// Copyright (C) 1999-2000 Id Software, Inc.
//
// cg_predict.c -- this file generates cg.predictedPlayerState by either
// interpolating between snapshots from the server or locally predicting
// ahead the client's movement.
// It also handles local physics interaction, like fragments bouncing off walls

/*
 *  Portions Copyright (C) 2000-2001 Tim Angus
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation; either version 2.1, 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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser 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.
 */

/*  To assertain which portions are licensed under the LGPL and which are
 *  licensed by Id Software, Inc. please run a diff between the equivalent
 *  versions of the "Tremulous" modification and the unmodified "Quake3"
 *  game source code.
 */
                    
#include "cg_local.h"

static  pmove_t   cg_pmove;

static  int     cg_numSolidEntities;
static  centity_t *cg_solidEntities[MAX_ENTITIES_IN_SNAPSHOT];
static  int     cg_numTriggerEntities;
static  centity_t *cg_triggerEntities[MAX_ENTITIES_IN_SNAPSHOT];

/*
====================
CG_BuildSolidList

When a new cg.snap has been set, this function builds a sublist
of the entities that are actually solid, to make for more
efficient collision detection
====================
*/
void CG_BuildSolidList( void ) {
  int     i;
  centity_t *cent;
  snapshot_t  *snap;
  entityState_t *ent;

  cg_numSolidEntities = 0;
  cg_numTriggerEntities = 0;

  if ( cg.nextSnap && !cg.nextFrameTeleport && !cg.thisFrameTeleport ) {
    snap = cg.nextSnap;
  } else {
    snap = cg.snap;
  }

  for ( i = 0 ; i < snap->numEntities ; i++ ) {
    cent = &cg_entities[ snap->entities[ i ].number ];
    ent = &cent->currentState;

    if ( ent->eType == ET_ITEM || ent->eType == ET_PUSH_TRIGGER || ent->eType == ET_TELEPORT_TRIGGER ) {
      cg_triggerEntities[cg_numTriggerEntities] = cent;
      cg_numTriggerEntities++;
      continue;
    }

    if ( cent->nextState.solid ) {
      cg_solidEntities[cg_numSolidEntities] = cent;
      cg_numSolidEntities++;
      continue;
    }
  }
}

/*
====================
CG_ClipMoveToEntities

====================
*/
static void CG_ClipMoveToEntities ( const vec3_t start, const vec3_t mins, const vec3_t maxs, const vec3_t end,
              int skipNumber, int mask, trace_t *tr ) {
  int     i, x, zd, zu;
  trace_t   trace;
  entityState_t *ent;
  clipHandle_t  cmodel;
  vec3_t    bmins, bmaxs;
  vec3_t    origin, angles;
  centity_t *cent;

  for ( i = 0 ; i < cg_numSolidEntities ; i++ ) {
    cent = cg_solidEntities[ i ];
    ent = &cent->currentState;

    if ( ent->number == skipNumber ) {
      continue;
    }

    if ( ent->solid == SOLID_BMODEL ) {
      // special value for bmodel
      cmodel = trap_CM_InlineModel( ent->modelindex );
      VectorCopy( cent->lerpAngles, angles );
      BG_EvaluateTrajectory( &cent->currentState.pos, cg.physicsTime, origin );
    } else {
      // encoded bbox
      x = (ent->solid & 255);
      zd = ((ent->solid>>8) & 255);
      zu = ((ent->solid>>16) & 255) - 32;

      bmins[0] = bmins[1] = -x;
      bmaxs[0] = bmaxs[1] = x;
      bmins[2] = -zd;
      bmaxs[2] = zu;

      cmodel = trap_CM_TempBoxModel( bmins, bmaxs );
      VectorCopy( vec3_origin, angles );
      VectorCopy( cent->lerpOrigin, origin );
    }


    trap_CM_TransformedBoxTrace ( &trace, start, end,
      mins, maxs, cmodel,  mask, origin, angles);

    if (trace.allsolid || trace.fraction < tr->fraction) {
      trace.entityNum = ent->number;
      *tr = trace;
    } else if (trace.startsolid) {
      tr->startsolid = qtrue;
    }
    if ( tr->allsolid ) {
      return;
    }
  }
}

