/*
 * 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 <dirent.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <libgen.h>

#include "talgo.h"
#include "tchecksum.h"
#include "tsdbMain.h"
#include "tutil.h"

const char *tsdbFileSuffix[] = {
    ".head",  // TSDB_FILE_TYPE_HEAD
    ".data",  // TSDB_FILE_TYPE_DATA
    ".last"   // TSDB_FILE_TYPE_LAST
};

static int compFGroupKey(const void *key, const void *fgroup);
static int compFGroup(const void *arg1, const void *arg2);
static int tsdbWriteFileHead(SFile *pFile);
static int tsdbWriteHeadFileIdx(SFile *pFile, int maxTables);
static int tsdbOpenFGroup(STsdbFileH *pFileH, char *dataDir, int fid);

STsdbFileH *tsdbInitFileH(char *dataDir, int maxFiles) {
  STsdbFileH *pFileH = (STsdbFileH *)calloc(1, sizeof(STsdbFileH) + sizeof(SFileGroup) * maxFiles);
  if (pFileH == NULL) {  // TODO: deal with ERROR here
    return NULL;
  }

  pFileH->maxFGroups = maxFiles;

  DIR *dir = opendir(dataDir);
  if (dir == NULL) {
    free(pFileH);
    return NULL;
  }

  struct dirent *dp = NULL;
  while ((dp = readdir(dir)) != NULL) {
    if (strncmp(dp->d_name, ".", 1) == 0 || strncmp(dp->d_name, "..", 1) == 0) continue;
    int fid = 0;
    sscanf(dp->d_name, "f%d", &fid);
    if (tsdbOpenFGroup(pFileH, dataDir, fid) < 0) {
      break;
      // TODO
    }
  }
  closedir(dir);

  return pFileH;
}

void tsdbCloseFileH(STsdbFileH *pFileH) { free(pFileH); }

static int tsdbInitFile(char *dataDir, int fid, const char *suffix, SFile *pFile) {
  tsdbGetFileName(dataDir, fid, suffix, pFile->fname);
  if (access(pFile->fname, F_OK|R_OK|W_OK) < 0) return -1;
  pFile->fd = -1;
  // TODO: recover the file info
  // pFile->info = {0};
  return 0;
}

static int tsdbOpenFGroup(STsdbFileH *pFileH, char *dataDir, int fid) {
  if (tsdbSearchFGroup(pFileH, fid) != NULL) return 0;

  SFileGroup fGroup = {0};
  fGroup.fileId = fid;

  for (int type = TSDB_FILE_TYPE_HEAD; type < TSDB_FILE_TYPE_MAX; type++) {
    if (tsdbInitFile(dataDir, fid, tsdbFileSuffix[type], &fGroup.files[type]) < 0) return -1;
  }
  pFileH->fGroup[pFileH->numOfFGroups++] = fGroup;
  qsort((void *)(pFileH->fGroup), pFileH->numOfFGroups, sizeof(SFileGroup), compFGroup);
  return 0;
}

/**
 * Create the file group if the file group not exists.
 *
 * @return A pointer to
 */
SFileGroup *tsdbCreateFGroup(STsdbFileH *pFileH, char *dataDir, int fid, int maxTables) {
  if (pFileH->numOfFGroups >= pFileH->maxFGroups) return NULL;

  SFileGroup  fGroup;
  SFileGroup *pFGroup = &fGroup;

  SFileGroup *pGroup = tsdbSearchFGroup(pFileH, fid);
  if (pGroup == NULL) {  // if not exists, create one
    pFGroup->fileId = fid;
    for (int type = TSDB_FILE_TYPE_HEAD; type < TSDB_FILE_TYPE_MAX; type++) {
      if (tsdbCreateFile(dataDir, fid, tsdbFileSuffix[type], maxTables, &(pFGroup->files[type]),
                         type == TSDB_FILE_TYPE_HEAD ? 1 : 0, 1) < 0)
        goto _err;
    }

    pFileH->fGroup[pFileH->numOfFGroups++] = fGroup;
    qsort((void *)(pFileH->fGroup), pFileH->numOfFGroups, sizeof(SFileGroup), compFGroup);
    return tsdbSearchFGroup(pFileH, fid);
  }

  return pGroup;

