/* Emacs style mode select   -*- C++ -*-
 *-----------------------------------------------------------------------------
 *
 *
 *  PrBoom: a Doom port merged with LxDoom and LSDLDoom
 *  based on BOOM, a modified and improved DOOM engine
 *  Copyright (C) 1999 by
 *  id Software, Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
 *  Copyright (C) 1999-2002 by
 *  Jess Haas, Nicolas Kalkhof, Colin Phipps, Florian Schulze
 *  Copyright 2005, 2006 by
 *  Florian Schulze, Colin Phipps, Neil Stevens, Andrey Budko
 *
 *  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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 *  02111-1307, USA.
 *
 * DESCRIPTION:
 *      Teleportation.
 *
 *-----------------------------------------------------------------------------*/

#include "doomdef.h"
#include "doomstat.h"
#include "p_spec.h"
#include "p_maputl.h"
#include "p_map.h"
#include "r_main.h"
#include "p_tick.h"
#include "s_sound.h"
#include "sounds.h"
#include "p_user.h"
#include "r_demo.h"

static mobj_t* P_TeleportDestination(line_t* line)
{
  int i;
  for (i = -1; (i = P_FindSectorFromLineTag(line, i)) >= 0;) {
    register thinker_t* th = NULL;
    while ((th = P_NextThinker(th,th_misc)) != NULL)
      if (th->function == P_MobjThinker) {
        register mobj_t* m = (mobj_t*)th;
        if (m->type == MT_TELEPORTMAN  &&
            m->subsector->sector->iSectorID == i)
            return m;
      }
  }
  return NULL;
}
//
// TELEPORTATION
//
// killough 5/3/98: reformatted, cleaned up

int EV_Teleport(line_t *line, int side, mobj_t *thing)
{
  mobj_t    *m;

  // don't teleport missiles
  // Don't teleport if hit back of line,
  //  so you can get out of teleporter.
  if (side || thing->flags & MF_MISSILE)
    return 0;

  // killough 1/31/98: improve performance by using
  // P_FindSectorFromLineTag instead of simple linear search.

  if ((m = P_TeleportDestination(line)) != NULL)
        {
          fixed_t oldx = thing->x, oldy = thing->y, oldz = thing->z;
          player_t *player = thing->player;

          // killough 5/12/98: exclude voodoo dolls:
          if (player && player->mo != thing)
            player = NULL;

          if (!P_TeleportMove(thing, m->x, m->y, false)) /* killough 8/9/98 */
            return 0;

          if (compatibility_level != finaldoom_compatibility)
            thing->z = thing->floorz;
          thing->PrevZ = thing->z;

          if (player)
            player->viewz = thing->z + player->viewheight;

          // spawn teleport fog and emit sound at source
          S_StartSound(P_SpawnMobj(oldx, oldy, oldz, MT_TFOG), sfx_telept);

          // spawn teleport fog and emit sound at destination
          S_StartSound(P_SpawnMobj(m->x +
                                    20*finecosine[m->angle>>ANGLETOFINESHIFT],
                                   m->y +
                                    20*finesine[m->angle>>ANGLETOFINESHIFT],
                                   thing->z, MT_TFOG),
                       sfx_telept);

    /* don't move for a bit
     * cph - DEMOSYNC - BOOM had (player) here? */
          if (thing->player)
            thing->reactiontime = 18;

          thing->angle = m->angle;

          thing->momx = thing->momy = thing->momz = 0;

    /* killough 10/98: kill all bobbing momentum too */
    if (player)
      player->momx = player->momy = 0;

     // e6y
     if (player && player->mo == thing)
      R_ResetAfterTeleport(player);

          return 1;
        }
  return 0;
}

//
// Silent TELEPORTATION, by Lee Killough
// Primarily for rooms-over-rooms etc.
//

int EV_SilentTeleport(line_t *line, int side, mobj_t *thing)
{
  mobj_t    *m;

  // don't teleport missiles
  // Don't teleport if hit back of line,
  // so you can get out of teleporter.

  if (side || thing->flags & MF_MISSILE)
    return 0;

  if ((m = P_TeleportDestination(line)) != NULL)
        {
          // Height of thing above ground, in case of mid-air teleports:
          fixed_t z = thing->z - thing->floorz;

          // Get the angle between the exit thing and source linedef.
          // Rotate 90 degrees, so that walking perpendicularly across
          // teleporter linedef causes thing to exit in the direction
          // indicated by the exit thing.
          angle_t angle =
            R_PointToAngle2(0, 0, line->dx, line->dy) - m->angle + ANG90;

          // Sine, cosine of angle adjustment
          fixed_t s = finesine[angle>>ANGLETOFINESHIFT];
          fixed_t c = finecosine[angle>>ANGLETOFINESHIFT];

          // Momentum of thing crossing teleporter linedef
          fixed_t momx = thing->momx;
          fixed_t momy = thing->momy;

          // Whether this is a player, and if so, a pointer to its player_t
          player_t *player = thing->player;

          // Attempt to teleport, aborting if blocked
          if (!P_TeleportMove(thing, m->x, m->y, false)) /* killough 8/9/98 */
            return 0;

          // Rotate thing according to difference in angles
          thing->angle += angle;

          // Adjust z position to be same height above ground as before
          thing->z = z + thing->floorz;
          thing->PrevZ = thing->z;

          // Rotate thing's momentum to come out of exit just like it entered
          thing->momx = FixedMul(momx, c) - FixedMul(momy, s);
          thing->momy = FixedMul(momy, c) + FixedMul(momx, s);

