

  // data in the check operation are all null, not output
  SET_VAL(GET_RES_INFO(pCtx), numOfElem, 1);
  return TSDB_CODE_SUCCESS;
}

void stddevFinalize(SqlFunctionCtx* pCtx) {
  functionFinalize(pCtx);

  SInputColumnInfoData* pInput = &pCtx->input;
  int32_t type = pInput->pData[0]->info.type;
  SStddevRes* pStddevRes = GET_ROWCELL_INTERBUF(GET_RES_INFO(pCtx));
  double avg;
  if (IS_INTEGER_TYPE(type)) {
    avg = pStddevRes->isum / ((double) pStddevRes->count);
    pStddevRes->result = sqrt(pStddevRes->quadraticISum/((double)pStddevRes->count) - avg*avg);
  } else {
    avg = pStddevRes->dsum / ((double) pStddevRes->count);
    pStddevRes->result = sqrt(pStddevRes->quadraticDSum/((double)pStddevRes->count) - avg*avg);
  }
}

bool getPercentileFuncEnv(SFunctionNode* pFunc, SFuncExecEnv* pEnv) {
  pEnv->calcMemSize = sizeof(SPercentileInfo);
  return true;
}

bool percentileFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResultInfo) {
  if (!functionSetup(pCtx, pResultInfo)) {
    return false;
  }

  // in the first round, get the min-max value of all involved data
  SPercentileInfo *pInfo = GET_ROWCELL_INTERBUF(pResultInfo);
  SET_DOUBLE_VAL(&pInfo->minval, DBL_MAX);
  SET_DOUBLE_VAL(&pInfo->maxval, -DBL_MAX);
  pInfo->numOfElems = 0;

  return true;
}

int32_t percentileFunction(SqlFunctionCtx *pCtx) {
  int32_t notNullElems = 0;
  SResultRowEntryInfo *pResInfo = GET_RES_INFO(pCtx);

  SInputColumnInfoData* pInput = &pCtx->input;
  SColumnDataAgg *pAgg = pInput->pColumnDataAgg[0];

  SColumnInfoData *pCol = pInput->pData[0];
  int32_t type = pCol->info.type;

  SPercentileInfo *pInfo = GET_ROWCELL_INTERBUF(pResInfo);
  if (pCtx->currentStage == REPEAT_SCAN && pInfo->stage == 0) {
    pInfo->stage += 1;

    // all data are null, set it completed
    if (pInfo->numOfElems == 0) {
      pResInfo->complete = true;
      return 0;
    } else {
      pInfo->pMemBucket = tMemBucketCreate(pCtx->inputBytes, pCtx->inputType, pInfo->minval, pInfo->maxval);
    }
  }

  // the first stage, only acquire the min/max value
  if (pInfo->stage == 0) {
    if (pCtx->input.colDataAggIsSet) {
      double tmin = 0.0, tmax = 0.0;
      if (IS_SIGNED_NUMERIC_TYPE(type)) {
        tmin = (double)GET_INT64_VAL(&pAgg->min);
        tmax = (double)GET_INT64_VAL(&pAgg->max);
      } else if (IS_FLOAT_TYPE(type)) {
        tmin = GET_DOUBLE_VAL(&pAgg->min);
        tmax = GET_DOUBLE_VAL(&pAgg->max);
      } else if (IS_UNSIGNED_NUMERIC_TYPE(type)) {
        tmin = (double)GET_UINT64_VAL(&pAgg->min);
        tmax = (double)GET_UINT64_VAL(&pAgg->max);
      }

      if (GET_DOUBLE_VAL(&pInfo->minval) > tmin) {
        SET_DOUBLE_VAL(&pInfo->minval, tmin);
      }

      if (GET_DOUBLE_VAL(&pInfo->maxval) < tmax) {
        SET_DOUBLE_VAL(&pInfo->maxval, tmax);
      }

      pInfo->numOfElems += (pInput->numOfRows - pAgg->numOfNull);
    } else {
      // check the valid data one by one
      int32_t start = pInput->startRowIndex;
      for (int32_t i = start; i < pInput->numOfRows + start; ++i) {
        if (colDataIsNull_f(pCol->nullbitmap, i)) {
          continue;
        }

        char *data = colDataGetData(pCol, i);

