#include "stdafx.h"
#include "openttd.h"
#include "debug.h"
#include "functions.h"
#include "map.h"

uint _map_log_x;
uint _map_log_y;

byte   *_map_type_and_height = NULL;
byte   *_map_owner           = NULL;
uint16 *_map2                = NULL;
byte   *_map3_lo             = NULL;
byte   *_map3_hi             = NULL;
byte   *_map5                = NULL;
byte   *_map_extra_bits      = NULL;


void InitMap(uint log_x, uint log_y)
{
	uint map_size;

	if (log_x < 6 || log_x > 11 || log_y < 6 || log_y > 11)
		error("Invalid map size");

	DEBUG(map, 1)("Allocating map of size %dx%d", log_x, log_y);

	// XXX - MSVC6 volatile workaround
	*(volatile uint*)&_map_log_x = log_x;
	*(volatile uint*)&_map_log_y = log_y;

	map_size = MapSize();

	_map_type_and_height =
		realloc(_map_type_and_height, map_size * sizeof(_map_type_and_height[0]));
	_map_owner = realloc(_map_owner, map_size * sizeof(_map_owner[0]));
	_map2      = realloc(_map2,      map_size * sizeof(_map2[0]));
	_map3_lo   = realloc(_map3_lo,   map_size * sizeof(_map3_lo[0]));
	_map3_hi   = realloc(_map3_hi,   map_size * sizeof(_map3_hi[0]));
	_map5      = realloc(_map5,      map_size * sizeof(_map5[0]));
	_map_extra_bits =
		realloc(_map_extra_bits, map_size * sizeof(_map_extra_bits[0] / 4));

	// XXX TODO handle memory shortage more gracefully
	if (_map_type_and_height == NULL ||
			_map_owner           == NULL ||
			_map2                == NULL ||
			_map3_lo             == NULL ||
			_map3_hi             == NULL ||
			_map5                == NULL ||
			_map_extra_bits      == NULL)
		error("Failed to allocate memory for the map");
}


#ifdef _DEBUG
TileIndex TileAdd(TileIndex tile, TileIndexDiff add,
	const char *exp, const char *file, int line)
{
	int dx;
	int dy;
	uint x;
	uint y;

	dx = add & MapMaxX();
	if (dx >= (int)MapSizeX() / 2) dx -= MapSizeX();
	dy = (add - dx) / (int)MapSizeX();

	x = TileX(tile) + dx;
	y = TileY(tile) + dy;

	if (x >= MapSizeX() || y >= MapSizeY()) {
		char buf[512];

		sprintf(buf, "TILE_ADD(%s) when adding 0x%.4X and 0x%.4X failed",
			exp, tile, add);
#if !defined(_MSC_VER)
		fprintf(stderr, "%s:%d %s\n", file, line, buf);
#else
		_assert(buf, (char*)file, line);
#endif
	}

	assert(TileXY(x,y) == TILE_MASK(tile + add));

	return TileXY(x,y);
}
#endif


uint ScaleByMapSize(uint n)
{
	int shift = (int)MapLogX() - 8 + (int)MapLogY() - 8;

	if (shift < 0)
		return (n + (1 << -shift) - 1) >> -shift;
	else
		return n << shift;
}


uint ScaleByMapSize1D(uint n)
{
	int shift = ((int)MapLogX() - 8 + (int)MapLogY() - 8) / 2;

	if (shift < 0)
		return (n + (1 << -shift) - 1) >> -shift;
	else
		return n << shift;
}


// This function checks if we add addx/addy to tile, if we
//  do wrap around the edges. For example, tile = (10,2) and
//  addx = +3 and addy = -4. This function will now return
//  INVALID_TILE, because the y is wrapped. This is needed in
//  for example, farmland. When the tile is not wrapped,
//  the result will be tile + TileDiffXY(addx, addy)
uint TileAddWrap(TileIndex tile, int addx, int addy)
{
	uint x, y;
	x = TileX(tile) + addx;
	y = TileY(tile) + addy;

	// Are we about to wrap?
	if (x < MapMaxX() && y < MapMaxY())
		return tile + TileDiffXY(addx, addy);

	return INVALID_TILE;
}

const TileIndexDiffC _tileoffs_by_dir[] = {
	{-1,  0},
	{ 0,  1},
	{ 1,  0},
	{ 0, -1}
};

uint DistanceManhattan(TileIndex t0, TileIndex t1)
{
	const uint dx = abs(TileX(t0) - TileX(t1));
	const uint dy = abs(TileY(t0) - TileY(t1));
	return dx + dy;
}


uint DistanceSquare(TileIndex t0, TileIndex t1)
{
	const int dx = TileX(t0) - TileX(t1);
	const int dy = TileY(t0) - TileY(t1);
	return dx * dx + dy * dy;
}


uint DistanceMax(TileIndex t0, TileIndex t1)
{
	const uint dx = abs(TileX(t0) - TileX(t1));
	const uint dy = abs(TileY(t0) - TileY(t1));
	return dx > dy ? dx : dy;
}


uint DistanceMaxPlusManhattan(TileIndex t0, TileIndex t1)
{
	const uint dx = abs(TileX(t0) - TileX(t1));
	const uint dy = abs(TileY(t0) - TileY(t1));
	return dx > dy ? 2 * dx + dy : 2 * dy + dx;
}

uint DistanceTrack(TileIndex t0, TileIndex t1)
{
	const uint dx = abs(TileX(t0) - TileX(t1));
	const uint dy = abs(TileY(t0) - TileY(t1));

	const uint straightTracks = 2 * min(dx, dy); /* The number of straight (not full length) tracks */
	/* OPTIMISATION:
	 * Original: diagTracks = max(dx, dy) - min(dx,dy);
	 * Proof:
	 * (dx-dy) - straightTracks  == (min + max) - straightTracks = min + // max - 2 * min = max - min */
	const uint diagTracks = dx + dy - straightTracks; /* The number of diagonal (full tile length) tracks. */

	return diagTracks + straightTracks * STRAIGHT_TRACK_LENGTH;
}

uint DistanceFromEdge(TileIndex tile)
{
	const uint xl = TileX(tile);
	const uint yl = TileY(tile);
	const uint xh = MapSizeX() - 1 - xl;
	const uint yh = MapSizeY() - 1 - yl;
	const uint minl = xl < yl ? xl : yl;
	const uint minh = xh < yh ? xh : yh;
	return minl < minh ? minl : minh;
}

