package org.bukkit.generator;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import org.bukkit.Location;
import org.bukkit.Material;
import org.bukkit.World;
import org.bukkit.block.Biome;
import org.bukkit.block.Block;

/**
 * A chunk generator is responsible for the initial shaping of an entire
 * chunk. For example, the nether chunk generator should shape netherrack and
 * soulsand
 */
public abstract class ChunkGenerator {

    /**
     * Interface to biome data for chunk to be generated: initialized with
     * default values for world type and seed.
     * <p>
     * Custom generator is free to access and tailor values during
     * generateBlockSections() or generateExtBlockSections().
     */
    public interface BiomeGrid {

        /**
         * Get biome at x, z within chunk being generated
         *
         * @param x - 0-15
         * @param z - 0-15
         * @return Biome value
         */
        Biome getBiome(int x, int z);

        /**
         * Set biome at x, z within chunk being generated
         *
         * @param x - 0-15
         * @param z - 0-15
         * @param bio - Biome value
         */
        void setBiome(int x, int z, Biome bio);
    }
    @Deprecated
    /**
     * Shapes the chunk for the given coordinates.
     * <p>
     * This method should return a byte[32768] in the following format:
     * <pre>
     * for (int x = 0; x &lt; 16; x++) {
     *     for (int z = 0; z &lt; 16; z++) {
     *         for (int y = 0; y &lt; 128; y++) {
     *             // result[(x * 16 + z) * 128 + y] = ??;
     *         }
     *     }
     * }
     * </pre>
     * <p>
     * Note that this method should <b>never</b> attempt to get the Chunk at
     * the passed coordinates, as doing so may cause an infinite loop
     * <p>
     * Note this deprecated method will only be called when both
     * generateExtBlockSections() and generateBlockSections() are
     * unimplemented and return null.
     *
     * @param world The world this chunk will be used for
     * @param random The random generator to use
     * @param x The X-coordinate of the chunk
     * @param z The Z-coordinate of the chunk
     * @return byte[] containing the types for each block created by this
     *     generator
     */
    public byte[] generate(World world, Random random, int x, int z) {
        throw new UnsupportedOperationException("Custom generator is missing required methods: generate(), generateBlockSections() and generateExtBlockSections()");
    }

    /**
     * Shapes the chunk for the given coordinates, with extended block IDs
     * supported (0-4095).
     * <p>
     * As of 1.2, chunks are represented by a vertical array of chunk
     * sections, each of which is 16 x 16 x 16 blocks. If a section is empty
     * (all zero), the section does not need to be supplied, reducing memory
     * usage.
     * <p>
     * This method must return a short[][] array in the following format:
     * <pre>
     *     short[][] result = new short[world-height / 16][];
     * </pre>
     * Each section (sectionID = (Y>>4)) that has blocks needs to be allocated
     * space for the 4096 blocks in that section:
     * <pre>
     *     result[sectionID] = new short[4096];
     * </pre>
     * while sections that are not populated can be left null.
     * <p>
     * Setting a block at X, Y, Z within the chunk can be done with the
     * following mapping function:
     * <pre>
     *    void setBlock(short[][] result, int x, int y, int z, short blkid) {
     *        if (result[y >> 4] == null) {
     *            result[y >> 4] = new short[4096];
     *        }
     *        result[y >> 4][((y & 0xF) << 8) | (z << 4) | x] = blkid;
     *    }
     * </pre>
     * while reading a block ID can be done with the following mapping
     * function:
     * <pre>
     *    short getBlock(short[][] result, int x, int y, int z) {
     *        if (result[y >> 4] == null) {
     *            return (short)0;
     *        }
     *        return result[y >> 4][((y & 0xF) << 8) | (z << 4) | x];
     *    }
     * </pre>
     * while sections that are not populated can be left null.
     * <p>
     * Setting a block at X, Y, Z within the chunk can be done with the
     * following mapping function:
     * <pre>
     *    void setBlock(short[][] result, int x, int y, int z, short blkid) {
     *        if (result[y >> 4) == null) {
     *            result[y >> 4] = new short[4096];
     *        }
     *        result[y >> 4][((y & 0xF) << 8) | (z << 4) | x] = blkid;
     *    }
     * </pre>
     * while reading a block ID can be done with the following mapping
     * function:
     * <pre>
     *    short getBlock(short[][] result, int x, int y, int z) {
     *        if (result[y >> 4) == null) {
     *            return (short)0;
     *        }
     *        return result[y >> 4][((y & 0xF) << 8) | (z << 4) | x];
     *    }
     * </pre>
     * <p>
     * Note that this method should <b>never</b> attempt to get the Chunk at
     * the passed coordinates, as doing so may cause an infinite loop
     * <p>
     * Note generators that do not return block IDs above 255 should not
     * implement this method, or should have it return null (which will result
     * in the generateBlockSections() method being called).
     *
     * @param world The world this chunk will be used for
     * @param random The random generator to use
     * @param x The X-coordinate of the chunk
     * @param z The Z-coordinate of the chunk
     * @param biomes Proposed biome values for chunk - can be updated by
     *     generator
     * @return short[][] containing the types for each block created by this
     *     generator
     * @deprecated Magic value
     */
    @Deprecated
    public short[][] generateExtBlockSections(World world, Random random, int x, int z, BiomeGrid biomes) {
        return null; // Default - returns null, which drives call to generateBlockSections()
    }

