/*
 * 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 "os.h"

#include "hash.h"
#include "taosdef.h"
#include "taoserror.h"
#include "tfs.h"
#include "tfsint.h"

#define TMPNAME_LEN (TSDB_FILENAME_LEN * 2 + 32)

typedef struct {
  pthread_spinlock_t lock;
  SFSMeta            meta;
  int                nlevel;
  STier              tiers[TSDB_MAX_TIERS];
  SHashObj *         map;  // name to did map
} SFS;

typedef struct {
  SDisk *pDisk;
} SDiskIter;

#define TFS_META() (pfs->meta)
#define TFS_NLEVEL() (pfs->nlevel)
#define TFS_TIERS() (pfs->tiers)
#define TFS_TIER_AT(level) (TFS_TIERS() + (level))
#define TFS_DISK_AT(level, id) DISK_AT_TIER(TFS_TIER_AT(level), id)
#define TFS_PRIMARY_DISK() TFS_DISK_AT(TFS_PRIMARY_LEVEL, TFS_PRIMARY_ID)
#define TFS_IS_VALID_LEVEL(level) (((level) >= 0) && ((level) < TFS_NLEVEL()))
#define TFS_IS_VALID_ID(level, id) (((id) >= 0) && ((id) < TIER_NDISKS(TFS_TIER_AT(level))))
#define TFS_IS_VALID_DISK(level, id) (TFS_IS_VALID_LEVEL(level) && TFS_IS_VALID_ID(level, id))

#define tfsLock() pthread_spin_lock(&(pfs->lock))
#define tfsUnLock() pthread_spin_unlock(&(pfs->lock))

static SFS  tfs = {0};
static SFS *pfs = &tfs;

// STATIC DECLARATION
static int    tfsMount(SDiskCfg *pCfg);
static int    tfsCheck();
static int    tfsCheckAndFormatCfg(SDiskCfg *pCfg);
static int    tfsFormatDir(char *idir, char *odir);
static SDisk *tfsGetDiskByID(SDiskID did);
static SDisk *tfsGetDiskByName(const char *dir);
static int    tfsOpendirImpl(TDIR *tdir);
static void   tfsInitDiskIter(SDiskIter *pIter);
static SDisk *tfsNextDisk(SDiskIter *pIter);

// FS APIs ====================================
int tfsInit(SDiskCfg *pDiskCfg, int ndisk) {
  ASSERT(ndisk > 0);

  for (int level = 0; level < TSDB_MAX_TIERS; level++) {
    if (tfsInitTier(TFS_TIER_AT(level), level) < 0) {
      while (true) {
        level--;
        if (level < 0) break;

        tfsDestroyTier(TFS_TIER_AT(level));
      }

      return -1;
    }
  }

  pthread_spin_init(&(pfs->lock), 0);

  pfs->map = taosHashInit(TSDB_MAX_TIERS * TSDB_MAX_DISKS_PER_TIER * 2,
                          taosGetDefaultHashFunction(TSDB_DATA_TYPE_BINARY), false, HASH_NO_LOCK);
  if (pfs->map == NULL) {
    terrno = TSDB_CODE_FS_OUT_OF_MEMORY;
    tfsDestroy();
    return -1;
  }

  for (int idisk = 0; idisk < ndisk; idisk++) {
    if (tfsMount(pDiskCfg + idisk) < 0) {
      tfsDestroy();
      return -1;
    }
  }

  if (tfsCheck() < 0) {
    tfsDestroy();
    return -1;
  }

  tfsUpdateInfo(NULL);
  for (int level = 0; level < TFS_NLEVEL(); level++) {
    tfsPosNextId(TFS_TIER_AT(level));
  }

  return 0;
}

void tfsDestroy() {
  taosHashCleanup(pfs->map);
  pfs->map = NULL;

  pthread_spin_destroy(&(pfs->lock));
  for (int level = 0; level < TFS_NLEVEL(); level++) {
    tfsDestroyTier(TFS_TIER_AT(level));
  }
}

void tfsUpdateInfo(SFSMeta *pFSMeta) {
  SFSMeta   fsMeta;
  STierMeta tierMeta;

