Notes:

  *  Using 32-bit frame numbers (not 16-bit).

  *  The ZonefileHeader object is 26 bytes in size. Which means that the
     ZoneFileIndex will not be 8-byte aligned. Problem?

  *  The offsets in the ZoneFileIndex.byteOffsetZoneFrame[] array are
     relative to the offset in ZoneFileHeader.byteOffsetFrames. This is
     necessary as we may not know the offset of the start of the frame data
     until after the ZoneFileIndex structure is compressed.

/*
** 2018-02-10
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
*/

#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#ifndef SQLITE_OMIT_VIRTUALTABLE

#ifndef SQLITE_AMALGAMATION
typedef sqlite3_int64 i64;
typedef sqlite3_uint64 u64;
typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned long u32;
#define MIN(a,b) ((a)<(b) ? (a) : (b))

#if defined(SQLITE_COVERAGE_TEST) || defined(SQLITE_MUTATION_TEST)
# define ALWAYS(X)      (1)
# define NEVER(X)       (0)
#elif !defined(NDEBUG)
# define ALWAYS(X)      ((X)?1:(assert(0),0))
# define NEVER(X)       ((X)?(assert(0),1):0)
#else
# define ALWAYS(X)      (X)
# define NEVER(X)       (X)
#endif
#endif   /* SQLITE_AMALGAMATION */

#define ZONEFILE_MAGIC_NUMBER 0x464B3138

#define ZONEFILE_SZ_HEADER 26

#define ZONEFILE_DEFAULT_MAXAUTOFRAMESIZE (64*1024)
#define ZONEFILE_DEFAULT_ENCRYPTION       0
#define ZONEFILE_DEFAULT_COMPRESSION      0


#include <stdio.h>
#include <string.h>
#include <assert.h>

typedef struct ZonefileWrite ZonefileWrite;
struct ZonefileWrite {
  int compressionTypeIndexData;
  int compressionTypeContent;
  int encryptionType;
  int maxAutoFrameSize;
};

typedef struct ZonefileBuffer ZonefileBuffer;
struct ZonefileBuffer {
  u8 *a;
  int n;
  int nAlloc;
};

/*
** Set the error message contained in context ctx to the results of
** vprintf(zFmt, ...).
*/
static void zonefileCtxError(sqlite3_context *ctx, const char *zFmt, ...){
  char *zMsg = 0;
  va_list ap;
  va_start(ap, zFmt);
  zMsg = sqlite3_vmprintf(zFmt, ap);
  sqlite3_result_error(ctx, zMsg, -1);
  sqlite3_free(zMsg);
  va_end(ap);
}

static void zonefileTransferError(sqlite3_context *pCtx){
  sqlite3 *db = sqlite3_context_db_handle(pCtx);
  const char *zErr = sqlite3_errmsg(db);
  sqlite3_result_error(pCtx, zErr, -1);
}

static sqlite3_stmt *zonefilePrepare(
  sqlite3_context *pCtx,
  const char *zFmt,
  ...
){
  sqlite3_stmt *pRet = 0;
  va_list ap;
  char *zSql;
  va_start(ap, zFmt);
  zSql = sqlite3_vmprintf(zFmt, ap);
  if( zSql ){
    sqlite3 *db = sqlite3_context_db_handle(pCtx);
    int rc = sqlite3_prepare(db, zSql, -1, &pRet, 0);
    if( rc!=SQLITE_OK ){
      zonefileTransferError(pCtx);
    }
  }else{
    sqlite3_result_error_nomem(pCtx);
  }
  return pRet;
}

