Fossil

**    (3) fossil revert             (7) fossil stash goto
**    (4) fossil stash pop
**
** If FILENAME is specified then restore the content of the named
** file(s) but otherwise leave the update or merge or revert in effect. 
** The redo command undoes the effect of the most recent undo.
**
** If the --explain option is present, no changes are made and instead
** If the -n|--dry-run option is present, no changes are made and instead
** the undo or redo command explains what actions the undo or redo would
** have done had the --explain been omitted.
** have done had the -n|--dry-run been omitted.
**
** A single level of undo/redo is supported.  The undo/redo stack
** is cleared by the commit and checkout commands.
**
** Options:
**   --explain    do not make changes but show what would be done
**   -n|--dry-run   do not make changes but show what would be done
**
** See also: commit, status
*/
void undo_cmd(void){
  int isRedo = g.argv[1][0]=='r';
  int undo_available;
  int explainFlag = find_option("explain", 0, 0)!=0;
  int dryRunFlag = find_option("dry-run", "n", 0)!=0;
  const char *zCmd = isRedo ? "redo" : "undo";

  if( !dryRunFlag ){
    dryRunFlag = find_option("explain", 0, 0)!=0;
  }
  db_must_be_within_tree();
  verify_all_options();
  db_begin_transaction();
  undo_available = db_lget_int("undo_available", 0);
  if( explainFlag ){
  if( dryRunFlag ){
    if( undo_available==0 ){
      fossil_print("No undo or redo is available\n");
    }else{
      Stmt q;
      int nChng = 0;
      zCmd = undo_available==1 ? "undo" : "redo";
      fossil_print("A %s is available for the following command:\n\n"