From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sat, 19 Jun 2021 10:54:52 -0700
Subject: [PATCH] Fix Codec log spam

Mojang did NOT add dataconverters for world gen configurations
that they CHANGED. So, the codec fails to parse old data.

This fixes two instances:
- IntProvider is new and Mojang did not account for old data.
  Thankfully, only ColumnPlace needed to be special cased.
- TreeConfiguration had changes. Thankfully, they were
  only renames for one value and thankfully defaults could
  be provided for two new values (WITHOUT changing behavior).

diff --git a/src/main/java/net/minecraft/server/MCUtil.java b/src/main/java/net/minecraft/server/MCUtil.java
index c4117dcffd705d044f07eb5840a177b1b5825bb9..f80791bd383dc6dc4a9c1aac5f8e4c1561e33ad9 100644
--- a/src/main/java/net/minecraft/server/MCUtil.java
+++ b/src/main/java/net/minecraft/server/MCUtil.java
@@ -723,4 +723,70 @@ public final class MCUtil {
     public static int getTicketLevelFor(net.minecraft.world.level.chunk.ChunkStatus status) {
         return net.minecraft.server.level.ChunkMap.MAX_VIEW_DISTANCE + net.minecraft.world.level.chunk.ChunkStatus.getDistance(status);
     }
+
+    public static <A> com.mojang.serialization.MapCodec<A> fieldWithFallbacks(com.mojang.serialization.Codec<A> codec, String name, String ...fallback) {
+        return com.mojang.serialization.MapCodec.of(
+            new com.mojang.serialization.codecs.FieldEncoder<>(name, codec),
+            new FieldFallbackDecoder<>(name, java.util.Arrays.asList(fallback), codec),
+            () -> "FieldFallback[" + name + ": " + codec.toString() + "]"
+        );
+    }
+
+    // This is likely a common occurrence, sadly
+    public static final class FieldFallbackDecoder<A> extends com.mojang.serialization.MapDecoder.Implementation<A> {
+        protected final String name;
+        protected final List<String> fallback;
+        private final com.mojang.serialization.Decoder<A> elementCodec;
+
+        public FieldFallbackDecoder(final String name, final List<String> fallback, final com.mojang.serialization.Decoder<A> elementCodec) {
+            this.name = name;
+            this.fallback = fallback;
+            this.elementCodec = elementCodec;
+        }
+
+        @Override
+        public <T> com.mojang.serialization.DataResult<A> decode(final com.mojang.serialization.DynamicOps<T> ops, final com.mojang.serialization.MapLike<T> input) {
+            T value = input.get(name);
+            if (value == null) {
+                for (String fall : fallback) {
+                    value = input.get(fall);
+                    if (value != null) {
+                        break;
+                    }
+                }
+                if (value == null) {
+                    return com.mojang.serialization.DataResult.error("No key " + name + " in " + input);
+                }
+            }
+            return elementCodec.parse(ops, value);
+        }
+
+        @Override
+        public <T> java.util.stream.Stream<T> keys(final com.mojang.serialization.DynamicOps<T> ops) {
+            return java.util.stream.Stream.of(ops.createString(name));
+        }
+
+        @Override
+        public boolean equals(final Object o) {
+            if (this == o) {
+                return true;
+            }
+            if (o == null || getClass() != o.getClass()) {
+                return false;
+            }
+            final FieldFallbackDecoder<?> that = (FieldFallbackDecoder<?>)o;
+            return java.util.Objects.equals(name, that.name) && java.util.Objects.equals(elementCodec, that.elementCodec)
+                && java.util.Objects.equals(fallback, that.fallback);
+        }
+
+        @Override
+        public int hashCode() {
+            return java.util.Objects.hash(name, fallback, elementCodec);
+        }
+
+        @Override
+        public String toString() {
+            return "FieldDecoder[" + name + ": " + elementCodec + ']';
+        }
+    }
 }
diff --git a/src/main/java/net/minecraft/util/valueproviders/IntProvider.java b/src/main/java/net/minecraft/util/valueproviders/IntProvider.java
index 020a19cd683dd3779c5116d12b3cdcd3b3ca69b4..c81a0eec12436c10869bfdcc21af09173f438331 100644
--- a/src/main/java/net/minecraft/util/valueproviders/IntProvider.java
+++ b/src/main/java/net/minecraft/util/valueproviders/IntProvider.java
@@ -9,13 +9,44 @@ import net.minecraft.core.Registry;
 
