Start implementing timelines

api/src/main/java/com/github/retrooper/packetevents/protocol/nbt/NBTCompound.java

@@ -18,6 +18,7 @@
 
 package com.github.retrooper.packetevents.protocol.nbt;
 
+import com.github.retrooper.packetevents.protocol.util.NbtCodecException;
 import com.github.retrooper.packetevents.protocol.util.NbtDecoder;
 import com.github.retrooper.packetevents.protocol.util.NbtEncoder;
 import com.github.retrooper.packetevents.wrapper.PacketWrapper;
@@ -62,10 +63,10 @@ public class NBTCompound extends NBT {
         return tags.size();
     }
 
-    public NBT getTagOrThrow(String key) {
+    public NBT getTagOrThrow(String key) throws NbtCodecException {
         NBT tag = getTagOrNull(key);
         if (tag == null) {
-            throw new IllegalStateException(MessageFormat.format("NBT {0} does not exist", key));
+            throw new NbtCodecException("Tag " + key + " doesn't exist");
         }
         return tag;
     }
@@ -75,12 +76,12 @@ public class NBTCompound extends NBT {
     }
 
     @SuppressWarnings("unchecked")
-    public <T extends NBT> T getTagOfTypeOrThrow(String key, Class<T> type) {
+    public <T extends NBT> T getTagOfTypeOrThrow(String key, Class<T> type) throws NbtCodecException {
         NBT tag = getTagOrThrow(key);
         if (type.isInstance(tag)) {
             return (T) tag;
         } else {
-            throw new IllegalStateException(MessageFormat.format("NBT {0} has unexpected type, expected {1}, but got {2}", key, type, tag.getClass()));
+            throw new NbtCodecException(MessageFormat.format("NBT {0} has unexpected type, expected {1}, but got {2}", key, type, tag.getClass()));
         }
     }
 
@@ -94,10 +95,10 @@ public class NBTCompound extends NBT {
     }
 
     @SuppressWarnings("unchecked")
-    public <T extends NBT> NBTList<T> getTagListOfTypeOrThrow(String key, Class<T> type) {
+    public <T extends NBT> NBTList<T> getTagListOfTypeOrThrow(String key, Class<T> type) throws NbtCodecException {
         NBTList<? extends NBT> list = getTagOfTypeOrThrow(key, NBTList.class);
         if (!type.isAssignableFrom(list.getTagsType().getNBTClass())) {
-            throw new IllegalStateException(MessageFormat.format("NBTList {0} tags type has unexpected type, expected {1}, but got {2}", key, type, list.getTagsType().getNBTClass()));
+            throw new NbtCodecException(MessageFormat.format("NBTList {0} tags type has unexpected type, expected {1}, but got {2}", key, type, list.getTagsType().getNBTClass()));
         }
         return (NBTList<T>) list;
     }

api/src/main/java/com/github/retrooper/packetevents/protocol/world/attributes/Keyframe.java

@@ -0,0 +1,49 @@
+package com.github.retrooper.packetevents.protocol.world.attributes;
+
+import com.github.retrooper.packetevents.protocol.nbt.NBTCompound;
+import com.github.retrooper.packetevents.protocol.nbt.NBTInt;
+import com.github.retrooper.packetevents.protocol.util.NbtCodec;
+import com.github.retrooper.packetevents.protocol.util.NbtCodecException;
+import com.github.retrooper.packetevents.protocol.util.NbtMapCodec;
+import com.github.retrooper.packetevents.wrapper.PacketWrapper;
+import org.jspecify.annotations.NullMarked;
+
+/**
+ * @versions 1.21.11+
+ */
+@NullMarked
+public class Keyframe<T> {
+
+    private final int ticks;
+    private final T value;
+
+    public Keyframe(int ticks, T value) {
+        this.ticks = ticks;
+        this.value = value;
+    }
+
+    public static <T> NbtCodec<Keyframe<T>> codec(NbtCodec<T> codec) {
+        return new NbtMapCodec<Keyframe<T>>() {
+            @Override
+            public Keyframe<T> decode(NBTCompound compound, PacketWrapper<?> wrapper) throws NbtCodecException {
+                int ticks = compound.getNumberTagOrThrow("ticks").getAsInt();
+                T value = compound.getOrThrow("value", codec, wrapper);
+                return new Keyframe<>(ticks, value);
+            }
+
+            @Override
+            public void encode(NBTCompound compound, PacketWrapper<?> wrapper, Keyframe<T> value) throws NbtCodecException {
+                compound.setTag("ticks", new NBTInt(value.ticks));
+                compound.set("value", value.value, codec, wrapper);
+            }
+        }.codec();
+    }
+
+    public int getTicks() {
+        return this.ticks;
+    }
+
+    public T getValue() {
+        return this.value;
+    }
+}

api/src/main/java/com/github/retrooper/packetevents/protocol/world/attributes/KeyframeTrack.java

@@ -0,0 +1,30 @@
+package com.github.retrooper.packetevents.protocol.world.attributes;
+
+import org.jspecify.annotations.NullMarked;
+
+import java.util.List;
+
+/**
+ * @versions 1.21.11+
+ */
+@NullMarked
+public class KeyframeTrack<T> {
+
+    private final List<Keyframe<T>> keyframes;
+    private final EasingType easingType;
+
+    public KeyframeTrack(List<Keyframe<T>> keyframes, EasingType easingType) {
+        this.keyframes = keyframes;
+        this.easingType = easingType;
+    }
+
+    // TODO
+
+    public List<Keyframe<T>> getKeyframes() {
+        return this.keyframes;
+    }
+
+    public EasingType getEasingType() {
+        return this.easingType;
+    }
+}

api/src/main/java/com/github/retrooper/packetevents/protocol/world/attributes/Timeline.java

@@ -0,0 +1,21 @@
+package com.github.retrooper.packetevents.protocol.world.attributes;
+
+import com.github.retrooper.packetevents.protocol.mapper.CopyableEntity;
+import com.github.retrooper.packetevents.protocol.mapper.DeepComparableEntity;
+import com.github.retrooper.packetevents.protocol.mapper.MappedEntity;
+import org.jspecify.annotations.NullMarked;
+
+import java.util.Map;
+
+/**
+ * @versions 1.21.11+
+ */
+@NullMarked
+public interface Timeline extends MappedEntity, CopyableEntity<Timeline>, DeepComparableEntity {
+
+    int getPeriodTicks();
+
+    Map<EnvironmentAttribute<?>, TimelineTrack<?, ?>> getTracks();
+
+    // TODO
+}

api/src/main/java/com/github/retrooper/packetevents/protocol/world/attributes/TimelineTrack.java

@@ -0,0 +1,28 @@
+package com.github.retrooper.packetevents.protocol.world.attributes;
+
+import org.jspecify.annotations.NullMarked;
+
+/**
+ * @versions 1.21.11+
+ */
+@NullMarked
+public class TimelineTrack<T, A> {
+
+    private final AttributeModifier<T, A> modifier;
+    private final KeyframeTrack<A> argumentTrack;
+
+    public TimelineTrack(AttributeModifier<T, A> modifier, KeyframeTrack<A> argumentTrack) {
+        this.modifier = modifier;
+        this.argumentTrack = argumentTrack;
+    }
+
+    // TODO
+
+    public AttributeModifier<T, A> getModifier() {
+        return this.modifier;
+    }
+
+    public KeyframeTrack<A> getArgumentTrack() {
+        return this.argumentTrack;
+    }
+}