/*
 * 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/>.
 */

#ifndef __INDEX_FST_COUNTING_WRITER_H__
#define __INDEX_FST_COUNTING_WRITER_H__

#ifdef __cplusplus
extern "C" {
#endif

#include "tfile.h"

#define DefaultMem 1024 * 1024

static char tmpFile[] = "./index";
typedef enum WriterType { TMemory, TFile } WriterType;

typedef struct WriterCtx {
  int (*write)(struct WriterCtx* ctx, uint8_t* buf, int len);
  int (*read)(struct WriterCtx* ctx, uint8_t* buf, int len);
  int (*flush)(struct WriterCtx* ctx);
  int (*readFrom)(struct WriterCtx* ctx, uint8_t* buf, int len, int32_t offset);
  WriterType type;
  union {
    struct {
      int  fd;
      bool readOnly;
    } file;
    struct {
      int32_t capa;
      char*   buf;
    } mem;
  };
  int32_t offset;
  int32_t limit;
} WriterCtx;

static int writeCtxDoWrite(WriterCtx* ctx, uint8_t* buf, int len);
static int writeCtxDoRead(WriterCtx* ctx, uint8_t* buf, int len);
static int writeCtxDoReadFrom(WriterCtx* ctx, uint8_t* buf, int len, int32_t offset);
static int writeCtxDoFlush(WriterCtx* ctx);

WriterCtx* writerCtxCreate(WriterType type, const char* path, bool readOnly, int32_t capacity);
void       writerCtxDestroy(WriterCtx* w);

typedef uint32_t CheckSummer;

typedef struct FstCountingWriter {
  void*       wrt;  // wrap any writer that counts and checksum bytes written
  uint64_t    count;
  CheckSummer summer;
} FstCountingWriter;

int fstCountingWriterWrite(FstCountingWriter* write, uint8_t* buf, uint32_t len);

int fstCountingWriterRead(FstCountingWriter* write, uint8_t* buf, uint32_t len);

int fstCountingWriterFlush(FstCountingWriter* write);

uint32_t fstCountingWriterMaskedCheckSum(FstCountingWriter* write);

FstCountingWriter* fstCountingWriterCreate(void* wtr);
void               fstCountingWriterDestroy(FstCountingWriter* w);

void    fstCountingWriterPackUintIn(FstCountingWriter* writer, uint64_t n, uint8_t nBytes);
uint8_t fstCountingWriterPackUint(FstCountingWriter* writer, uint64_t n);

#define FST_WRITER_COUNT(writer) (writer->count)
#define FST_WRITER_INTER_WRITER(writer) (writer->wtr)
#define FST_WRITE_CHECK_SUMMER(writer) (writer->summer)

#ifdef __cplusplus
}
#endif

#endif