SQLite

#ifndef __SQLITESESSION_H_
#define __SQLITESESSION_H_ 1

/*
** Make sure we can call this stuff from C++.
*/
#ifdef __cplusplus
extern "C" {
#endif

#include "sqlite3.h"

/*
** CAPI3REF: Session Object Handle
*/
typedef struct sqlite3_session sqlite3_session;

/*
** CAPI3REF: Changeset Iterator Handle
*/
typedef struct sqlite3_changeset_iter sqlite3_changeset_iter;

/*
** CAPI3REF: Create A New Session Object
**
** Create a new session object attached to database handle db. If successful,
** a pointer to the new object is written to *ppSession and SQLITE_OK is
** returned. If an error occurs, *ppSession is set to NULL and an SQLite
** error code (e.g. SQLITE_NOMEM) is returned.
**
** It is possible to create multiple session objects attached to a single
** database handle.

int sqlite3session_create(
  sqlite3 *db,                    /* Database handle */
  const char *zDb,                /* Name of db (e.g. "main") */
  sqlite3_session **ppSession     /* OUT: New session object */
);

/*
** CAPI3REF: Delete A Session Object
**
** Delete a session object previously allocated using 
** [sqlite3session_create()]. Once a session object has been deleted, the
** results of attempting to use pSession with any other session module
** function are undefined.
**
** Session objects must be deleted before the database handle to which they
** are attached is closed. Refer to the documentation for 
** [sqlite3session_create()] for details.
*/
void sqlite3session_delete(sqlite3_session *pSession);

/*
** CAPI3REF: Enable Or Disable A Session Object
**
** Enable or disable the recording of changes by a session object. When
** enabled, a session object records changes made to the database. When
** disabled - it does not. A newly created session object is enabled.
** Refer to the documentation for [sqlite3session_changeset()] for further
** details regarding how enabling and disabling a session object affects
** the eventual changesets.
**
** Passing zero to this function disables the session. Passing a value
** greater than zero enables it. Passing a value less than zero is a 
** no-op, and may be used to query the current state of the session.
**
** The return value indicates the final state of the session object: 0 if 
** the session is disabled, or 1 if it is enabled.
*/
int sqlite3session_enable(sqlite3_session *pSession, int bEnable);

/*
** CAPI3REF: Attach a Table to a Session Object
**
** Attach a table to a session. All subsequent changes made to the table
** while the session object is enabled will be recorded. See documentation
** for [sqlite3session_changeset()] for further details.
**
** Changes can only be recorded for tables that have a PRIMARY KEY explicitly
** defined as part of their CREATE TABLE statement. It does not matter if the 
** PRIMARY KEY is an "INTEGER PRIMARY KEY" (rowid alias) or not. The PRIMARY

*/
int sqlite3session_attach(
  sqlite3_session *pSession,      /* Session object */
  const char *zTab                /* Table name */
);

/*
** CAPI3REF: Generate A Changeset From A Session Object
**
** Obtain a changeset containing changes to the tables attached to the 
** session object passed as the first argument. If successful, 
** set *ppChangeset to point to a buffer containing the changeset 
** and *pnChangeset to the size of the changeset in bytes before returning
** SQLITE_OK. If an error occurs, set both *ppChangeset and *pnChangeset to
** zero and return an SQLite error code.
**
** A changeset consists of zero or more INSERT, UPDATE and/or DELETE changes,
** each representing a change to a single row of an attached table. An INSERT
** change contains the values of each field of a new database row. A DELETE
** contains the original values of each field of a deleted database row. An
** UPDATE change contains the original values of each field of an updated
** database row along with the updated values for each updated non-primary-key
** column. It is not possible for an UPDATE change to represent a change that
** modifies the values of primary key columns. If such a change is made, it
** is represented in a changeset as a DELETE followed by an INSERT.
**
** The contents of a changeset may be traversed using an iterator created
** using the [sqlite3changeset_start()] API. A changeset may be applied to
** a database with a compatible schema using the [sqlite3changeset_apply()]
** API.
**
** Following a successful call to this function, it is the responsibility of
** the caller to eventually free the buffer that *ppChangeset points to using
** [sqlite3_free()].
**
** <h3>Changeset Generation</h3>
**
** Once a table has been attached to a session object, the session object
** records the primary key values of all new rows inserted into the table.
** It also records the original primary key and other column values of any
** deleted or updated rows. For each unique primary key value, data is only
** recorded once - the first time a row with said primary key is inserted,
** updated or deleted in the lifetime of the session.

