Paper/src/main/java/net/minecraft/server/BlockFlowing.java

package net.minecraft.server;

import java.util.Random;

import org.bukkit.BlockFace;
import org.bukkit.craftbukkit.CraftBlock;
import org.bukkit.event.Event.Type;
import org.bukkit.event.block.BlockFromToEvent;

public class BlockFlowing extends BlockFluids
{

    protected BlockFlowing(int i1, Material material)
    {
        super(i1, material);
        a = 0;
        b = new boolean[4];
        c = new int[4];
    }

    private void i(World world, int i1, int j1, int k1)
    {
        int l1 = world.b(i1, j1, k1);
        world.a(i1, j1, k1, bh + 1, l1);
        world.b(i1, j1, k1, i1, j1, k1);
        world.g(i1, j1, k1);
    }

    public void a(World world, int i1, int j1, int k1, Random random)
    {
        int l1 = g(world, i1, j1, k1);
        byte byte0 = 1;
        if(bs == Material.g && !world.q.d)
            byte0 = 2;
        boolean flag = true;
        if(l1 > 0)
        {
            int i2 = -100;
            a = 0;
            i2 = e(world, i1 - 1, j1, k1, i2);
            i2 = e(world, i1 + 1, j1, k1, i2);
            i2 = e(world, i1, j1, k1 - 1, i2);
            i2 = e(world, i1, j1, k1 + 1, i2);
            int j2 = i2 + byte0;
            if(j2 >= 8 || i2 < 0)
                j2 = -1;
            if(g(world, i1, j1 + 1, k1) >= 0)
            {
                int l2 = g(world, i1, j1 + 1, k1);
                if(l2 >= 8)
                    j2 = l2;
                else
                    j2 = l2 + 8;
            }
            if(a >= 2 && bs == Material.f)
                if(world.d(i1, j1 - 1, k1))
                    j2 = 0;
                else
                if(world.c(i1, j1 - 1, k1) == bs && world.b(i1, j1, k1) == 0)
                    j2 = 0;
            if(bs == Material.g && l1 < 8 && j2 < 8 && j2 > l1 && random.nextInt(4) != 0)
            {
                j2 = l1;
                flag = false;
            }
            if(j2 != l1)
            {
                l1 = j2;
                if(l1 < 0)
                {
                    world.d(i1, j1, k1, 0);
                } else
                {
                    world.b(i1, j1, k1, l1);
                    world.h(i1, j1, k1, bh);
                    world.g(i1, j1, k1, bh);
                }
            } else
            if(flag)
                i(world, i1, j1, k1);
        } else
        {
            i(world, i1, j1, k1);
        }
    	
        // Craftbukkit start
        CraftBlock source = (CraftBlock) ((WorldServer) world).getWorld().getBlockAt(i1, j1, k1);
        
        if(l(world, i1, j1 - 1, k1))
        {	
        	// Craftbucket send "down" to the server
        	BlockFromToEvent blockFlow = new BlockFromToEvent(Type.BLOCK_FLOW, source, BlockFace.Down);
            ((WorldServer) world).getServer().getPluginManager().callEvent(blockFlow);
            
        	if (!blockFlow.isCancelled()) {
	            if(l1 >= 8)
	                world.b(i1, j1 - 1, k1, bh, l1);
	            else
	                world.b(i1, j1 - 1, k1, bh, l1 + 8);
        	}
        } else
        if(l1 >= 0 && (l1 == 0 || k(world, i1, j1 - 1, k1)))
        {
            boolean aflag[] = j(world, i1, j1, k1);
            int k2 = l1 + byte0;
            if(l1 >= 8)
                k2 = 1;
            if(k2 >= 8)
                return;
            