/*
** Return zero if the two SQL values passed as arguments are equal, or
** non-zero otherwise. Values with different types are considered unequal,
** even if they both contain the same numeric value (e.g. 2 and 2.0).
*/
static int zonefileCompareValue(sqlite3_value *p1, sqlite3_value *p2){
  int eType;
  assert( p1 );
  if( p2==0 ) return 1;
  eType = sqlite3_value_type(p1);
  if( sqlite3_value_type(p2)!=eType ) return 1;
  switch( eType ){
    case SQLITE_INTEGER:
      return sqlite3_value_int64(p1)==sqlite3_value_int64(p2);
    case SQLITE_FLOAT:
      return sqlite3_value_double(p1)==sqlite3_value_double(p2);
    case SQLITE_TEXT:
    case SQLITE_BLOB: {
      int n1 = sqlite3_value_bytes(p1);
      int n2 = sqlite3_value_bytes(p2);
      if( n1!=n2 ) return 1;
      return memcmp(sqlite3_value_blob(p1), sqlite3_value_blob(p2), n1);
    }
    default:
      assert( eType==SQLITE_NULL);
  }

  return 0;
}

int zonefileIsAutoFrame(sqlite3_value *pFrame){
  return (
      sqlite3_value_type(pFrame)==SQLITE_INTEGER 
   && sqlite3_value_int64(pFrame)==-1
  );
}

static int zonefileGetParams(
  sqlite3_context *pCtx,          /* Leave any error message here */
  const char *zJson,              /* JSON configuration parameter (or NULL) */
  ZonefileWrite *p                /* Populate this object before returning */
){
  memset(p, 0, sizeof(ZonefileWrite));
  p->maxAutoFrameSize = ZONEFILE_DEFAULT_MAXAUTOFRAMESIZE;
  return SQLITE_OK;
}

/*
** Check that there is room in buffer pBuf for at least nByte bytes more 
** data. If not, attempt to allocate more space. If the allocation attempt
** fails, leave an error message in context pCtx and return SQLITE_ERROR.
**
** If no error occurs, SQLITE_OK is returned.
*/
static int zonefileBufferGrow(
  sqlite3_context *pCtx, 
  ZonefileBuffer *pBuf, 
  int nByte
){
  int nReq = pBuf->n + nByte;
  if( nReq>pBuf->nAlloc ){
    u8 *aNew;
    int nNew = pBuf->nAlloc ? pBuf->nAlloc*2 : 128;
    while( nNew<nReq ) nNew = nNew*2;
    aNew = sqlite3_realloc(pBuf->a, nNew);
    if( aNew==0 ){
      sqlite3_result_error_nomem(pCtx);
      return SQLITE_ERROR;
    }
    pBuf->a = aNew;
    pBuf->nAlloc = nNew;
  }
  return SQLITE_OK;
}

static void zonefileBufferFree(ZonefileBuffer *pBuf){
  sqlite3_free(pBuf->a);
  memset(pBuf, 0, sizeof(ZonefileBuffer));
}

static void zonefilePut32(u8 *aBuf, u32 v){
  aBuf[0] = (v >> 24) & 0xFF;
  aBuf[1] = (v >> 16) & 0xFF;
  aBuf[2] = (v >>  8) & 0xFF;
  aBuf[3] = v & 0xFF;
}

static void zonefileAppend32(ZonefileBuffer *pBuf, u32 v){
  zonefilePut32(&pBuf->a[pBuf->n], v);
  pBuf->n += 4;
}

static void zonefileAppend64(ZonefileBuffer *pBuf, u64 v){
  zonefileAppend32(pBuf, v>>32);
  zonefileAppend32(pBuf, v & 0xFFFFFFFF);
}

static void zonefileAppendBlob(ZonefileBuffer *pBuf, const u8 *p, int n){
  memcpy(&pBuf->a[pBuf->n], p, n);
  pBuf->n += n;
}

static int zonefileWrite(FILE *pFd, const u8 *aBuf, int nBuf){
  size_t res = fwrite(aBuf, 1, nBuf, pFd);
  return res!=nBuf ? SQLITE_ERROR : SQLITE_OK;
}