int sqlite3session_changeset(
  sqlite3_session *pSession,      /* Session object */
  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
  void **ppChangeset              /* OUT: Buffer containing changeset */
);

/*
** CAPI3REF: Create An Iterator To Traverse A Changeset 
**
** Create an iterator used to iterate through the contents of a changeset.
** If successful, *pp is set to point to the iterator handle and SQLITE_OK
** is returned. Otherwise, if an error occurs, *pp is set to zero and an
** SQLite error code is returned.
**
** The following functions can be used to advance and query a changeset 
** iterator created by this function:

int sqlite3changeset_start(
  sqlite3_changeset_iter **pp,    /* OUT: New changeset iterator handle */
  int nChangeset,                 /* Size of changeset blob in bytes */
  void *pChangeset                /* Pointer to blob containing changeset */
);

/*
** CAPI3REF: Advance A Changeset Iterator
**
** This function may only be used with iterators created by function
** [sqlite3changeset_start()]. If it is called on an iterator passed to
** a conflict-handler callback by [sqlite3changeset_apply()], SQLITE_MISUSE
** is returned and the call has no effect.
**
** Immediately after an iterator is created by sqlite3changeset_start(), it
** does not point to any change in the changeset. Assuming the changeset

** If an error occurs, an SQLite error code is returned. Possible error 
** codes include SQLITE_CORRUPT (if the changeset buffer is corrupt) or 
** SQLITE_NOMEM.
*/
int sqlite3changeset_next(sqlite3_changeset_iter *pIter);

/*
** CAPI3REF: Obtain The Current Operation From A Changeset Iterator
**
** The pIter argument passed to this function may either be an iterator
** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
** created by [sqlite3changeset_start()]. In the latter case, the most recent
** call to [sqlite3changeset_next()] must have returned SQLITE_ROW. If this
** is not the case, this function returns SQLITE_MISUSE.
**
** If argument pzTab is not NULL, then *pzTab is set to point to a

  sqlite3_changeset_iter *pIter,  /* Iterator object */
  const char **pzTab,             /* OUT: Pointer to table name */
  int *pnCol,                     /* OUT: Number of columns in table */
  int *pOp                        /* OUT: SQLITE_INSERT, DELETE or UPDATE */
);

/*
** CAPI3REF: Obtain old.* Values From A Changeset Iterator
**
** The pIter argument passed to this function may either be an iterator
** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
** created by [sqlite3changeset_start()]. In the latter case, the most recent
** call to [sqlite3changeset_next()] must have returned SQLITE_ROW. 
** Furthermore, it may only be called if the type of change that the iterator
** currently points to is either SQLITE_DELETE or SQLITE_UPDATE. Otherwise,
** this function returns SQLITE_MISUSE and sets *ppValue to NULL.

int sqlite3changeset_old(
  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
  int iVal,                       /* Column number */
  sqlite3_value **ppValue         /* OUT: Old value (or NULL pointer) */
);

/*
** CAPI3REF: Obtain new.* Values From A Changeset Iterator
**
** The pIter argument passed to this function may either be an iterator
** passed to a conflict-handler by [sqlite3changeset_apply()], or an iterator
** created by [sqlite3changeset_start()]. In the latter case, the most recent
** call to [sqlite3changeset_next()] must have returned SQLITE_ROW. 
** Furthermore, it may only be called if the type of change that the iterator
** currently points to is either SQLITE_UPDATE or SQLITE_INSERT. Otherwise,
** this function returns SQLITE_MISUSE and sets *ppValue to NULL.

int sqlite3changeset_new(
  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
  int iVal,                       /* Column number */
  sqlite3_value **ppValue         /* OUT: New value (or NULL pointer) */
);

