
#include "nx.h"
#include "slope.fdh"

static SlopeTable slopetable[SLOPE_LAST+1];

// creates the slope tables
bool initslopetable(void)
{
int x, y, ya, mx;
int curtable, opposing_table;
int inverttable, invertfliptable;
int flipmx, flipy;

	NX_LOG("initslopetable: generating slopetables.\n");
	memset(slopetable, 0, sizeof(slopetable));
	
	ya = TILE_H-1;
	for(x=0;x<TILE_W*2;x++)
	{
		if (x < TILE_W)
		{
			mx = x;
			curtable = SLOPE_FWD1;
			opposing_table = SLOPE_BACK2;
			inverttable = SLOPE_CEIL_BACK1;
			invertfliptable = SLOPE_CEIL_FWD2;
		}
		else
		{
			mx = x - TILE_W;
			curtable = SLOPE_FWD2;
			opposing_table = SLOPE_BACK1;
			inverttable = SLOPE_CEIL_BACK2;
			invertfliptable = SLOPE_CEIL_FWD1;
		}
		
		for(y=ya;y<TILE_H;y++)
		{
			flipmx = TILE_W-1-mx;
			flipy = TILE_H-1-y;
			
			slopetable[curtable].table[mx][y] = 1;
			slopetable[opposing_table].table[flipmx][y] = 1;
			slopetable[inverttable].table[mx][flipy] = 1;
			slopetable[invertfliptable].table[flipmx][flipy] = 1;
		}
		
		if (x & 1) ya--;
	}
	
	return 0;
}

/*
void c------------------------------() {}
*/

// X and Y are non-CSFd pixel coordinates relative to the upper-left of the map.
// if the given pixel is inside of a slope, returns the slope type 1-8. else, returns 0.
uint8_t ReadSlopeTable(int x, int y)
{
int mx, my;
int slopetype;
uint8_t t;

	// convert coordinates into a tile and check if the tile is a slope tile
	mx = (x / TILE_W);
	my = (y / TILE_H);
	
	if (mx < 0 || my < 0 || mx >= map.xsize || my >= map.ysize)
		return 0;
	
	t = map.tiles[mx][my];
	
	if (tileattr[t] & TA_SLOPE)
	{
		slopetype = (tilecode[t] & 0x07) + 1;	// extract slope type from tile code
		
		// get offset from the tile
		x %= TILE_W; y %= TILE_H;
		
		if (slopetable[slopetype].table[x][y])
			return slopetype;
	}
	
	return 0;
}

// returns true if any of the points in the given point list
// are on the solid portion of a slope tile.
bool IsSlopeAtPointList(Object *o, SIFPointList *points)
{
int x, y, i;

	for(i=0;i<points->count;i++)
	{
		x = (o->x >> CSF) + points->point[i].x;
		y = (o->y >> CSF) + points->point[i].y;
		if (ReadSlopeTable(x, y)) return 1;
	}
	
	return 0;
}

/*
void c------------------------------() {}
*/

// returns nonzero (the slope type) if the object is standing on a slope.
int CheckStandOnSlope(Object *o)
{
int x, y, st;

	y = (o->y >> CSF) + sprites[o->sprite].slopebox.y2 + 1;
	x = (o->x >> CSF);
	
	if ((st = ReadSlopeTable(x + sprites[o->sprite].slopebox.x1, y))) return st;
	if ((st = ReadSlopeTable(x + sprites[o->sprite].slopebox.x2, y))) return st;
	
	return 0;
}

// returns nonzero (the slope type) if the objects blocku should be set
// because of a ceiling slope.
int CheckBoppedHeadOnSlope(Object *o)
{
int x, y, st;

	y = (o->y >> CSF) + sprites[o->sprite].slopebox.y1 - 1;
	x = (o->x >> CSF);
	
	// without this, you get stuck in the save area below Gum Door in Grasstown
	//if (o == player) y += 4;
	
	if ((st = ReadSlopeTable(x + sprites[o->sprite].slopebox.x1, y))) return st;
	if ((st = ReadSlopeTable(x + sprites[o->sprite].slopebox.x2, y))) return st;
	
	return 0;
}


// move an object laterally, and have it climb slopes as it approaches them.
// We also have to move the object down as it goes down the slope.
// Otherwise, it would "skip" down the slope ungracefully.
// returns 1 if the object was blocked by a wall.
bool movehandleslope(Object *o, int xinertia)
{
int xoff, opposing_x;
int newx, newy, oldy;
char blocked_wall;

	if (!xinertia) return 0;
	
