SQLite

  catch { S delete }

  if {$rc} {
    error $changeset
  }
  return $changeset
}

proc patchset_from_sql {sql {dbname main}} {
  set rc [catch {
    sqlite3session S db $dbname
    db eval "SELECT name FROM $dbname.sqlite_master WHERE type = 'table'" {
      S attach $name
    }
    db eval $sql
    S patchset
  } patchset]
  catch { S delete }

  if {$rc} {
    error $patchset
  }
  return $patchset
}

proc do_then_apply_sql {sql {dbname main}} {
  proc xConflict args { return "OMIT" }
  set rc [catch {
    sqlite3session S db $dbname
    db eval "SELECT name FROM $dbname.sqlite_master WHERE type = 'table'" {
      S attach $name

# 2018 October 18
#
# 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.
#
#***********************************************************************
# This file implements regression tests for SQLite library.
#

if {![info exists testdir]} {
  set testdir [file join [file dirname [info script]] .. .. test]
} 
source [file join [file dirname [info script]] session_common.tcl]
source $testdir/tester.tcl
ifcapable !session {finish_test; return}

set testprefix sessioninvert

proc do_invert_test {tn sql} {

  forcecopy test.db test.db2
  sqlite3 db2 test.db2

  set C [changeset_from_sql $sql]

  forcecopy test.db test.db3
  sqlite3 db3 test.db3
  uplevel [list do_test $tn.1 [list compare_db db db3] {}]

  set I [sqlite3changeset_invert $C]
  sqlite3changeset_apply db $I {}
  uplevel [list do_test $tn.2 [list compare_db db db2] {}]
  
  sqlite3changeset_apply_v2 -invert db3 $C {}
  uplevel [list do_test $tn.3 [list compare_db db db3] {}]

  catch { db2 close }
  catch { db3 close }
}

do_execsql_test 1.0 {
  CREATE TABLE t1(a PRIMARY KEY, b, c);
  CREATE TABLE t2(d, e, f, PRIMARY KEY(e, f));

  INSERT INTO t1 VALUES(1, 'one', 'i');
  INSERT INTO t1 VALUES(2, 'two', 'ii');
  INSERT INTO t1 VALUES(3, 'three', 'iii');
  INSERT INTO t1 VALUES(4, 'four', 'iv');
  INSERT INTO t1 VALUES(5, 'five', 'v');
  INSERT INTO t1 VALUES(6, 'six', 'vi');

  INSERT INTO t2 SELECT * FROM t1;
}

do_invert_test 1.1 {
  INSERT INTO t1 VALUES(7, 'seven', 'vii');
}

do_invert_test 1.2 {
  DELETE FROM t1 WHERE a<4;
}

do_invert_test 1.2 {
  UPDATE t1 SET c=5;
}

do_invert_test 1.3 {
  UPDATE t1 SET b = a+1 WHERE a%2;
  DELETE FROM t2;
  INSERT INTO t1 VALUES(10, 'ten', NULL);
}

do_invert_test 1.4 {
  UPDATE t2 SET d = d-1;
}

do_execsql_test 2.0 { 
  ANALYZE;
  PRAGMA writable_schema = 1;
  DROP TABLE IF EXISTS sqlite_stat4;
  SELECT * FROM sqlite_stat1;
} {
  t2 sqlite_autoindex_t2_1 {6 1 1} 
  t1 sqlite_autoindex_t1_1 {6 1}
}

do_invert_test 2.1 {
  INSERT INTO sqlite_stat1 VALUES('t3', 'idx2', '1 2 3');
}

do_invert_test 2.2 {
  DELETE FROM sqlite_stat1;
}

do_invert_test 2.3 {
  UPDATE sqlite_stat1 SET stat = 'hello world';
}

do_test 3.0 {
  forcecopy test.db test.db2
  sqlite3 db2 test.db2
  set P [patchset_from_sql {
    INSERT INTO t2 VALUES(1, 2, 3);
    DELETE FROM t2 WHERE d = 3;
  }]

  list [catch { sqlite3changeset_apply_v2 -invert db2 $P {} } msg] $msg
} {1 SQLITE_CORRUPT}

do_test 3.1 {
  sqlite3changeset_apply_v2 db2 $P {} 
  compare_db db db2
} {}


finish_test

/*
** Structure for changeset iterators.
*/
struct sqlite3_changeset_iter {
  SessionInput in;                /* Input buffer or stream */
  SessionBuffer tblhdr;           /* Buffer to hold apValue/zTab/abPK/ */
  int bPatchset;                  /* True if this is a patchset */
  int bInvert;                    /* True to invert changeset */
  int rc;                         /* Iterator error code */
  sqlite3_stmt *pConflict;        /* Points to conflicting row, if any */
  char *zTab;                     /* Current table */
  int nCol;                       /* Number of columns in zTab */
  int op;                         /* Current operation */
  int bIndirect;                  /* True if current change was indirect */
  u8 *abPK;                       /* Primary key array */

