/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL: https://scummvm.svn.sourceforge.net/svnroot/scummvm/scummvm/tags/release-1-1-1/engines/sky/autoroute.cpp $
 * $Id: autoroute.cpp 45616 2009-11-02 21:54:57Z fingolfin $
 *
 */


#include "common/endian.h"
#include "common/util.h"

#include "sky/autoroute.h"
#include "sky/compact.h"
#include "sky/grid.h"
#include "sky/skydefs.h"
#include "sky/struc.h"

namespace Sky {

#define ROUTE_GRID_WIDTH ((GAME_SCREEN_WIDTH/8)+2)
#define ROUTE_GRID_HEIGHT ((GAME_SCREEN_HEIGHT/8)+2)
#define ROUTE_GRID_SIZE (ROUTE_GRID_WIDTH*ROUTE_GRID_HEIGHT*2)
#define WALK_JUMP 8      // walk in blocks of 8

const int16 AutoRoute::_routeDirections[4] = {    -1,     1, -ROUTE_GRID_WIDTH, ROUTE_GRID_WIDTH };
const uint16 AutoRoute::_logicCommands[4] = { RIGHTY, LEFTY,             DOWNY,              UPY };

AutoRoute::AutoRoute(Grid *pGrid, SkyCompact *compact) {
	_grid = pGrid;
	_skyCompact = compact;
	_routeGrid = (uint16 *)malloc(ROUTE_GRID_SIZE);
	_routeBuf = (uint16 *)malloc(ROUTE_SPACE);
}

AutoRoute::~AutoRoute() {
	free(_routeGrid);
	free(_routeBuf);
}

uint16 AutoRoute::checkBlock(uint16 *blockPos) {
	uint16 retVal = 0xFFFF;

	for (uint8 cnt = 0; cnt < 4; cnt++) {
		uint16 fieldVal = *(blockPos + _routeDirections[cnt]);
		if (fieldVal && (fieldVal < retVal))
			retVal = fieldVal;
	}
	return retVal;
}

void AutoRoute::clipCoordX(uint16 x, uint8 &blkX, int16 &initX) {
	if (x < TOP_LEFT_X) {
		blkX = 0;
		initX = x - TOP_LEFT_X;
	} else if (x >= TOP_LEFT_X + GAME_SCREEN_WIDTH) {
		blkX = (GAME_SCREEN_WIDTH - 1) >> 3;
		initX = x - (TOP_LEFT_X + GAME_SCREEN_WIDTH - 1);
	} else {
		blkX = (x - TOP_LEFT_X) >> 3;
		initX = 0;
	}
}

void AutoRoute::clipCoordY(uint16 y, uint8 &blkY, int16 &initY) {
	if (y < TOP_LEFT_Y) {
		blkY = 0;
		initY = y - TOP_LEFT_Y;
	} else if (y >= TOP_LEFT_Y + GAME_SCREEN_HEIGHT) {
		blkY = (GAME_SCREEN_HEIGHT - 1) >> 3;
		initY = y - (TOP_LEFT_Y + GAME_SCREEN_HEIGHT);
	} else {
		blkY = (y - TOP_LEFT_Y) >> 3;
		initY = 0;
	}
}

void AutoRoute::initWalkGrid(uint8 screen, uint8 width) {
	uint16 *wGridPos;
	uint8 stretch = 0;
	uint8 *screenGrid = _grid->giveGrid(screen);
	screenGrid += GRID_SIZE;
	wGridPos = _routeGrid + (ROUTE_GRID_SIZE >> 1) - ROUTE_GRID_WIDTH - 2;

	memset(_routeGrid, 0, ROUTE_GRID_SIZE);
	uint8 bitsLeft = 0; uint32 gridData = 0;
	for (uint8 gridCntY = 0; gridCntY < ROUTE_GRID_HEIGHT - 2; gridCntY++) {
		for (uint8 gridCntX = 0; gridCntX < ROUTE_GRID_WIDTH - 2; gridCntX++) {
			if (!bitsLeft) {
				screenGrid -= 4;
				gridData = READ_LE_UINT32(screenGrid);
				bitsLeft = 32;
			}
			if (gridData & 1) {
				*wGridPos = 0xFFFF; // block is not accessible
				stretch = width;
			} else if (stretch) {
				*wGridPos = 0xFFFF;
				stretch--;
			}
			wGridPos--;
			bitsLeft--;
			gridData >>= 1;
		}
		wGridPos -= 2;
		stretch = 0;
	}
}

bool AutoRoute::calcWalkGrid(uint8 startX, uint8 startY, uint8 destX, uint8 destY) {
	int16 directionX, directionY;
	uint8 roiX, roiY; // Rectangle Of Interest in the walk grid
	if (startY > destY) {
		directionY = -ROUTE_GRID_WIDTH;
		roiY = startY;
	} else {
		directionY = ROUTE_GRID_WIDTH;
		roiY = (ROUTE_GRID_HEIGHT-1) - startY;
	}
	if (startX > destX) {
		directionX = -1;
		roiX = startX + 2;
	} else {
		directionX = 1;
		roiX = (ROUTE_GRID_WIDTH - 1) - startX;
	}

	uint16 *walkDest  = _routeGrid + (destY + 1) * ROUTE_GRID_WIDTH + destX + 1;
	uint16 *walkStart = _routeGrid + (startY + 1) * ROUTE_GRID_WIDTH + startX + 1;
	*walkStart = 1;

