/*
** 2014 Dec 01
**
** 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.
**
******************************************************************************
**
*/

#ifdef SQLITE_TEST

#include "fts5.h"
#include <tcl.h>
#include <string.h>
#include <assert.h>

/*************************************************************************
** This is a copy of the first part of the SqliteDb structure in 
** tclsqlite.c.  We need it here so that the get_sqlite_pointer routine
** can extract the sqlite3* pointer from an existing Tcl SQLite
** connection.
*/
struct SqliteDb {
  sqlite3 *db;
};

/*
** Decode a pointer to an sqlite3 object.
*/
static int f5tDbPointer(Tcl_Interp *interp, Tcl_Obj *pObj, sqlite3 **ppDb){
  struct SqliteDb *p;
  Tcl_CmdInfo cmdInfo;
  char *z = Tcl_GetString(pObj);
  if( Tcl_GetCommandInfo(interp, z, &cmdInfo) ){
    p = (struct SqliteDb*)cmdInfo.objClientData;
    *ppDb = p->db;
    return TCL_OK;
  }
  return TCL_ERROR;
}

/* End of code that accesses the SqliteDb struct.
**************************************************************************/

static int f5tDbAndApi(
  Tcl_Interp *interp, 
  Tcl_Obj *pObj, 
  sqlite3 **ppDb, 
  fts5_api **ppApi
){
  sqlite3 *db = 0;
  int rc = f5tDbPointer(interp, pObj, &db);
  if( rc!=TCL_OK ){
    return TCL_ERROR;
  }else{
    sqlite3_stmt *pStmt = 0;
    fts5_api *pApi = 0;

    rc = sqlite3_prepare_v2(db, "SELECT fts5()", -1, &pStmt, 0);
    if( rc!=SQLITE_OK ){
      Tcl_AppendResult(interp, "error: ", sqlite3_errmsg(db), 0);
      return TCL_ERROR;
    }

    if( SQLITE_ROW==sqlite3_step(pStmt) ){
      const void *pPtr = sqlite3_column_blob(pStmt, 0);
      memcpy((void*)&pApi, pPtr, sizeof(pApi));
    }

    if( sqlite3_finalize(pStmt)!=SQLITE_OK ){
      Tcl_AppendResult(interp, "error: ", sqlite3_errmsg(db), 0);
      return TCL_ERROR;
    }

    *ppDb = db;
    *ppApi = pApi;
  }

  return TCL_OK;
}

typedef struct F5tFunction F5tFunction;
struct F5tFunction {
  Tcl_Interp *interp;
  Tcl_Obj *pScript;
};

typedef struct F5tApi F5tApi;
struct F5tApi {
  const Fts5ExtensionApi *pApi;
  Fts5Context *pFts;
};

/*
** An object of this type is used with the xSetAuxdata() and xGetAuxdata()
** API test wrappers. The tcl interface allows a single tcl value to be 
** saved using xSetAuxdata(). Instead of simply storing a pointer to the
** tcl object, the code in this file wraps it in an sqlite3_malloc'd 
** instance of the following struct so that if the destructor is not 
** correctly invoked it will be reported as an SQLite memory leak.
*/
typedef struct F5tAuxData F5tAuxData;
struct F5tAuxData {
  Tcl_Obj *pObj;
};

static int xTokenizeCb(
  void *pCtx, 
  const char *zToken, int nToken, 
  int iStart, int iEnd, int iPos
){
  F5tFunction *p = (F5tFunction*)pCtx;
  Tcl_Obj *pEval = Tcl_DuplicateObj(p->pScript);
  int rc;

