// Emacs style mode select   -*- C++ -*- 
//-----------------------------------------------------------------------------
//
// $Id:$
//
// Copyright (C) 1993-1996 by id Software, Inc.
//
// This source is available for distribution and/or modification
// only under the terms of the DOOM Source Code License as
// published by id Software. All rights reserved.
//
// The source is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
// for more details.
//
// $Log:$
//
// DESCRIPTION:
//	Movement, collision handling.
//	Shooting and aiming.
//
//-----------------------------------------------------------------------------

static const char
rcsid[] = "$Id: p_map.c,v 1.5 1997/02/03 22:45:11 b1 Exp $";

#include <stdlib.h>

#include "m_bbox.h"
#include "m_random.h"
#include "i_system.h"

#include "doomdef.h"
#include "p_local.h"

#include "s_sound.h"

// State.
#include "doomstat.h"
#include "r_state.h"
// Data.
#include "sounds.h"


fixed_t		tmbbox[4];
mobj_t*		tmthing;
int		tmflags;
fixed_t		tmx;
fixed_t		tmy;


// If "floatok" true, move would be ok
// if within "tmfloorz - tmceilingz".
boolean		floatok;

fixed_t		tmfloorz;
fixed_t		tmceilingz;
fixed_t		tmdropoffz;

// keep track of the line that lowers the ceiling,
// so missiles don't explode against sky hack walls
line_t*		ceilingline;

// keep track of special lines as they are hit,
// but don't process them until the move is proven valid
#define MAXSPECIALCROSS		8

line_t*		spechit[MAXSPECIALCROSS];
int		numspechit;



//
// TELEPORT MOVE
// 

//
// PIT_StompThing
//
boolean PIT_StompThing (mobj_t* thing)
{
    fixed_t	blockdist;
		
    if (!(thing->flags & MF_SHOOTABLE) )
	return true;
		
    blockdist = thing->radius + tmthing->radius;
    
    if ( abs(thing->x - tmx) >= blockdist
	 || abs(thing->y - tmy) >= blockdist )
    {
	// didn't hit it
	return true;
    }
    
    // don't clip against self
    if (thing == tmthing)
	return true;
    
    // monsters don't stomp things except on boss level
    if ( !tmthing->player && gamemap != 30)
	return false;	
		
    P_DamageMobj (thing, tmthing, tmthing, 10000);
	
    return true;
}


//
// P_TeleportMove
//
boolean
P_TeleportMove
( mobj_t*	thing,
  fixed_t	x,
  fixed_t	y )
{
    int			xl;
    int			xh;
    int			yl;
    int			yh;
    int			bx;
    int			by;
    
    subsector_t*	newsubsec;
    
    // kill anything occupying the position
    tmthing = thing;
    tmflags = thing->flags;
	
    tmx = x;
    tmy = y;
	
    tmbbox[BOXTOP] = y + tmthing->radius;
    tmbbox[BOXBOTTOM] = y - tmthing->radius;
    tmbbox[BOXRIGHT] = x + tmthing->radius;
    tmbbox[BOXLEFT] = x - tmthing->radius;

    newsubsec = R_PointInSubsector (x,y);
    ceilingline = NULL;
    
    // The base floor/ceiling is from the subsector
    // that contains the point.
    // Any contacted lines the step closer together
    // will adjust them.
    tmfloorz = tmdropoffz = newsubsec->sector->floorheight;
    tmceilingz = newsubsec->sector->ceilingheight;
			
    validcount++;
    numspechit = 0;
    
    // stomp on any things contacted
    xl = (tmbbox[BOXLEFT] - bmaporgx - MAXRADIUS)>>MAPBLOCKSHIFT;
    xh = (tmbbox[BOXRIGHT] - bmaporgx + MAXRADIUS)>>MAPBLOCKSHIFT;
    yl = (tmbbox[BOXBOTTOM] - bmaporgy - MAXRADIUS)>>MAPBLOCKSHIFT;
    yh = (tmbbox[BOXTOP] - bmaporgy + MAXRADIUS)>>MAPBLOCKSHIFT;

    for (bx=xl ; bx<=xh ; bx++)
	for (by=yl ; by<=yh ; by++)
	    if (!P_BlockThingsIterator(bx,by,PIT_StompThing))
		return false;
    
    // the move is ok,
    // so link the thing into its new position
    P_UnsetThingPosition (thing);

    thing->floorz = tmfloorz;
    thing->ceilingz = tmceilingz;	
    thing->x = x;
    thing->y = y;