/*
** Function:     zonefile_write(F,T[,J])
*/
static void zonefileWriteFunc(
  sqlite3_context *pCtx,       /* Context object */
  int objc,                       /* Number of SQL arguments */
  sqlite3_value **objv            /* Array of SQL arguments */
){
  const char *zFile = 0;          /* File to write to */
  const char *zTbl = 0;           /* Database object to read from */
  const char *zJson = 0;          /* JSON configuration parameters */
  ZonefileWrite sWrite;           /* Decoded JSON parameters */
  int nKey = 0;                   /* Number of keys in new zonefile */
  int nFrame = 0;                 /* Number of frames in new zonefile */
  int szFrame = 0;                /* Size of current frame */
  sqlite3_stmt *pStmt = 0;        /* SQL used to read data from source table */
  FILE *pFd = 0;
  int rc;
  sqlite3_value *pPrev = 0;

  ZonefileBuffer sFrameIdx = {0, 0, 0};
  ZonefileBuffer sKeyIdx = {0, 0, 0};
  ZonefileBuffer sFrames = {0, 0, 0};
  u8 aHdr[ZONEFILE_SZ_HEADER];    /* Space to assemble zonefile header */

  assert( objc==2 || objc==3 );
  zFile = (const char*)sqlite3_value_text(objv[0]);
  zTbl = (const char*)sqlite3_value_text(objv[1]);
  if( objc==3 ){
    zJson = (const char*)sqlite3_value_text(objv[2]);
  }
  if( zonefileGetParams(pCtx, zJson, &sWrite) ) return;

  /* Prepare the SQL statement used to read data from the source table. This
  ** also serves to verify the suitability of the source table schema. */
  pStmt = zonefilePrepare(pCtx, 
      "SELECT k, frame, v FROM %Q ORDER BY frame, idx, k", zTbl
  );
  if( pStmt==0 ) return;

  /* Open a file-handle used to write out the zonefile */ 
  pFd = fopen(zFile, "w");
  if( pFd==0 ){
    zonefileCtxError(pCtx, "error opening file \"%s\" (fopen())", zFile);
    sqlite3_finalize(pStmt);
    return;
  }

  while( SQLITE_ROW==sqlite3_step(pStmt) ){
    sqlite3_int64 k = sqlite3_column_int64(pStmt, 0);
    sqlite3_value *pFrame = sqlite3_column_value(pStmt, 1);
    int nBlob = sqlite3_column_bytes(pStmt, 2);
    const u8 *pBlob = (const u8*)sqlite3_column_blob(pStmt, 2);

    int bAuto = zonefileIsAutoFrame(pFrame);
    if( zonefileCompareValue(pFrame, pPrev) 
     || (bAuto && szFrame && (szFrame+nBlob)>sWrite.maxAutoFrameSize)
    ){
      /* Add new entry to sFrameIdx */
      szFrame = 0;
      if( zonefileBufferGrow(pCtx, &sFrameIdx, 4) ) goto zone_write_out;
      zonefileAppend32(&sFrameIdx, sFrames.n);
      sqlite3_value_free(pPrev);
      pPrev = sqlite3_value_dup(pFrame);
      if( pPrev==0 ){
        sqlite3_result_error_nomem(pCtx);
        goto zone_write_out;
      }
      nFrame++;
    }

    /* Add new entry to sKeyIdx */
    if( zonefileBufferGrow(pCtx, &sKeyIdx, 20) ) goto zone_write_out;
    zonefileAppend64(&sKeyIdx, k);
    zonefileAppend32(&sKeyIdx, nFrame-1);
    zonefileAppend32(&sKeyIdx, szFrame);
    zonefileAppend32(&sKeyIdx, nBlob);

    /* Add data for new entry to sFrames */
    if( zonefileBufferGrow(pCtx, &sFrames, nBlob) ) goto zone_write_out;
    zonefileAppendBlob(&sFrames, pBlob, nBlob);
    szFrame += nBlob;
    nKey++;
  }