  Tcl_IncrRefCount(pEval);
  Tcl_ListObjAppendElement(p->interp, pEval, Tcl_NewStringObj(zToken, nToken));
  Tcl_ListObjAppendElement(p->interp, pEval, Tcl_NewIntObj(iStart));
  Tcl_ListObjAppendElement(p->interp, pEval, Tcl_NewIntObj(iEnd));
  Tcl_ListObjAppendElement(p->interp, pEval, Tcl_NewIntObj(iPos));

  rc = Tcl_EvalObjEx(p->interp, pEval, 0);
  Tcl_DecrRefCount(pEval);

  return rc;
}

static int xF5tApi(void*, Tcl_Interp*, int, Tcl_Obj *CONST []);

static int xQueryPhraseCb(
  const Fts5ExtensionApi *pApi, 
  Fts5Context *pFts, 
  void *pCtx
){
  F5tFunction *p = (F5tFunction*)pCtx;
  static sqlite3_int64 iCmd = 0;
  Tcl_Obj *pEval;
  int rc;

  char zCmd[64];
  F5tApi sApi;

  sApi.pApi = pApi;
  sApi.pFts = pFts;
  sprintf(zCmd, "f5t_2_%lld", iCmd++);
  Tcl_CreateObjCommand(p->interp, zCmd, xF5tApi, &sApi, 0);

  pEval = Tcl_DuplicateObj(p->pScript);
  Tcl_IncrRefCount(pEval);
  Tcl_ListObjAppendElement(p->interp, pEval, Tcl_NewStringObj(zCmd, -1));
  rc = Tcl_EvalObjEx(p->interp, pEval, 0);
  Tcl_DecrRefCount(pEval);
  Tcl_DeleteCommand(p->interp, zCmd);

  return rc;
}

static void xSetAuxdataDestructor(void *p){
  F5tAuxData *pData = (F5tAuxData*)p;
  Tcl_DecrRefCount(pData->pObj);
  sqlite3_free(pData);
}

/*
**      api sub-command...
**
** Description...
*/
static int xF5tApi(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  struct Sub {
    const char *zName;
    int nArg;
    const char *zMsg;
  } aSub[] = {
    { "xColumnCount",      0, "" },
    { "xRowCount",         0, "" },
    { "xColumnTotalSize",  1, "COL" },
    { "xTokenize",         2, "TEXT SCRIPT" },
    { "xPhraseCount",      0, "" },
    { "xPhraseSize",       1, "PHRASE" },
    { "xInstCount",        0, "" },
    { "xInst",             1, "IDX" },
    { "xRowid",            0, "" },
    { "xColumnText",       1, "COL" },
    { "xColumnSize",       1, "COL" },
    { "xQueryPhrase",      2, "PHRASE SCRIPT" },
    { "xSetAuxdata",       1, "VALUE" },
    { "xGetAuxdata",       1, "CLEAR" },
    { 0, 0, 0}
  };

  int rc;
  int iSub = 0;
  F5tApi *p = (F5tApi*)clientData;

  if( objc<2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "SUB-COMMAND");
    return TCL_ERROR;
  }

  rc = Tcl_GetIndexFromObjStruct(
      interp, objv[1], aSub, sizeof(aSub[0]), "SUB-COMMAND", 0, &iSub
  );
  if( rc!=TCL_OK ) return rc;
  if( aSub[iSub].nArg!=objc-2 ){
    Tcl_WrongNumArgs(interp, 1, objv, aSub[iSub].zMsg);
    return TCL_ERROR;
  }