    P_SetThingPosition (thing);
	
    return true;
}


//
// MOVEMENT ITERATOR FUNCTIONS
//


//
// PIT_CheckLine
// Adjusts tmfloorz and tmceilingz as lines are contacted
//
boolean PIT_CheckLine (line_t* ld)
{
    if (tmbbox[BOXRIGHT] <= ld->bbox[BOXLEFT]
	|| tmbbox[BOXLEFT] >= ld->bbox[BOXRIGHT]
	|| tmbbox[BOXTOP] <= ld->bbox[BOXBOTTOM]
	|| tmbbox[BOXBOTTOM] >= ld->bbox[BOXTOP] )
	return true;

    if (P_BoxOnLineSide (tmbbox, ld) != -1)
	return true;
		
    // A line has been hit
    
    // The moving thing's destination position will cross
    // the given line.
    // If this should not be allowed, return false.
    // If the line is special, keep track of it
    // to process later if the move is proven ok.
    // NOTE: specials are NOT sorted by order,
    // so two special lines that are only 8 pixels apart
    // could be crossed in either order.
    
    if (!ld->backsector)
	return false;		// one sided line
		
    if (!(tmthing->flags & MF_MISSILE) )
    {
	if ( ld->flags & ML_BLOCKING )
	    return false;	// explicitly blocking everything

	if ( !tmthing->player && ld->flags & ML_BLOCKMONSTERS )
	    return false;	// block monsters only
    }

    // set openrange, opentop, openbottom
    P_LineOpening (ld);	
	
    // adjust floor / ceiling heights
    if (opentop < tmceilingz)
    {
	tmceilingz = opentop;
	ceilingline = ld;
    }

    if (openbottom > tmfloorz)
	tmfloorz = openbottom;	

    if (lowfloor < tmdropoffz)
	tmdropoffz = lowfloor;
		
    // if contacted a special line, add it to the list
    if (ld->special)
    {
	spechit[numspechit] = ld;
	numspechit++;
    }

    return true;
}

//
// PIT_CheckThing
//
boolean PIT_CheckThing (mobj_t* thing)
{
    fixed_t		blockdist;
    boolean		solid;
    int			damage;
		
    if (!(thing->flags & (MF_SOLID|MF_SPECIAL|MF_SHOOTABLE) ))
	return true;
    
    blockdist = thing->radius + tmthing->radius;

    if ( abs(thing->x - tmx) >= blockdist
	 || abs(thing->y - tmy) >= blockdist )
    {
	// didn't hit it
	return true;	
    }
    
    // don't clip against self
    if (thing == tmthing)
	return true;
    
    // check for skulls slamming into things
    if (tmthing->flags & MF_SKULLFLY)
    {
	damage = ((P_Random()%8)+1)*tmthing->info->damage;
	
	P_DamageMobj (thing, tmthing, tmthing, damage);
	
	tmthing->flags &= ~MF_SKULLFLY;
	tmthing->momx = tmthing->momy = tmthing->momz = 0;
	
	P_SetMobjState (tmthing, tmthing->info->spawnstate);
	
	return false;		// stop moving
    }

    
    // missiles can hit other things
    if (tmthing->flags & MF_MISSILE)
    {
	// see if it went over / under
	if (tmthing->z > thing->z + thing->height)
	    return true;		// overhead
	if (tmthing->z+tmthing->height < thing->z)
	    return true;		// underneath
		
	if (tmthing->target && (
	    tmthing->target->type == thing->type || 
	    (tmthing->target->type == MT_KNIGHT && thing->type == MT_BRUISER)||
	    (tmthing->target->type == MT_BRUISER && thing->type == MT_KNIGHT) ) )
	{
	    // Don't hit same species as originator.
	    if (thing == tmthing->target)
		return true;

	    if (thing->type != MT_PLAYER)
	    {
		// Explode, but do no damage.
		// Let players missile other players.
		return false;
	    }
	}
	
	if (! (thing->flags & MF_SHOOTABLE) )
	{
	    // didn't do any damage
	    return !(thing->flags & MF_SOLID);	
	}
	
	// damage / explode
	damage = ((P_Random()%8)+1)*tmthing->info->damage;
	P_DamageMobj (thing, tmthing, tmthing->target, damage);