  if (pFSMeta == NULL) {
    pFSMeta = &fsMeta;
  }

  memset(pFSMeta, 0, sizeof(*pFSMeta));

  for (int level = 0; level < TFS_NLEVEL(); level++) {
    STier *pTier = TFS_TIER_AT(level);
    tfsUpdateTierInfo(pTier, &tierMeta);
    pFSMeta->tsize += tierMeta.size;
    pFSMeta->avail += tierMeta.free;
    pFSMeta->used += tierMeta.used;
  }

  tfsLock();
  pfs->meta = *pFSMeta;
  tfsUnLock();
}

void tfsGetMeta(SFSMeta *pMeta) {
  ASSERT(pMeta);

  tfsLock();
  *pMeta = pfs->meta;
  tfsUnLock();
}

/* Allocate an existing available tier level
 */
void tfsAllocDisk(int expLevel, int *level, int *id) {
  ASSERT(expLevel >= 0);

  *level = expLevel;
  *id = TFS_UNDECIDED_ID;

  if (*level >= TFS_NLEVEL()) {
    *level = TFS_NLEVEL() - 1;
  }

  while (*level >= 0) {
    *id = tfsAllocDiskOnTier(TFS_TIER_AT(*level));
    if (*id == TFS_UNDECIDED_ID) {
      (*level)--;
      continue;
    }

    return;
  }

  *level = TFS_UNDECIDED_LEVEL;
  *id = TFS_UNDECIDED_ID;
}

const char *TFS_PRIMARY_PATH() { return DISK_DIR(TFS_PRIMARY_DISK()); }
const char *TFS_DISK_PATH(int level, int id) { return DISK_DIR(TFS_DISK_AT(level, id)); }

// TFILE APIs ====================================
void tfsInitFile(TFILE *pf, int level, int id, const char *bname) {
  ASSERT(TFS_IS_VALID_DISK(level, id));

  SDisk *pDisk = TFS_DISK_AT(level, id);

  pf->level = level;
  pf->id = id;
  tstrncpy(pf->rname, bname, TSDB_FILENAME_LEN);

  char tmpName[TMPNAME_LEN] = {0};
  snprintf(tmpName, TMPNAME_LEN, "%s/%s", DISK_DIR(pDisk), bname);
  tstrncpy(pf->aname, tmpName, TSDB_FILENAME_LEN);
}

bool tfsIsSameFile(const TFILE *pf1, const TFILE *pf2) {
  ASSERT(pf1 != NULL || pf2 != NULL);
  if (pf1 == NULL || pf2 == NULL) return false;
  if (pf1->level != pf2->level) return false;
  if (pf1->id != pf2->id) return false;
  if (strncmp(pf1->rname, pf2->rname, TSDB_FILENAME_LEN) != 0) return false;
  return true;
}

int tfsEncodeFile(void **buf, TFILE *pf) {
  int tlen = 0;

  tlen += taosEncodeVariantI32(buf, pf->level);
  tlen += taosEncodeVariantI32(buf, pf->id);
  tlen += taosEncodeString(buf, pf->rname);

  return tlen;
}

void *tfsDecodeFile(void *buf, TFILE *pf) {
  int32_t level, id;
  char *  rname;

  buf = taosDecodeVariantI32(buf, &(level));
  buf = taosDecodeVariantI32(buf, &(id));
  buf = taosDecodeString(buf, &rname);

  tfsInitFile(pf, level, id, rname);

  tfree(rname);
  return buf;
}

void tfsbasename(const TFILE *pf, char *dest) {
  char tname[TSDB_FILENAME_LEN] = "\0";

  tstrncpy(tname, pf->aname, TSDB_FILENAME_LEN);
  tstrncpy(dest, basename(tname), TSDB_FILENAME_LEN);
}

void tfsdirname(const TFILE *pf, char *dest) {
  char tname[TSDB_FILENAME_LEN] = "\0";

  tstrncpy(tname, pf->aname, TSDB_FILENAME_LEN);
  tstrncpy(dest, dirname(tname), TSDB_FILENAME_LEN);
}

