/*
** Title:          TopK
** SCCSid:         %W% %E% %U%
** CCid:           %W% %E% %U%
** Author:         Informix Software, Inc.
** Created:        06/22/1998 15:59
** Description:    This is the generated 'C' file for the TopK DataBlade.
** Comments:       Generated for project TopK.3.6
*/

/*
**  The following is placed here to insure
**  that name "mangling" does not occur.
*/
#ifdef __cplusplus

extern "C"
{

#endif

/* Standard library includes. */
#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <stddef.h>

/* Used by Informix GLS routines. */
#include <ifxgls.h>

/* Include when accessing the Informix API. */
#include <mi.h>

/* This is the project include file. */
#include "TopK.h"

/* Private forward declaration */
static void topk_error(char* msg);
static mi_integer topk_setinit(MI_COLLECTION *intset,
			       mi_integer k,
			       MI_FPARAM *fParam);
static mi_integer topk_setretone(MI_FPARAM *fParam);
static mi_integer topk_setend(MI_FPARAM *fParam);


/* Private data structure */
/* we keep the top K integers in this structure */
typedef struct _topk_terms
{
	int		tk_k;
	int		tk_nterms;
	int		tk_curterm;
	mi_integer	*tk_terms;
} topk_terms;


struct _StateInfo
{
	MI_CONNECTION * Conn;      /* The current connection.            */
	topk_terms *    StateInfo; /* Private state information.         */
};


/* {{FUNCTION(9f039a80-836c-11d0-93b2-00a0c9202325) (MergeSection) */

/****************************************************************
**
** Function name:
**
**	TopK
**
** Description:
**
**	This  function  is an iterator function.   As such,  it  must  be
**	registered using SQL as an iterator function:
**
**	     create function TopK( args )
**	      	returns mi_integer
**	       	with
**	       	(
**	              	iterator
**	       	)
**	       	external name "yourpath/TopK.bld(TopK)"
**	       	language C
**	     end function;
**
**	Iterator functions are called with state information.   There are
**	three  states:  SET_INIT,  SET_RETONE,  and SET_END.   This state
**	information  is  passed  in via the Gen_fparam  argument  to  the
**	function  and placed in Gen_IteratorState.   During the  SET_INIT
**	state,   the   iterator  function  must  perform   any   required
**	initialization.   Typically, this means allocating memory to hold
**	any  information  that  is needed across calls to  the  function.
**	This  allocated  memory must be stored back  into  Gen_fparam  by
**	calling  mi_fp_setfuncstate  and  can  be  retrieved  by  calling
**	mi_fp_funcstate.  Values passed back from this state are ignored.
**
**	Following  initialization,  the function is repeatedly called  in
**	the SET_RETONE state.   The return value returned from this state
**	is  passed back to the user.   The function is called  repeatedly
**	until  the  iterator function signals that no more data is to  be
**	passed back.  The iterator function *MUST* call:
**
**		mi_fp_setisdone( Gen_fparam, MI_TRUE );
**
**	to conclude looping.   Failing to call this function will  result
**	in infinite looping!
**
**	Finally, the iterator function is called in the SET_END state and
**	the  function  is given a chance to perform any cleanup  that  is
**	required.  Values passed back from this state are ignored.
**
**	N.B.: If mi_db_error_raise is called during the processing of the
**	iterator function,  the function  is not  called in  the  SET_END
**	state. Resources allocated using mi_dalloc on a PER_COMMAND basis
**	are freed for you but all other resources should be  freed before
**	calling mi_db_error_raise.
**
**
** Special Comments:
**
**	Entrypoint for the SQL routine TopK (set (integer not null),integer) returns integer.
**
** Parameters:
**
** Return value:
**
**	mi_integer
**
** History:
**
**	06/22/1998 - Generated by BladeSmith Version 3.60.TC1B1.
**
** Identification:
**
** NOTE:
**
**	BladeSmith will add and remove parameters from the function
**	prototype, and will generate tracing calls.  ONLY EDIT code
**	in blocks marked  Your_<section>.  Any other  modifications
**	will require manual merging.
**
*****************************************************************
*/
UDREXPORT 
mi_integer TopK
(
MI_COLLECTION *         intset,
mi_integer              k,
MI_FPARAM *             Gen_fparam        /* Standard info - see DBDK docs.*/
)
{


	int             Gen_IteratorState;              /* This is the iteration state.   */
	MI_CONNECTION * Gen_Con;                        /* The current connection.        */
	mi_integer      Gen_RetVal = 0;                 /* TopK's return value.    */

	/* ------ {{Your_StateInfoDeclaration (PreserveSection) BEGIN ------ */
		struct _StateInfo
		{
			MI_CONNECTION * Conn;      /* The current connection.            */
			topk_terms *    StateInfo; /* Private state information.         */
		}* Gen_StateInfo;                      /* TopK's state information. */


