/*
Copyright (C) 1996-1997 Id Software, Inc.

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.

*/
// sv_move.c -- monster movement

#include "qwsvdef.h"

#define STEPSIZE  18

/*
=============
SV_CheckBottom

Returns false if any part of the bottom of the entity is off an edge that
is not a staircase.

=============
*/
int c_yes, c_no;

qboolean SV_CheckBottom (edict_t *ent)
{
  vec3_t  mins, maxs, start, stop;
  trace_t trace;
  int   x, y;
  float mid, bottom;
  
  VectorAdd (ent->v.origin, ent->v.mins, mins);
  VectorAdd (ent->v.origin, ent->v.maxs, maxs);

// if all of the points under the corners are solid world, don't bother
// with the tougher checks
// the corners must be within 16 of the midpoint
  start[2] = mins[2] - 1;
  for (x=0 ; x<=1 ; x++)
    for (y=0 ; y<=1 ; y++)
    {
      start[0] = x ? maxs[0] : mins[0];
      start[1] = y ? maxs[1] : mins[1];
      if (SV_PointContents (start) != CONTENTS_SOLID)
        goto realcheck;
    }

  c_yes++;
  return true;    // we got out easy

realcheck:
  c_no++;
//
// check it for real...
//
  start[2] = mins[2];
  
// the midpoint must be within 16 of the bottom
  start[0] = stop[0] = (mins[0] + maxs[0])*0.5;
  start[1] = stop[1] = (mins[1] + maxs[1])*0.5;
  stop[2] = start[2] - 2*STEPSIZE;
  trace = SV_Move (start, vec3_origin, vec3_origin, stop, true, ent);

  if (trace.fraction == 1.0)
    return false;
  mid = bottom = trace.endpos[2];
  
// the corners must be within 16 of the midpoint  
  for (x=0 ; x<=1 ; x++)
    for (y=0 ; y<=1 ; y++)
    {
      start[0] = stop[0] = x ? maxs[0] : mins[0];
      start[1] = stop[1] = y ? maxs[1] : mins[1];
      
      trace = SV_Move (start, vec3_origin, vec3_origin, stop, true, ent);
      
      if (trace.fraction != 1.0 && trace.endpos[2] > bottom)
        bottom = trace.endpos[2];
      if (trace.fraction == 1.0 || mid - trace.endpos[2] > STEPSIZE)
        return false;
    }

  c_yes++;
  return true;
}


/*
=============
SV_movestep

Called by monster program code.
The move will be adjusted for slopes and stairs, but if the move isn't
possible, no move is done, false is returned, and
pr_global_struct->trace_normal is set to the normal of the blocking wall
=============
*/
qboolean SV_movestep (edict_t *ent, vec3_t move, qboolean relink)
{
  float   dz;
  vec3_t    oldorg, neworg, end;
  trace_t   trace;
  int     i;
  edict_t   *enemy;

// try the move 
  VectorCopy (ent->v.origin, oldorg);
  VectorAdd (ent->v.origin, move, neworg);

// flying monsters don't step up
  if ( (int)ent->v.flags & (FL_SWIM | FL_FLY) )
  {
  // try one move with vertical motion, then one without
    for (i=0 ; i<2 ; i++)
    {
      VectorAdd (ent->v.origin, move, neworg);
      enemy = PROG_TO_EDICT(ent->v.enemy);
      if (i == 0 && enemy != sv.edicts)
      {
        dz = ent->v.origin[2] - PROG_TO_EDICT(ent->v.enemy)->v.origin[2];
        if (dz > 40)
          neworg[2] -= 8;
        if (dz < 30)
          neworg[2] += 8;
      }
      trace = SV_Move (ent->v.origin, ent->v.mins, ent->v.maxs, neworg, false, ent);
  
      if (trace.fraction == 1)
      {
        if ( ((int)ent->v.flags & FL_SWIM) && SV_PointContents(trace.endpos) == CONTENTS_EMPTY )
          return false; // swim monster left water
  
        VectorCopy (trace.endpos, ent->v.origin);
        if (relink)
          SV_LinkEdict (ent, true);
        return true;
      }
      
      if (enemy == sv.edicts)
        break;
    }
    
    return false;
  }

// push down from a step height above the wished position
  neworg[2] += STEPSIZE;
  VectorCopy (neworg, end);
  end[2] -= STEPSIZE*2;

  trace = SV_Move (neworg, ent->v.mins, ent->v.maxs, end, false, ent);

  if (trace.allsolid)
    return false;

  if (trace.startsolid)
  {
    neworg[2] -= STEPSIZE;
    trace = SV_Move (neworg, ent->v.mins, ent->v.maxs, end, false, ent);
    if (trace.allsolid || trace.startsolid)
      return false;
  }
  if (trace.fraction == 1)
  {
  // if monster had the ground pulled out, go ahead and fall
    if ( (int)ent->v.flags & FL_PARTIALGROUND )
    {
      VectorAdd (ent->v.origin, move, ent->v.origin);
      if (relink)
        SV_LinkEdict (ent, true);
      ent->v.flags = (int)ent->v.flags & ~FL_ONGROUND;
//  Con_Printf ("fall down\n"); 
      return true;
    }
  
    return false;   // walked off an edge
  }

// check point traces down for dangling corners
  VectorCopy (trace.endpos, ent->v.origin);
  
  if (!SV_CheckBottom (ent))
  {
    if ( (int)ent->v.flags & FL_PARTIALGROUND )
    { // entity had floor mostly pulled out from underneath it
      // and is trying to correct
      if (relink)
        SV_LinkEdict (ent, true);
      return true;
    }
    VectorCopy (oldorg, ent->v.origin);
    return false;
  }

  if ( (int)ent->v.flags & FL_PARTIALGROUND )
  {
//    Con_Printf ("back on ground\n"); 
    ent->v.flags = (int)ent->v.flags & ~FL_PARTIALGROUND;
  }
  ent->v.groundentity = EDICT_TO_PROG(trace.ent);

// the move is ok
  if (relink)
    SV_LinkEdict (ent, true);
  return true;
}


//============================================================================

/*
======================
SV_StepDirection

Turns to the movement direction, and walks the current distance if
facing it.