        double v = 0;
        GET_TYPED_DATA(v, double, pCtx->inputType, data);
        if (v < GET_DOUBLE_VAL(&pInfo->minval)) {
          SET_DOUBLE_VAL(&pInfo->minval, v);
        }

        if (v > GET_DOUBLE_VAL(&pInfo->maxval)) {
          SET_DOUBLE_VAL(&pInfo->maxval, v);
        }

        pInfo->numOfElems += 1;
      }
    }

    return 0;
  }

  // the second stage, calculate the true percentile value
  int32_t start = pInput->startRowIndex;
  for (int32_t i = start; i < pInput->numOfRows + start; ++i) {
    if (colDataIsNull_f(pCol->nullbitmap, i)) {
      continue;
    }

    char *data = colDataGetData(pCol, i);

    notNullElems += 1;
    tMemBucketPut(pInfo->pMemBucket, data, 1);
  }

  SET_VAL(pResInfo, notNullElems, 1);
  return TSDB_CODE_SUCCESS;
}

// TODO set the correct parameter.
void percentileFinalize(SqlFunctionCtx* pCtx) {
  double v = 50;//pCtx->param[0].nType == TSDB_DATA_TYPE_INT ? pCtx->param[0].i64 : pCtx->param[0].dKey;

  SResultRowEntryInfo *pResInfo = GET_RES_INFO(pCtx);
  SPercentileInfo* ppInfo = (SPercentileInfo *) GET_ROWCELL_INTERBUF(pResInfo);

  tMemBucket * pMemBucket = ppInfo->pMemBucket;
  if (pMemBucket != NULL && pMemBucket->total > 0) {  // check for null
    SET_DOUBLE_VAL(&ppInfo->result, getPercentile(pMemBucket, v));
  }

  tMemBucketDestroy(pMemBucket);
  functionFinalize(pCtx);
}

bool getFirstLastFuncEnv(SFunctionNode* pFunc, SFuncExecEnv* pEnv) {
  SColumnNode* pNode = nodesListGetNode(pFunc->pParameterList, 0);
  pEnv->calcMemSize = pNode->node.resType.bytes + sizeof(int64_t);
  return true;
}

static FORCE_INLINE TSKEY getRowPTs(SColumnInfoData* pTsColInfo, int32_t rowIndex) {
  if (pTsColInfo == NULL) {
    return 0;
  }

  return *(TSKEY*) colDataGetData(pTsColInfo, rowIndex);
}

// This ordinary first function does not care if current scan is ascending order or descending order scan
// the OPTIMIZED version of first function will only handle the ascending order scan
int32_t firstFunction(SqlFunctionCtx *pCtx) {
  int32_t numOfElems = 0;

  SResultRowEntryInfo *pResInfo = GET_RES_INFO(pCtx);
  char* buf = GET_ROWCELL_INTERBUF(pResInfo);

  SInputColumnInfoData* pInput = &pCtx->input;
  SColumnInfoData* pInputCol = pInput->pData[0];

  int32_t bytes = pInputCol->info.bytes;

  // All null data column, return directly.
  if (pInput->colDataAggIsSet && (pInput->pColumnDataAgg[0]->numOfNull == pInput->totalRows)) {
    ASSERT(pInputCol->hasNull == true);
    return 0;
  }

  SColumnDataAgg* pColAgg = (pInput->colDataAggIsSet)? pInput->pColumnDataAgg[0]:NULL;

  TSKEY startKey = getRowPTs(pInput->pPTS, 0);
  TSKEY endKey = getRowPTs(pInput->pPTS, pInput->totalRows - 1);

  int32_t blockDataOrder = (startKey <= endKey)? TSDB_ORDER_ASC:TSDB_ORDER_DESC;

  if (blockDataOrder == TSDB_ORDER_ASC) {
    // filter according to current result firstly
    if (pResInfo->numOfRes > 0) {
      TSKEY ts = *(TSKEY*)(buf + bytes);
      if (ts < startKey) {
        return TSDB_CODE_SUCCESS;
      }
    }

    for (int32_t i = pInput->startRowIndex; i < pInput->startRowIndex + pInput->numOfRows; ++i) {
      if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, pColAgg)) {
        continue;
      }

      numOfElems++;

      char* data = colDataGetData(pInputCol, i);
      TSKEY cts = getRowPTs(pInput->pPTS, i);