_err:
  // TODO: deal with the err here
  return NULL;
}

int tsdbRemoveFileGroup(STsdbFileH *pFileH, int fid) {
  SFileGroup *pGroup =
      bsearch((void *)&fid, (void *)(pFileH->fGroup), pFileH->numOfFGroups, sizeof(SFileGroup), compFGroupKey);
  if (pGroup == NULL) return -1;

  // Remove from disk
  for (int type = TSDB_FILE_TYPE_HEAD; type < TSDB_FILE_TYPE_MAX; type++) {
    remove(pGroup->files[type].fname);
  }

  // Adjust the memory
  int filesBehind = pFileH->numOfFGroups - (((char *)pGroup - (char *)(pFileH->fGroup)) / sizeof(SFileGroup) + 1);
  if (filesBehind > 0) {
    memmove((void *)pGroup, (void *)((char *)pGroup + sizeof(SFileGroup)), sizeof(SFileGroup) * filesBehind);
  }
  pFileH->numOfFGroups--;

  return 0;
}

void tsdbInitFileGroupIter(STsdbFileH *pFileH, SFileGroupIter *pIter, int direction) {
  pIter->direction = direction;
  pIter->base = pFileH->fGroup;
  pIter->numOfFGroups = pFileH->numOfFGroups;
  if (pFileH->numOfFGroups == 0){
    pIter->pFileGroup = NULL;
  } else {
    if (direction == TSDB_FGROUP_ITER_FORWARD) {
      pIter->pFileGroup = pFileH->fGroup;
    } else {
      pIter->pFileGroup = pFileH->fGroup + pFileH->numOfFGroups - 1;
    }
  }
}

void tsdbSeekFileGroupIter(SFileGroupIter *pIter, int fid) {
  if (pIter->numOfFGroups == 0) {
    assert(pIter->pFileGroup == NULL);
    return;
  }
  
  int flags = (pIter->direction == TSDB_FGROUP_ITER_FORWARD) ? TD_GE : TD_LE;
  void *ptr = taosbsearch(&fid, pIter->base, pIter->numOfFGroups, sizeof(SFileGroup), compFGroupKey, flags);
  if (ptr == NULL) {
    pIter->pFileGroup = NULL;
  } else {
    pIter->pFileGroup = (SFileGroup *)ptr;
  }
}

SFileGroup *tsdbGetFileGroupNext(SFileGroupIter *pIter) {
  SFileGroup *ret = pIter->pFileGroup;
  if (ret == NULL) return NULL;

  if (pIter->direction == TSDB_FGROUP_ITER_FORWARD) {
    if ((pIter->pFileGroup + 1) == (pIter->base + pIter->numOfFGroups)) {
      pIter->pFileGroup = NULL;
    } else {
      pIter->pFileGroup += 1;
    }
  } else {
    if (pIter->pFileGroup == pIter->base) {
      pIter->pFileGroup = NULL;
    } else {
      pIter->pFileGroup -= 1;
    }
  }
  return ret;
}

// int tsdbLoadDataBlock(SFile *pFile, SCompBlock *pStartBlock, int numOfBlocks, SDataCols *pCols, SCompData *pCompData) {
//   SCompBlock *pBlock = pStartBlock;
//   for (int i = 0; i < numOfBlocks; i++) {
//     if (tsdbLoadCompCols(pFile, pBlock, (void *)pCompData) < 0) return -1;
//     pCols->numOfPoints += (pCompData->cols[0].len / 8);
//     for (int iCol = 0; iCol < pBlock->numOfCols; iCol++) {
//       SCompCol *pCompCol = &(pCompData->cols[iCol]);
//       // pCols->numOfPoints += pBlock->numOfPoints;
//       int k = 0;
//       for (; k < pCols->numOfCols; k++) {
//         if (pCompCol->colId == pCols->cols[k].colId) break;
//       }

