/*
  Copyright (c) 2010 Joachim Bonnet <joachim.bonnet@studium.uni-hamburg.de>

  Permission to use, copy, modify, and distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include <stdio.h>
#include "core/array_api.h"
#include "core/bittab_api.h"
#include "core/class_alloc_lock.h"
#include "core/ensure.h"
#include "core/ma.h"
#include "core/unused_api.h"
#include "extended/clustered_set.h"
#include "extended/clustered_set_uf.h"
#include "extended/clustered_set_rep.h"

#define CLUSTERED_SET_UNION_FIND_TEST_SIZE  1024

#define CLUSTERNIL (cs_uf->num_of_elems)

#define SINGLETON(E) !gt_bittab_bit_is_set(cs_uf->in_cluster, E)

#define CINFO(C) ((GtClusteredSetUFClusterInfo*)\
                 gt_array_get(cs_uf->cluster_info, C))

#define CHECKCLUSTER(C)\
        if ((C) >= cs_uf->next_free_cluster_info)\
        {\
         gt_error_set(err, "cluster "GT_WU" is too large, must be smaller than"\
                      ""GT_WU"", C, cs_uf->next_free_cluster_info);\
          had_err = -1;\
        }\
        if (CINFO(C)->cluster_size == 0)\
        {\
         gt_error_set(err, "cluster "GT_WU" is empty", C);\
         had_err = -1;\
        }

struct GtClusteredSetUFElem {
  GtUword cluster_num, next_elem;
};

struct GtClusteredSetUFClusterInfo {
  GtUword first_elem, last_elem, cluster_size;
};

struct GtClusteredSetUF {
  const GtClusteredSet parent_instance;
  GtClusteredSetUFElem *cluster_elems;
  GtArray *cluster_info;
  GtBittab *in_cluster;
  GtUword num_of_elems, next_free_cluster_info;
};

static void
gt_clustered_set_union_find_change_cluster_number(GtClusteredSetUF *cs_uf,
                                                  GtUword first_elem,
                                                  GtUword target)
{

  GtUword i;
  i = first_elem;
  while (1)
  {
    cs_uf->cluster_elems[i].cluster_num = target;
    if ((i = cs_uf->cluster_elems[i].next_elem) == cs_uf->num_of_elems)
      break;
  }
}

static void
gt_clustered_set_union_find_make_new_cluster(GtClusteredSetUF *cs_uf,
                                             GtUword elem1,
                                             GtUword elem2,
                                             GT_UNUSED GtError *err)
{
  GtUword cluster_num;
  cluster_num = cs_uf->next_free_cluster_info++;

  cs_uf->cluster_elems[elem1].cluster_num = cluster_num;
  cs_uf->cluster_elems[elem2].cluster_num = cluster_num;
  cs_uf->cluster_elems[elem1].next_elem = elem2;
  cs_uf->cluster_elems[elem2].next_elem = cs_uf->num_of_elems;

  GtClusteredSetUFClusterInfo cluster_info;
  cluster_info.cluster_size = (GtUword) 2;
  cluster_info.first_elem = elem1;
  cluster_info.last_elem = elem2;

  gt_array_add(cs_uf->cluster_info, cluster_info);
}

static void
gt_clustered_set_union_find_append_elem(GtClusteredSetUF *cs_uf,
                                        GtUword c,
                                        GtUword elem,
                                        GT_UNUSED GtError *err)
{
  GtClusteredSetUFClusterInfo *cluster_info;
  cs_uf->cluster_elems[elem].cluster_num = c;
  cs_uf->cluster_elems[elem].next_elem = cs_uf->num_of_elems;
  cluster_info = CINFO(c);
  cs_uf->cluster_elems[cluster_info->last_elem].next_elem = elem;
  cluster_info->last_elem = elem;
  cluster_info->cluster_size++;
}

