//------------------------------------------------------------------------------
// CHOLMOD/MATLAB/mwrite: write a matrix in Matrix Market format
//------------------------------------------------------------------------------

// CHOLMOD/MATLAB Module.  Copyright (C) 2005-2023, Timothy A. Davis.
// All Rights Reserved.
// SPDX-License-Identifier: GPL-2.0+

//------------------------------------------------------------------------------

// Write a matrix to a file in Matrix Market form.
//
//      symmetry = mwrite (filename, A, Z, comments_filename)
//
// A can be sparse or full.
//
// If present and non-empty, A and Z must have the same dimension.  Z contains
// the explicit zero entries in the matrix (which MATLAB drops).  The entries
// of Z appear as explicit zeros in the output file.  Z is optional.  If it is
// an empty matrix it is ignored.  Z must be sparse or empty, if present.
// It is ignored if A is full.
//
// filename is the name of the output file.  comments_file is file whose
// contents are include after the Matrix Market header and before the first
// data line.  Ignored if an empty string or not present.

#include "sputil2.h"

#define MAXLEN 1030

void mexFunction
(
    int nargout,
    mxArray *pargout [ ],
    int nargin,
    const mxArray *pargin [ ]
)
{
    double dummy = 0 ;
    cholmod_sparse Amatrix, Zmatrix, *A, *Z ;
    cholmod_dense Xmatrix, *X ;
    cholmod_common Common, *cm ;
    int64_t arg_z, arg_comments, sym ;
    char filename [MAXLEN], comments [MAXLEN] ;

    //--------------------------------------------------------------------------
    // start CHOLMOD and set parameters
    //--------------------------------------------------------------------------

    cm = &Common ;
    cholmod_l_start (cm) ;
    sputil2_config (SPUMONI, cm) ;

    //--------------------------------------------------------------------------
    // check inputs
    //--------------------------------------------------------------------------

    if (nargin < 2 || nargin > 4 || nargout > 1)
    {
        mexErrMsgTxt ("Usage: mwrite (filename, A, Z, comments_filename)") ;
    }

    //--------------------------------------------------------------------------
    // get the output filename
    //--------------------------------------------------------------------------

    if (!mxIsChar (pargin [0]))
    {
        mexErrMsgTxt ("first parameter must be a filename") ;
    }
    mxGetString (pargin [0], filename, MAXLEN) ;

    //--------------------------------------------------------------------------
    // get the A matrix (sparse or dense)
    //--------------------------------------------------------------------------

    size_t A_xsize = 0 ;
    size_t X_xsize = 0 ;

    if (mxIsSparse (pargin [1]))
    {
        A = sputil2_get_sparse (pargin [1], 0, CHOLMOD_DOUBLE, &Amatrix,
            &A_xsize, cm) ;
        X = NULL ;
    }
    else
    {
        X = sputil2_get_dense (pargin [1], CHOLMOD_DOUBLE, &Xmatrix,
            &X_xsize, cm) ;
        A = NULL ;
    }

    //--------------------------------------------------------------------------
    // determine if the Z matrix and comments_file are present
    //--------------------------------------------------------------------------

    if (nargin == 3)
    {
        if (mxIsChar (pargin [2]))
        {
            // mwrite (file, A, comments)
            arg_z = -1 ;
            arg_comments = 2 ;
        }
        else
        {
            // mwrite (file, A, Z).  Ignore Z if A is full
            arg_z = (A == NULL) ? -1 : 2 ;
            arg_comments = -1 ;
        }
    }
    else if (nargin == 4)
    {
        // mwrite (file, A, Z, comments).  Ignore Z is A is full
        arg_z = (A == NULL) ? -1 : 2 ;
        arg_comments = 3 ;
    }
    else
    {
        arg_z = -1 ;
        arg_comments = -1 ;
    }

    //--------------------------------------------------------------------------
    // get the Z matrix
    //--------------------------------------------------------------------------

    size_t Z_xsize = 0 ;
    if (arg_z == -1 ||
        mxGetM (pargin [arg_z]) == 0 || mxGetN (pargin [arg_z]) == 0)
    {
        // A is dense, Z is not present, or Z is empty.  Ignore Z.
        Z = NULL ;
    }
    else
    {
        // A is sparse and Z is present and not empty
        if (!mxIsSparse (pargin [arg_z]))
        {
            mexErrMsgTxt ("Z must be sparse") ;
        }
        Z = sputil2_get_sparse (pargin [arg_z], 0, CHOLMOD_DOUBLE, &Zmatrix,
            &Z_xsize, cm) ;
    }

    //--------------------------------------------------------------------------
    // get the comments filename
    //--------------------------------------------------------------------------

    comments [0] = '\0' ;
    if (arg_comments != -1)
    {
        if (!mxIsChar (pargin [arg_comments]))
        {
            mexErrMsgTxt ("comments filename must be a string") ;
        }
        mxGetString (pargin [arg_comments], comments, MAXLEN) ;
    }

    //--------------------------------------------------------------------------
    // write the matrix to the file
    //--------------------------------------------------------------------------

    sputil2_file = fopen (filename, "w") ;
    if (sputil2_file == NULL)
    {
        mexErrMsgTxt ("error opening file") ;
    }
    if (A != NULL)
    {
        sym = cholmod_l_write_sparse (sputil2_file, A, Z, comments, cm) ;
    }
    else
    {
        sym = cholmod_l_write_dense (sputil2_file, X, comments, cm) ;
    }
    fclose (sputil2_file) ;
    sputil2_file = NULL ;
    if (sym < 0)
    {
        mexErrMsgTxt ("mwrite failed") ;
    }

    //--------------------------------------------------------------------------
    // free workspace and return symmetry
    //--------------------------------------------------------------------------


    sputil2_free_sparse (&A, &Amatrix, A_xsize, cm) ;
    sputil2_free_sparse (&Z, &Zmatrix, Z_xsize, cm) ;
    sputil2_free_dense  (&X, &Xmatrix, X_xsize, cm) ;
    pargout [0] = sputil2_put_int (&sym, 1, 0) ;
    cholmod_l_finish (cm) ;
    if (SPUMONI > 0) cholmod_l_print_common (" ", cm) ;
}