#define CASE(i,str) case i: assert( strcmp(aSub[i].zName, str)==0 );
  switch( iSub ){
    CASE(0, "xColumnCount") {
      int nCol;
      nCol = p->pApi->xColumnCount(p->pFts);
      if( rc==SQLITE_OK ){
        Tcl_SetObjResult(interp, Tcl_NewIntObj(nCol));
      }
      break;
    }
    CASE(1, "xRowCount") {
      sqlite3_int64 nRow;
      rc = p->pApi->xRowCount(p->pFts, &nRow);
      if( rc==SQLITE_OK ){
        Tcl_SetObjResult(interp, Tcl_NewWideIntObj(nRow));
      }
      break;
    }
    CASE(2, "xColumnTotalSize") {
      int iCol;
      sqlite3_int64 nSize;
      if( Tcl_GetIntFromObj(interp, objv[2], &iCol) ) return TCL_ERROR;
      rc = p->pApi->xColumnTotalSize(p->pFts, iCol, &nSize);
      if( rc==SQLITE_OK ){
        Tcl_SetObjResult(interp, Tcl_NewWideIntObj(nSize));
      }
      break;
    }
    CASE(3, "xTokenize") {
      int nText;
      char *zText = Tcl_GetStringFromObj(objv[2], &nText);
      F5tFunction ctx;
      ctx.interp = interp;
      ctx.pScript = objv[3];
      rc = p->pApi->xTokenize(p->pFts, zText, nText, &ctx, xTokenizeCb);
      if( rc==SQLITE_OK ){
        Tcl_ResetResult(interp);
      }
      return rc;
    }
    CASE(4, "xPhraseCount") {
      int nPhrase;
      nPhrase = p->pApi->xPhraseCount(p->pFts);
      if( rc==SQLITE_OK ){
        Tcl_SetObjResult(interp, Tcl_NewIntObj(nPhrase));
      }
      break;
    }
    CASE(5, "xPhraseSize") {
      int iPhrase;
      int sz;
      if( Tcl_GetIntFromObj(interp, objv[2], &iPhrase) ){
        return TCL_ERROR;
      }
      sz = p->pApi->xPhraseSize(p->pFts, iPhrase);
      if( rc==SQLITE_OK ){
        Tcl_SetObjResult(interp, Tcl_NewIntObj(sz));
      }
      break;
    }
    CASE(6, "xInstCount") {
      int nInst;
      rc = p->pApi->xInstCount(p->pFts, &nInst);
      if( rc==SQLITE_OK ){
        Tcl_SetObjResult(interp, Tcl_NewIntObj(nInst));
      }
      break;
    }
    CASE(7, "xInst") {
      int iIdx, ip, ic, io;
      if( Tcl_GetIntFromObj(interp, objv[2], &iIdx) ){
        return TCL_ERROR;
      }
      rc = p->pApi->xInst(p->pFts, iIdx, &ip, &ic, &io);
      if( rc==SQLITE_OK ){
        Tcl_Obj *pList = Tcl_NewObj();
        Tcl_ListObjAppendElement(interp, pList, Tcl_NewIntObj(ip));
        Tcl_ListObjAppendElement(interp, pList, Tcl_NewIntObj(ic));
        Tcl_ListObjAppendElement(interp, pList, Tcl_NewIntObj(io));
        Tcl_SetObjResult(interp, pList);
      }
      break;
    }
    CASE(8, "xRowid") {
      sqlite3_int64 iRowid = p->pApi->xRowid(p->pFts);
      Tcl_SetObjResult(interp, Tcl_NewWideIntObj(iRowid));
      break;
    }
    CASE(9, "xColumnText") {
      const char *z = 0;
      int n = 0;
      int iCol;
      if( Tcl_GetIntFromObj(interp, objv[2], &iCol) ){
        return TCL_ERROR;
      }
      rc = p->pApi->xColumnText(p->pFts, iCol, &z, &n);
      if( rc==SQLITE_OK ){
        Tcl_SetObjResult(interp, Tcl_NewStringObj(z, n));
      }
      break;
    }
    CASE(10, "xColumnSize") {
      int n = 0;
      int iCol;
      if( Tcl_GetIntFromObj(interp, objv[2], &iCol) ){
        return TCL_ERROR;
      }
      rc = p->pApi->xColumnSize(p->pFts, iCol, &n);
      if( rc==SQLITE_OK ){
        Tcl_SetObjResult(interp, Tcl_NewIntObj(n));
      }
      break;
    }
    CASE(11, "xQueryPhrase") {
      int iPhrase;
      F5tFunction ctx;
      if( Tcl_GetIntFromObj(interp, objv[2], &iPhrase) ){
        return TCL_ERROR;
      }
      ctx.interp = interp;
      ctx.pScript = objv[3];
      rc = p->pApi->xQueryPhrase(p->pFts, iPhrase, &ctx, xQueryPhraseCb);
      if( rc==SQLITE_OK ){
        Tcl_ResetResult(interp);
      }
      break;
    }
    CASE(12, "xSetAuxdata") {
      F5tAuxData *pData = (F5tAuxData*)sqlite3_malloc(sizeof(F5tAuxData));
      if( pData==0 ){
        Tcl_AppendResult(interp, "out of memory", 0);
        return TCL_ERROR;
      }
      pData->pObj = objv[2];
      Tcl_IncrRefCount(pData->pObj);
      rc = p->pApi->xSetAuxdata(p->pFts, pData, xSetAuxdataDestructor);
      break;
    }
    CASE(13, "xGetAuxdata") {
      F5tAuxData *pData;
      int bClear;
      if( Tcl_GetBooleanFromObj(interp, objv[2], &bClear) ){
        return TCL_ERROR;
      }
      pData = (F5tAuxData*)p->pApi->xGetAuxdata(p->pFts, bClear);
      if( pData==0 ){
        Tcl_ResetResult(interp);
      }else{
        Tcl_SetObjResult(interp, pData->pObj);
        if( bClear ){
          xSetAuxdataDestructor((void*)pData);
        }
      }
      break;
    }

