#include <stdlib.h>
#include <float.h>
#include <R.h>
#include <Rinternals.h>
#include <Rmath.h>

#include <stdio.h>

// (K,L): dim(medoids)
// mi: medoids indices
SEXP computeMedoidsIndices(SEXP medoids_, SEXP ref_series_)
{
	double *medoids = (double*) R_ExternalPtrAddr(medoids_),
		*ref_series = REAL(ref_series_);
	int nb_series = INTEGER(getAttrib(ref_series_, R_DimSymbol))[0],
		K = INTEGER(getAttrib(medoids_, R_DimSymbol))[0],
		L = INTEGER(getAttrib(ref_series_, R_DimSymbol))[1],
		*mi = (int*)malloc(nb_series*sizeof(int));

	//TODO: debug this: medoids have same addresses on both sides, but this side fails
	printf("MED: %x\n",medoids);

	for (int i=0; i<nb_series ; i++)
	{
		// mi[i] <- which.min( rowSums( sweep(medoids, 2, ref_series[i,], '-')^2 ) )
		mi[i] = 0;
		double best_dist = DBL_MAX;
		for (int j=0; j<K; j++)
		{
			double dist_ij = 0.;
			for (int k=0; k<L; k++)
			{
				double delta = ref_series[k*K+i] - medoids[k*K+j];
				dist_ij += delta * delta;
			}
			if (dist_ij < best_dist)
			{
				mi[i] = j+1; //R indices start at 1
				best_dist = dist_ij;
			}
		}
	}

	SEXP R_mi;
	PROTECT(R_mi = allocVector(INTSXP, nb_series));
	for (int i = 0; i < nb_series; i++)
		INTEGER(R_mi)[i] = mi[i];
	UNPROTECT(1);
	free(mi);
	return R_mi;
}