//       if (tsdbLoadColData(pFile, pCompCol, pBlock->offset,
//                           (void *)((char *)(pCols->cols[k].pData) + pCols->cols[k].len)) < 0)
//         return -1;
//     }
//     pStartBlock++;
//   }
//   return 0;
// }

int tsdbCopyBlockDataInFile(SFile *pOutFile, SFile *pInFile, SCompInfo *pCompInfo, int idx, int isLast, SDataCols *pCols) {
  SCompBlock *pSuperBlock = TSDB_COMPBLOCK_AT(pCompInfo, idx);
  SCompBlock *pStartBlock = NULL;
  SCompBlock *pBlock = NULL;
  int         numOfBlocks = pSuperBlock->numOfSubBlocks;

  if (numOfBlocks == 1)
    pStartBlock = pSuperBlock;
  else
    pStartBlock = TSDB_COMPBLOCK_AT(pCompInfo, pSuperBlock->offset);

  int maxNumOfCols = 0;
  pBlock = pStartBlock;
  for (int i = 0; i < numOfBlocks; i++) {
    if (pBlock->numOfCols > maxNumOfCols) maxNumOfCols = pBlock->numOfCols;
    pBlock++;
  }

  SCompData *pCompData = (SCompData *)malloc(sizeof(SCompData) + sizeof(SCompCol) * maxNumOfCols);
  if (pCompData == NULL) return -1;

  // Load data from the block
  // if (tsdbLoadDataBlock(pOutFile, pStartBlock, numOfBlocks, pCols, pCompData));

  // Write data block to the file
  {
    // TODO
  }


  if (pCompData) free(pCompData);
  return 0;
}

// int tsdbLoadCompIdx(SFileGroup *pGroup, void *buf, int maxTables) {
//   SFile *pFile = &(pGroup->files[TSDB_FILE_TYPE_HEAD]);
//   if (lseek(pFile->fd, TSDB_FILE_HEAD_SIZE, SEEK_SET) < 0) return -1;

//   if (read(pFile->fd, buf, sizeof(SCompIdx) * maxTables) < 0) return -1;
//   // TODO: need to check the correctness
//   return 0;
// }

// int tsdbLoadCompBlocks(SFileGroup *pGroup, SCompIdx *pIdx, void *buf) {
//   SFile *pFile = &(pGroup->files[TSDB_FILE_TYPE_HEAD]);

//   if (lseek(pFile->fd, pIdx->offset, SEEK_SET) < 0) return -1;

//   if (read(pFile->fd, buf, pIdx->len) < 0) return -1;

//   // TODO: need to check the correctness

//   return 0;
// }

// int tsdbLoadCompCols(SFile *pFile, SCompBlock *pBlock, void *buf) {
//   // assert(pBlock->numOfSubBlocks == 0 || pBlock->numOfSubBlocks == 1);

//   if (lseek(pFile->fd, pBlock->offset, SEEK_SET) < 0) return -1;
//   size_t size = sizeof(SCompData) + sizeof(SCompCol) * pBlock->numOfCols;
//   if (read(pFile->fd, buf, size) < 0) return -1;

//   return 0;
// }

// int tsdbLoadColData(SFile *pFile, SCompCol *pCol, int64_t blockBaseOffset, void *buf) {
//   if (lseek(pFile->fd, blockBaseOffset + pCol->offset, SEEK_SET) < 0) return -1;
//   if (read(pFile->fd, buf, pCol->len) < 0) return -1;
//   return 0;
// }

static int compFGroupKey(const void *key, const void *fgroup) {
  int         fid = *(int *)key;
  SFileGroup *pFGroup = (SFileGroup *)fgroup;
  return (fid - pFGroup->fileId);
}

static int compFGroup(const void *arg1, const void *arg2) {
  return ((SFileGroup *)arg1)->fileId - ((SFileGroup *)arg2)->fileId;
}

static int tsdbWriteFileHead(SFile *pFile) {
  char head[TSDB_FILE_HEAD_SIZE] = "\0";

  pFile->info.size += TSDB_FILE_HEAD_SIZE;

