/*
 * WorldEdit, a Minecraft world manipulation toolkit
 * Copyright (C) sk89q <http://www.sk89q.com>
 * Copyright (C) WorldEdit team and contributors
 *
 * 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 3 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, see <https://www.gnu.org/licenses/>.
 */

package com.sk89q.worldedit.command.tool.brush;

import com.sk89q.worldedit.EditSession;
import com.sk89q.worldedit.MaxChangedBlocksException;
import com.sk89q.worldedit.function.pattern.Pattern;
import com.sk89q.worldedit.math.BlockVector3;
import com.sk89q.worldedit.world.block.BlockState;
import com.sk89q.worldedit.world.block.BlockTypes;

public class GravityBrush implements Brush {

    private final boolean fullHeight;

    public GravityBrush(boolean fullHeight) {
        this.fullHeight = fullHeight;
    }

    @Override
    public void build(EditSession editSession, BlockVector3 position, Pattern pattern, double size) throws
            MaxChangedBlocksException {
        //FAWE start - Ours operates differently to upstream, but does the same
        double endY = position.getY() + size;
        double startPerformY = Math.max(editSession.getMinY(), position.getY() - size);
        double startCheckY = fullHeight ? editSession.getMinY() : startPerformY;
        for (double x = position.getX() + size; x > position.getX() - size; --x) {
            for (double z = position.getZ() + size; z > position.getZ() - size; --z) {
                double freeSpot = startCheckY;
                for (double y = startCheckY; y <= endY; y++) {
                    BlockState block = editSession.getBlock((int) x, (int) y, (int) z);
                    if (!block.getBlockType().getMaterial().isAir()) {
                        if (y != freeSpot) {
                            editSession.setBlock((int) x, (int) y, (int) z, BlockTypes.AIR.getDefaultState());
                            editSession.setBlock((int) x, (int) freeSpot, (int) z, block);
                        }
                        freeSpot = y + 1;
                    }
                }
            }
        }
        //FAWE end
    }

}
