/*
 * Licensed Materials - Property of HCL
 *
 * IBM Informix  DataBlade Module
 * (C) Copyright International Business Machines Corporation 2002.
 * (c) Copyright HCL Technologies Ltd. 2017.  All Rights Reserved.
 *
 * COPYRIGHT LICENSE: 
 * This information contains sample application programs in source language,
 * which illustrate programming techniques on various operating platforms.
 * You may copy, modify, and distribute these sample programs in any form
 * without payment to IBM, for the purposes of developing, using, marketing 
 * or distributing application programs conforming to the application 
 * programming interface for the operating platform for which the sample 
 * programs are written. These examples have not been thoroughly tested under 
 * all conditions. IBM, therefore, cannot guarantee or imply reliability, 
 * serviceability, or function of these programs. You may copy, modify, and 
 * distribute these sample programs in any form without payment to IBM for 
 * the purposes of developing, using, marketing, or distributing application 
 * programs conforming to IBM's application programming interfaces. 
 * Each copy or any portion of these sample programs or any derivative work, 
 * must include a copyright notice as follows: 
 * © (your company name) (year). Portions of this code are derived from 
 * IBM Corp. Sample Programs. © Copyright IBM Corp. (enter the year or 
 * years). All rights reserved. 
 *
 */

/* 
 * SETUP:
 * create function Interp(TimeSeries) returns TimeSeries
 * external name 'Interpolate.so(ts_interp)'
 * language c not variant;
 * 
 *
 * USAGE:
 * select Interp(stock_data) from daily_stocks where stock_id = 901;
 */

#include <stdio.h>
#include <mi.h>
#include <tseries.h>

# define TS_MAX_COLS	100
# define DATATYPE	"smallfloat"

/*
 * This example interpolates between values to fill in null elements.
 * It assumes that all columns are of type smallfloat and that there are 
 * less than 100 columns in each element.
 */

#ifdef NT
__declspec(dllexport) 
#endif
ts_timeseries *
ts_interp(tsPtr, fParamPtr)
    ts_timeseries	*tsPtr;
    MI_FPARAM		*fParamPtr;
{
    ts_tsdesc		*descPtr;
    ts_tselem		tselem;
    ts_tscan		*scan;
    MI_CONNECTION       *conn;
    ts_typeinfo		*typeinfo;
    int			scancode;
    mi_real	        *values[TS_MAX_COLS];
    mi_real	        lastValues[TS_MAX_COLS], newValues[TS_MAX_COLS];
    mi_boolean		nulls[TS_MAX_COLS];
    mi_integer		minElem, curElem, elem;
    mi_integer		i;
    mi_boolean		noneYet;
    mi_integer		ncols;
    char		strbuf[100];
    
    /* get a connection for libmi */
    conn = mi_open(NULL,NULL,NULL);

    /* open a descriptor for the timeseries */
    descPtr = ts_open(conn, tsPtr, mi_fp_rettype(fParamPtr, 0), 0);

    if ((ncols = (mi_integer) mi_fp_funcstate(fParamPtr)) == 0) {
	ncols = ts_col_cnt(descPtr);

	if (ncols > TS_MAX_COLS) {
	    sprintf(strbuf, "Timeseries elements have too many columns, 100 is the max, got %d instead.", ncols);
	    mi_db_error_raise(NULL, MI_FATAL, strbuf, 0);
	}

	for (i = 1; i < ncols; i++) {
	    typeinfo = ts_colinfo_number(descPtr, i);

	    if (strlen(typeinfo->ti_typename) != strlen(DATATYPE) ||
		memcmp(typeinfo->ti_typename, DATATYPE, strlen(DATATYPE)) != 0){
		sprintf(strbuf, "column was not a %s, got %s instead.", DATATYPE, typeinfo->ti_typename);
		mi_db_error_raise(NULL, MI_FATAL, strbuf, 0);
	    }
	}

	mi_fp_setfuncstate(fParamPtr, (void *) ncols);
    }

    noneYet = MI_TRUE;
    minElem = -1;
    curElem = 0;
    /* begin a scan of the whole timeseries */
    scan = ts_begin_scan(descPtr, 0, NULL, NULL);
    while ((scancode = ts_next(scan, &tselem)) != TS_SCAN_EOS) {
	switch(scancode) {
	    case TS_SCAN_ELEM:
		/* if this element is not null expand its values */
		noneYet = MI_FALSE;
		ts_get_all_cols(descPtr, tselem, (void **) values, nulls, curElem);
		if (minElem == -1) {
		    /* save each element */
		    for (i = 1; i < ncols; i++) 
			lastValues[i] = *values[i];
		}
		else {
		    /* calculate the average */
		    for (i = 1; i < ncols; i++) {
			newValues[i] = (*values[i] + lastValues[i])/2.0;
			lastValues[i] = *values[i];
			values[i] = &newValues[i];
		    }

		    /* update the missing elements */

		    tselem = ts_make_elem(descPtr, (void **) values, nulls, &elem);
		    for (elem = minElem; elem < curElem; elem++)
			ts_put_nth_elem(descPtr, tselem, elem);

		    minElem = -1;
		}
		    
		break;
	    case TS_SCAN_NULL:
		if (noneYet) 
		    break;
		/* remember the first null element */
		if (minElem == -1)
		    minElem = curElem;
		break;
	}

	curElem++;
    }
    ts_end_scan(scan);
    ts_close(descPtr);
    return(tsPtr);
}