Paper/nms-patches/Explosion.patch

--- a/net/minecraft/server/Explosion.java
+++ b/net/minecraft/server/Explosion.java
@@ -15,6 +15,13 @@
 import java.util.Set;
 import javax.annotation.Nullable;
 
+// CraftBukkit start
+import org.bukkit.craftbukkit.event.CraftEventFactory;
+import org.bukkit.event.entity.EntityExplodeEvent;
+import org.bukkit.Location;
+import org.bukkit.event.block.BlockExplodeEvent;
+// CraftBukkit end
+
 public class Explosion {
 
     private final boolean a;
@@ -31,11 +38,12 @@
     private final ExplosionDamageCalculator k;
     private final List<BlockPosition> blocks = Lists.newArrayList();
     private final Map<EntityHuman, Vec3D> m = Maps.newHashMap();
+    public boolean wasCanceled = false; // CraftBukkit - add field
 
     public Explosion(World world, @Nullable Entity entity, @Nullable DamageSource damagesource, @Nullable ExplosionDamageCalculator explosiondamagecalculator, double d0, double d1, double d2, float f, boolean flag, Explosion.Effect explosion_effect) {
         this.world = world;
         this.source = entity;
-        this.size = f;
+        this.size = (float) Math.max(f, 0.0); // CraftBukkit - clamp bad values
         this.posX = d0;
         this.posY = d1;
         this.posZ = d2;
@@ -85,6 +93,11 @@
     }
 
     public void a() {
+        // CraftBukkit start
+        if (this.size < 0.1F) {
+            return;
+        }
+        // CraftBukkit end
         Set<BlockPosition> set = Sets.newHashSet();
         boolean flag = true;
 
@@ -118,7 +131,7 @@
                                 f -= ((Float) optional.get() + 0.3F) * 0.3F;
                             }
 
-                            if (f > 0.0F && this.k.a(this, this.world, blockposition, iblockdata, f)) {
+                            if (f > 0.0F && this.k.a(this, this.world, blockposition, iblockdata, f) && blockposition.getY() < 256 && blockposition.getY() >= 0) { // CraftBukkit - don't wrap explosions
                                 set.add(blockposition);
                             }
 
@@ -162,7 +175,16 @@
                         double d12 = (double) a(vec3d, entity);
                         double d13 = (1.0D - d7) * d12;
 
-                        entity.damageEntity(this.b(), (float) ((int) ((d13 * d13 + d13) / 2.0D * 7.0D * (double) f2 + 1.0D)));
+                        // CraftBukkit start
+                        // entity.damageEntity(this.b(), (float) ((int) ((d13 * d13 + d13) / 2.0D * 7.0D * (double) f2 + 1.0D)));
+                        CraftEventFactory.entityDamage = source;
+                        entity.forceExplosionKnockback = false;
+                        boolean wasDamaged = entity.damageEntity(this.b(), (float) ((int) ((d13 * d13 + d13) / 2.0D * 7.0D * (double) f2 + 1.0D)));
+                        CraftEventFactory.entityDamage = null;
+                        if (!wasDamaged && !(entity instanceof EntityTNTPrimed || entity instanceof EntityFallingBlock) && !entity.forceExplosionKnockback) {
+                            continue;
+                        }
+                        // CraftBukkit end
                         double d14 = d13;
 