/*
================
CG_Trace
================
*/
void  CG_Trace( trace_t *result, const vec3_t start, const vec3_t mins, const vec3_t maxs, const vec3_t end,
           int skipNumber, int mask ) {
  trace_t t;

  trap_CM_BoxTrace ( &t, start, end, mins, maxs, 0, mask);
  t.entityNum = t.fraction != 1.0 ? ENTITYNUM_WORLD : ENTITYNUM_NONE;
  // check all other solid models
  CG_ClipMoveToEntities (start, mins, maxs, end, skipNumber, mask, &t);

  *result = t;
}

/*
================
CG_PointContents
================
*/
int   CG_PointContents( const vec3_t point, int passEntityNum ) {
  int     i;
  entityState_t *ent;
  centity_t *cent;
  clipHandle_t cmodel;
  int     contents;

  contents = trap_CM_PointContents (point, 0);

  for ( i = 0 ; i < cg_numSolidEntities ; i++ ) {
    cent = cg_solidEntities[ i ];

    ent = &cent->currentState;

    if ( ent->number == passEntityNum ) {
      continue;
    }

    if (ent->solid != SOLID_BMODEL) { // special value for bmodel
      continue;
    }

    cmodel = trap_CM_InlineModel( ent->modelindex );
    if ( !cmodel ) {
      continue;
    }

    contents |= trap_CM_TransformedPointContents( point, cmodel, ent->origin, ent->angles );
  }

  return contents;
}


/*
========================
CG_InterpolatePlayerState

Generates cg.predictedPlayerState by interpolating between
cg.snap->player_state and cg.nextFrame->player_state
========================
*/
static void CG_InterpolatePlayerState( qboolean grabAngles ) {
  float     f;
  int       i;
  playerState_t *out;
  snapshot_t    *prev, *next;

  out = &cg.predictedPlayerState;
  prev = cg.snap;
  next = cg.nextSnap;

  *out = cg.snap->ps;

  // if we are still allowing local input, short circuit the view angles
  if ( grabAngles ) {
    usercmd_t cmd;
    int     cmdNum;

    cmdNum = trap_GetCurrentCmdNumber();
    trap_GetUserCmd( cmdNum, &cmd );

    PM_UpdateViewAngles( out, &cmd );
  }

  // if the next frame is a teleport, we can't lerp to it
  if ( cg.nextFrameTeleport ) {
    return;
  }

  if ( !next || next->serverTime <= prev->serverTime ) {
    return;
  }

  f = (float)( cg.time - prev->serverTime ) / ( next->serverTime - prev->serverTime );

  i = next->ps.bobCycle;
  if ( i < prev->ps.bobCycle ) {
    i += 256;   // handle wraparound
  }
  out->bobCycle = prev->ps.bobCycle + f * ( i - prev->ps.bobCycle );

  for ( i = 0 ; i < 3 ; i++ ) {
    out->origin[i] = prev->ps.origin[i] + f * (next->ps.origin[i] - prev->ps.origin[i] );
    if ( !grabAngles ) {
      out->viewangles[i] = LerpAngle(
        prev->ps.viewangles[i], next->ps.viewangles[i], f );
    }
    out->velocity[i] = prev->ps.velocity[i] +
      f * (next->ps.velocity[i] - prev->ps.velocity[i] );
  }

}

/*
===================
CG_TouchItem
===================
*/
static void CG_TouchItem( centity_t *cent ) {
  gitem_t   *item;
  int       ammo, clips, maxclips;

  BG_unpackAmmoArray( item->giTag, cg.predictedPlayerState.ammo, cg.predictedPlayerState.powerups, &ammo, &clips, &maxclips );

  if ( !cg_predictItems.integer ) {
    return;
  }
  if ( !BG_PlayerTouchesItem( &cg.predictedPlayerState, &cent->currentState, cg.time ) ) {
    return;
  }