      if (pResInfo->numOfRes == 0 || *(TSKEY*)(buf + bytes) > cts) {
        memcpy(buf, data, bytes);
        *(TSKEY*)(buf + bytes) = cts;
//        DO_UPDATE_TAG_COLUMNS(pCtx, ts);

        pResInfo->numOfRes = 1;
        break;
      }
    }
  } else {
    // in case of descending order time stamp serial, which usually happens as the results of the nest query,
    // all data needs to be check.
    if (pResInfo->numOfRes > 0) {
      TSKEY ts = *(TSKEY*)(buf + bytes);
      if (ts < endKey) {
        return TSDB_CODE_SUCCESS;
      }
    }

    for (int32_t i = pInput->numOfRows + pInput->startRowIndex - 1; i >= pInput->startRowIndex; --i) {
      if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, pColAgg)) {
        continue;
      }

      numOfElems++;

      char* data = colDataGetData(pInputCol, i);
      TSKEY cts = getRowPTs(pInput->pPTS, i);

      if (pResInfo->numOfRes == 0 || *(TSKEY*)(buf + bytes) > cts) {
        memcpy(buf, data, bytes);
        *(TSKEY*)(buf + bytes) = cts;
//        DO_UPDATE_TAG_COLUMNS(pCtx, ts);
        pResInfo->numOfRes = 1;
        break;
      }
    }
  }

  SET_VAL(pResInfo, numOfElems, 1);
  return TSDB_CODE_SUCCESS;
}

int32_t lastFunction(SqlFunctionCtx *pCtx) {
  int32_t numOfElems = 0;

  SResultRowEntryInfo *pResInfo = GET_RES_INFO(pCtx);
  char* buf = GET_ROWCELL_INTERBUF(pResInfo);

  SInputColumnInfoData* pInput = &pCtx->input;
  SColumnInfoData* pInputCol = pInput->pData[0];

  int32_t bytes = pInputCol->info.bytes;

  // All null data column, return directly.
  if (pInput->colDataAggIsSet && (pInput->pColumnDataAgg[0]->numOfNull == pInput->totalRows)) {
    ASSERT(pInputCol->hasNull == true);
    return 0;
  }

  SColumnDataAgg* pColAgg = (pInput->colDataAggIsSet)? pInput->pColumnDataAgg[0]:NULL;

  TSKEY startKey = getRowPTs(pInput->pPTS, 0);
  TSKEY endKey = getRowPTs(pInput->pPTS, pInput->totalRows - 1);

  int32_t blockDataOrder = (startKey <= endKey)? TSDB_ORDER_ASC:TSDB_ORDER_DESC;

  if (blockDataOrder == TSDB_ORDER_ASC) {
    for (int32_t i = pInput->numOfRows + pInput->startRowIndex - 1; i >= pInput->startRowIndex; --i) {
      if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, pColAgg)) {
        continue;
      }

      numOfElems++;

      char* data = colDataGetData(pInputCol, i);
      TSKEY cts = getRowPTs(pInput->pPTS, i);
      if (pResInfo->numOfRes == 0 || *(TSKEY*)(buf + bytes) < cts) {
        memcpy(buf, data, bytes);
        *(TSKEY*)(buf + bytes) = cts;
        //        DO_UPDATE_TAG_COLUMNS(pCtx, ts);
        pResInfo->numOfRes = 1;
      }
      break;
    }
  } else {  // descending order
    for (int32_t i = pInput->startRowIndex; i < pInput->numOfRows + pInput->startRowIndex; ++i) {
      if (pInputCol->hasNull && colDataIsNull(pInputCol, pInput->totalRows, i, pColAgg)) {
        continue;
      }

      numOfElems++;

      char* data = colDataGetData(pInputCol, i);
      TSKEY cts = getRowPTs(pInput->pPTS, i);
      if (pResInfo->numOfRes == 0 || *(TSKEY*)(buf + bytes) < cts) {
        memcpy(buf, data, bytes);
        *(TSKEY*)(buf + bytes) = cts;
        pResInfo->numOfRes = 1;
//        DO_UPDATE_TAG_COLUMNS(pCtx, ts);
      }
      break;
    }
  }