// DIR APIs ====================================
int tfsMkdirAt(const char *rname, int level, int id) {
  SDisk *pDisk = TFS_DISK_AT(level, id);
  char   aname[TMPNAME_LEN];

  snprintf(aname, TMPNAME_LEN, "%s/%s", DISK_DIR(pDisk), rname);
  if (taosMkDir(aname, 0755) != 0) {
    terrno = TAOS_SYSTEM_ERROR(errno);
    return -1;
  }

  return 0;
}

int tfsMkdirRecurAt(const char *rname, int level, int id) {
  if (tfsMkdirAt(rname, level, id) < 0) {
    if (errno == ENOENT) {
      // Try to create upper
      char *s = strdup(rname);

      // Make a copy of dirname(s) because the implementation of 'dirname' differs on different platforms.
      // Some platform may modify the contents of the string passed into dirname(). Others may return a pointer to
      // internal static storage space that will be overwritten by next call. For case like that, we should not use
      // the pointer directly in this recursion.
      // See https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/dirname.3.html
      char *dir = strdup(dirname(s));

      if (tfsMkdirRecurAt(dir, level, id) < 0) {
        free(s);
        free(dir);
        return -1;
      }
      free(s);
      free(dir);

      if (tfsMkdirAt(rname, level, id) < 0) {
        return -1;
      }
    } else {
      return -1;
    }
  }

  return 0;
}

int tfsMkdir(const char *rname) {
  for (int level = 0; level < TFS_NLEVEL(); level++) {
    STier *pTier = TFS_TIER_AT(level);
    for (int id = 0; id < TIER_NDISKS(pTier); id++) {
      if (tfsMkdirAt(rname, level, id) < 0) {
        return -1;
      }
    }
  }

  return 0;
}

int tfsRmdir(const char *rname) {
  char aname[TMPNAME_LEN] = "\0";

  for (int level = 0; level < TFS_NLEVEL(); level++) {
    STier *pTier = TFS_TIER_AT(level);
    for (int id = 0; id < TIER_NDISKS(pTier); id++) {
      SDisk *pDisk = DISK_AT_TIER(pTier, id);

      snprintf(aname, TMPNAME_LEN, "%s/%s", DISK_DIR(pDisk), rname);

      taosRemoveDir(aname);
    }
  }

  return 0;
}

int tfsRename(char *orname, char *nrname) {
  char oaname[TMPNAME_LEN] = "\0";
  char naname[TMPNAME_LEN] = "\0";

  for (int level = 0; level < pfs->nlevel; level++) {
    STier *pTier = TFS_TIER_AT(level);
    for (int id = 0; id < TIER_NDISKS(pTier); id++) {
      SDisk *pDisk = DISK_AT_TIER(pTier, id);

      snprintf(oaname, TMPNAME_LEN, "%s/%s", DISK_DIR(pDisk), orname);
      snprintf(naname, TMPNAME_LEN, "%s/%s", DISK_DIR(pDisk), nrname);

      taosRename(oaname, naname);
    }
  }

  return 0;
}

struct TDIR {
  SDiskIter iter;
  int       level;
  int       id;
  char      dirname[TSDB_FILENAME_LEN];
  TFILE     tfile;
  DIR *     dir;
};

TDIR *tfsOpendir(const char *rname) {
  TDIR *tdir = (TDIR *)calloc(1, sizeof(*tdir));
  if (tdir == NULL) {
    terrno = TSDB_CODE_FS_OUT_OF_MEMORY;
    return NULL;
  }

  tfsInitDiskIter(&(tdir->iter));
  tstrncpy(tdir->dirname, rname, TSDB_FILENAME_LEN);

  if (tfsOpendirImpl(tdir) < 0) {
    free(tdir);
    return NULL;
  }

  return tdir;
}

const TFILE *tfsReaddir(TDIR *tdir) {
  if (tdir == NULL || tdir->dir == NULL) return NULL;
  char bname[TMPNAME_LEN * 2] = "\0";

  while (true) {
    struct dirent *dp = NULL;
    dp = readdir(tdir->dir);
    if (dp != NULL) {
      // Skip . and ..
      if (strcmp(dp->d_name, ".") == 0 || strcmp(dp->d_name, "..") == 0) continue;