  // never pick an item up twice in a prediction
  if ( cent->miscTime == cg.time ) {
    return;
  }

  if ( !BG_CanItemBeGrabbed( cgs.gametype, &cent->currentState, &cg.predictedPlayerState ) ) {
    return;   // can't hold it
  }

  item = &bg_itemlist[ cent->currentState.modelindex ];

  // grab it
  BG_AddPredictableEventToPlayerstate( EV_ITEM_PICKUP, cent->currentState.modelindex , &cg.predictedPlayerState);

  // remove it from the frame so it won't be drawn
  cent->currentState.eFlags |= EF_NODRAW;

  // don't touch it again this prediction
  cent->miscTime = cg.time;

  // if its a weapon, give them some predicted ammo so the autoswitch will work
  if ( item->giType == IT_WEAPON ) {
    BG_packWeapon( item->giTag, cg.predictedPlayerState.stats );
    if ( ammo == 0 && clips == 0 ) {
      BG_packAmmoArray( item->giTag, cg.predictedPlayerState.ammo, cg.predictedPlayerState.powerups, 1, 0, 0 );
    }
  }
}


/*
=========================
CG_TouchTriggerPrediction

Predict push triggers and items
=========================
*/
static void CG_TouchTriggerPrediction( void ) {
  int     i;
  trace_t   trace;
  entityState_t *ent;
  clipHandle_t cmodel;
  centity_t *cent;
  qboolean  spectator;

  // dead clients don't activate triggers
  if ( cg.predictedPlayerState.stats[STAT_HEALTH] <= 0 ) {
    return;
  }

  spectator = ( cg.predictedPlayerState.pm_type == PM_SPECTATOR );

  if ( cg.predictedPlayerState.pm_type != PM_NORMAL && !spectator ) {
    return;
  }

  for ( i = 0 ; i < cg_numTriggerEntities ; i++ ) {
    cent = cg_triggerEntities[ i ];
    ent = &cent->currentState;

    if ( ent->eType == ET_ITEM && !spectator ) {
      CG_TouchItem( cent );
      continue;
    }

    if ( ent->solid != SOLID_BMODEL ) {
      continue;
    }

    cmodel = trap_CM_InlineModel( ent->modelindex );
    if ( !cmodel ) {
      continue;
    }

    trap_CM_BoxTrace( &trace, cg.predictedPlayerState.origin, cg.predictedPlayerState.origin,
      cg_pmove.mins, cg_pmove.maxs, cmodel, -1 );

    if ( !trace.startsolid ) {
      continue;
    }

    if ( ent->eType == ET_TELEPORT_TRIGGER ) {
      cg.hyperspace = qtrue;
    } else if ( ent->eType == ET_PUSH_TRIGGER ) {
      BG_TouchJumpPad( &cg.predictedPlayerState, ent );
    }
  }

  // if we didn't touch a jump pad this pmove frame
  if ( cg.predictedPlayerState.jumppad_frame != cg.predictedPlayerState.pmove_framecount ) {
    cg.predictedPlayerState.jumppad_frame = 0;
    cg.predictedPlayerState.jumppad_ent = 0;
  }
}



/*
=================
CG_PredictPlayerState

Generates cg.predictedPlayerState for the current cg.time
cg.predictedPlayerState is guaranteed to be valid after exiting.

For demo playback, this will be an interpolation between two valid
playerState_t.

For normal gameplay, it will be the result of predicted usercmd_t on
top of the most recent playerState_t received from the server.

Each new snapshot will usually have one or more new usercmd over the last,
but we simulate all unacknowledged commands each time, not just the new ones.
This means that on an internet connection, quite a few pmoves may be issued
each frame.

OPTIMIZE: don't re-simulate unless the newly arrived snapshot playerState_t
differs from the predicted one.  Would require saving all intermediate
playerState_t during prediction.