	// for objects which don't follow slope, just treat the slope as a blockl/r
	if (!(o->nxflags & NXFLAG_FOLLOW_SLOPE))
	{
		if (xinertia > 0)
		{
			if (o->blockr) return 1;
		}
		else
		{
			if (o->blockl) return 1;
		}
		
		o->x += xinertia;
		return 0;
	}
	
	newx = o->x;
	newy = o->y;
	
	// determine which side of the bounding box to use based on which way
	// we're traveling
	if (xinertia > 0)
	{	// moving right (right side of slopebox hits slopes first)
		opposing_x = sprites[o->sprite].slopebox.x1;
		xoff = sprites[o->sprite].slopebox.x2;
	}
	else
	{	// move left (left side of slopebox hits slopes first)
		opposing_x = sprites[o->sprite].slopebox.x2;
		xoff = sprites[o->sprite].slopebox.x1;
	}
	
	// check the opposing side at y+1 to see if we were standing on a slope before the move.
	uint8_t old_floor_slope, old_ceil_slope;
	old_floor_slope = ReadSlopeTable((newx>>CSF) + opposing_x, \
									 (newy>>CSF) + sprites[o->sprite].slopebox.y2 + 1);
	
	old_ceil_slope = ReadSlopeTable((newx>>CSF) + opposing_x, \
									(newy>>CSF) + sprites[o->sprite].slopebox.y1 - 1);
	
	// move the object
	newx += xinertia;
	
	// check the opposing side again and if now we're not standing any more,
	// we moved down the slope, so add +1 to the object's Y coordinate.
	if (old_floor_slope && !ReadSlopeTable((newx>>CSF) + opposing_x, \
										(newy>>CSF) + sprites[o->sprite].slopebox.y2 + 1))
	{
		bool walking_down = false;
		
		// only trigger if it's the correct slope type so that we would be walking down it if
		// we were going in the direction we're going. prevents being shoved down 1px when
		// exiting the top of a slope.
		if (xinertia < 0)
		{
			if (old_floor_slope == SLOPE_FWD1 || \
				old_floor_slope == SLOPE_FWD2)
			{
				walking_down = true;
			}
		}
		else if (xinertia > 0)
		{
			if (old_floor_slope == SLOPE_BACK1 || \
				old_floor_slope == SLOPE_BACK2)
			{
				walking_down = true;
			}
		}
		
		if (walking_down)
		{
			newy += (1<<CSF);
		}
	}
	
	// the same for ceiling slopes
	if (old_ceil_slope && !ReadSlopeTable((newx>>CSF) + opposing_x, \
										(newy>>CSF) + sprites[o->sprite].slopebox.y1 - 1))
	{
		bool moveme = false;
		
		if (xinertia < 0)
		{
			if (old_ceil_slope == SLOPE_CEIL_BACK1 || \
				old_ceil_slope == SLOPE_CEIL_BACK2)
			{
				moveme = true;
			}
		}
		else if (xinertia > 0)
		{
			if (old_ceil_slope == SLOPE_CEIL_FWD1 || \
				old_ceil_slope == SLOPE_CEIL_FWD2)
			{
				moveme = true;
			}
		}
		
		if (moveme)
		{	// moving down (actually up) the "descending" (closer to real ceil) portion
			// of a ceiling slope tile. Reverse of floor slope thingy above.
			newy -= (1<<CSF);
		}
	}
	
	// check the coordinate and see if it's inside a slope tile.
	// if so, move the object up 1 Y pixel.
	uint8_t moved_into_ceil_slope = ReadSlopeTable((newx>>CSF) + xoff, \
									(newy>>CSF) + sprites[o->sprite].slopebox.y1);
	if (moved_into_ceil_slope)
	{
		newy += (1<<CSF);
	}
	
	uint8_t moved_into_floor_slope = ReadSlopeTable((newx>>CSF) + xoff, \
									(newy>>CSF) + sprites[o->sprite].slopebox.y2);
	if (moved_into_floor_slope)
	{
		newy -= (1<<CSF);
	}
	
	// can't move if blocked by a wall. but if we've moved up or down 1px, be sure and update
	// the blockr/l state before declaring we can't move--otherwise we can get stuck at the
	// top of a slope with the bottom blockr/l stuck at the top px of the adjacent solid tile.
	oldy = o->y;
	o->y = newy;
	
	if (xinertia > 0)
	{
		if (oldy != newy)
			o->UpdateBlockStates(RIGHTMASK);
		
		blocked_wall = o->blockr;
	}
	else
	{
		if (oldy != newy)
			o->UpdateBlockStates(LEFTMASK);
		
		blocked_wall = o->blockl;
	}
	
	if (blocked_wall)
	{	// we can't actually move...so reset Y position
		o->y = oldy;
	}
	else
	{	// can move...complete the move by setting the X position too
		o->x = newx;
	}
	
	return blocked_wall;
}