            // Craftbukkit start
            BlockFace[] faces = new BlockFace[]{ BlockFace.North, BlockFace.South, BlockFace.East, BlockFace.West };
            for (BlockFace currentFace : faces) {
            	int index = 0;
            	if (aflag[index]) {
	            	BlockFromToEvent event = new BlockFromToEvent(Type.BLOCK_FLOW, source, currentFace);
	            	((WorldServer) world).getServer().getPluginManager().callEvent(event);
	            	if (!event.isCancelled())
	            		f(world, i1 + currentFace.getModX(), j1, k1 + currentFace.getModZ(), k2);
            	}
            	index++;
            }
            // Craftbukkit stop
        }
    }

    private void f(World world, int i1, int j1, int k1, int l1)
    {
        if(l(world, i1, j1, k1))
        {
            int i2 = world.a(i1, j1, k1);
            if(i2 > 0)
                if(bs == Material.g)
                    h(world, i1, j1, k1);
                else
                    Block.m[i2].a_(world, i1, j1, k1, world.b(i1, j1, k1));
            world.b(i1, j1, k1, bh, l1);
        }
    }

    private int a(World world, int i1, int j1, int k1, int l1, int i2)
    {
        int j2 = 1000;
        for(int k2 = 0; k2 < 4; k2++)
        {
            if(k2 == 0 && i2 == 1 || k2 == 1 && i2 == 0 || k2 == 2 && i2 == 3 || k2 == 3 && i2 == 2)
                continue;
            int l2 = i1;
            int i3 = j1;
            int j3 = k1;
            if(k2 == 0)
                l2--;
            if(k2 == 1)
                l2++;
            if(k2 == 2)
                j3--;
            if(k2 == 3)
                j3++;
            if(k(world, l2, i3, j3) || world.c(l2, i3, j3) == bs && world.b(l2, i3, j3) == 0)
                continue;
            if(!k(world, l2, i3 - 1, j3))
                return l1;
            if(l1 >= 4)
                continue;
            int k3 = a(world, l2, i3, j3, l1 + 1, k2);
            if(k3 < j2)
                j2 = k3;
        }

        return j2;
    }

    private boolean[] j(World world, int i1, int j1, int k1)
    {
        for(int l1 = 0; l1 < 4; l1++)
        {
            c[l1] = 1000;
            int j2 = i1;
            int i3 = j1;
            int j3 = k1;
            if(l1 == 0)
                j2--;
            if(l1 == 1)
                j2++;
            if(l1 == 2)
                j3--;
            if(l1 == 3)
                j3++;
            if(k(world, j2, i3, j3) || world.c(j2, i3, j3) == bs && world.b(j2, i3, j3) == 0)
                continue;
            if(!k(world, j2, i3 - 1, j3))
                c[l1] = 0;
            else
                c[l1] = a(world, j2, i3, j3, 1, l1);
        }

        int i2 = c[0];
        for(int k2 = 1; k2 < 4; k2++)
            if(c[k2] < i2)
                i2 = c[k2];

        for(int l2 = 0; l2 < 4; l2++)
            b[l2] = c[l2] == i2;

        return b;
    }

    private boolean k(World world, int i1, int j1, int k1)
    {
        int l1 = world.a(i1, j1, k1);
        if(l1 == Block.aE.bh || l1 == Block.aL.bh || l1 == Block.aD.bh || l1 == Block.aF.bh || l1 == Block.aX.bh)
            return true;
        if(l1 == 0)
            return false;
        Material material = Block.m[l1].bs;
        return material.a();
    }

    protected int e(World world, int i1, int j1, int k1, int l1)
    {
        int i2 = g(world, i1, j1, k1);
        if(i2 < 0)
            return l1;
        if(i2 == 0)
            a++;
        if(i2 >= 8)
            i2 = 0;
        return l1 >= 0 && i2 >= l1 ? l1 : i2;
    }

    private boolean l(World world, int i1, int j1, int k1)
    {
        Material material = world.c(i1, j1, k1);
        if(material == bs)
            return false;
        if(material == Material.g)
            return false;
        else
            return !k(world, i1, j1, k1);
    }

    public void e(World world, int i1, int j1, int k1)
    {
        super.e(world, i1, j1, k1);
        if(world.a(i1, j1, k1) == bh)
            world.h(i1, j1, k1, bh);
    }

    int a;
    boolean b[];
    int c[];
}