We detect prediction errors and allow them to be decayed off over several frames
to ease the jerk.
=================
*/
void CG_PredictPlayerState( void ) {
  int     cmdNum, current;
  playerState_t oldPlayerState;
  qboolean  moved;
  usercmd_t oldestCmd;
  usercmd_t latestCmd;

  cg.hyperspace = qfalse; // will be set if touching a trigger_teleport

  // if this is the first frame we must guarantee
  // predictedPlayerState is valid even if there is some
  // other error condition
  if ( !cg.validPPS ) {
    cg.validPPS = qtrue;
    cg.predictedPlayerState = cg.snap->ps;
  }


  // demo playback just copies the moves
  if ( cg.demoPlayback || (cg.snap->ps.pm_flags & PMF_FOLLOW) ) {
    CG_InterpolatePlayerState( qfalse );
    return;
  }

  // non-predicting local movement will grab the latest angles
  if ( cg_nopredict.integer || cg_synchronousClients.integer ) {
    CG_InterpolatePlayerState( qtrue );
    return;
  }

  // prepare for pmove
  cg_pmove.ps = &cg.predictedPlayerState;
  cg_pmove.trace = CG_Trace;
  cg_pmove.pointcontents = CG_PointContents;
  if ( cg_pmove.ps->pm_type == PM_DEAD ) {
    cg_pmove.tracemask = MASK_PLAYERSOLID & ~CONTENTS_BODY;
  }
  else {
    cg_pmove.tracemask = MASK_PLAYERSOLID;
  }
  if ( cg.snap->ps.persistant[PERS_TEAM] == TEAM_SPECTATOR ) {
    cg_pmove.tracemask &= ~CONTENTS_BODY; // spectators can fly through bodies
  }
  cg_pmove.noFootsteps = ( cgs.dmflags & DF_NO_FOOTSTEPS ) > 0;

  // save the state before the pmove so we can detect transitions
  oldPlayerState = cg.predictedPlayerState;

  current = trap_GetCurrentCmdNumber();

  // if we don't have the commands right after the snapshot, we
  // can't accurately predict a current position, so just freeze at
  // the last good position we had
  cmdNum = current - CMD_BACKUP + 1;
  trap_GetUserCmd( cmdNum, &oldestCmd );
  if ( oldestCmd.serverTime > cg.snap->ps.commandTime
    && oldestCmd.serverTime < cg.time ) { // special check for map_restart
    if ( cg_showmiss.integer ) {
      CG_Printf ("exceeded PACKET_BACKUP on commands\n");
    }
    return;
  }

  // get the latest command so we can know which commands are from previous map_restarts
  trap_GetUserCmd( current, &latestCmd );

  // get the most recent information we have, even if
  // the server time is beyond our current cg.time,
  // because predicted player positions are going to
  // be ahead of everything else anyway
  if ( cg.nextSnap && !cg.nextFrameTeleport && !cg.thisFrameTeleport ) {
    cg.predictedPlayerState = cg.nextSnap->ps;
    cg.physicsTime = cg.nextSnap->serverTime;
  } else {
    cg.predictedPlayerState = cg.snap->ps;
    cg.physicsTime = cg.snap->serverTime;
  }

  if ( pmove_msec.integer < 8 ) {
    trap_Cvar_Set("pmove_msec", "8");
  }
  else if (pmove_msec.integer > 33) {
    trap_Cvar_Set("pmove_msec", "33");
  }

  cg_pmove.pmove_fixed = pmove_fixed.integer;// | cg_pmove_fixed.integer;
  cg_pmove.pmove_msec = pmove_msec.integer;

  // run cmds
  moved = qfalse;
  for ( cmdNum = current - CMD_BACKUP + 1 ; cmdNum <= current ; cmdNum++ ) {
    // get the command
    trap_GetUserCmd( cmdNum, &cg_pmove.cmd );

    if ( cg_pmove.pmove_fixed ) {
      PM_UpdateViewAngles( cg_pmove.ps, &cg_pmove.cmd );
    }

    // don't do anything if the time is before the snapshot player time
    if ( cg_pmove.cmd.serverTime <= cg.predictedPlayerState.commandTime ) {
      continue;
    }