  // TODO: write version and File statistic to the head
  lseek(pFile->fd, 0, SEEK_SET);
  if (write(pFile->fd, head, TSDB_FILE_HEAD_SIZE) < 0) return -1;

  return 0;
}

static int tsdbWriteHeadFileIdx(SFile *pFile, int maxTables) {
  int   size = sizeof(SCompIdx) * maxTables + sizeof(TSCKSUM);
  void *buf = calloc(1, size);
  if (buf == NULL) return -1;

  if (lseek(pFile->fd, TSDB_FILE_HEAD_SIZE, SEEK_SET) < 0) {
    free(buf);
    return -1;
  }

  taosCalcChecksumAppend(0, (uint8_t *)buf, size);

  if (write(pFile->fd, buf, size) < 0) {
    free(buf);
    return -1;
  }

  pFile->info.size += size;

  free(buf);
  return 0;
}

int tsdbGetFileName(char *dataDir, int fileId, const char *suffix, char *fname) {
  if (dataDir == NULL || fname == NULL) return -1;

  sprintf(fname, "%s/f%d%s", dataDir, fileId, suffix);

  return 0;
}

int tsdbOpenFile(SFile *pFile, int oflag) { // TODO: change the function
  if (TSDB_IS_FILE_OPENED(pFile)) return -1;

  pFile->fd = open(pFile->fname, oflag, 0755);
  if (pFile->fd < 0) return -1;

  return 0;
}

int tsdbCloseFile(SFile *pFile) {
  int ret = close(pFile->fd);
  pFile->fd = -1;
  return ret;
}

SFileGroup * tsdbOpenFilesForCommit(STsdbFileH *pFileH, int fid) {
  SFileGroup *pGroup = tsdbSearchFGroup(pFileH, fid);
  if (pGroup == NULL) return NULL;

  for (int type = TSDB_FILE_TYPE_HEAD; type < TSDB_FILE_TYPE_MAX; type++) {
    tsdbOpenFile(&(pGroup->files[type]), O_RDWR);
  }
  return pGroup;
}

int tsdbCreateFile(char *dataDir, int fileId, const char *suffix, int maxTables, SFile *pFile, int writeHeader, int toClose) {
  memset((void *)pFile, 0, sizeof(SFile));
  pFile->fd = -1;

  tsdbGetFileName(dataDir, fileId, suffix, pFile->fname);
  
  if (access(pFile->fname, F_OK) == 0) {
    // File already exists
    return -1;
  }

  if (tsdbOpenFile(pFile, O_RDWR | O_CREAT) < 0) {
    // TODO: deal with the ERROR here
    return -1;
  }

  if (writeHeader) {
    if (tsdbWriteHeadFileIdx(pFile, maxTables) < 0) {
      tsdbCloseFile(pFile);
      return -1;
    }
  }

  if (tsdbWriteFileHead(pFile) < 0) {
    tsdbCloseFile(pFile);
    return -1;
  }

  if (toClose) tsdbCloseFile(pFile);

  return 0;
}

void tsdbGetKeyRangeOfFileId(int32_t daysPerFile, int8_t precision, int32_t fileId, TSKEY *minKey,
                                    TSKEY *maxKey) {
  *minKey = fileId * daysPerFile * tsMsPerDay[precision];
  *maxKey = *minKey + daysPerFile * tsMsPerDay[precision] - 1;
}

SFileGroup *tsdbSearchFGroup(STsdbFileH *pFileH, int fid) {
  if (pFileH->numOfFGroups == 0 || fid < pFileH->fGroup[0].fileId || fid > pFileH->fGroup[pFileH->numOfFGroups - 1].fileId)
    return NULL;
  void *ptr = bsearch((void *)&fid, (void *)(pFileH->fGroup), pFileH->numOfFGroups, sizeof(SFileGroup), compFGroupKey);
  if (ptr == NULL) return NULL;
  return (SFileGroup *)ptr;
}