  /* Create the zonefile header in the in-memory buffer */
  zonefilePut32(&aHdr[0], ZONEFILE_MAGIC_NUMBER);
  aHdr[4] = sWrite.compressionTypeIndexData;
  aHdr[5] = sWrite.compressionTypeContent;
  zonefilePut32(&aHdr[6], 0);     /* Compression dictionary byte offset */
  zonefilePut32(&aHdr[10], ZONEFILE_SZ_HEADER + sFrameIdx.n + sKeyIdx.n); 
  zonefilePut32(&aHdr[14], nFrame);
  zonefilePut32(&aHdr[18], nKey);
  aHdr[22] = sWrite.encryptionType;
  aHdr[23] = 0;                   /* Encryption key index */
  aHdr[24] = 0;                   /* extended header version */
  aHdr[25] = 0;                   /* extended header size */
  assert( ZONEFILE_SZ_HEADER==26 );

  rc = zonefileWrite(pFd, aHdr, ZONEFILE_SZ_HEADER);
  if( rc==SQLITE_OK ) rc = zonefileWrite(pFd, sFrameIdx.a, sFrameIdx.n);
  if( rc==SQLITE_OK ) rc = zonefileWrite(pFd, sKeyIdx.a, sKeyIdx.n);
  if( rc==SQLITE_OK ) rc = zonefileWrite(pFd, sFrames.a, sFrames.n);
  if( rc ){
    zonefileCtxError(pCtx, "error writing file \"%s\" (fwrite())", zFile);
    goto zone_write_out;
  }

  if( fclose(pFd) ){
    zonefileCtxError(pCtx, "error writing file \"%s\" (fclose())", zFile);
  }
  pFd = 0;

 zone_write_out:
  if( pFd ) fclose(pFd);
  sqlite3_finalize(pStmt);
  zonefileBufferFree(&sFrameIdx);
  zonefileBufferFree(&sKeyIdx);
  zonefileBufferFree(&sFrames);
}

/*
** Register the "zonefile" extensions.
*/
static int zonefileRegister(sqlite3 *db){
  struct Func {
    const char *z;
    int n;
    void (*x)(sqlite3_context*,int,sqlite3_value**);
  } aFunc[] = {
    { "zonefile_write", 2, zonefileWriteFunc },
    { "zonefile_write", 3, zonefileWriteFunc },
  };
  int rc = SQLITE_OK;
  int i;

  for(i=0; rc==SQLITE_OK && i<sizeof(aFunc)/sizeof(aFunc[0]); i++){
    struct Func *p = &aFunc[i];
    rc = sqlite3_create_function(db, p->z, p->n, SQLITE_ANY, 0, p->x, 0, 0);
  }

  return rc;
}

#else         /* SQLITE_OMIT_VIRTUALTABLE */
# define zonefileRegister(x) SQLITE_OK
#endif

#ifdef _WIN32
__declspec(dllexport)
#endif
int sqlite3_zonefile_init(
  sqlite3 *db, 
  char **pzErrMsg, 
  const sqlite3_api_routines *pApi
){
  SQLITE_EXTENSION_INIT2(pApi);
  (void)pzErrMsg;  /* Unused parameter */
  return zonefileRegister(db);
}

# 2018 Feb 11
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# The focus of this file is testing the zonefile extension.
#

if {![info exists testdir]} {
  set testdir [file join [file dirname [info script]] .. .. test]
}
source [file join $testdir tester.tcl]
set testprefix zonefile1
load_static_extension db zonefile


do_execsql_test 1.0 {
  CREATE TABLE zz(k INTEGER PRIMARY KEY, frame INTEGER, idx INTEGER, v BLOB);
  INSERT INTO zz VALUES(1, -1, -1, randomblob(100));
  INSERT INTO zz VALUES(2, -1, -1, randomblob(100));
  INSERT INTO zz VALUES(3, -1, -1, randomblob(100));
}

do_execsql_test 1.1 {
  SELECT zonefile_write('test.zonefile', 'zz');
}

finish_test

  $(TOP)/ext/misc/series.c \
  $(TOP)/ext/misc/spellfix.c \
  $(TOP)/ext/misc/totype.c \
  $(TOP)/ext/misc/unionvtab.c \
  $(TOP)/ext/misc/wholenumber.c \
  $(TOP)/ext/misc/vfslog.c \
  $(TOP)/ext/misc/zipfile.c \