	/* ------ }}Your_StateInfoDeclaration (#0JN8) END ------ */

	/* ------ {{Your_AutoVariable_Declarations (PreserveSection) BEGIN ------ */
	MI_COLL_DESC  	* colldesc;	     /* The collection handle */
	mi_integer      result;
	mi_integer 	curVal;
	mi_integer      curValLength;
	mi_integer 	* term;
	int 		i, j;
	topk_terms 	* tk;


	/* ------ }}Your_AutoVariable_Declarations (#0000) END ------ */

	/* Get the iteration state. */
	Gen_IteratorState = mi_fp_request( Gen_fparam );

	/*
	** Based  on the iteration  state,
	** calculate the iterator's return
	** value.
	*/
	switch( Gen_IteratorState )
	{
		case SET_INIT:			/* Initialize */

			/*
			** Get the current connection handle.
			** This connection handle is held in
			** the state information for the duration
			** of the running of TopK.
			*/
			Gen_Con = mi_open( NULL, NULL, NULL );

			/* Verify that the connection has been established. */
			if( Gen_Con == 0 )
			{
				/*
				** Opening the current connection has failed
				** so issue the following message and quit.
				**
				** 	"Connection has failed in TopK."
				*/
				DBDK_TRACE_ERROR( "TopK", ERRORMESG1, 10 );

				/* not reached */
			}


			/* ------ {{Your_InitializationCode (PreserveSection) BEGIN ------ */
			{
				/*
				** Write to the trace file indicating
				** that TopK has been called.
				*/
				DBDK_TRACE_ENTER( "TopK_setinit" );

				/* Test k */
				if (k <= 0)
				{
					DBDK_TRACE_EXIT( "TopK_setinit" );
					mi_db_error_raise(Gen_Con, MI_MESSAGE, 
							  "K must be > 0 in TopKIntegers", NULL);	
				}

				/*
				** Allocate the  state  information.   Both
				** the   private  state   information   and
				** connection are stored here.
				*/
				Gen_StateInfo = (struct _StateInfo *)
								   mi_dalloc( sizeof( struct _StateInfo ), PER_COMMAND );
				if( Gen_StateInfo == NULL )
				{
					DBDK_TRACE_ERROR( "TopK", ERRORMESG2, 10 );
				}

				/* Save the connection. */
				Gen_StateInfo->Conn = Gen_Con;

				/*
				** allocate and protect memory for sorted set
				*/
				tk = (topk_terms *) mi_dalloc(sizeof(topk_terms),PER_COMMAND);
				if( tk == NULL )
				{
					DBDK_TRACE_ERROR( "TopK", ERRORMESG2, 10 );
				}
				term = (mi_integer *) mi_dalloc((k+1) * sizeof(mi_integer), 
								PER_COMMAND);
				if( term == NULL )
				{
					DBDK_TRACE_ERROR( "TopK", ERRORMESG2, 10 );
				}

				/* save set in state information */
				Gen_StateInfo->StateInfo = tk;

				/* Register the private state info in Gen_fParam. */
				mi_fp_setfuncstate( Gen_fparam, Gen_StateInfo );


				/* initialize tk */
				tk->tk_k = k;
				tk->tk_nterms = 0;
				tk->tk_curterm = 0;
				tk->tk_terms = term;

				/* open the collection */
				if ((colldesc = mi_collection_open(Gen_Con, intset)) == NULL)
				{
					mi_db_error_raise(Gen_Con, MI_MESSAGE, 
						"mi_collection_open failed", NULL);	
					/* not reached */
				}

				/*
				 * Now iterate over the set, and find the top K values.
				 * We do an expensive insertion sort here; this could
				 * be recoded to be more efficient.
				 */
				result = mi_collection_fetch(Gen_Con,
								 colldesc,
								 MI_CURSOR_FIRST,
								 0,
								 (MI_DATUM*)&curVal,
								 &curValLength);

				while (result != MI_END_OF_DATA)
				{
					if (result == MI_NORMAL_VALUE)
					{
						/*
						 * Find the insertion point for this entry in the top
						 * k terms.
						 */
						
						for (i = 0;
							 i < tk->tk_nterms && curVal < term[i];
							 i++)
						  {
							continue;
						  }

						/* insert this entry if it qualifies */
						if (i < tk->tk_k)
						  {
							for (j = tk->tk_nterms; j > i; j--)
							  term[j] = term[j - 1];

							term[i] = curVal;

							if (tk->tk_nterms < tk->tk_k)
							  tk->tk_nterms++;
						  }
					}

					/* get next item in the set */
					result = mi_collection_fetch(Gen_Con,
									 colldesc,
									 MI_CURSOR_NEXT,
									 0,
									 (MI_DATUM*)&curVal,
									 &curValLength);
				}

				/* close the collection */
				mi_collection_close(Gen_Con,colldesc);