  SET_VAL(pResInfo, numOfElems, 1);
  return TSDB_CODE_SUCCESS;
}

bool getDiffFuncEnv(SFunctionNode* UNUSED_PARAM(pFunc), SFuncExecEnv* pEnv) {
  pEnv->calcMemSize = sizeof(SDiffInfo);
  return true;
}

bool diffFunctionSetup(SqlFunctionCtx *pCtx, SResultRowEntryInfo* pResInfo) {
  if (!functionSetup(pCtx, pResInfo)) {
    return false;
  }

  SDiffInfo* pDiffInfo = GET_ROWCELL_INTERBUF(pResInfo);
  pDiffInfo->hasPrev  = false;
  pDiffInfo->prev.i64 = 0;
  pDiffInfo->ignoreNegative = false; // TODO set correct param
  pDiffInfo->includeNull = false;
  pDiffInfo->firstOutput = false;
  return true;
}

int32_t diffFunction(SqlFunctionCtx *pCtx) {
  SResultRowEntryInfo *pResInfo = GET_RES_INFO(pCtx);
  SDiffInfo *pDiffInfo = GET_ROWCELL_INTERBUF(pResInfo);

  SInputColumnInfoData* pInput = &pCtx->input;
  SColumnInfoData* pInputCol = pInput->pData[0];

  bool  isFirstBlock = (pDiffInfo->hasPrev == false);
  int32_t numOfElems = 0;

  int32_t step = GET_FORWARD_DIRECTION_FACTOR(pCtx->order);
//  int32_t i = (pCtx->order == TSDB_ORDER_ASC) ? 0 : pCtx->size - 1;

  SColumnInfoData* pTsOutput = pCtx->pTsOutput;
  TSKEY* tsList = (int64_t*)pInput->pPTS->pData;

  int32_t startOffset = pCtx->offset;
  switch (pInputCol->info.type) {
    case TSDB_DATA_TYPE_INT: {
      SColumnInfoData *pOutput = (SColumnInfoData *)pCtx->pOutput;
      for (int32_t i = pInput->startRowIndex; i < pInput->numOfRows + pInput->startRowIndex; i += step) {

        int32_t pos = startOffset + (isFirstBlock? (numOfElems-1):numOfElems);
        if (colDataIsNull_f(pInputCol->nullbitmap, i)) {
          if (pDiffInfo->includeNull) {
            colDataSetNull_f(pOutput->nullbitmap, pos);
            if (tsList != NULL) {
              colDataAppendInt64(pTsOutput, pos, &tsList[i]);
            }

            numOfElems += 1;
          }
          continue;
        }

        int32_t v = *(int32_t*) colDataGetData(pInputCol, i);
        if (pDiffInfo->hasPrev) {
          int32_t delta = (int32_t)(v - pDiffInfo->prev.i64);  // direct previous may be null
          if (delta < 0 && pDiffInfo->ignoreNegative) {
            colDataSetNull_f(pOutput->nullbitmap, pos);
          } else {
            colDataAppendInt32(pOutput, pos, &delta);
          }

          if (pTsOutput != NULL) {
            colDataAppendInt64(pTsOutput, pos, &tsList[i]);
          }
        }

        pDiffInfo->prev.i64 = v;
        pDiffInfo->hasPrev  = true;
        numOfElems++;
      }
      break;
    }

    case TSDB_DATA_TYPE_BIGINT: {
      SColumnInfoData *pOutput = (SColumnInfoData *)pCtx->pOutput;
      for (int32_t i = pInput->startRowIndex; i < pInput->numOfRows + pInput->startRowIndex; i += step) {
        if (colDataIsNull_f(pInputCol->nullbitmap, i)) {
          continue;
        }

        int32_t v = 0;
        if (pDiffInfo->hasPrev) {
          v = *(int64_t*) colDataGetData(pInputCol, i);
          int64_t delta = (int64_t)(v - pDiffInfo->prev.i64);  // direct previous may be null
          if (pDiffInfo->ignoreNegative) {
            continue;
          }

