/* vi: set ts=2:
 +-------------------+
 |                   |  Christian Schlittchen <corwin@amber.kn-bremen.de>
 | Eressea PBEM host |  Enno Rehling <enno@eressea.de>
 | (c) 1998 - 2004   |  Katja Zedel <katze@felidae.kn-bremen.de>
 |                   |
 +-------------------+

 This program may not be used, modified or distributed
 without prior permission by the authors of Eressea.
*/

#include <platform.h>
#include <kernel/config.h>
#include "settings.h"

#include "wormhole.h"

/* kernel includes */
#include <kernel/building.h>
#include <kernel/faction.h>
#include <kernel/message.h>
#include <kernel/plane.h>
#include <kernel/region.h>
#include <kernel/unit.h>
#include <kernel/version.h>

/* util includes */
#include <util/attrib.h>
#include <util/language.h>
#include <util/resolve.h>
#include <util/rng.h>
#include <util/quicklist.h>
#include <util/storage.h>

/* libc includes */
#include <assert.h>
#include <stdlib.h>

static boolean good_region(const region * r)
{
  return (!fval(r, RF_CHAOTIC) && r->age > 30 && rplane(r) == NULL
    && r->units != NULL && r->land != NULL);
}

static int cmp_age(const void *v1, const void *v2)
{
  const region *r1 = (const region *)v1;
  const region *r2 = (const region *)v2;
  if (r1->age < r2->age)
    return -1;
  if (r1->age > r2->age)
    return 1;
  return 0;
}

typedef struct wormhole_data {
  building *entry;
  region *exit;
} wormhole_data;

static void wormhole_init(struct attrib *a)
{
  a->data.v = calloc(1, sizeof(wormhole_data));
}

static void wormhole_done(struct attrib *a)
{
  free(a->data.v);
}

static int wormhole_age(struct attrib *a)
{
  wormhole_data *data = (wormhole_data *) a->data.v;
  int maxtransport = data->entry->size;
  region *r = data->entry->region;
  unit *u = r->units;

  for (; u != NULL && maxtransport != 0; u = u->next) {
    if (u->building == data->entry) {
      message *m = NULL;
      if (u->number > maxtransport || has_limited_skills(u)) {
        m = msg_message("wormhole_requirements", "unit region", u, u->region);
      } else if (data->exit != NULL) {
        move_unit(u, data->exit, NULL);
        maxtransport -= u->number;
        m = msg_message("wormhole_exit", "unit region", u, data->exit);
        add_message(&data->exit->msgs, m);
      }
      if (m != NULL) {
        add_message(&u->faction->msgs, m);
        msg_release(m);
      }
    }
  }

  remove_building(&r->buildings, data->entry);
  ADDMSG(&r->msgs, msg_message("wormhole_dissolve", "region", r));

  /* age returns 0 if the attribute needs to be removed, !=0 otherwise */
  return AT_AGE_KEEP;
}

static void
wormhole_write(const struct attrib *a, const void *owner, struct storage *store)
{
  wormhole_data *data = (wormhole_data *) a->data.v;
  write_building_reference(data->entry, store);
  write_region_reference(data->exit, store);
}

/** conversion code, turn 573, 2008-05-23 */
static int resolve_exit(variant id, void *address)
{
  building *b = findbuilding(id.i);
  region **rp = address;
  if (b) {
    *rp = b->region;
    return 0;
  }
  *rp = NULL;
  return -1;
}

static int wormhole_read(struct attrib *a, void *owner, struct storage *store)
{
  wormhole_data *data = (wormhole_data *) a->data.v;
  resolve_fun resolver =
    (store->version < UIDHASH_VERSION) ? resolve_exit : resolve_region_id;
  read_fun reader =
    (store->version <
    UIDHASH_VERSION) ? read_building_reference : read_region_reference;

  int rb =
    read_reference(&data->entry, store, read_building_reference,
    resolve_building);
  int rr = read_reference(&data->exit, store, reader, resolver);
  if (rb == 0 && rr == 0) {
    if (!data->exit || !data->entry) {
      return AT_READ_FAIL;
    }
  }
  return AT_READ_OK;
}

static attrib_type at_wormhole = {
  "wormhole",
  wormhole_init,
  wormhole_done,
  wormhole_age,
  wormhole_write,
  wormhole_read,
  ATF_UNIQUE
};

static void
make_wormhole(const building_type * bt_wormhole, region * r1, region * r2)
{
  building *b1 = new_building(bt_wormhole, r1, default_locale);
  building *b2 = new_building(bt_wormhole, r2, default_locale);
  attrib *a1 = a_add(&b1->attribs, a_new(&at_wormhole));
  attrib *a2 = a_add(&b2->attribs, a_new(&at_wormhole));
  wormhole_data *d1 = (wormhole_data *) a1->data.v;
  wormhole_data *d2 = (wormhole_data *) a2->data.v;
  d1->entry = b1;
  d2->entry = b2;
  d1->exit = b2->region;
  d2->exit = b1->region;
  b1->size = bt_wormhole->maxsize;
  b2->size = bt_wormhole->maxsize;
  ADDMSG(&r1->msgs, msg_message("wormhole_appear", "region", r1));
  ADDMSG(&r2->msgs, msg_message("wormhole_appear", "region", r2));
}

void create_wormholes(void)
{
#define WORMHOLE_CHANCE 10000
  const building_type *bt_wormhole = bt_find("wormhole");
  quicklist *ql, *rlist = 0;
  region *r = regions;
  int qi, i = 0, count = 0;
  region **match;

  if (bt_wormhole == NULL)
    return;
  /*
   * select a list of regions. we'll sort them by age later.
   */
  while (r != NULL) {
    int next = rng_int() % (2 * WORMHOLE_CHANCE);
    while (r != NULL && (next != 0 || !good_region(r))) {
      if (good_region(r)) {
        --next;
      }
      r = r->next;
    }
    if (r == NULL)
      break;
    ql_push(&rlist, r);
    ++count;
    r = r->next;
  }

  if (count < 2)
    return;

  match = (region **) malloc(sizeof(region *) * count);
  
  for (ql = rlist,qi = 0; i != count; ql_advance(&ql, &qi, 1)) {
    match[i++] = (region *)ql_get(ql, qi);
  }
  qsort(match, count, sizeof(region *), cmp_age);
  ql_free(rlist);

  count /= 2;
  for (i = 0; i != count; ++i) {
    make_wormhole(bt_wormhole, match[i], match[i + count]);
  }
  free(match);
}

void register_wormholes(void)
{
  at_register(&at_wormhole);
}