static void
gt_clustered_set_union_find_join_clusters(GtClusteredSetUF *cs_uf,
                                           GtUword c1,
                                           GtUword c2,
                                           GT_UNUSED GtError *err)
{
  GtClusteredSetUFClusterInfo *cluster_info_c1;
  GtClusteredSetUFClusterInfo *cluster_info_c2;

  cluster_info_c1 = CINFO(c1);
  cluster_info_c2 = CINFO(c2);

  gt_clustered_set_union_find_change_cluster_number(cs_uf,
                                                    cluster_info_c2->first_elem,
                                                    c1);

  cs_uf->cluster_elems[cluster_info_c1->last_elem].next_elem =
    cluster_info_c2->first_elem;

  cluster_info_c2->first_elem = cs_uf->num_of_elems;
  cluster_info_c1->cluster_size += cluster_info_c2->cluster_size;
  cluster_info_c1->last_elem = cluster_info_c2->last_elem;
  cluster_info_c2->cluster_size = (GtUword) 0;
}

GtClusteredSetIterator*
gt_clustered_set_union_find_iterator_new(GtClusteredSet *cs,
                                         GtUword c,
                                         GT_UNUSED GtError *err)
{
  gt_assert(cs);
  GtClusteredSetUF *cs_uf = (GtClusteredSetUF*) cs;
  GtClusteredSetIterator *cs_i = gt_calloc(1, sizeof (GtClusteredSetIterator));
  GtUword i = 0, j = 0;
  if (SINGLETON(c)) {
    cs_i->length = (GtUword) 1;
    cs_i->curpos = (GtUword) 0;
    cs_i->elems = gt_calloc(1, sizeof (GtUword));
    cs_i->elems[j] = c;
  }
  else {
    if (CINFO(c)->cluster_size > 0) {
      GtClusteredSetUFClusterInfo *cluster_info;
      cluster_info = CINFO(c);
      cs_i->length = cluster_info->cluster_size;
      cs_i->curpos = (GtUword) 0;
      cs_i->elems = gt_calloc(cluster_info->cluster_size,
                              sizeof (GtUword));
      i = cluster_info->first_elem;

      do {
        cs_i->elems[j] = i;
        j++;
      } while ((i = cs_uf->cluster_elems[i].next_elem) < cs_uf->num_of_elems);

    } else {
      gt_free(cs_i);
      return NULL;
    }
  }
  return cs_i;
}

void gt_clustered_set_union_find_delete(GtClusteredSet *cs,
                                        GT_UNUSED GtError *err)
{
  if (!cs) return;
  GtClusteredSetUF *cs_uf = (GtClusteredSetUF*) cs;
  gt_free(cs_uf->cluster_elems);
  gt_array_delete(cs_uf->cluster_info);
  gt_bittab_delete(cs_uf->in_cluster);
}

GtUword gt_clustered_set_union_find_num_of_clusters(GtClusteredSet *cs,
                                                       GT_UNUSED GtError *err)
{
  gt_assert(cs);
  GtClusteredSetUF *cs_uf = (GtClusteredSetUF*) cs;
  return cs_uf->next_free_cluster_info;
}

GtUword gt_clustered_set_union_find_num_of_elements(GtClusteredSet *cs,
                                                       GT_UNUSED GtError *err)
{
  gt_assert(cs);
  GtClusteredSetUF *cs_uf = (GtClusteredSetUF*) cs;
  return cs_uf->num_of_elems;
}

