src/main/java/net/glowstone/GlowChunk.java

package net.glowstone;

import net.glowstone.block.BlockProperties;
import net.glowstone.block.GlowBlock;
import net.glowstone.block.GlowBlockState;
import net.glowstone.msg.CompressedChunkMessage;
import net.glowstone.net.message.Message;
import net.glowstone.net.message.game.ChunkDataMessage;
import org.bukkit.Chunk;
import org.bukkit.ChunkSnapshot;
import org.bukkit.World;
import org.bukkit.entity.Entity;

import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.logging.Level;

/**
 * Represents a chunk of the map.
 * @author Graham Edgecombe
 */
public final class GlowChunk implements Chunk {

    /**
     * The radius (not including the current chunk) of the chunks that the
     * player can see. Used as a default when no custom value is specified.
     */
    public static final int VISIBLE_RADIUS = 8;

    /**
     * A chunk key represents the X and Z coordinates of a chunk and implements
     * the {@link #hashCode()} and {@link #equals(Object)} methods making it
     * suitable for use as a key in a hash table or set.
     * @author Graham Edgecombe
     */
    public static final class Key {

        /**
         * The coordinates.
         */
        private final int x, z;

        /**
         * Creates a new chunk key with the specified X and Z coordinates.
         * @param x The X coordinate.
         * @param z The Z coordinate.
         */
        public Key(int x, int z) {
            this.x = x;
            this.z = z;
        }

        /**
         * Gets the X coordinate.
         * @return The X coordinate.
         */
        public int getX() {
            return x;
        }

        /**
         * Gets the Z coordinate.
         * @return The Z coordinate.
         */
        public int getZ() {
            return z;
        }

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + x;
            result = prime * result + z;
            return result;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            Key other = (Key) obj;
            if (x != other.x)
                return false;
            if (z != other.z)
                return false;
            return true;
        }

    }

    /**
     * The dimensions of a chunk.
     */
    public static final int WIDTH = 16, HEIGHT = 16, DEPTH = 128;
    
    /**
     * The world of this chunk.
     */
    private final GlowWorld world;

    /**
     * The coordinates of this chunk.
     */
    private final int x, z;

    /**
     * The data in this chunk representing all of the blocks and their state.
     */
    private byte[] types, metaData, skyLight, blockLight;
    
    /**
     * The tile entities that reside in this chunk.
     */
    private final HashMap<Integer, GlowBlockState> tileEntities = new HashMap<Integer, GlowBlockState>();
    
    /**
     * Whether the chunk has been populated by special features.
     * Used in map generation.
     */
    private boolean populated = false;

    /**
     * Creates a new chunk with a specified X and Z coordinate.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     */
    public GlowChunk(GlowWorld world, int x, int z) {
        this.world = world;
        this.x = x;
        this.z = z;
    }
    
    // ======== Basic stuff ========

    /**
     * Gets the world containing this chunk
     *
     * @return Parent World
     */
    public GlowWorld getWorld() {
        return world;
    }

    /**
     * Gets the X coordinate of this chunk.
     * @return The X coordinate of this chunk.
     */
    public int getX() {
        return x;
    }

    /**
     * Gets the Z coordinate of this chunk.
     * @return The Z coordinate of this chunk.
     */
    public int getZ() {
        return z;
    }
    
    /**
     * Gets a block from this chunk
     *
     * @param x 0-15
     * @param y 0-127
     * @param z 0-15
     * @return the Block
     */
    public GlowBlock getBlock(int x, int y, int z) {
        return getWorld().getBlockAt(this.x << 4 | x, y, this.z << 4 | z);
    }

    public Entity[] getEntities() {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    public GlowBlockState[] getTileEntities() {
        return tileEntities.values().toArray(new GlowBlockState[tileEntities.size()]);
    }
    
    /**
     * Capture thread-safe read-only snapshot of chunk data
     * @return ChunkSnapshot
     */
    public ChunkSnapshot getChunkSnapshot() {
        return getChunkSnapshot(true, false, false);
    }