      snprintf(bname, TMPNAME_LEN * 2, "%s/%s", tdir->dirname, dp->d_name);
      tfsInitFile(&(tdir->tfile), tdir->level, tdir->id, bname);
      return &(tdir->tfile);
    }

    if (tfsOpendirImpl(tdir) < 0) {
      return NULL;
    }

    if (tdir->dir == NULL) {
      terrno = TSDB_CODE_SUCCESS;
      return NULL;
    }
  }
}

void tfsClosedir(TDIR *tdir) {
  if (tdir) {
    if (tdir->dir != NULL) {
      closedir(tdir->dir);
      tdir->dir = NULL;
    }
    free(tdir);
  }
}

// private
static int tfsMount(SDiskCfg *pCfg) {
  SDiskID did;
  SDisk * pDisk = NULL;

  if (tfsCheckAndFormatCfg(pCfg) < 0) return -1;

  did.level = pCfg->level;
  pDisk = tfsMountDiskToTier(TFS_TIER_AT(did.level), pCfg);
  if (pDisk == NULL) {
    fError("failed to mount disk %s to level %d since %s", pCfg->dir, pCfg->level, tstrerror(terrno));
    return -1;
  }
  did.id = DISK_ID(pDisk);

  taosHashPut(pfs->map, (void *)(pCfg->dir), strnlen(pCfg->dir, TSDB_FILENAME_LEN), (void *)(&did), sizeof(did));
  if (pfs->nlevel < pCfg->level + 1) pfs->nlevel = pCfg->level + 1;

  return 0;
}

static int tfsCheckAndFormatCfg(SDiskCfg *pCfg) {
  char        dirName[TSDB_FILENAME_LEN] = "\0";
  struct stat pstat;

  if (pCfg->level < 0 || pCfg->level >= TSDB_MAX_TIERS) {
    fError("failed to mount %s to FS since invalid level %d", pCfg->dir, pCfg->level);
    terrno = TSDB_CODE_FS_INVLD_CFG;
    return -1;
  }

  if (pCfg->primary) {
    if (pCfg->level != 0) {
      fError("failed to mount %s to FS since disk is primary but level %d not 0", pCfg->dir, pCfg->level);
      terrno = TSDB_CODE_FS_INVLD_CFG;
      return -1;
    }

    if (TFS_PRIMARY_DISK() != NULL) {
      fError("failed to mount %s to FS since duplicate primary mount", pCfg->dir);
      terrno = TSDB_CODE_FS_DUP_PRIMARY;
      return -1;
    }
  }

  if (tfsFormatDir(pCfg->dir, dirName) < 0) {
    fError("failed to mount %s to FS since invalid dir format", pCfg->dir);
    terrno = TSDB_CODE_FS_INVLD_CFG;
    return -1;
  }

  if (tfsGetDiskByName(dirName) != NULL) {
    fError("failed to mount %s to FS since duplicate mount", pCfg->dir);
    terrno = TSDB_CODE_FS_INVLD_CFG;
    return -1;
  }

  if (access(dirName, W_OK | R_OK | F_OK) != 0) {
    fError("failed to mount %s to FS since no R/W access rights", pCfg->dir);
    terrno = TSDB_CODE_FS_INVLD_CFG;
    return -1;
  }

  if (stat(dirName, &pstat) < 0) {
    fError("failed to mount %s to FS since %s", pCfg->dir, strerror(errno));
    terrno = TAOS_SYSTEM_ERROR(errno);
    return -1;
  }

  if (!S_ISDIR(pstat.st_mode)) {
    fError("failed to mount %s to FS since not a directory", pCfg->dir);
    terrno = TSDB_CODE_FS_INVLD_CFG;
    return -1;
  }

  strncpy(pCfg->dir, dirName, TSDB_FILENAME_LEN);

  return 0;
}

static int tfsFormatDir(char *idir, char *odir) {
  wordexp_t wep = {0};

  int code = wordexp(idir, &wep, 0);
  if (code != 0) {
    terrno = TAOS_SYSTEM_ERROR(code);
    return -1;
  }

  char tmp[PATH_MAX] = {0};
  if (realpath(wep.we_wordv[0], tmp) == NULL) {
    terrno = TAOS_SYSTEM_ERROR(errno);
    wordfree(&wep);
    return -1;
  }
  strcpy(odir, tmp);

  wordfree(&wep);
  return 0;