GtUword gt_clustered_set_union_find_cluster_num(GtClusteredSet *cs,
                                                      GtUword e,
                                                      GT_UNUSED GtError *err
                                                      )
{
  gt_assert(cs);
  GtClusteredSetUF *cs_uf = (GtClusteredSetUF*) cs;
  if (SINGLETON(e))
    return CLUSTERNIL;
  else
    return cs_uf->cluster_elems[e].cluster_num;
}

int gt_clustered_set_union_find_merge_clusters(GtClusteredSet *cs,
                                               GtUword e1,
                                               GtUword e2,
                                               GtError *err)
{
  gt_assert(cs);
  int had_err = 0;
  GtClusteredSetUFClusterInfo *cluster_info_c1 = NULL;
  GtClusteredSetUFClusterInfo *cluster_info_c2 = NULL;
  GtUword target = 0, source = 0, c1 = 0, c2 = 0;
  GtClusteredSetUF *cs_uf = (GtClusteredSetUF*) cs;
  if (e1 == e2) {
    gt_error_set(err, "expected "GT_WU" to be unequal "GT_WU"", e1, e2 );
    had_err = -1;
  }

  if (e1 >= cs_uf->num_of_elems || e2 >= cs_uf->num_of_elems) {
    gt_error_set(err, ""GT_WU" and "GT_WU" must not be larger than "GT_WU"",
                 e1, e2, cs_uf->num_of_elems);
    had_err = -1;
  }

  if (!had_err) {
    if (SINGLETON(e1)) {
       /* printf(""GT_WU" is singleton\n", e1); */
      if (SINGLETON(e2)) {
        /* printf(""GT_WU" is singleton\n", e2);*/
        gt_clustered_set_union_find_make_new_cluster(cs_uf, e1, e2, err);
        gt_bittab_set_bit(cs_uf->in_cluster, e2);
      }
      else {
        c2 = cs_uf->cluster_elems[e2].cluster_num;
        CHECKCLUSTER(c2);
        gt_clustered_set_union_find_append_elem(cs_uf, c2, e1, err);
      }
      gt_bittab_set_bit(cs_uf->in_cluster, e1);
    }
    else {
      c1 = cs_uf->cluster_elems[e1].cluster_num;
      CHECKCLUSTER(c1);
      if (SINGLETON(e2)) {
        gt_clustered_set_union_find_append_elem(cs_uf, c1, e2, err);
        gt_bittab_set_bit(cs_uf->in_cluster, e2);
      }
      else {
        c2 = cs_uf->cluster_elems[e2].cluster_num;
        CHECKCLUSTER(c2);
        cluster_info_c1 = CINFO(c1);
        cluster_info_c2 = CINFO(c2);
        if (cluster_info_c1->cluster_size > cluster_info_c2->cluster_size) {
          target = c1;
          source = c2;
        }
        else {
          target = c1;
          source = c2;
        }
        if (target != source)
          gt_clustered_set_union_find_join_clusters(cs_uf, target, source, err);
      }
    }
  }
  return had_err;
}

const GtClusteredSetClass* gt_clustered_set_union_find_class(void)
{

  static const GtClusteredSetClass *csc = NULL;
  gt_class_alloc_lock_enter();
  if (!csc) {
    csc = gt_clustered_set_class_new(sizeof (GtClusteredSetUF),
      gt_clustered_set_union_find_num_of_clusters,
      gt_clustered_set_union_find_merge_clusters,
      gt_clustered_set_union_find_delete,
      gt_clustered_set_union_find_iterator_new,
      gt_clustered_set_union_find_num_of_elements,
      gt_clustered_set_union_find_cluster_num);
  }
  gt_class_alloc_lock_leave();
  return csc;
}

GtClusteredSet*
gt_clustered_set_union_find_new(GtUword num_of_elems,
                                GT_UNUSED GtError *err)
{
  GtClusteredSet *cs;
  GtClusteredSetUF *cs_uf;
  cs = gt_clustered_set_create(gt_clustered_set_union_find_class());
  cs_uf = (GtClusteredSetUF*) cs;
  cs_uf->num_of_elems = num_of_elems;
  cs_uf->cluster_elems = gt_calloc(num_of_elems, sizeof (GtClusteredSetUFElem));
  cs_uf->cluster_info = gt_array_new(sizeof (GtClusteredSetUFClusterInfo));
  cs_uf->in_cluster = gt_bittab_new(num_of_elems);
  cs_uf->next_free_cluster_info = (GtUword) 0;