	// don't traverse any more
	return false;				
    }
    
    // check for special pickup
    if (thing->flags & MF_SPECIAL)
    {
	solid = thing->flags&MF_SOLID;
	if (tmflags&MF_PICKUP)
	{
	    // can remove thing
	    P_TouchSpecialThing (thing, tmthing);
	}
	return !solid;
    }
	
    return !(thing->flags & MF_SOLID);
}


//
// MOVEMENT CLIPPING
//

//
// P_CheckPosition
// This is purely informative, nothing is modified
// (except things picked up).
// 
// in:
//  a mobj_t (can be valid or invalid)
//  a position to be checked
//   (doesn't need to be related to the mobj_t->x,y)
//
// during:
//  special things are touched if MF_PICKUP
//  early out on solid lines?
//
// out:
//  newsubsec
//  floorz
//  ceilingz
//  tmdropoffz
//   the lowest point contacted
//   (monsters won't move to a dropoff)
//  speciallines[]
//  numspeciallines
//
boolean
P_CheckPosition
( mobj_t*	thing,
  fixed_t	x,
  fixed_t	y )
{
    int			xl;
    int			xh;
    int			yl;
    int			yh;
    int			bx;
    int			by;
    subsector_t*	newsubsec;

    tmthing = thing;
    tmflags = thing->flags;
	
    tmx = x;
    tmy = y;
	
    tmbbox[BOXTOP] = y + tmthing->radius;
    tmbbox[BOXBOTTOM] = y - tmthing->radius;
    tmbbox[BOXRIGHT] = x + tmthing->radius;
    tmbbox[BOXLEFT] = x - tmthing->radius;

    newsubsec = R_PointInSubsector (x,y);
    ceilingline = NULL;
    
    // The base floor / ceiling is from the subsector
    // that contains the point.
    // Any contacted lines the step closer together
    // will adjust them.
    tmfloorz = tmdropoffz = newsubsec->sector->floorheight;
    tmceilingz = newsubsec->sector->ceilingheight;
			
    validcount++;
    numspechit = 0;

    if ( tmflags & MF_NOCLIP )
	return true;
    
    // Check things first, possibly picking things up.
    // The bounding box is extended by MAXRADIUS
    // because mobj_ts are grouped into mapblocks
    // based on their origin point, and can overlap
    // into adjacent blocks by up to MAXRADIUS units.
    xl = (tmbbox[BOXLEFT] - bmaporgx - MAXRADIUS)>>MAPBLOCKSHIFT;
    xh = (tmbbox[BOXRIGHT] - bmaporgx + MAXRADIUS)>>MAPBLOCKSHIFT;
    yl = (tmbbox[BOXBOTTOM] - bmaporgy - MAXRADIUS)>>MAPBLOCKSHIFT;
    yh = (tmbbox[BOXTOP] - bmaporgy + MAXRADIUS)>>MAPBLOCKSHIFT;

    for (bx=xl ; bx<=xh ; bx++)
	for (by=yl ; by<=yh ; by++)
	    if (!P_BlockThingsIterator(bx,by,PIT_CheckThing))
		return false;
    
    // check lines
    xl = (tmbbox[BOXLEFT] - bmaporgx)>>MAPBLOCKSHIFT;
    xh = (tmbbox[BOXRIGHT] - bmaporgx)>>MAPBLOCKSHIFT;
    yl = (tmbbox[BOXBOTTOM] - bmaporgy)>>MAPBLOCKSHIFT;
    yh = (tmbbox[BOXTOP] - bmaporgy)>>MAPBLOCKSHIFT;

    for (bx=xl ; bx<=xh ; bx++)
	for (by=yl ; by<=yh ; by++)
	    if (!P_BlockLinesIterator (bx,by,PIT_CheckLine))
		return false;

    return true;
}


//
// P_TryMove
// Attempt to move to a new position,
// crossing special lines unless MF_TELEPORT is set.
//
boolean
P_TryMove
( mobj_t*	thing,
  fixed_t	x,
  fixed_t	y )
{
    fixed_t	oldx;
    fixed_t	oldy;
    int		side;
    int		oldside;
    line_t*	ld;

    floatok = false;
    if (!P_CheckPosition (thing, x, y))
	return false;		// solid wall or thing
    
    if ( !(thing->flags & MF_NOCLIP) )
    {
	if (tmceilingz - tmfloorz < thing->height)
	    return false;	// doesn't fit

	floatok = true;
	
	if ( !(thing->flags&MF_TELEPORT) 
	     &&tmceilingz - thing->z < thing->height)
	    return false;	// mobj must lower itself to fit

	if ( !(thing->flags&MF_TELEPORT)
	     && tmfloorz - thing->z > 24*FRACUNIT )
	    return false;	// too big a step up

	if ( !(thing->flags&(MF_DROPOFF|MF_FLOAT))
	     && tmfloorz - tmdropoffz > 24*FRACUNIT )
	    return false;	// don't stand over a dropoff
    }
    