** Do the work for either sqlite3changeset_start() or start_strm().
*/
static int sessionChangesetStart(
  sqlite3_changeset_iter **pp,    /* OUT: Changeset iterator handle */
  int (*xInput)(void *pIn, void *pData, int *pnData),
  void *pIn,
  int nChangeset,                 /* Size of buffer pChangeset in bytes */
  void *pChangeset,               /* Pointer to buffer containing changeset */
  int bInvert                     /* True to invert changeset */
){
  sqlite3_changeset_iter *pRet;   /* Iterator to return */
  int nByte;                      /* Number of bytes to allocate for iterator */

  assert( xInput==0 || (pChangeset==0 && nChangeset==0) );

  /* Zero the output variable in case an error occurs. */
  *pp = 0;

  /* Allocate and initialize the iterator structure. */
  nByte = sizeof(sqlite3_changeset_iter);
  pRet = (sqlite3_changeset_iter *)sqlite3_malloc(nByte);
  if( !pRet ) return SQLITE_NOMEM;
  memset(pRet, 0, sizeof(sqlite3_changeset_iter));
  pRet->in.aData = (u8 *)pChangeset;
  pRet->in.nData = nChangeset;
  pRet->in.xInput = xInput;
  pRet->in.pIn = pIn;
  pRet->in.bEof = (xInput ? 0 : 1);
  pRet->bInvert = bInvert;

  /* Populate the output variable and return success. */
  *pp = pRet;
  return SQLITE_OK;
}

/*
** Create an iterator used to iterate through the contents of a changeset.
*/
int sqlite3changeset_start(
  sqlite3_changeset_iter **pp,    /* OUT: Changeset iterator handle */
  int nChangeset,                 /* Size of buffer pChangeset in bytes */
  void *pChangeset                /* Pointer to buffer containing changeset */
){
  return sessionChangesetStart(pp, 0, 0, nChangeset, pChangeset, 0);
}

/*
** Streaming version of sqlite3changeset_start().
*/
int sqlite3changeset_start_strm(
  sqlite3_changeset_iter **pp,    /* OUT: Changeset iterator handle */
  int (*xInput)(void *pIn, void *pData, int *pnData),
  void *pIn
){
  return sessionChangesetStart(pp, xInput, pIn, 0, 0, 0);
}

/*
** If the SessionInput object passed as the only argument is a streaming
** object and the buffer is full, discard some data to free up space.
*/
static void sessionDiscardData(SessionInput *pIn){

    if( sessionChangesetReadTblhdr(p) ) return p->rc;
    if( (p->rc = sessionInputBuffer(&p->in, 2)) ) return p->rc;
    p->in.iCurrent = p->in.iNext;
    if( p->in.iNext>=p->in.nData ) return SQLITE_DONE;
    op = p->in.aData[p->in.iNext++];
  }

  if( p->zTab==0 || (p->bPatchset && p->bInvert) ){
    /* The first record in the changeset is not a table header. Must be a
    ** corrupt changeset. */
    assert( p->in.iNext==1 || p->zTab );
    return (p->rc = SQLITE_CORRUPT_BKPT);
  }

  p->op = op;
  p->bIndirect = p->in.aData[p->in.iNext++];
  if( p->op!=SQLITE_UPDATE && p->op!=SQLITE_DELETE && p->op!=SQLITE_INSERT ){
    return (p->rc = SQLITE_CORRUPT_BKPT);

      nVal = p->nCol;
    }
    p->rc = sessionChangesetBufferRecord(&p->in, nVal, pnRec);
    if( p->rc!=SQLITE_OK ) return p->rc;
    *paRec = &p->in.aData[p->in.iNext];
    p->in.iNext += *pnRec;
  }else{
    sqlite3_value **apOld = (p->bInvert ? &p->apValue[p->nCol] : p->apValue);
    sqlite3_value **apNew = (p->bInvert ? p->apValue : &p->apValue[p->nCol]);

    /* If this is an UPDATE or DELETE, read the old.* record. */
    if( p->op!=SQLITE_INSERT && (p->bPatchset==0 || p->op==SQLITE_DELETE) ){
      u8 *abPK = p->bPatchset ? p->abPK : 0;
      p->rc = sessionReadRecord(&p->in, p->nCol, abPK, apOld);
      if( p->rc!=SQLITE_OK ) return p->rc;
    }

    /* If this is an INSERT or UPDATE, read the new.* record. */
    if( p->op!=SQLITE_DELETE ){
      p->rc = sessionReadRecord(&p->in, p->nCol, 0, apNew);
      if( p->rc!=SQLITE_OK ) return p->rc;
    }

    if( (p->bPatchset || p->bInvert) && p->op==SQLITE_UPDATE ){
      /* If this is an UPDATE that is part of a patchset, then all PK and
      ** modified fields are present in the new.* record. The old.* record
      ** is currently completely empty. This block shifts the PK fields from
      ** new.* to old.*, to accommodate the code that reads these arrays.  */
      for(i=0; i<p->nCol; i++){
        assert( p->bPatchset==0 || p->apValue[i]==0 );
        if( p->abPK[i] ){
          assert( p->apValue[i]==0 );
          p->apValue[i] = p->apValue[i+p->nCol];
          if( p->apValue[i]==0 ) return (p->rc = SQLITE_CORRUPT_BKPT);
          p->apValue[i+p->nCol] = 0;
        }
      }
    }else if( p->bInvert ){
      if( p->op==SQLITE_INSERT ) p->op = SQLITE_DELETE;
      else if( p->op==SQLITE_DELETE ) p->op = SQLITE_INSERT;
    }
  }