/*
** CAPI3REF: Obtain Conflicting Row Values From A Changeset Iterator
**
** This function should only be used with iterator objects passed to a
** conflict-handler callback by [sqlite3changeset_apply()] with either
** SQLITE_CHANGESET_DATA or SQLITE_CHANGESET_CONFLICT. If this function
** is called on any other iterator, SQLITE_MISUSE is returned and *ppValue
** is set to NULL.
**
** Argument iVal must be greater than or equal to 0, and less than the number

  sqlite3_changeset_iter *pIter,  /* Changeset iterator */
  int iVal,                       /* Column number */
  sqlite3_value **ppValue         /* OUT: Value from conflicting row */
);


/*
** CAPI3REF: Finalize a Changeset Iterator
**
** This function is used to finalize an iterator allocated with
** sqlite3changeset_start().
**
** This function should only be called on iterators created using the
** [sqlite3changeset_start()] function. If an application calls this
** function with an iterator passed to a conflict-handler by
** [sqlite3changeset_apply()], SQLITE_MISUSE is immediately returned and the
** call has no effect.
**

**   if( rc!=SQLITE_OK ){
**     // An error has occurred 
**   }
*/
int sqlite3changeset_finalize(sqlite3_changeset_iter *pIter);

/*
** CAPI3REF: Invert A Changeset
**
** This function is used to "invert" a changeset object. Applying an inverted
** changeset to a database reverses the effects of applying the uninverted
** changeset. Specifically:
**
** <ul>
**   <li> Each DELETE change is changed to an INSERT, and
**   <li> Each INSERT change is changed to a DELETE, and

*/
int sqlite3changeset_invert(
  int nIn, void *pIn,             /* Input changeset */
  int *pnOut, void **ppOut        /* OUT: Inverse of input */
);

/*
** CAPI3REF: Apply A Changeset To A Database
**
** Apply a changeset to a database. This function attempts to update the
** "main" database attached to handle db with the changes found in the
** changeset passed via the second and third arguments.
**
** For each change in the changeset, this function tests that the target
** database contains a compatible table. A table is considered compatible
** if all of the following are true:

**   violation (e.g. NOT NULL or UNIQUE), the conflict handler function is 
**   invoked with the second argument set to [SQLITE_CHANGESET_CONSTRAINT].
**   This includes the case where the INSERT operation is re-attempted because 
**   an earlier call to the conflict handler function returned 
**   [SQLITE_CHANGESET_REPLACE].
**
** <dt>UPDATE Changes<dd>
**   For each UPDATE change, this function checks if the target database 
**   contains a row with the same primary key value (or values) as the 
**   original row values stored in the changeset. If it does, and the values 
**   stored in all non-primary key columns also match the values stored in 
**   the changeset the row is updated within the target database.
**
**   If a row with matching primary key values is found, but one or more of
**   the non-primary key fields contains a value different from an original

    int eConflict,                /* DATA, MISSING, CONFLICT, CONSTRAINT */
    sqlite3_changeset_iter *p     /* Handle describing change and conflict */
  ),
  void *pCtx                      /* First argument passed to xConflict */
);

/* 
** CAPI3REF: Constants Passed to The Conflict Handler
**
** Values that may be passed as the second argument to a conflict-handler.
**
** <dl>
** <dt>SQLITE_CHANGESET_DATA<dd>
**   The conflict handler is invoked with CHANGESET_DATA as the second argument
**   when processing a DELETE or UPDATE change if a row with the required
**   PRIMARY KEY fields is present in the database, but one or more other 

*/
#define SQLITE_CHANGESET_DATA       1
#define SQLITE_CHANGESET_NOTFOUND   2
#define SQLITE_CHANGESET_CONFLICT   3
#define SQLITE_CHANGESET_CONSTRAINT 4

/* 
** CAPI3REF: Constants Returned By The Conflict Handler
**
** A conflict handler callback must return one of the following three values.
**
** <dl>
** <dt>SQLITE_CHANGESET_OMIT<dd>
**   If a conflict handler returns this value no special action is taken. The
**   change that caused the conflict is not applied. The session module 
**   continues to the next change in the changeset.
**