    /**
     * Shapes the chunk for the given coordinates.
     * <p>
     * As of 1.2, chunks are represented by a vertical array of chunk
     * sections, each of which is 16 x 16 x 16 blocks.  If a section is empty
     * (all zero), the section does not need to be supplied, reducing memory
     * usage.
     * <p>
     * This method must return a byte[][] array in the following format:
     * <pre>
     *     byte[][] result = new byte[world-height / 16][];
     * </pre>
     * Each section (sectionID = (Y>>4)) that has blocks needs to be allocated
     * space for the 4096 blocks in that section:
     * <pre>
     *     result[sectionID] = new byte[4096];
     * </pre>
     * while sections that are not populated can be left null.
     * <p>
     * Setting a block at X, Y, Z within the chunk can be done with the
     * following mapping function:
     * <pre>
     *    void setBlock(byte[][] result, int x, int y, int z, byte blkid) {
     *        if (result[y >> 4) == null) {
     *            result[y >> 4] = new byte[4096];
     *        }
     *        result[y >> 4][((y & 0xF) << 8) | (z << 4) | x] = blkid;
     *    }
     * </pre>
     * while reading a block ID can be done with the following mapping
     * function:
     * <pre>
     *    byte getBlock(byte[][] result, int x, int y, int z) {
     *        if (result[y >> 4) == null) {
     *            return (byte)0;
     *        }
     *        return result[y >> 4][((y & 0xF) << 8) | (z << 4) | x];
     *    }
     * </pre>
     *
     * Note that this method should <b>never</b> attempt to get the Chunk at
     * the passed coordinates, as doing so may cause an infinite loop
     *
     * @param world The world this chunk will be used for
     * @param random The random generator to use
     * @param x The X-coordinate of the chunk
     * @param z The Z-coordinate of the chunk
     * @param biomes Proposed biome values for chunk - can be updated by
     *     generator
     * @return short[][] containing the types for each block created by this
     *     generator
     * @deprecated Magic value
     */
    @Deprecated
    public byte[][] generateBlockSections(World world, Random random, int x, int z, BiomeGrid biomes) {
        return null; // Default - returns null, which drives call to generate()
    }

    /**
     * Tests if the specified location is valid for a natural spawn position
     *
     * @param world The world we're testing on
     * @param x X-coordinate of the block to test
     * @param z Z-coordinate of the block to test
     * @return true if the location is valid, otherwise false
     */
    public boolean canSpawn(World world, int x, int z) {
        Block highest = world.getBlockAt(x, world.getHighestBlockYAt(x, z), z);

        switch (world.getEnvironment()) {
        case NETHER:
            return true;
        case THE_END:
            return highest.getType() != Material.AIR && highest.getType() != Material.WATER && highest.getType() != Material.LAVA;
        case NORMAL:
        default:
            return highest.getType() == Material.SAND || highest.getType() == Material.GRAVEL;
        }
    }

    /**
     * Gets a list of default {@link BlockPopulator}s to apply to a given
     * world
     *
     * @param world World to apply to
     * @return List containing any amount of BlockPopulators
     */
    public List<BlockPopulator> getDefaultPopulators(World world) {
        return new ArrayList<BlockPopulator>();
    }

    /**
     * Gets a fixed spawn location to use for a given world.
     * <p>
     * A null value is returned if a world should not use a fixed spawn point,
     * and will instead attempt to find one randomly.
     *
     * @param world The world to locate a spawn point for
     * @param random Random generator to use in the calculation
     * @return Location containing a new spawn point, otherwise null
     */
    public Location getFixedSpawnLocation(World world, Random random) {
        return null;
    }
}
