BlockWater.java

package net.glowstone.block.blocktype;

import net.glowstone.EventFactory;
import net.glowstone.block.GlowBlock;
import net.glowstone.block.GlowBlockState;
import net.glowstone.constants.GlowBiomeClimate;
import org.bukkit.Material;
import org.bukkit.block.BlockFace;
import org.bukkit.event.block.BlockSpreadEvent;
import org.bukkit.material.MaterialData;

public class BlockWater extends BlockLiquid {

    private static final BlockFace[] SOLID_FACES = {BlockFace.NORTH, BlockFace.SOUTH, BlockFace.EAST, BlockFace.WEST};

    public BlockWater() {
        super(Material.WATER_BUCKET);
    }

    @Override
    public boolean isCollectible(GlowBlockState target) {
        return (target.getType() == Material.WATER || target.getType() == Material.STATIONARY_WATER) &&
                (target.getRawData() == 0 || target.getRawData() == 8); // 8 for backwards compatibility
    }

    @Override
    public void updateBlock(GlowBlock block) {
        super.updateBlock(block);
        if (block.getLightFromBlocks() <= 11 - block.getMaterialValues().getLightOpacity()) {
            if (block.getRelative(BlockFace.UP).isEmpty() && hasNearSolidBlock(block) && GlowBiomeClimate.isCold(block)) {
                final GlowBlockState state = block.getState();
                state.setType(Material.ICE);
                state.setData(new MaterialData(Material.ICE));
                BlockSpreadEvent spreadEvent = new BlockSpreadEvent(state.getBlock(), block, state);
                EventFactory.callEvent(spreadEvent);
                if (!spreadEvent.isCancelled()) {
                    state.update(true);
                }
            }
        }
    }

    private boolean hasNearSolidBlock(GlowBlock block) {
        // check there's at least a solid block around
        for (BlockFace face : SOLID_FACES) {
            if (block.getRelative(face).getType().isSolid()) {
                return true;
            }
        }
        return false;
    }
}