//          *(pOutput++) = delta;
//          *pTimestamp  = (tsList != NULL)? tsList[i]:0;
//
//          pOutput    += 1;
//          pTimestamp += 1;
        }

        pDiffInfo->prev.i64 = v;
        pDiffInfo->hasPrev = true;
        numOfElems++;
      }
      break;
    }
#if 0
    case TSDB_DATA_TYPE_DOUBLE: {
      double *pData = (double *)data;
      double *pOutput = (double *)pCtx->pOutput;

      for (; i < pCtx->size && i >= 0; i += step) {
        if (pCtx->hasNull && isNull((const char*) &pData[i], pCtx->inputType)) {
          continue;
        }
        if ((pDiffInfo->ignoreNegative) && (pData[i] < 0)) {
          continue;
        }

        if (pDiffInfo->hasPrev) {  // initial value is not set yet
          SET_DOUBLE_VAL(pOutput, pData[i] - pDiffInfo->d64Prev);  // direct previous may be null
          *pTimestamp = (tsList != NULL)? tsList[i]:0;
          pOutput    += 1;
          pTimestamp += 1;
        }

        pDiffInfo->d64Prev = pData[i];
        pDiffInfo->hasPrev = true;
        numOfElems++;
      }
      break;
    }
    case TSDB_DATA_TYPE_FLOAT: {
      float *pData = (float *)data;
      float *pOutput = (float *)pCtx->pOutput;

      for (; i < pCtx->size && i >= 0; i += step) {
        if (pCtx->hasNull && isNull((const char*) &pData[i], pCtx->inputType)) {
          continue;
        }
        if ((pDiffInfo->ignoreNegative) && (pData[i] < 0)) {
          continue;
        }

        if (pDiffInfo->hasPrev) {  // initial value is not set yet
          *pOutput = (float)(pData[i] - pDiffInfo->d64Prev);  // direct previous may be null
          *pTimestamp = (tsList != NULL)? tsList[i]:0;
          pOutput    += 1;
          pTimestamp += 1;
        }

        pDiffInfo->d64Prev = pData[i];
        pDiffInfo->hasPrev = true;
        numOfElems++;
      }
      break;
    }
    case TSDB_DATA_TYPE_SMALLINT: {
      int16_t *pData = (int16_t *)data;
      int16_t *pOutput = (int16_t *)pCtx->pOutput;

      for (; i < pCtx->size && i >= 0; i += step) {
        if (pCtx->hasNull && isNull((const char*) &pData[i], pCtx->inputType)) {
          continue;
        }
        if ((pDiffInfo->ignoreNegative) && (pData[i] < 0)) {
          continue;
        }

        if (pDiffInfo->hasPrev) {  // initial value is not set yet
          *pOutput = (int16_t)(pData[i] - pDiffInfo->i64Prev);  // direct previous may be null
          *pTimestamp = (tsList != NULL)? tsList[i]:0;
          pOutput    += 1;
          pTimestamp += 1;
        }

        pDiffInfo->i64Prev = pData[i];
        pDiffInfo->hasPrev = true;
        numOfElems++;
      }
      break;
    }

    case TSDB_DATA_TYPE_TINYINT: {
      int8_t *pData = (int8_t *)data;
      int8_t *pOutput = (int8_t *)pCtx->pOutput;

      for (; i < pCtx->size && i >= 0; i += step) {
        if (pCtx->hasNull && isNull((char *)&pData[i], pCtx->inputType)) {
          continue;
        }
        if ((pDiffInfo->ignoreNegative) && (pData[i] < 0)) {
          continue;
        }

        if (pDiffInfo->hasPrev) {  // initial value is not set yet
          *pOutput = (int8_t)(pData[i] - pDiffInfo->i64Prev);  // direct previous may be null
          *pTimestamp = (tsList != NULL)? tsList[i]:0;
          pOutput    += 1;
          pTimestamp += 1;
        }

        pDiffInfo->i64Prev = pData[i];
        pDiffInfo->hasPrev = true;
        numOfElems++;
      }
      break;
    }
#endif
    default:
      break;
//      qError("error input type");
  }

  // initial value is not set yet
  if (!pDiffInfo->hasPrev || numOfElems <= 0) {
    /*
     * 1. current block and blocks before are full of null
     * 2. current block may be null value
     */
    assert(pCtx->hasNull);
    return 0;
  } else {
//    for (int t = 0; t < pCtx->tagInfo.numOfTagCols; ++t) {
//      SqlFunctionCtx* tagCtx = pCtx->tagInfo.pTagCtxList[t];
//      if (tagCtx->functionId == TSDB_FUNC_TAG_DUMMY) {
//        aAggs[TSDB_FUNC_TAGPRJ].xFunction(tagCtx);
//      }
//    }

    int32_t forwardStep = (isFirstBlock) ? numOfElems - 1 : numOfElems;
    return forwardStep;
  }
}