    // the move is ok,
    // so link the thing into its new position
    P_UnsetThingPosition (thing);

    oldx = thing->x;
    oldy = thing->y;
    thing->floorz = tmfloorz;
    thing->ceilingz = tmceilingz;	
    thing->x = x;
    thing->y = y;

    P_SetThingPosition (thing);
    
    // if any special lines were hit, do the effect
    if (! (thing->flags&(MF_TELEPORT|MF_NOCLIP)) )
    {
	while (numspechit--)
	{
	    // see if the line was crossed
	    ld = spechit[numspechit];
	    side = P_PointOnLineSide (thing->x, thing->y, ld);
	    oldside = P_PointOnLineSide (oldx, oldy, ld);
	    if (side != oldside)
	    {
		if (ld->special)
		    P_CrossSpecialLine (ld-lines, oldside, thing);
	    }
	}
    }

    return true;
}


//
// P_ThingHeightClip
// Takes a valid thing and adjusts the thing->floorz,
// thing->ceilingz, and possibly thing->z.
// This is called for all nearby monsters
// whenever a sector changes height.
// If the thing doesn't fit,
// the z will be set to the lowest value
// and false will be returned.
//
boolean P_ThingHeightClip (mobj_t* thing)
{
    boolean		onfloor;
	
    onfloor = (thing->z == thing->floorz);
	
    P_CheckPosition (thing, thing->x, thing->y);	
    // what about stranding a monster partially off an edge?
	
    thing->floorz = tmfloorz;
    thing->ceilingz = tmceilingz;
	
    if (onfloor)
    {
	// walking monsters rise and fall with the floor
	thing->z = thing->floorz;
    }
    else
    {
	// don't adjust a floating monster unless forced to
	if (thing->z+thing->height > thing->ceilingz)
	    thing->z = thing->ceilingz - thing->height;
    }
	
    if (thing->ceilingz - thing->floorz < thing->height)
	return false;
		
    return true;
}



//
// SLIDE MOVE
// Allows the player to slide along any angled walls.
//
fixed_t		bestslidefrac;
fixed_t		secondslidefrac;

line_t*		bestslideline;
line_t*		secondslideline;

mobj_t*		slidemo;

fixed_t		tmxmove;
fixed_t		tmymove;



//
// P_HitSlideLine
// Adjusts the xmove / ymove
// so that the next move will slide along the wall.
//
void P_HitSlideLine (line_t* ld)
{
    int			side;

    angle_t		lineangle;
    angle_t		moveangle;
    angle_t		deltaangle;
    
    fixed_t		movelen;
    fixed_t		newlen;
	
	
    if (ld->slopetype == ST_HORIZONTAL)
    {
	tmymove = 0;
	return;
    }
    
    if (ld->slopetype == ST_VERTICAL)
    {
	tmxmove = 0;
	return;
    }
	
    side = P_PointOnLineSide (slidemo->x, slidemo->y, ld);
	
    lineangle = R_PointToAngle2 (0,0, ld->dx, ld->dy);

    if (side == 1)
	lineangle += ANG180;

    moveangle = R_PointToAngle2 (0,0, tmxmove, tmymove);
    deltaangle = moveangle-lineangle;

    if (deltaangle > ANG180)
	deltaangle += ANG180;
    //	I_Error ("SlideLine: ang>ANG180");

    lineangle >>= ANGLETOFINESHIFT;
    deltaangle >>= ANGLETOFINESHIFT;
	
    movelen = P_AproxDistance (tmxmove, tmymove);
    newlen = FixedMul (movelen, finecosine[deltaangle]);

    tmxmove = FixedMul (newlen, finecosine[lineangle]);	
    tmymove = FixedMul (newlen, finesine[lineangle]);	
}


//
// PTR_SlideTraverse
//
boolean PTR_SlideTraverse (intercept_t* in)
{
    line_t*	li;
	
    if (!in->isaline)
	I_Error ("PTR_SlideTraverse: not a line?");
		
    li = in->d.line;
    
    if ( ! (li->flags & ML_TWOSIDED) )
    {
	if (P_PointOnLineSide (slidemo->x, slidemo->y, li))
	{
	    // don't hit the back side
	    return true;		
	}
	goto isblocking;
    }

    // set openrange, opentop, openbottom
    P_LineOpening (li);
    
    if (openrange < slidemo->height)
	goto isblocking;		// doesn't fit
		
    if (opentop - slidemo->z < slidemo->height)
	goto isblocking;		// mobj is too high

    if (openbottom - slidemo->z > 24*FRACUNIT )
	goto isblocking;		// too big a step up

    // this line doesn't block movement
    return true;		
	
    // the line does block movement,