    default: 
      assert( 0 );
      break;
  }
#undef CASE

  if( rc!=SQLITE_OK ){
    Tcl_AppendResult(interp, "error in api call", 0);
    return TCL_ERROR;
  }

  return TCL_OK;
}

static void xF5tFunction(
  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
  Fts5Context *pFts,              /* First arg to pass to pApi functions */
  sqlite3_context *pCtx,          /* Context for returning result/error */
  int nVal,                       /* Number of values in apVal[] array */
  sqlite3_value **apVal           /* Array of trailing arguments */
){
  F5tFunction *p = (F5tFunction*)pApi->xUserData(pFts);
  Tcl_Obj *pEval;                 /* Script to evaluate */
  int i;
  int rc;

  static sqlite3_int64 iCmd = 0;
  char zCmd[64];
  F5tApi sApi;
  sApi.pApi = pApi;
  sApi.pFts = pFts;

  sprintf(zCmd, "f5t_%lld", iCmd++);
  Tcl_CreateObjCommand(p->interp, zCmd, xF5tApi, &sApi, 0);
  pEval = Tcl_DuplicateObj(p->pScript);
  Tcl_IncrRefCount(pEval);
  Tcl_ListObjAppendElement(p->interp, pEval, Tcl_NewStringObj(zCmd, -1));

  for(i=0; i<nVal; i++){
    Tcl_Obj *pObj = 0;
    switch( sqlite3_value_type(apVal[i]) ){
      case SQLITE_TEXT:
        pObj = Tcl_NewStringObj((const char*)sqlite3_value_text(apVal[i]), -1);
        break;
      case SQLITE_BLOB:
        pObj = Tcl_NewByteArrayObj(
            sqlite3_value_blob(apVal[i]), sqlite3_value_bytes(apVal[i])
        );
        break;
      case SQLITE_INTEGER:
        pObj = Tcl_NewWideIntObj(sqlite3_value_int64(apVal[i]));
        break;
      case SQLITE_FLOAT:
        pObj = Tcl_NewDoubleObj(sqlite3_value_double(apVal[i]));
        break;
      default:
        pObj = Tcl_NewObj();
        break;
    }
    Tcl_ListObjAppendElement(p->interp, pEval, pObj);
  }

  rc = Tcl_EvalObjEx(p->interp, pEval, TCL_GLOBAL_ONLY);
  Tcl_DecrRefCount(pEval);
  Tcl_DeleteCommand(p->interp, zCmd);

  if( rc!=TCL_OK ){
    sqlite3_result_error(pCtx, Tcl_GetStringResult(p->interp), -1);
  }else{
    Tcl_Obj *pVar = Tcl_GetObjResult(p->interp);
    int n;
    const char *zType = (pVar->typePtr ? pVar->typePtr->name : "");
    char c = zType[0];
    if( c=='b' && strcmp(zType,"bytearray")==0 && pVar->bytes==0 ){
      /* Only return a BLOB type if the Tcl variable is a bytearray and
      ** has no string representation. */
      unsigned char *data = Tcl_GetByteArrayFromObj(pVar, &n);
      sqlite3_result_blob(pCtx, data, n, SQLITE_TRANSIENT);
    }else if( c=='b' && strcmp(zType,"boolean")==0 ){
      Tcl_GetIntFromObj(0, pVar, &n);
      sqlite3_result_int(pCtx, n);
    }else if( c=='d' && strcmp(zType,"double")==0 ){
      double r;
      Tcl_GetDoubleFromObj(0, pVar, &r);
      sqlite3_result_double(pCtx, r);
    }else if( (c=='w' && strcmp(zType,"wideInt")==0) ||
          (c=='i' && strcmp(zType,"int")==0) ){
      Tcl_WideInt v;
      Tcl_GetWideIntFromObj(0, pVar, &v);
      sqlite3_result_int64(pCtx, v);
    }else{
      unsigned char *data = (unsigned char *)Tcl_GetStringFromObj(pVar, &n);
      sqlite3_result_text(pCtx, (char *)data, n, SQLITE_TRANSIENT);
    }
  }
}