    /**
     * Capture thread-safe read-only snapshot of chunk data
     * @param includeMaxblocky - if true, snapshot includes per-coordinate maximum Y values
     * @param includeBiome - if true, snapshot includes per-coordinate biome type
     * @param includeBiomeTempRain - if true, snapshot includes per-coordinate raw biome temperature and rainfall
     * @return ChunkSnapshot
     */
    public ChunkSnapshot getChunkSnapshot(boolean includeMaxblocky, boolean includeBiome, boolean includeBiomeTempRain) {
        return new GlowChunkSnapshot(x, z, world, types, metaData, skyLight, blockLight, includeMaxblocky, includeBiome, includeBiomeTempRain);
    }
    
    /**
     * Gets whether this chunk has been populated by special features.
     * @return Population status.
     */
    public boolean getPopulated() {
        return populated;
    }
    
    /**
     * Sets the population status of this chunk.
     * @param populated Population status.
     */
    public void setPopulated(boolean populated) {
        this.populated = populated;
    }
    
    // ======== Helper Functions ========

    public boolean isLoaded() {
        return types != null;
    }

    public boolean load() {
        return load(true);
    }

    public boolean load(boolean generate) {
        if (isLoaded()) return true;
        return world.getChunkManager().loadChunk(x, z, generate);
    }

    public boolean unload() {
        return unload(true, true);
    }

    public boolean unload(boolean save) {
        return unload(save, true);
    }

    public boolean unload(boolean save, boolean safe) {
        if (safe) {
            if (false /* TODO: if we ought not to unload */) {
                return false;
            }
        }
        
        if (save) {
            world.getChunkManager().forceSave(x, z);
        }
        
        // any other pre-unload actions
        
        types = metaData = skyLight = blockLight = null;
        return true;
    }

    /**
     * Sets the types of all tiles within the chunk.
     * @param types The array of types.
     */
    public void initializeTypes(byte[] types) {
        if (isLoaded()) {
            GlowServer.logger.log(Level.SEVERE, "Tried to initialize already loaded chunk ({0},{1})", new Object[]{x, z});
            return;
        }
        
        this.types = new byte[WIDTH * HEIGHT * DEPTH];
        metaData = new byte[WIDTH * HEIGHT * DEPTH];
        skyLight = new byte[WIDTH * HEIGHT * DEPTH];
        blockLight = new byte[WIDTH * HEIGHT * DEPTH];
        for (int i = 0; i < WIDTH * HEIGHT * DEPTH; ++i) {
            skyLight[i] = 15;
        }
        
        //System.out.println("Init'd types, isLoaded = " + isLoaded());
        
        if (types.length != WIDTH * HEIGHT * DEPTH) {
            throw new IllegalArgumentException();
        }
        System.arraycopy(types, 0, this.types, 0, types.length);
        
        for (int cx = 0; cx < WIDTH; ++cx) {
            for (int cy = 0; cy < DEPTH; ++cy) {
                for (int cz = 0; cz < HEIGHT; ++cz) {
                    BlockProperties properties = BlockProperties.get(getType(cx, cz, cy));
                    Class<? extends GlowBlockState> clazz = properties == null ? null : properties.getEntityClass();
                    if (clazz != null && clazz != GlowBlockState.class) {
                        try {
                            Constructor<? extends GlowBlockState> constructor = clazz.getConstructor(GlowBlock.class);
                            GlowBlockState state = constructor.newInstance(getBlock(cx, cy, cz));
                            tileEntities.put(coordToIndex(cx, cz, cy), state);
                        } catch (Exception ex) {
                            GlowServer.logger.log(Level.SEVERE, "Unable to initialize tile entity {0}: {1}", new Object[]{clazz.getName(), ex.getMessage()});
                            ex.printStackTrace();
                        }
                    }
                }
            }
        }
    }
    