  $(TOP)/ext/fts5/fts5_tcl.c \
  $(TOP)/ext/fts5/fts5_test_mi.c \
  $(TOP)/ext/fts5/fts5_test_tok.c


#TESTSRC += $(TOP)/ext/fts2/fts2_tokenizer.c
#TESTSRC += $(TOP)/ext/fts3/fts3_tokenizer.c

  $(TOP)/ext/misc/series.c \
  $(TOP)/ext/misc/spellfix.c \
  $(TOP)/ext/misc/totype.c \
  $(TOP)/ext/misc/unionvtab.c \
  $(TOP)/ext/misc/wholenumber.c \
  $(TOP)/ext/misc/vfslog.c \
  $(TOP)/ext/misc/zipfile.c \
  $(TOP)/ext/zonefile/zonefile.c \
  $(TOP)/ext/fts5/fts5_tcl.c \
  $(TOP)/ext/fts5/fts5_test_mi.c \
  $(TOP)/ext/fts5/fts5_test_tok.c


#TESTSRC += $(TOP)/ext/fts2/fts2_tokenizer.c
#TESTSRC += $(TOP)/ext/fts3/fts3_tokenizer.c

  extern int sqlite3_spellfix_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_totype_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_wholenumber_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_unionvtab_init(sqlite3*,char**,const sqlite3_api_routines*);
#ifdef SQLITE_HAVE_ZLIB
  extern int sqlite3_zipfile_init(sqlite3*,char**,const sqlite3_api_routines*);
#endif

  static const struct {
    const char *zExtName;
    int (*pInit)(sqlite3*,char**,const sqlite3_api_routines*);
  } aExtension[] = {
    { "amatch",                sqlite3_amatch_init               },
    { "carray",                sqlite3_carray_init               },
    { "closure",               sqlite3_closure_init              },
................................................................................
    { "spellfix",              sqlite3_spellfix_init             },
    { "totype",                sqlite3_totype_init               },
    { "unionvtab",             sqlite3_unionvtab_init            },
    { "wholenumber",           sqlite3_wholenumber_init          },
#ifdef SQLITE_HAVE_ZLIB
    { "zipfile",               sqlite3_zipfile_init              },
#endif

  };
  sqlite3 *db;
  const char *zName;
  int i, j, rc;
  char *zErrMsg = 0;
  if( objc<3 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB NAME ...");

  extern int sqlite3_spellfix_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_totype_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_wholenumber_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_unionvtab_init(sqlite3*,char**,const sqlite3_api_routines*);
#ifdef SQLITE_HAVE_ZLIB
  extern int sqlite3_zipfile_init(sqlite3*,char**,const sqlite3_api_routines*);
#endif
  extern int sqlite3_zonefile_init(sqlite3*,char**,const sqlite3_api_routines*);
  static const struct {
    const char *zExtName;
    int (*pInit)(sqlite3*,char**,const sqlite3_api_routines*);
  } aExtension[] = {
    { "amatch",                sqlite3_amatch_init               },
    { "carray",                sqlite3_carray_init               },
    { "closure",               sqlite3_closure_init              },
................................................................................
    { "spellfix",              sqlite3_spellfix_init             },
    { "totype",                sqlite3_totype_init               },
    { "unionvtab",             sqlite3_unionvtab_init            },
    { "wholenumber",           sqlite3_wholenumber_init          },
#ifdef SQLITE_HAVE_ZLIB
    { "zipfile",               sqlite3_zipfile_init              },
#endif
    { "zonefile",              sqlite3_zonefile_init             },
  };
  sqlite3 *db;
  const char *zName;
  int i, j, rc;
  char *zErrMsg = 0;
  if( objc<3 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB NAME ...");