/*
 * Copyright (c) 2014, Sandia Corporation.
 * Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
 * the U.S. Government retains certain rights in this software.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * Redistributions in binary form must reproduce the above
 *       copyright notice, this list of conditions and the following
 *       disclaimer in the documentation and/or other materials provided
 *       with the distribution.
 *
 *     * Neither the name of Sandia Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "structs.h"
#include <stdio.h> // for printf

/* Find a maximal matching in a graph using one of several algorithms. */

int maxmatch(struct vtx_data **graph,       /* array of vtx data for graph */
             int               nvtxs,       /* number of vertices in graph */
             int               nedges,      /* number of edges in graph */
             int *             mflag,       /* flag indicating vtx selected or not */
             int               using_ewgts, /* are edge weights being used? */
             int               igeom,       /* geometric dimensionality */
             float **          coords       /* coordinates for each vertex */
             )
{
  extern int DEBUG_COARSEN; /* debug output for coarsening? */
  extern int MATCH_TYPE;    /* which matching routine to use */
  int        nmerged = 0;   /* number of matching edges found */
  int        maxmatch1(), maxmatch2(), maxmatch3(), maxmatch4();
  int        maxmatch5(), maxmatch9();

  if (MATCH_TYPE == 1 || (MATCH_TYPE == 5 && coords == NULL)) {
    /* Dumb, fast routine. */
    nmerged = maxmatch1(graph, nvtxs, mflag, using_ewgts);
  }

  else if (MATCH_TYPE == 2) { /* More random but somewhat slower. */
    nmerged = maxmatch2(graph, nvtxs, mflag, using_ewgts);
  }

  else if (MATCH_TYPE == 3) { /* Much more random but slower still. */
    nmerged = maxmatch3(graph, nvtxs, mflag, using_ewgts);
  }

  else if (MATCH_TYPE == 4) { /* Truly random but very slow. */
    nmerged = maxmatch4(graph, nvtxs, nedges, mflag, using_ewgts);
  }
  else if (MATCH_TYPE == 5 && coords != NULL) { /* Geometric nearness. */
    nmerged = maxmatch5(graph, nvtxs, mflag, igeom, coords);
  }

  else if (MATCH_TYPE == 9) { /* Minimum degree of merged vertex */
    nmerged = maxmatch9(graph, nvtxs, mflag, using_ewgts);
  }

  if (DEBUG_COARSEN > 0) {
    printf("Number of matching edges = %d\n", nmerged);
  }

  return (nmerged);
}
