/*
 *  R : A Computer Language for Statistical Data Analysis
 *  Copyright (C) 2012--2019 The R Core Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, a copy is available at
 *  https://www.R-project.org/Licenses/
 */

#include <R.h>
#include <Rinternals.h>
#include "statsR.h"
#include "stats.h"

SEXP influence(SEXP mqr, SEXP e, SEXP stol)
{
    SEXP qr = getListElement(mqr, "qr"), qraux = getListElement(mqr, "qraux");
    int n = nrows(qr), k = asInteger(getListElement(mqr, "rank")),
	q = ncols(e);
    double tol = asReal(stol);

    SEXP hat = PROTECT(allocVector(REALSXP, n));
    double *rh = REAL(hat);
    SEXP sigma = PROTECT(allocMatrix(REALSXP, n, q));
    F77_CALL(lminfl)(REAL(qr), &n, &n, &k, &q, REAL(qraux),
		     REAL(e), rh, REAL(sigma), &tol);

    for (int i = 0; i < n; i++) if (rh[i] > 1. - tol) rh[i] = 1.;
    SEXP ans = PROTECT(allocVector(VECSXP, 2));
    SEXP nm =  allocVector(STRSXP, 2);
    setAttrib(ans, R_NamesSymbol, nm);
    int m = 0;
    SET_VECTOR_ELT(ans, m, hat);
    SET_STRING_ELT(nm, m++, mkChar("hat"));
    SET_VECTOR_ELT(ans, m, sigma);
    SET_STRING_ELT(nm, m++, mkChar("sigma"));
    UNPROTECT(3);
    return ans;
}