    // don't do anything if the command was from a previous map_restart
    if ( cg_pmove.cmd.serverTime > latestCmd.serverTime ) {
      continue;
    }

    // check for a prediction error from last frame
    // on a lan, this will often be the exact value
    // from the snapshot, but on a wan we will have
    // to predict several commands to get to the point
    // we want to compare
    if ( cg.predictedPlayerState.commandTime == oldPlayerState.commandTime ) {
      vec3_t  delta;
      float len;

      if ( cg.thisFrameTeleport ) {
        // a teleport will not cause an error decay
        VectorClear( cg.predictedError );
        if ( cg_showmiss.integer ) {
          CG_Printf( "PredictionTeleport\n" );
        }
        cg.thisFrameTeleport = qfalse;
      } else {
        vec3_t  adjusted;
        CG_AdjustPositionForMover( cg.predictedPlayerState.origin,
          cg.predictedPlayerState.groundEntityNum, cg.physicsTime, cg.oldTime, adjusted );

        if ( cg_showmiss.integer ) {
          if (!VectorCompare( oldPlayerState.origin, adjusted )) {
            CG_Printf("prediction error\n");
          }
        }
        VectorSubtract( oldPlayerState.origin, adjusted, delta );
        len = VectorLength( delta );
        if ( len > 0.1 ) {
          if ( cg_showmiss.integer ) {
            CG_Printf("Prediction miss: %f\n", len);
          }
          if ( cg_errorDecay.integer ) {
            int   t;
            float f;

            t = cg.time - cg.predictedErrorTime;
            f = ( cg_errorDecay.value - t ) / cg_errorDecay.value;
            if ( f < 0 ) {
              f = 0;
            }
            if ( f > 0 && cg_showmiss.integer ) {
              CG_Printf("Double prediction decay: %f\n", f);
            }
            VectorScale( cg.predictedError, f, cg.predictedError );
          } else {
            VectorClear( cg.predictedError );
          }
          VectorAdd( delta, cg.predictedError, cg.predictedError );
          cg.predictedErrorTime = cg.oldTime;
        }
      }
    }

    // don't predict gauntlet firing, which is only supposed to happen
    // when it actually inflicts damage
    cg_pmove.gauntletHit = qfalse;

    if ( cg_pmove.pmove_fixed ) {
      cg_pmove.cmd.serverTime = ((cg_pmove.cmd.serverTime + pmove_msec.integer-1) / pmove_msec.integer) * pmove_msec.integer;
    }

    Pmove (&cg_pmove);

    moved = qtrue;

    // add push trigger movement effects
    CG_TouchTriggerPrediction();

    // check for predictable events that changed from previous predictions
    //CG_CheckChangedPredictableEvents(&cg.predictedPlayerState);
  }

  if ( cg_showmiss.integer > 1 ) {
    CG_Printf( "[%i : %i] ", cg_pmove.cmd.serverTime, cg.time );
  }

  if ( !moved ) {
    if ( cg_showmiss.integer ) {
      CG_Printf( "not moved\n" );
    }
    return;
  }

  // adjust for the movement of the groundentity
  CG_AdjustPositionForMover( cg.predictedPlayerState.origin,
    cg.predictedPlayerState.groundEntityNum,
    cg.physicsTime, cg.time, cg.predictedPlayerState.origin );

  if ( cg_showmiss.integer ) {
    if (cg.predictedPlayerState.eventSequence > oldPlayerState.eventSequence + MAX_PS_EVENTS) {
      CG_Printf("WARNING: dropped event\n");
    }
  }

  // fire events and other transition triggered things
  CG_TransitionPlayerState( &cg.predictedPlayerState, &oldPlayerState );

  if ( cg_showmiss.integer ) {
    if (cg.eventSequence > cg.predictedPlayerState.eventSequence) {
      CG_Printf("WARNING: double event\n");
      cg.eventSequence = cg.predictedPlayerState.eventSequence;
    }
  }
}