static void xF5tDestroy(void *pCtx){
  F5tFunction *p = (F5tFunction*)pCtx;
  Tcl_DecrRefCount(p->pScript);
  ckfree(p);
}

/*
**      sqlite3_fts5_create_function DB NAME SCRIPT
**
** Description...
*/
static int f5tCreateFunction(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  char *zName;
  Tcl_Obj *pScript;
  sqlite3 *db = 0;
  fts5_api *pApi = 0;
  F5tFunction *pCtx = 0;
  int rc;

  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB NAME SCRIPT");
    return TCL_ERROR;
  }
  if( f5tDbAndApi(interp, objv[1], &db, &pApi) ) return TCL_ERROR;

  zName = Tcl_GetString(objv[2]);
  pScript = objv[3];
  pCtx = (F5tFunction*)ckalloc(sizeof(F5tFunction));
  pCtx->interp = interp;
  pCtx->pScript = pScript;
  Tcl_IncrRefCount(pScript);

  rc = pApi->xCreateFunction(
      pApi, zName, (void*)pCtx, xF5tFunction, xF5tDestroy
  );
  if( rc!=SQLITE_OK ){
    Tcl_AppendResult(interp, "error: ", sqlite3_errmsg(db), 0);
    return TCL_ERROR;
  }

  return TCL_OK;
}

static int xTokenizeCb2(
  void *pCtx, 
  const char *zToken, int nToken, 
  int iStart, int iEnd, int iPos
){
  Tcl_Obj *pRet = (Tcl_Obj*)pCtx;
  Tcl_ListObjAppendElement(0, pRet, Tcl_NewStringObj(zToken, nToken));
  Tcl_ListObjAppendElement(0, pRet, Tcl_NewIntObj(iStart));
  Tcl_ListObjAppendElement(0, pRet, Tcl_NewIntObj(iEnd));
  Tcl_ListObjAppendElement(0, pRet, Tcl_NewIntObj(iPos));
  return SQLITE_OK;
}


/*
**      sqlite3_fts5_tokenize DB TOKENIZER TEXT
**
** Description...
*/
static int f5tTokenize(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  char *zName;
  char *zText;
  int nText;
  sqlite3 *db = 0;
  fts5_api *pApi = 0;
  Fts5Tokenizer *pTok = 0;
  fts5_tokenizer tokenizer;
  Tcl_Obj *pRet = 0;
  void *pUserdata;
  int rc;

  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB NAME TEXT");
    return TCL_ERROR;
  }
  if( f5tDbAndApi(interp, objv[1], &db, &pApi) ) return TCL_ERROR;
  zName = Tcl_GetString(objv[2]);
  zText = Tcl_GetStringFromObj(objv[3], &nText);

  rc = pApi->xFindTokenizer(pApi, zName, &pUserdata, &tokenizer);
  if( rc!=SQLITE_OK ){
    Tcl_AppendResult(interp, "no such tokenizer: ", zName, 0);
    return TCL_ERROR;
  }

  rc = tokenizer.xCreate(pUserdata, 0, 0, &pTok);
  if( rc!=SQLITE_OK ){
    Tcl_AppendResult(interp, "error in tokenizer.xCreate()", 0);
    return TCL_ERROR;
  }

  pRet = Tcl_NewObj();
  Tcl_IncrRefCount(pRet);
  rc = tokenizer.xTokenize(pTok, pRet, zText, nText, xTokenizeCb2);
  tokenizer.xDelete(pTok);
  if( rc!=SQLITE_OK ){
    Tcl_AppendResult(interp, "error in tokenizer.xTokenize()", 0);
    Tcl_DecrRefCount(pRet);
    return TCL_ERROR;
  }


