package net.minecraft.util.datafix.fixes;

import com.mojang.datafixers.DataFix;
import com.mojang.datafixers.OpticFinder;
import com.mojang.datafixers.TypeRewriteRule;
import com.mojang.datafixers.Typed;
import com.mojang.datafixers.schemas.Schema;
import com.mojang.datafixers.types.Type;
import com.mojang.datafixers.util.Pair;
import com.mojang.serialization.Dynamic;
import com.mojang.serialization.DynamicOps;
import java.util.List;

public class SpawnerDataFix extends DataFix {
	public SpawnerDataFix(final Schema outputSchema) {
		super(outputSchema, true);
	}

	@Override
	protected TypeRewriteRule makeRule() {
		Type<?> oldType = this.getInputSchema().getType(References.UNTAGGED_SPAWNER);
		Type<?> newType = this.getOutputSchema().getType(References.UNTAGGED_SPAWNER);
		OpticFinder<?> spawnDataFinder = oldType.findField("SpawnData");
		Type<?> newSpawnDataType = newType.findField("SpawnData").type();
		OpticFinder<?> spawnPotentialsFinder = oldType.findField("SpawnPotentials");
		Type<?> newSpawnPotentialsType = newType.findField("SpawnPotentials").type();
		return this.fixTypeEverywhereTyped(
			"Fix mob spawner data structure",
			oldType,
			newType,
			spawner -> spawner.updateTyped(spawnDataFinder, newSpawnDataType, spawnData -> this.wrapEntityToSpawnData(newSpawnDataType, spawnData))
				.updateTyped(
					spawnPotentialsFinder, newSpawnPotentialsType, spawnPotentials -> this.wrapSpawnPotentialsToWeightedEntries(newSpawnPotentialsType, spawnPotentials)
				)
		);
	}

	private <T> Typed<T> wrapEntityToSpawnData(final Type<T> newType, final Typed<?> spawnData) {
		DynamicOps<?> ops = spawnData.getOps();
		return new Typed<>(newType, ops, (T)Pair.<Object, Dynamic<?>>of(spawnData.getValue(), new Dynamic<>(ops)));
	}

	private <T> Typed<T> wrapSpawnPotentialsToWeightedEntries(final Type<T> newType, final Typed<?> spawnPotentials) {
		DynamicOps<?> ops = spawnPotentials.getOps();
		List<?> entries = (List<?>)spawnPotentials.getValue();
		List<?> wrappedEntries = entries.stream().map(o -> {
			Pair<Object, Dynamic<?>> entry = (Pair<Object, Dynamic<?>>)o;
			int weight = ((Number)entry.getSecond().get("Weight").asNumber().result().orElse(1)).intValue();
			Dynamic<?> newEntryRemainder = new Dynamic<>(ops);
			newEntryRemainder = newEntryRemainder.set("weight", newEntryRemainder.createInt(weight));
			Dynamic<?> newInnerRemainder = entry.getSecond().remove("Weight").remove("Entity");
			return Pair.of(Pair.of(entry.getFirst(), newInnerRemainder), newEntryRemainder);
		}).toList();
		return new Typed<>(newType, ops, (T)wrappedEntries);
	}
}