}

static int tfsCheck() {
  if (TFS_PRIMARY_DISK() == NULL) {
    fError("no primary disk is set");
    terrno = TSDB_CODE_FS_NO_PRIMARY_DISK;
    return -1;
  }

  for (int level = 0; level < TFS_NLEVEL(); level++) {
    if (TIER_NDISKS(TFS_TIER_AT(level)) == 0) {
      fError("no disk at level %d", level);
      terrno = TSDB_CODE_FS_NO_MOUNT_AT_TIER;
      return -1;
    }
  }

  return 0;
}

static SDisk *tfsGetDiskByID(SDiskID did) { return TFS_DISK_AT(did.level, did.id); }
static SDisk *tfsGetDiskByName(const char *dir) {
  SDiskID did;
  SDisk * pDisk = NULL;
  void *  pr = NULL;

  pr = taosHashGet(pfs->map, (void *)dir, strnlen(dir, TSDB_FILENAME_LEN));
  if (pr == NULL) return NULL;

  did = *(SDiskID *)pr;
  pDisk = tfsGetDiskByID(did);
  ASSERT(pDisk != NULL);

  return pDisk;
}

static int tfsOpendirImpl(TDIR *tdir) {
  SDisk *pDisk = NULL;
  char   adir[TMPNAME_LEN * 2] = "\0";

  if (tdir->dir != NULL) {
    closedir(tdir->dir);
    tdir->dir = NULL;
  }

  while (true) {
    pDisk = tfsNextDisk(&(tdir->iter));
    if (pDisk == NULL) return 0;

    tdir->level = DISK_LEVEL(pDisk);
    tdir->id = DISK_ID(pDisk);

    snprintf(adir, TMPNAME_LEN * 2, "%s/%s", DISK_DIR(pDisk), tdir->dirname);
    tdir->dir = opendir(adir);
    if (tdir->dir != NULL) break;
  }

  return 0;
}

static void tfsInitDiskIter(SDiskIter *pIter) { pIter->pDisk = TFS_DISK_AT(0, 0); }

static SDisk *tfsNextDisk(SDiskIter *pIter) {
  SDisk *pDisk = pIter->pDisk;

  if (pDisk == NULL) return NULL;

  int level = DISK_LEVEL(pDisk);
  int id = DISK_ID(pDisk);

  id++;
  if (id < TIER_NDISKS(TFS_TIER_AT(level))) {
    pIter->pDisk = TFS_DISK_AT(level, id);
    ASSERT(pIter->pDisk != NULL);
  } else {
    level++;
    id = 0;
    if (level < TFS_NLEVEL()) {
      pIter->pDisk = TFS_DISK_AT(level, id);
      ASSERT(pIter->pDisk != NULL);
    } else {
      pIter->pDisk = NULL;
    }
  }

  return pDisk;
}

// OTHER FUNCTIONS ===================================
void taosGetDisk() {
  const double unit = 1024 * 1024 * 1024;
  SysDiskSize  diskSize;
  SFSMeta      fsMeta;

  if (tscEmbedded) {
    tfsUpdateInfo(&fsMeta);
    tsTotalDataDirGB = (float)(fsMeta.tsize / unit);
    tsUsedDataDirGB = (float)(fsMeta.used / unit);
    tsAvailDataDirGB = (float)(fsMeta.avail / unit);
  }

  if (taosGetDiskSize(tsLogDir, &diskSize) == 0) {
    tsTotalLogDirGB = (float)(diskSize.tsize / unit);
    tsAvailLogDirGB = (float)(diskSize.avail / unit);
  }

  if (taosGetDiskSize(tsTempDir, &diskSize) == 0) {
    tsTotalTmpDirGB = (float)(diskSize.tsize / unit);
    tsAvailTmpDirectorySpace = (float)(diskSize.avail / unit);
  }
}