                         if (entity instanceof EntityLiving) {
@@ -204,6 +226,51 @@
 
             Collections.shuffle(this.blocks, this.world.random);
             Iterator iterator = this.blocks.iterator();
+            // CraftBukkit start
+            org.bukkit.World bworld = this.world.getWorld();
+            org.bukkit.entity.Entity explode = this.source == null ? null : this.source.getBukkitEntity();
+            Location location = new Location(bworld, this.posX, this.posY, this.posZ);
+
+            List<org.bukkit.block.Block> blockList = Lists.newArrayList();
+            for (int i1 = this.blocks.size() - 1; i1 >= 0; i1--) {
+                BlockPosition cpos = (BlockPosition) this.blocks.get(i1);
+                org.bukkit.block.Block bblock = bworld.getBlockAt(cpos.getX(), cpos.getY(), cpos.getZ());
+                if (!bblock.getType().isAir()) {
+                    blockList.add(bblock);
+                }
+            }
+
+            boolean cancelled;
+            List<org.bukkit.block.Block> bukkitBlocks;
+            float yield;
+
+            if (explode != null) {
+                EntityExplodeEvent event = new EntityExplodeEvent(explode, location, blockList, this.b == Explosion.Effect.DESTROY ? 1.0F / this.size : 1.0F);
+                this.world.getServer().getPluginManager().callEvent(event);
+                cancelled = event.isCancelled();
+                bukkitBlocks = event.blockList();
+                yield = event.getYield();
+            } else {
+                BlockExplodeEvent event = new BlockExplodeEvent(location.getBlock(), blockList, this.b == Explosion.Effect.DESTROY ? 1.0F / this.size : 1.0F);
+                this.world.getServer().getPluginManager().callEvent(event);
+                cancelled = event.isCancelled();
+                bukkitBlocks = event.blockList();
+                yield = event.getYield();
+            }
+
+            this.blocks.clear();
+
+            for (org.bukkit.block.Block bblock : bukkitBlocks) {
+                BlockPosition coords = new BlockPosition(bblock.getX(), bblock.getY(), bblock.getZ());
+                blocks.add(coords);
+            }
+
+            if (cancelled) {
+                this.wasCanceled = true;
+                return;
+            }
+            // CraftBukkit end
+            iterator = this.blocks.iterator();
 
             while (iterator.hasNext()) {
                 BlockPosition blockposition = (BlockPosition) iterator.next();
@@ -218,8 +285,8 @@
                         TileEntity tileentity = block.isTileEntity() ? this.world.getTileEntity(blockposition) : null;
                         LootTableInfo.Builder loottableinfo_builder = (new LootTableInfo.Builder((WorldServer) this.world)).a(this.world.random).set(LootContextParameters.POSITION, blockposition).set(LootContextParameters.TOOL, ItemStack.b).setOptional(LootContextParameters.BLOCK_ENTITY, tileentity).setOptional(LootContextParameters.THIS_ENTITY, this.source);
 
-                        if (this.b == Explosion.Effect.DESTROY) {
-                            loottableinfo_builder.set(LootContextParameters.EXPLOSION_RADIUS, this.size);
+                        if (this.b == Explosion.Effect.DESTROY || yield < 1.0F) { // CraftBukkit - add yield
+                            loottableinfo_builder.set(LootContextParameters.EXPLOSION_RADIUS, 1.0F / yield); // CraftBukkit - add yield
                         }
 
                         iblockdata.a(loottableinfo_builder).forEach((itemstack) -> {
@@ -249,7 +316,11 @@
                 BlockPosition blockposition2 = (BlockPosition) iterator1.next();
 
                 if (this.c.nextInt(3) == 0 && this.world.getType(blockposition2).isAir() && this.world.getType(blockposition2.down()).i(this.world, blockposition2.down())) {
-                    this.world.setTypeUpdate(blockposition2, BlockFireAbstract.a((IBlockAccess) this.world, blockposition2));
+                    // CraftBukkit start - Ignition by explosion
+                    if (!org.bukkit.craftbukkit.event.CraftEventFactory.callBlockIgniteEvent(this.world, blockposition2.getX(), blockposition2.getY(), blockposition2.getZ(), this).isCancelled()) {
+                        this.world.setTypeUpdate(blockposition2, BlockFireAbstract.a((IBlockAccess) this.world, blockposition2));
+                    }
+                    // CraftBukkit end
                 }
             }
         }
@@ -257,6 +328,7 @@
     }
 
     private static void a(ObjectArrayList<Pair<ItemStack, BlockPosition>> objectarraylist, ItemStack itemstack, BlockPosition blockposition) {
+        if (itemstack.isEmpty()) return; // CraftBukkit - SPIGOT-5425
         int i = objectarraylist.size();
 
         for (int j = 0; j < i; ++j) {