    // ======== Data access ========
    
    /**
     * Attempt to get the tile entity located at the given coordinates.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @param y The Y coordinate.
     * @return A GlowBlockState if the entity exists, or null otherwise.
     */
    public GlowBlockState getEntity(int x, int y, int z) {
        if (y >= world.getMaxHeight() - 1 || y < 0) return null;
        load();
        return tileEntities.get(coordToIndex(x, z, y));
    }

    /**
     * Gets the type of a block within this chunk.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @param y The Y coordinate.
     * @return The type.
     */
    public int getType(int x, int z, int y) {
        if (y >= world.getMaxHeight() - 1 || y < 0) return 0;
        load();
        return types[coordToIndex(x, z, y)];
    }

    /**
     * Sets the type of a block within this chunk.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @param y The Y coordinate.
     * @param type The type.
     */
    public void setType(int x, int z, int y, int type) {
        load();
        if (type < 0 || type >= 256)
            throw new IllegalArgumentException();

        if (tileEntities.containsKey(coordToIndex(x, z, y))) {
            getEntity(x, y, z).destroy();
            tileEntities.remove(coordToIndex(x, z, y));
        }
        
        types[coordToIndex(x, z, y)] = (byte) type;
        BlockProperties property = BlockProperties.get(type);
        if (property != null) {
            Class<? extends GlowBlockState> clazz = property.getEntityClass();
            if (clazz != null && clazz != GlowBlockState.class) {
                try {
                    Constructor<? extends GlowBlockState> constructor = clazz.getConstructor(GlowBlock.class);
                    GlowBlockState state = constructor.newInstance(getBlock(x, y, z));
                    tileEntities.put(coordToIndex(x, z, y), state);
                } catch (Exception ex) {
                    GlowServer.logger.log(Level.SEVERE, "Unable to initialize tile entity {0}: {1}", new Object[]{clazz.getName(), ex.getMessage()});
                    ex.printStackTrace();
                }
            }
        }
    }

    /**
     * Gets the metadata of a block within this chunk.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @param y The Y coordinate.
     * @return The metadata.
     */
    public int getMetaData(int x, int z, int y) {
        if (y >= world.getMaxHeight() - 1 || y < 0) return 0;
        load();
        return metaData[coordToIndex(x, z, y)];
    }

    /**
     * Sets the metadata of a block within this chunk.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @param y The Y coordinate.
     * @param metaData The metadata.
     */
    public void setMetaData(int x, int z, int y, int metaData) {
        load();
        if (metaData < 0 || metaData >= 16)
            throw new IllegalArgumentException();

        this.metaData[coordToIndex(x, z, y)] = (byte) metaData;
    }

    /**
     * Gets the sky light level of a block within this chunk.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @param y The Y coordinate.
     * @return The sky light level.
     */
    public int getSkyLight(int x, int z, int y) {
        if (y >= world.getMaxHeight() - 1 || y < 0) return 0;
        load();
        return skyLight[coordToIndex(x, z, y)];
    }

    /**
     * Sets the sky light level of a block within this chunk.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @param y The Y coordinate.
     * @param skyLight The sky light level.
     */
    public void setSkyLight(int x, int z, int y, int skyLight) {
        load();
        if (skyLight < 0 || skyLight >= 16)
            throw new IllegalArgumentException();

        this.skyLight[coordToIndex(x, z, y)] = (byte) skyLight;
    }

    /**
     * Gets the block light level of a block within this chunk.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @param y The Y coordinate.
     * @return The block light level.
     */
    public int getBlockLight(int x, int z, int y) {
        if (y >= world.getMaxHeight() - 1 || y < 0) return 0;
        load();
        return blockLight[coordToIndex(x, z, y)];
    }