  Tcl_SetObjResult(interp, pRet);
  Tcl_DecrRefCount(pRet);
  return TCL_OK;
}

/*************************************************************************
** Start of tokenizer wrapper.
*/

typedef struct F5tTokenizerContext F5tTokenizerContext;
typedef struct F5tTokenizerCb F5tTokenizerCb;
typedef struct F5tTokenizerModule F5tTokenizerModule;
typedef struct F5tTokenizerModule F5tTokenizerInstance;

struct F5tTokenizerContext {
  void *pCtx;
  int (*xToken)(void*, const char*, int, int, int, int);
};

struct F5tTokenizerModule {
  Tcl_Interp *interp;
  Tcl_Obj *pScript;
  F5tTokenizerContext *pContext;
};

static int f5tTokenizerCreate(
  void *pCtx, 
  const char **azArg, 
  int nArg, 
  Fts5Tokenizer **ppOut
){
  F5tTokenizerModule *pMod = (F5tTokenizerModule*)pCtx;
  Tcl_Obj *pEval;
  int rc = TCL_OK;
  int i;

  pEval = Tcl_DuplicateObj(pMod->pScript);
  Tcl_IncrRefCount(pEval);
  for(i=0; rc==TCL_OK && i<nArg; i++){
    Tcl_Obj *pObj = Tcl_NewStringObj(azArg[i], -1);
    rc = Tcl_ListObjAppendElement(pMod->interp, pEval, pObj);
  }

  if( rc==TCL_OK ){
    rc = Tcl_EvalObjEx(pMod->interp, pEval, TCL_GLOBAL_ONLY);
  }
  Tcl_DecrRefCount(pEval);

  if( rc==TCL_OK ){
    F5tTokenizerInstance *pInst = ckalloc(sizeof(F5tTokenizerInstance));
    memset(pInst, 0, sizeof(F5tTokenizerInstance));
    pInst->interp = pMod->interp;
    pInst->pScript = Tcl_GetObjResult(pMod->interp);
    pInst->pContext = pMod->pContext;
    Tcl_IncrRefCount(pInst->pScript);
    *ppOut = (Fts5Tokenizer*)pInst;
  }

  return rc;
}


static void f5tTokenizerDelete(Fts5Tokenizer *p){
  F5tTokenizerInstance *pInst = (F5tTokenizerInstance*)p;
  Tcl_DecrRefCount(pInst->pScript);
  ckfree(pInst);
}

static int f5tTokenizerTokenize(
  Fts5Tokenizer *p, 
  void *pCtx,
  const char *pText, int nText, 
  int (*xToken)(void*, const char*, int, int, int, int)
){
  F5tTokenizerInstance *pInst = (F5tTokenizerInstance*)p;
  void *pOldCtx;
  int (*xOldToken)(void*, const char*, int, int, int, int);
  Tcl_Obj *pEval;
  int rc;

  pOldCtx = pInst->pContext->pCtx;
  xOldToken = pInst->pContext->xToken;

  pEval = Tcl_DuplicateObj(pInst->pScript);
  Tcl_IncrRefCount(pEval);
  rc = Tcl_ListObjAppendElement(
      pInst->interp, pEval, Tcl_NewStringObj(pText, nText)
  );
  if( rc==TCL_OK ){
    rc = Tcl_EvalObjEx(pInst->interp, pEval, TCL_GLOBAL_ONLY);
  }
  Tcl_DecrRefCount(pEval);

  pInst->pContext->pCtx = pOldCtx;
  pInst->pContext->xToken = xOldToken;
  return rc;
}

extern const char *sqlite3ErrName(int);

/*
** sqlite3_fts5_token TEXT START END POS
*/
static int f5tTokenizerReturn(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  F5tTokenizerContext *p = (F5tTokenizerContext*)clientData;
  int iStart;
  int iEnd;
  int iPos;
  int nToken;
  char *zToken;
  int rc;

  assert( p );
  if( objc!=5 ){
    Tcl_WrongNumArgs(interp, 1, objv, "TEXT START END POS");
    return TCL_ERROR;
  }
  if( p->xToken==0 ){
    Tcl_AppendResult(interp, 
        "sqlite3_fts5_token may only be used by tokenizer callback", 0
    );
    return TCL_ERROR;
  }