          // Adjust player's view, in case there has been a height change
          // Voodoo dolls are excluded by making sure player->mo == thing.
          if (player && player->mo == thing)
            {
              // Save the current deltaviewheight, used in stepping
              fixed_t deltaviewheight = player->deltaviewheight;

              // Clear deltaviewheight, since we don't want any changes
              player->deltaviewheight = 0;

              // Set player's view according to the newly set parameters
              P_CalcHeight(player);

              // Reset the delta to have the same dynamics as before
              player->deltaviewheight = deltaviewheight;
            }
          
          // e6y
          if (player && player->mo == thing)
            R_ResetAfterTeleport(player);

          return 1;
        }
  return 0;
}

//
// Silent linedef-based TELEPORTATION, by Lee Killough
// Primarily for rooms-over-rooms etc.
// This is the complete player-preserving kind of teleporter.
// It has advantages over the teleporter with thing exits.
//

// maximum fixed_t units to move object to avoid hiccups
#define FUDGEFACTOR 10

int EV_SilentLineTeleport(line_t *line, int side, mobj_t *thing,
                          dboolean reverse)
{
  int i;
  line_t *l;

  if (side || thing->flags & MF_MISSILE)
    return 0;

  for (i = -1; (i = P_FindLineFromLineTag(line, i)) >= 0;)
    if ((l=lines+i) != line && l->backsector)
      {
        // Get the thing's position along the source linedef
        fixed_t pos = D_abs(line->dx) > D_abs(line->dy) ?
          FixedDiv(thing->x - line->v1->x, line->dx) :
          FixedDiv(thing->y - line->v1->y, line->dy) ;

        // Get the angle between the two linedefs, for rotating
        // orientation and momentum. Rotate 180 degrees, and flip
        // the position across the exit linedef, if reversed.
        angle_t angle = (reverse ? pos = FRACUNIT-pos, 0 : ANG180) +
          R_PointToAngle2(0, 0, l->dx, l->dy) -
          R_PointToAngle2(0, 0, line->dx, line->dy);

        // Interpolate position across the exit linedef
        fixed_t x = l->v2->x - FixedMul(pos, l->dx);
        fixed_t y = l->v2->y - FixedMul(pos, l->dy);

        // Sine, cosine of angle adjustment
        fixed_t s = finesine[angle>>ANGLETOFINESHIFT];
        fixed_t c = finecosine[angle>>ANGLETOFINESHIFT];

        // Maximum distance thing can be moved away from interpolated
        // exit, to ensure that it is on the correct side of exit linedef
        int fudge = FUDGEFACTOR;

        // Whether this is a player, and if so, a pointer to its player_t.
        // Voodoo dolls are excluded by making sure thing->player->mo==thing.
        player_t *player = thing->player && thing->player->mo == thing ?
          thing->player : NULL;

        // Whether walking towards first side of exit linedef steps down
        int stepdown =
          l->frontsector->floorheight < l->backsector->floorheight;

        // Height of thing above ground
        fixed_t z = thing->z - thing->floorz;

        // Side to exit the linedef on positionally.
        //
        // Notes:
        //
        // This flag concerns exit position, not momentum. Due to
        // roundoff error, the thing can land on either the left or
        // the right side of the exit linedef, and steps must be
        // taken to make sure it does not end up on the wrong side.
        //
        // Exit momentum is always towards side 1 in a reversed
        // teleporter, and always towards side 0 otherwise.
        //
        // Exiting positionally on side 1 is always safe, as far
        // as avoiding oscillations and stuck-in-wall problems,
        // but may not be optimum for non-reversed teleporters.
        //
        // Exiting on side 0 can cause oscillations if momentum
        // is towards side 1, as it is with reversed teleporters.
        //
        // Exiting on side 1 slightly improves player viewing
        // when going down a step on a non-reversed teleporter.

        int side = reverse || (player && stepdown);

        // Make sure we are on correct side of exit linedef.
        while (P_PointOnLineSide(x, y, l) != side && --fudge>=0)
          if (D_abs(l->dx) > D_abs(l->dy))
            y -= (l->dx < 0) != side ? -1 : 1;
          else
            x += (l->dy < 0) != side ? -1 : 1;

        // Attempt to teleport, aborting if blocked
        if (!P_TeleportMove(thing, x, y, false)) /* killough 8/9/98 */
          return 0;

        // e6y
        if (player && player->mo == thing)
          R_ResetAfterTeleport(player);

        // Adjust z position to be same height above ground as before.
        // Ground level at the exit is measured as the higher of the
        // two floor heights at the exit linedef.
        thing->z = z + sides[l->sidenum[stepdown]].sector->floorheight;
        thing->PrevZ = thing->z;

        // Rotate thing's orientation according to difference in linedef angles
        thing->angle += angle;

        // Momentum of thing crossing teleporter linedef
        x = thing->momx;
        y = thing->momy;

        // Rotate thing's momentum to come out of exit just like it entered
        thing->momx = FixedMul(x, c) - FixedMul(y, s);
        thing->momy = FixedMul(y, c) + FixedMul(x, s);

        // Adjust a player's view, in case there has been a height change
        if (player)
          {
            // Save the current deltaviewheight, used in stepping
            fixed_t deltaviewheight = player->deltaviewheight;

            // Clear deltaviewheight, since we don't want any changes now
            player->deltaviewheight = 0;

            // Set player's view according to the newly set parameters
            P_CalcHeight(player);

            // Reset the delta to have the same dynamics as before
            player->deltaviewheight = deltaviewheight;
          }

        // e6y
        if (player && player->mo == thing)
          R_ResetAfterTeleport(player);

        return 1;
      }
  return 0;
}