  return cs;
}

int gt_clustered_set_union_find_unit_test(GtError *err)
{
  int had_err = 0, i = 0, j = 0;
  GtClusteredSet *cs = NULL;
  cs = gt_clustered_set_union_find_new(1, err);
  gt_ensure(
            gt_clustered_set_union_find_num_of_elements(cs, err) ==
            gt_clustered_set_union_find_cluster_num(cs, 0, err));
  gt_ensure(
            gt_clustered_set_union_find_num_of_clusters(cs, err) == 0);
  gt_clustered_set_union_find_delete(cs, err);

  if (!had_err) {
    cs = gt_clustered_set_union_find_new(2, err);
    gt_clustered_set_union_find_merge_clusters(cs, 0, 1, err);

    gt_ensure(
              gt_clustered_set_union_find_num_of_clusters(cs, err) == 1);
    gt_ensure(
              gt_clustered_set_union_find_cluster_num(cs, 0, err) ==
              gt_clustered_set_union_find_cluster_num(cs, 1, err));
    gt_ensure(
              gt_clustered_set_union_find_num_of_clusters(cs, err) == 1);

    gt_clustered_set_union_find_delete(cs, err);
  }

  if (!had_err) {
    cs = gt_clustered_set_union_find_new(3, err);
    gt_clustered_set_union_find_merge_clusters(cs, 0, 1, err);
    gt_clustered_set_union_find_merge_clusters(cs, 1, 2, err);

    gt_ensure(
               gt_clustered_set_union_find_num_of_clusters(cs, err) == 1);
    gt_ensure(
               gt_clustered_set_union_find_cluster_num(cs, 0, err) ==
               gt_clustered_set_union_find_cluster_num(cs, 1, err));

    gt_ensure(
               gt_clustered_set_union_find_cluster_num(cs, 0, err) ==
               gt_clustered_set_union_find_cluster_num(cs, 2, err));

    gt_ensure(
              gt_clustered_set_union_find_cluster_num(cs, 1, err) ==
              gt_clustered_set_union_find_cluster_num(cs, 2, err));

    gt_clustered_set_union_find_delete(cs, err);
  }

  if (!had_err) {
    cs = gt_clustered_set_union_find_new(4, err);
    gt_clustered_set_union_find_merge_clusters(cs, 0, 1, err);
    gt_clustered_set_union_find_merge_clusters(cs, 2, 3, err);

    gt_ensure(
              gt_clustered_set_union_find_num_of_clusters(cs, err) == 2);

    gt_clustered_set_union_find_merge_clusters(cs, 0, 2, err);

    for (i = 0; i < 4 - 1; i++) {
      for (j = i + 1; j < 4; j++) {
        gt_ensure(
                  gt_clustered_set_union_find_cluster_num(cs, i, err) ==
                  gt_clustered_set_union_find_cluster_num(cs, j, err));
      }
    }
    gt_clustered_set_union_find_delete(cs, err);
  }

  if (!had_err) {
    cs = gt_clustered_set_union_find_new(CLUSTERED_SET_UNION_FIND_TEST_SIZE,
                                         err);

    for (i = 0; !had_err && i < CLUSTERED_SET_UNION_FIND_TEST_SIZE; i++) {
      gt_ensure(
                gt_clustered_set_union_find_num_of_elements(cs, err) ==
                gt_clustered_set_union_find_cluster_num(cs, i, err));
    }
    for (i = 1;!had_err && i < CLUSTERED_SET_UNION_FIND_TEST_SIZE; i++) {
      gt_clustered_set_union_find_merge_clusters(cs, 0, i, err);
    }

    for (i = 0; !had_err && i < CLUSTERED_SET_UNION_FIND_TEST_SIZE; i++) {
      gt_ensure(
                gt_clustered_set_union_find_cluster_num(cs, i, err) == 0);
    }
    gt_clustered_set_union_find_delete(cs, err);
  }

  return had_err;
}