 public abstract class IntProvider {
     private static final Codec<Either<Integer, IntProvider>> CONSTANT_OR_DISPATCH_CODEC = Codec.either(Codec.INT, Registry.INT_PROVIDER_TYPES.dispatch(IntProvider::getType, IntProviderType::codec));
-    public static final Codec<IntProvider> CODEC = CONSTANT_OR_DISPATCH_CODEC.xmap((either) -> {
+    public static final Codec<IntProvider> CODEC_REAL = CONSTANT_OR_DISPATCH_CODEC.xmap((either) -> { // Paper - used by CODEC below
         return either.map(ConstantInt::of, (intProvider) -> {
             return intProvider;
         });
     }, (intProvider) -> {
         return intProvider.getType() == IntProviderType.CONSTANT ? Either.left(((ConstantInt)intProvider).getValue()) : Either.right(intProvider);
     });
+    // Paper start
+    public static final Codec<IntProvider> CODEC = new Codec<>() {
+        @Override
+        public <T> DataResult<com.mojang.datafixers.util.Pair<IntProvider, T>> decode(com.mojang.serialization.DynamicOps<T> ops, T input) {
+            /*
+            UniformInt:
+            count -> { (old format)
+                base, spread
+            } -> {UniformInt} { (new format & type)
+                base, base + spread
+            } */
+
+
+            if (ops.get(input, "base").result().isPresent() && ops.get(input, "spread").result().isPresent()) {
+                // detected old format
+                int base = ops.getNumberValue(ops.get(input, "base").result().get()).result().get().intValue();
+                int spread = ops.getNumberValue(ops.get(input, "spread").result().get()).result().get().intValue();
+                return DataResult.success(new com.mojang.datafixers.util.Pair<>(UniformInt.of(base, base + spread), input));
+            }
+
+            // not old format, forward to real codec
+            return CODEC_REAL.decode(ops, input);
+        }
+
+        @Override
+        public <T> DataResult<T> encode(IntProvider input, com.mojang.serialization.DynamicOps<T> ops, T prefix) {
+            // forward to real codec
+            return CODEC_REAL.encode(input, ops, prefix);
+        }
+    };
+    // Paper end
     public static final Codec<IntProvider> NON_NEGATIVE_CODEC = codec(0, Integer.MAX_VALUE);
     public static final Codec<IntProvider> POSITIVE_CODEC = codec(1, Integer.MAX_VALUE);
 
diff --git a/src/main/java/net/minecraft/world/level/levelgen/feature/blockplacers/ColumnPlacer.java b/src/main/java/net/minecraft/world/level/levelgen/feature/blockplacers/ColumnPlacer.java
index 05bba5410fbd9f8e333584ccbd65a909f3040322..82859e1b048ba8a96cc67e085e9ed01b6bd3a6cd 100644
--- a/src/main/java/net/minecraft/world/level/levelgen/feature/blockplacers/ColumnPlacer.java
+++ b/src/main/java/net/minecraft/world/level/levelgen/feature/blockplacers/ColumnPlacer.java
@@ -10,11 +10,28 @@ import net.minecraft.world.level.LevelAccessor;
 import net.minecraft.world.level.block.state.BlockState;
 