  zToken = Tcl_GetStringFromObj(objv[1], &nToken);
  if( Tcl_GetIntFromObj(interp, objv[2], &iStart) 
   || Tcl_GetIntFromObj(interp, objv[3], &iEnd) 
   || Tcl_GetIntFromObj(interp, objv[4], &iPos) 
  ){
    return TCL_ERROR;
  }

  rc = p->xToken(p->pCtx, zToken, nToken, iStart, iEnd, iPos);
  Tcl_SetResult(interp, (char*)sqlite3ErrName(rc), TCL_VOLATILE);
  return TCL_OK;
}

static void f5tDelTokenizer(void *pCtx){
  F5tTokenizerModule *pMod = (F5tTokenizerModule*)pCtx;
  Tcl_DecrRefCount(pMod->pScript);
  ckfree(pMod);
}

/*
**      sqlite3_fts5_create_tokenizer DB NAME SCRIPT
**
** Register a tokenizer named NAME implemented by script SCRIPT. When
** a tokenizer instance is created (fts5_tokenizer.xCreate), any tokenizer
** arguments are appended to SCRIPT and the result executed.
**
** The value returned by (SCRIPT + args) is itself a tcl script. This 
** script - call it SCRIPT2 - is executed to tokenize text using the
** tokenizer instance "returned" by SCRIPT. Specifically, to tokenize
** text SCRIPT2 is invoked with a single argument appended to it - the
** text to tokenize.
**
** SCRIPT2 should invoke the [sqlite3_fts5_token] command once for each
** token within the tokenized text.
*/
static int f5tCreateTokenizer(
  ClientData clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  F5tTokenizerContext *pContext = (F5tTokenizerContext*)clientData;
  sqlite3 *db;
  fts5_api *pApi;
  char *zName;
  Tcl_Obj *pScript;
  fts5_tokenizer t;
  F5tTokenizerModule *pMod;
  int rc;

  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB NAME SCRIPT");
    return TCL_ERROR;
  }
  if( f5tDbAndApi(interp, objv[1], &db, &pApi) ){
    return TCL_ERROR;
  }
  zName = Tcl_GetString(objv[2]);
  pScript = objv[3];

  t.xCreate = f5tTokenizerCreate;
  t.xTokenize = f5tTokenizerTokenize;
  t.xDelete = f5tTokenizerDelete;

  pMod = (F5tTokenizerModule*)ckalloc(sizeof(F5tTokenizerModule));
  pMod->interp = interp;
  pMod->pScript = pScript;
  pMod->pContext = pContext;
  Tcl_IncrRefCount(pScript);
  rc = pApi->xCreateTokenizer(pApi, zName, (void*)pMod, &t, f5tDelTokenizer);
  if( rc!=SQLITE_OK ){
    Tcl_AppendResult(interp, "error in fts5_api.xCreateTokenizer()", 0);
    return TCL_ERROR;
  }

  return TCL_OK;
}

static void xF5tFree(ClientData clientData){
  ckfree(clientData);
}

/*
** Entry point.
*/
int Fts5tcl_Init(Tcl_Interp *interp){
  static struct Cmd {
    char *zName;
    Tcl_ObjCmdProc *xProc;
    int bTokenizeCtx;
  } aCmd[] = {
    { "sqlite3_fts5_create_tokenizer", f5tCreateTokenizer, 1 },
    { "sqlite3_fts5_token",            f5tTokenizerReturn, 1 },
    { "sqlite3_fts5_tokenize",         f5tTokenize, 0 },
    { "sqlite3_fts5_create_function",  f5tCreateFunction, 0 }
  };
  int i;
  F5tTokenizerContext *pContext;

  pContext = ckalloc(sizeof(F5tTokenizerContext));
  memset(pContext, 0, sizeof(*pContext));

  for(i=0; i<sizeof(aCmd)/sizeof(aCmd[0]); i++){
    struct Cmd *p = &aCmd[i];
    void *pCtx = 0;
    if( p->bTokenizeCtx ) pCtx = (void*)pContext;
    Tcl_CreateObjCommand(interp, p->zName, p->xProc, pCtx, (i ? 0 : xF5tFree));
  }

  return TCL_OK;
}

#endif