======================
*/
void PF_changeyaw (void);
qboolean SV_StepDirection (edict_t *ent, float yaw, float dist)
{
  vec3_t    move, oldorigin;
  float   delta;
  
  ent->v.ideal_yaw = yaw;
  PF_changeyaw();
  
  yaw = yaw*M_PI*2 / 360;
  move[0] = cos(yaw)*dist;
  move[1] = sin(yaw)*dist;
  move[2] = 0;

  VectorCopy (ent->v.origin, oldorigin);
  if (SV_movestep (ent, move, false))
  {
    delta = ent->v.angles[YAW] - ent->v.ideal_yaw;
    if (delta > 45 && delta < 315)
    {   // not turned far enough, so don't take the step
      VectorCopy (oldorigin, ent->v.origin);
    }
    SV_LinkEdict (ent, true);
    return true;
  }
  SV_LinkEdict (ent, true);
    
  return false;
}

/*
======================
SV_FixCheckBottom

======================
*/
void SV_FixCheckBottom (edict_t *ent)
{
//  Con_Printf ("SV_FixCheckBottom\n");
  
  ent->v.flags = (int)ent->v.flags | FL_PARTIALGROUND;
}



/*
================
SV_NewChaseDir

================
*/
#define DI_NODIR  -1
void SV_NewChaseDir (edict_t *actor, edict_t *enemy, float dist)
{
  float   deltax,deltay;
  float     d[3];
  float   tdir, olddir, turnaround;

  olddir = anglemod( (int)(actor->v.ideal_yaw/45)*45 );
  turnaround = anglemod(olddir - 180);

  deltax = enemy->v.origin[0] - actor->v.origin[0];
  deltay = enemy->v.origin[1] - actor->v.origin[1];
  if (deltax>10)
    d[1]= 0;
  else if (deltax<-10)
    d[1]= 180;
  else
    d[1]= DI_NODIR;
  if (deltay<-10)
    d[2]= 270;
  else if (deltay>10)
    d[2]= 90;
  else
    d[2]= DI_NODIR;

// try direct route
  if (d[1] != DI_NODIR && d[2] != DI_NODIR)
  {
    if (d[1] == 0)
      tdir = d[2] == 90 ? 45 : 315;
    else
      tdir = d[2] == 90 ? 135 : 215;
      
    if (tdir != turnaround && SV_StepDirection(actor, tdir, dist))
      return;
  }

// try other directions
  if ( ((rand()&3) & 1) ||  abs(deltay)>abs(deltax))
  {
    tdir=d[1];
    d[1]=d[2];
    d[2]=tdir;
  }

  if (d[1]!=DI_NODIR && d[1]!=turnaround 
  && SV_StepDirection(actor, d[1], dist))
      return;

  if (d[2]!=DI_NODIR && d[2]!=turnaround
  && SV_StepDirection(actor, d[2], dist))
      return;

/* there is no direct path to the player, so pick another direction */

  if (olddir!=DI_NODIR && SV_StepDirection(actor, olddir, dist))
      return;

  if (rand()&1)   /*randomly determine direction of search*/
  {
    for (tdir=0 ; tdir<=315 ; tdir += 45)
      if (tdir!=turnaround && SV_StepDirection(actor, tdir, dist) )
          return;
  }
  else
  {
    for (tdir=315 ; tdir >=0 ; tdir -= 45)
      if (tdir!=turnaround && SV_StepDirection(actor, tdir, dist) )
          return;
  }

  if (turnaround != DI_NODIR && SV_StepDirection(actor, turnaround, dist) )
      return;

  actor->v.ideal_yaw = olddir;    // can't move

// if a bridge was pulled out from underneath a monster, it may not have
// a valid standing position at all

  if (!SV_CheckBottom (actor))
    SV_FixCheckBottom (actor);

}

/*
======================
SV_CloseEnough

======================
*/
qboolean SV_CloseEnough (edict_t *ent, edict_t *goal, float dist)
{
  int   i;
  
  for (i=0 ; i<3 ; i++)
  {
    if (goal->v.absmin[i] > ent->v.absmax[i] + dist)
      return false;
    if (goal->v.absmax[i] < ent->v.absmin[i] - dist)
      return false;
  }
  return true;
}

/*
======================
SV_MoveToGoal

======================
*/
void SV_MoveToGoal (void)
{
  edict_t   *ent, *goal;
  float   dist;
  
  ent = PROG_TO_EDICT(pr_global_struct->self);
  goal = PROG_TO_EDICT(ent->v.goalentity);
  dist = G_FLOAT(OFS_PARM0);

  if ( !( (int)ent->v.flags & (FL_ONGROUND|FL_FLY|FL_SWIM) ) )
  {
    G_FLOAT(OFS_RETURN) = 0;
    return;
  }

// if the next step hits the enemy, return immediately
  if ( PROG_TO_EDICT(ent->v.enemy) != sv.edicts &&  SV_CloseEnough (ent, goal, dist) )
    return;

// bump around...
  if ( (rand()&3)==1 ||
  !SV_StepDirection (ent, ent->v.ideal_yaw, dist))
  {
    SV_NewChaseDir (ent, goal, dist);
  }
}