				/*
				 * By here, return set is initialized and stored in the fParam.
				 */
				mi_fp_setisdone( Gen_fparam, MI_FALSE );
				mi_fp_setreturnisnull( Gen_fparam, 0, MI_TRUE );

				/*
				** Write to the trace file indicating
				** that TopK has successfully exited.
				*/
				DBDK_TRACE_EXIT( "TopK_setinit" );

				Gen_RetVal = 0;
			}
			/* ------ }}Your_InitializationCode (#Q0EM) END ------ */

			if( Gen_StateInfo->StateInfo == NULL )
			{
					DBDK_TRACE_ERROR( "TopK", ERRORMESG2, 10 );
			}

			/* Register the private state info in Gen_fParam. */
			mi_fp_setfuncstate( Gen_fparam, Gen_StateInfo );

			break;

		case SET_RETONE:		/* Iterate */

			/*
			** Before  using,  insure  that  the  state
			** information  is valid. It might  not  be
			** if the function has not been  called  as
			** an iterator.
			*/
			Gen_StateInfo = (struct _StateInfo *)mi_fp_funcstate( Gen_fparam );
			if( Gen_StateInfo == NULL )
			{
				DBDK_TRACE_ERROR( "TopK", ERRORMESG2, 10 );
			}

			/* Retrieve the connection. */
			Gen_Con = Gen_StateInfo->Conn;



			/* ------ {{Your_SetReturnCode (PreserveSection) BEGIN ------ */
			{
				/*
				** Write to the trace file indicating
				** that TopK has been called.
				*/
				DBDK_TRACE_ENTER( "TopK_setretone" );
				tk = Gen_StateInfo->StateInfo;

				/* notify the caller if we're done */
				if (tk->tk_curterm == tk->tk_nterms)
				{
					mi_fp_setisdone( Gen_fparam, MI_TRUE );
					mi_fp_setreturnisnull( Gen_fparam, 0, MI_TRUE );
					Gen_RetVal = 0;
				}
				else
				{
					mi_fp_setreturnisnull( Gen_fparam, 0, MI_FALSE );

					/* otherwise, return the next value */
					Gen_RetVal = tk->tk_terms[tk->tk_curterm++];
				}
				/*
				** Write to the trace file indicating
				** that TopK has successfully exited.
				*/
				DBDK_TRACE_EXIT( "TopK_setretone" );

			}
			/* ------ }}Your_SetReturnCode (#6MM0) END ------ */


			/* Check for a NULL return value. */
			if( Gen_RetVal == 0 )
			{
				mi_fp_setreturnisnull( Gen_fparam, 0, MI_TRUE );
			}
			else
			{
				mi_fp_setreturnisnull( Gen_fparam, 0, MI_FALSE );
			}


			return ( Gen_RetVal );

		case SET_END:			/* Conclude */

			/* Get the state information. */
			Gen_StateInfo = (struct _StateInfo *)mi_fp_funcstate( Gen_fparam );

			if( Gen_StateInfo != NULL )
			{
				/* Retrieve the connection. */
				Gen_Con = Gen_StateInfo->Conn;


				/* Close the open connection. */
				mi_close( Gen_Con );

				/* ------ {{Your_SetFinalCode (PreserveSection) BEGIN ------ */
				/*
				** Write to the trace file indicating
				** that TopK has been called.
				*/
				DBDK_TRACE_ENTER( "TopK_setretone" );

				/* Free the private state information. */
				tk = Gen_StateInfo->StateInfo;
				mi_free((char *) tk->tk_terms);
				mi_free((char *) tk);

				/*
				** Write to the trace file indicating
				** that TopK has successfully exited.
				*/
				DBDK_TRACE_EXIT( "TopK_setretone" );

				/* ------ }}Your_SetFinalCode (#000J) END ------ */


				/* Free the private state information. */
				if( Gen_StateInfo->StateInfo != NULL )
				{
					mi_free( Gen_StateInfo->StateInfo );
				}

				/* Free the state information. */
				mi_free( Gen_StateInfo );
			}

			break;

		default:

			/* Get the state information. */
			Gen_StateInfo = (struct _StateInfo *)mi_fp_funcstate( Gen_fparam );

			if( Gen_StateInfo != NULL )
			{
				/* Retrieve the connection. */
				Gen_Con = Gen_StateInfo->Conn;
			}

			/*
			** This is an invalid state so issue
			** the following message and quit.
			**
			** 	"Invalid iterator state used in TopK."
			*/
			DBDK_TRACE_ERROR( "TopK", ERRORMESG17, 10 );

			/* not reached */

			break;
	}


	mi_fp_setreturnisnull( Gen_fparam, 0, MI_TRUE );
	return ( 0 );
}
/* }}FUNCTION (#OHP8G1K6) */



#ifdef __cplusplus

}

#endif