 public class ColumnPlacer extends BlockPlacer {
+    // Paper start
     public static final Codec<ColumnPlacer> CODEC = RecordCodecBuilder.create((instance) -> {
-        return instance.group(IntProvider.NON_NEGATIVE_CODEC.fieldOf("size").forGetter((columnPlacer) -> {
-            return columnPlacer.size;
-        })).apply(instance, ColumnPlacer::new);
+        return instance.group(
+            IntProvider.NON_NEGATIVE_CODEC.optionalFieldOf("size").forGetter((columnPlacer) -> {
+                return java.util.Optional.of(columnPlacer.size);
+            }),
+            Codec.INT.optionalFieldOf("min_size").forGetter((columnPlacer) -> {
+                return java.util.Optional.empty();
+            }),
+            Codec.INT.optionalFieldOf("extra_size").forGetter((columnPlacer) -> {
+                return java.util.Optional.empty();
+            })
+        ).apply(instance, ColumnPlacer::new);
     });
+    public ColumnPlacer(java.util.Optional<IntProvider> size, java.util.Optional<Integer> minSize, java.util.Optional<Integer> extraSize) {
+        if (size.isPresent()) {
+            this.size = size.get();
+        } else {
+            this.size = net.minecraft.util.valueproviders.BiasedToBottomInt.of(minSize.get().intValue(), minSize.get().intValue() + extraSize.get().intValue());
+        }
+    }
+    // Paper end
     private final IntProvider size;
 
     public ColumnPlacer(IntProvider size) {
diff --git a/src/main/java/net/minecraft/world/level/levelgen/feature/configurations/TreeConfiguration.java b/src/main/java/net/minecraft/world/level/levelgen/feature/configurations/TreeConfiguration.java
index 5da68897148192905c2747676c1ee2ee649f923f..b990099cf274f8cb0d96c139345cf0bf328affd6 100644
--- a/src/main/java/net/minecraft/world/level/levelgen/feature/configurations/TreeConfiguration.java
+++ b/src/main/java/net/minecraft/world/level/levelgen/feature/configurations/TreeConfiguration.java
@@ -18,13 +18,13 @@ public class TreeConfiguration implements FeatureConfiguration {
             return treeConfiguration.trunkProvider;
         }), TrunkPlacer.CODEC.fieldOf("trunk_placer").forGetter((treeConfiguration) -> {
             return treeConfiguration.trunkPlacer;
-        }), BlockStateProvider.CODEC.fieldOf("foliage_provider").forGetter((treeConfiguration) -> {
+        }), net.minecraft.server.MCUtil.fieldWithFallbacks(BlockStateProvider.CODEC, "foliage_provider", "leaves_provider").forGetter((treeConfiguration) -> { // Paper - provide fallback for rename
             return treeConfiguration.foliageProvider;
-        }), BlockStateProvider.CODEC.fieldOf("sapling_provider").forGetter((treeConfiguration) -> {
+        }), BlockStateProvider.CODEC.optionalFieldOf("sapling_provider", new SimpleStateProvider(Blocks.OAK_SAPLING.defaultBlockState())).forGetter((treeConfiguration) -> { // Paper - provide default - it looks like for now this is OK because it's just used to check canSurvive. Same check happens in 1.16.5 for the default we provide - so it should retain behavior...
             return treeConfiguration.saplingProvider;
         }), FoliagePlacer.CODEC.fieldOf("foliage_placer").forGetter((treeConfiguration) -> {
             return treeConfiguration.foliagePlacer;
-        }), BlockStateProvider.CODEC.fieldOf("dirt_provider").forGetter((treeConfiguration) -> {
+        }), BlockStateProvider.CODEC.optionalFieldOf("dirt_provider", new SimpleStateProvider(Blocks.DIRT.defaultBlockState())).forGetter((treeConfiguration) -> { // Paper - provide defaults, old data DOES NOT have this key (thankfully ALL OLD DATA used DIRT)
             return treeConfiguration.dirtProvider;
         }), FeatureSize.CODEC.fieldOf("minimum_size").forGetter((treeConfiguration) -> {
             return treeConfiguration.minimumSize;