	// if we are on the edge, move diagonally from start
	if (roiY < ROUTE_GRID_HEIGHT-3)
		walkStart -= directionY;

	if (roiX < ROUTE_GRID_WIDTH-2)
		walkStart -= directionX;

	bool gridChanged = true;
	bool foundRoute = false;

	while ((!foundRoute) && gridChanged) {
		gridChanged = false;
		uint16 *yWalkCalc = walkStart;
		for (uint8 cnty = 0; cnty < roiY; cnty++) {
			uint16 *xWalkCalc = yWalkCalc;
			for (uint8 cntx = 0; cntx < roiX; cntx++) {
				if (!*xWalkCalc) { // block wasn't done, yet
					uint16 blockRet = checkBlock(xWalkCalc);
					if (blockRet < 0xFFFF) {
						*xWalkCalc = blockRet + 1;
						gridChanged = true;
					}
				}
				xWalkCalc += directionX;
			}
			yWalkCalc += directionY;
		}
		if (*walkDest) { // okay, finished
			foundRoute = true;
		} else { // we couldn't find the route, let's extend the ROI
			if (roiY < ROUTE_GRID_HEIGHT - 4) {
				walkStart -= directionY;
				roiY++;
			}
			if (roiX < ROUTE_GRID_WIDTH - 4) {
				walkStart -= directionX;
				roiX++;
			}
		}
	}
	return foundRoute;
}

uint16 *AutoRoute::makeRouteData(uint8 startX, uint8 startY, uint8 destX, uint8 destY) {
	memset(_routeBuf, 0, ROUTE_SPACE);

	uint16 *routePos = _routeGrid + (destY + 1) * ROUTE_GRID_WIDTH + destX + 1;
	uint16 *dataTrg = _routeBuf + (ROUTE_SPACE >> 1) - 2;

	uint16 lastVal = (*routePos) - 1;
	while (lastVal) { // lastVal == 0 means route is done.
		dataTrg -= 2;

		int16 walkDirection = 0;
		for (uint8 cnt = 0; cnt < 4; cnt++)
			if (lastVal == *(routePos + _routeDirections[cnt])) {
				*(dataTrg + 1) = _logicCommands[cnt];
				walkDirection = _routeDirections[cnt];
				break;
			}

		if (!walkDirection)
			error("makeRouteData:: can't find way through walkGrid (pos %d)", lastVal);
		while (lastVal && (lastVal == *(routePos + walkDirection))) {
			*dataTrg += WALK_JUMP;
			lastVal--;
			routePos += walkDirection;
		}
	}
	return dataTrg;
}

uint16 *AutoRoute::checkInitMove(uint16 *data, int16 initStaX) {
	if (initStaX < 0) {
		data -= 2;
		*(data + 1) = RIGHTY;
		*data = ((-initStaX) + 7) & 0xFFF8;
	} else if (initStaX > 0) {
		data -= 2;
		*(data + 1) = LEFTY;
		*data = (initStaX + 7) & 0xFFF8;
	}
	return data;
}

uint16 AutoRoute::autoRoute(Compact *cpt) {
	uint8 cptScreen = (uint8)cpt->screen;
	uint8 cptWidth = (uint8)SkyCompact::getMegaSet(cpt)->gridWidth;
	initWalkGrid(cptScreen, cptWidth);

	uint8 startX, startY, destX, destY;
	int16 initStaX, initStaY, initDestX, initDestY;

	clipCoordX(cpt->xcood, startX, initStaX);
	clipCoordY(cpt->ycood, startY, initStaY);
	clipCoordX(cpt->arTargetX, destX, initDestX);
	clipCoordY(cpt->arTargetY, destY, initDestY);

	uint16 *routeDest = (uint16*)_skyCompact->fetchCpt(cpt->animScratchId);
	memset(routeDest, 0, 64);
	if ((startX == destX) && (startY == destY))
		return 2;

	if (_routeGrid[(destY + 1) * ROUTE_GRID_WIDTH + destX + 1]) {
		//if ((cpt == &Sky::SkyCompact::foster) && (cptScreen == 12) && (destX == 2) && (destY == 14)) {
		if (_skyCompact->cptIsId(cpt, CPT_FOSTER) && (cptScreen == 12) && (destX == 2) && (destY == 14)) {
			/* workaround for Scriptbug #1043047
			   In screen 12 (the pipe factory) Joey can block Foster's target
			   coordinates (2/14). This is normally not too tragic, but in the
			   scene when foster gets thrown out by Lamb (first time you enter
			   the pipe factory), the game would enter an infinite loop. */
			_routeGrid[(destY + 1) * ROUTE_GRID_WIDTH + destX + 1] = 0;
			// hide this part joey from the grid
		} else
			return 1; // AR destination is an unaccessible block
	}

	if (!calcWalkGrid(startX, startY, destX, destY))
		return 1; // can't find route to block

	uint16 *routeData = makeRouteData(startX, startY, destX, destY);
	// the route is done.
	// if there was an initial x movement (due to clipping) tag it onto the start
	routeData = checkInitMove(routeData, initStaX);

	uint8 cnt = 0;
	do {
		routeDest[cnt]     = routeData[cnt];
		routeDest[cnt + 1] = routeData[cnt + 1];
		cnt += 2;
	} while (routeData[cnt - 2]);
	return 0;
}

} // End of namespace Sky