  return SQLITE_ROW;
}

/*

  int rc = SQLITE_OK;

  while( pApply->constraints.nBuf ){
    sqlite3_changeset_iter *pIter2 = 0;
    SessionBuffer cons = pApply->constraints;
    memset(&pApply->constraints, 0, sizeof(SessionBuffer));

    rc = sessionChangesetStart(&pIter2, 0, 0, cons.nBuf, cons.aBuf, 0);
    if( rc==SQLITE_OK ){
      int nByte = 2*pApply->nCol*sizeof(sqlite3_value*);
      int rc2;
      pIter2->bPatchset = bPatchset;
      pIter2->zTab = (char*)zTab;
      pIter2->nCol = pApply->nCol;
      pIter2->abPK = pApply->abPK;

    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
  ),
  void *pCtx,                     /* First argument passed to xConflict */
  void **ppRebase, int *pnRebase,
  int flags
){
  sqlite3_changeset_iter *pIter;  /* Iterator to skip through changeset */  
  int bInverse = !!(flags & SQLITE_CHANGESETAPPLY_INVERT);
  int rc = sessionChangesetStart(&pIter, 0, 0, nChangeset, pChangeset,bInverse);
  if( rc==SQLITE_OK ){
    rc = sessionChangesetApply(
        db, pIter, xFilter, xConflict, pCtx, ppRebase, pnRebase, flags
    );
  }
  return rc;
}

    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
  ),
  void *pCtx,                     /* First argument passed to xConflict */
  void **ppRebase, int *pnRebase,
  int flags
){
  sqlite3_changeset_iter *pIter;  /* Iterator to skip through changeset */  
  int bInverse = !!(flags & SQLITE_CHANGESETAPPLY_INVERT);
  int rc = sessionChangesetStart(&pIter, xInput, pIn, 0, 0, bInverse);
  if( rc==SQLITE_OK ){
    rc = sessionChangesetApply(
        db, pIter, xFilter, xConflict, pCtx, ppRebase, pnRebase, flags
    );
  }
  return rc;
}

**   Usually, the sessions module encloses all operations performed by
**   a single call to apply_v2() or apply_v2_strm() in a [SAVEPOINT]. The
**   SAVEPOINT is committed if the changeset or patchset is successfully
**   applied, or rolled back if an error occurs. Specifying this flag
**   causes the sessions module to omit this savepoint. In this case, if the
**   caller has an open transaction or savepoint when apply_v2() is called, 
**   it may revert the partially applied changeset by rolling it back.
**
** <dt>SQLITE_CHANGESETAPPLY_INVERT <dd>
**   Invert the changeset before applying it. This is equivalent to inverting
**   a changeset using sqlite3changeset_invert() before applying it. It is
**   an error to specify this flag with a patchset.
*/
#define SQLITE_CHANGESETAPPLY_NOSAVEPOINT   0x0001
#define SQLITE_CHANGESETAPPLY_INVERT        0x0002

/* 
** CAPI3REF: Constants Passed To The Conflict Handler
**
** Values that may be passed as the second argument to a conflict-handler.
**
** <dl>

  int nRebase = 0;
  int flags = 0;                  /* Flags for apply_v2() */

  memset(&sStr, 0, sizeof(sStr));
  sStr.nStream = test_tcl_integer(interp, SESSION_STREAM_TCL_VAR);

  /* Check for the -nosavepoint flag */
  if( bV2 ){
    if( objc>1 ){
      const char *z1 = Tcl_GetString(objv[1]);
      int n = strlen(z1);
      if( n>1 && n<=12 && 0==sqlite3_strnicmp("-nosavepoint", z1, n) ){
        flags |= SQLITE_CHANGESETAPPLY_NOSAVEPOINT;
        objc--;
        objv++;
      }
    }
    if( objc>1 ){
      const char *z1 = Tcl_GetString(objv[1]);
      int n = strlen(z1);
      if( n>1 && n<=7 && 0==sqlite3_strnicmp("-invert", z1, n) ){
        flags |= SQLITE_CHANGESETAPPLY_INVERT;
        objc--;
        objv++;
      }
    }
  }

  if( objc!=4 && objc!=5 ){
    const char *zMsg;
    if( bV2 ){
      zMsg = "?-nosavepoint? ?-inverse? "
        "DB CHANGESET CONFLICT-SCRIPT ?FILTER-SCRIPT?";
    }else{
      zMsg = "DB CHANGESET CONFLICT-SCRIPT ?FILTER-SCRIPT?";
    }
    Tcl_WrongNumArgs(interp, 1, objv, zMsg);
    return TCL_ERROR;
  }
  if( 0==Tcl_GetCommandInfo(interp, Tcl_GetString(objv[1]), &info) ){