    /**
     * Sets the block light level of a block within this chunk.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @param y The Y coordinate.
     * @param blockLight The block light level.
     */
    public void setBlockLight(int x, int z, int y, int blockLight) {
        load();
        if (blockLight < 0 || blockLight >= 16)
            throw new IllegalArgumentException();

        this.blockLight[coordToIndex(x, z, y)] = (byte) blockLight;
    }

    public byte[] getTypes() {
        load();
        return types.clone();
    }
    
    // ======== Helper functions ========

    /**
     * Creates a new {@link Message} which can be sent to a client to stream
     * this chunk to them.
     * @return The {@link CompressedChunkMessage}.
     */
    public Message toMessage() {
        int primaryBitmask = (1 << (DEPTH / 16)) - 1; // 0xff, defines which chunks are being sent
        int addBitmask = 0; // used for extended-value chunks which are not yet supported
        boolean skylight = world.getEnvironment() == World.Environment.NORMAL;
        byte[] tileData = serializeTileData(primaryBitmask, addBitmask, skylight);
        return new ChunkDataMessage(x, z, true, primaryBitmask, addBitmask, tileData);
    }

    /**
     * Converts a three-dimensional coordinate to an index within the
     * one-dimensional arrays.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @param y The Y coordinate.
     * @return The index within the arrays.
     */
    private int coordToIndex(int x, int z, int y) {
        if (y >= world.getMaxHeight())
            y = 127; // temporary hack because the world height is wrong
        if (x < 0 || z < 0 || y < 0 || x >= WIDTH || z >= HEIGHT || y >= world.getMaxHeight())
            throw new IndexOutOfBoundsException("Coords (x=" + x + ",y=" + y + ",z=" + z + ") invalid");

        return (y * 16 + z) * 16 + x;  // make constants cleaner later
        //return (x * HEIGHT + z) * world.getMaxHeight() + y;
    }

    /**
     * Serializes tile data into a byte array.
     * @return The byte array populated with the tile data.
     * @param primaryBitmask primary bitmask
     * @param addBitmask add bitmask
     * @param skylight skylight
     */
    private byte[] serializeTileData(int primaryBitmask, int addBitmask, boolean skylight) {
        // http://wiki.vg/SMP_Map_Format
        // right now, assumes inputs are exactly what is given by default in toMessage above
        // assuming ground up continuous is true
        // also assuming addBitmask is zero, for simplicity (it always is right now)

        //int numChunks = countBits(primaryBitmask);

        int numBlocks = WIDTH * HEIGHT * DEPTH;
        int bytes = 2 * numBlocks; // type, metadata, light
        if (skylight) {
            bytes += numBlocks / 2; // skylight
        }
        /*if (addArray) { bytes += numBlocks / 2; }*/
        /*if (groundUpContinuous)*/ {
            bytes += 256; // biomes
        }

        byte[] dest = new byte[bytes];

        load();
        System.arraycopy(types, 0, dest, 0, types.length);

        int pos = types.length;

        for (int i = 0; i < metaData.length; i += 2) {
            byte meta1 = metaData[i];
            byte meta2 = metaData[i + 1];
            dest[pos++] = (byte) ((meta2 << 4) | meta1);
        }

        for (int i = 0; i < blockLight.length; i += 2) {
            byte light1 = blockLight[i];
            byte light2 = blockLight[i + 1];
            dest[pos++] = (byte) ((light2 << 4) | light1);
        }

        if (skylight) {
            for (int i = 0; i < skyLight.length; i += 2) {
                byte light1 = skyLight[i];
                byte light2 = skyLight[i + 1];
                dest[pos++] = (byte) ((light2 << 4) | light1);
            }
        }

        /*if (addArray) ... */

        /*if (groundUpContinuous)*/ {
            //Biome biome = world.getBiome(0, 0);
            //int value = biome.ordinal(); // maybe this isn't right
            for (int i = 0; i < 256; ++i) {
                dest[pos++] = 0;
            }
        }

        if (pos != bytes) {
            throw new IllegalStateException("only wrote " + pos + " out of expected " + bytes + " bytes");
        }

        return dest;
    }

    private int countBits(int v) {
        // http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetKernighan
        int c;
        for (c = 0; v > 0; c++) {
            v &= v - 1;
        }
        return c;
    }

}