/*
 * Copyright (c) Forge Development LLC and contributors
 * SPDX-License-Identifier: LGPL-2.1-only
 */

package net.minecraftforge.registries;

import com.google.common.collect.Multimap;
import com.google.common.collect.Multimaps;
import com.google.common.collect.Sets;
import com.mojang.datafixers.util.Pair;
import com.mojang.logging.LogUtils;
import com.mojang.serialization.Lifecycle;
import it.unimi.dsi.fastutil.objects.ObjectArrayList;
import it.unimi.dsi.fastutil.objects.ObjectList;
import net.minecraft.Util;
import net.minecraft.core.Holder;
import net.minecraft.core.HolderGetter;
import net.minecraft.core.HolderSet;
import net.minecraft.core.MappedRegistry;
import net.minecraft.core.Registry;
import net.minecraft.resources.ResourceKey;
import net.minecraft.resources.ResourceLocation;
import net.minecraft.tags.TagKey;
import net.minecraft.util.RandomSource;
import org.apache.commons.lang3.Validate;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.slf4j.Logger;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.Set;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;

class NamespacedWrapper<T> extends MappedRegistry<T> implements ILockableRegistry
{
    static final Logger LOGGER = LogUtils.getLogger();
    private final ForgeRegistry<T> delegate;
    @Nullable
    private final Function<T, Holder.Reference<T>> intrusiveHolderCallback;
    private final Multimap<TagKey<T>, Supplier<T>> optionalTags = Multimaps.newSetMultimap(new IdentityHashMap<>(), HashSet::new);

    boolean locked = false;
    Lifecycle registryLifecycle = Lifecycle.stable();
    private boolean frozen = false; // Frozen is vanilla's variant of locked, but it can be unfrozen
    private List<Holder.Reference<T>> holdersSorted;
    private ObjectList<Holder.Reference<T>> holdersById = new ObjectArrayList<>(256);
    private Map<ResourceLocation, Holder.Reference<T>> holdersByName = new HashMap<>();
    private Map<T, Holder.Reference<T>> holders = new IdentityHashMap<>();
    private RegistryManager stage;
    private volatile Map<TagKey<T>, HolderSet.Named<T>> tags = new IdentityHashMap<>();

    NamespacedWrapper(ForgeRegistry<T> fowner, Function<T, Holder.Reference<T>> intrusiveHolderCallback, RegistryManager stage)
    {
        super(fowner.getRegistryKey(), Lifecycle.stable(), intrusiveHolderCallback != null);
        this.delegate = fowner;
        this.intrusiveHolderCallback = intrusiveHolderCallback;
        this.stage = stage;
    }

    @Override
    public Holder.Reference<T> registerMapping(int id, ResourceKey<T> key, T value, Lifecycle lifecycle)
    {
        if (locked)
            throw new IllegalStateException("Can not register to a locked registry. Modder should use Forge Register methods.");

        Validate.notNull(value);
        markKnown();
        this.registryLifecycle = this.registryLifecycle.add(lifecycle);

        int realId = this.delegate.add(id, key.location(), value);
        if (realId != id && id != -1)
            LOGGER.warn("Registered object did not get ID it asked for. Name: {} Expected: {} Got: {}", key, id, realId);

        return getHolder(key, value);
    }

    @Override
    public Holder.Reference<T> register(ResourceKey<T> key, T value, Lifecycle lifecycle)
    {
        return registerMapping(-1, key, value, lifecycle);
    }

    // Reading Functions
    @Override
    @Nullable
    public T get(@Nullable ResourceLocation name)
    {
        return this.delegate.getRaw(name); //get without default
    }

    @Override
    public Optional<T> getOptional(@Nullable ResourceLocation name)
    {
        return Optional.ofNullable(this.delegate.getRaw(name)); //get without default
    }

    @Override
    @Nullable
    public T get(@Nullable ResourceKey<T> name)
    {
        return name == null ? null : this.delegate.getRaw(name.location()); //get without default
    }

    @Override
    @Nullable
    public ResourceLocation getKey(T value)
    {
        return this.delegate.getKey(value);
    }

    @Override
    public Optional<ResourceKey<T>> getResourceKey(T p_122755_)
    {
        return this.delegate.getResourceKey(p_122755_);
    }

    @Override
    public boolean containsKey(ResourceLocation key)
    {
        return this.delegate.containsKey(key);
    }

    @Override
    public boolean containsKey(ResourceKey<T> key)
    {
        return this.delegate.getRegistryName().equals(key.registry()) && containsKey(key.location());
    }

    @Override
    public int getId(@Nullable T value)
    {
        return this.delegate.getID(value);
    }

    @Override
    @Nullable
    public T byId(int id)
    {
        return this.delegate.getValue(id);
    }

    @Override
    public Lifecycle lifecycle(T value)
    {
        return Lifecycle.stable();
    }

    @Override
    public Lifecycle registryLifecycle()
    {
        return this.registryLifecycle;
    }

    @Override
    public Iterator<T> iterator()
    {
        return this.delegate.iterator();
    }

    @Override
    public Set<ResourceLocation> keySet()
    {
        return this.delegate.getKeys();
    }

    @Override
    public Set<ResourceKey<T>> registryKeySet()
    {
        return this.delegate.getResourceKeys();
    }

    @Override
    public Set<Map.Entry<ResourceKey<T>, T>> entrySet()
    {
        return this.delegate.getEntries();
    }

    @Override
    public boolean isEmpty()
    {
        return this.delegate.isEmpty();
    }

    @Override
    public int size()
    {
        return this.delegate.size();
    }

    /**
     * @deprecated Forge: For internal use only. Use the Register events when registering values.
     */
    @Deprecated
    @Override
    public void lock()
    {
        this.locked = true;
    }

    @Override
    public Optional<Holder.Reference<T>> getHolder(int id)
    {
        return id >= 0 && id < this.holdersById.size() ? Optional.ofNullable(this.holdersById.get(id)) : Optional.empty();
    }

    @Override
    public Optional<Holder.Reference<T>> getHolder(ResourceKey<T> key)
    {
        return Optional.ofNullable(this.holdersByName.get(key.location()));
    }

    @Override
    public @NotNull Holder<T> wrapAsHolder(@NotNull T value)
    {
        final Holder<T> holder = this.holders.get(value);
        return holder == null ? Holder.direct(value) : holder;
    }

    Optional<Holder<T>> getHolder(ResourceLocation location)
    {
        return Optional.ofNullable(this.holdersByName.get(location));
    }

    Optional<Holder<T>> getHolder(T value)
    {
        return Optional.ofNullable(this.holders.get(value));
    }

    @Override
    public HolderGetter<T> createRegistrationLookup()
    {
        this.validateWrite();
        return new HolderGetter<T>()
        {
            public Optional<Holder.Reference<T>> get(ResourceKey<T> p_259097_)
            {
                return Optional.of(this.getOrThrow(p_259097_));
            }

            public Holder.Reference<T> getOrThrow(ResourceKey<T> p_259750_)
            {
                return NamespacedWrapper.this.getOrCreateHolderOrThrow(p_259750_);
            }

            public Optional<HolderSet.Named<T>> get(TagKey<T> p_259486_)
            {
                return Optional.of(this.getOrThrow(p_259486_));
            }

            public HolderSet.Named<T> getOrThrow(TagKey<T> p_260298_)
            {
                return NamespacedWrapper.this.getOrCreateTag(p_260298_);
            }
        };
    }

    void validateWrite()
    {
        if (this.frozen)
            throw new IllegalStateException("Registry is already frozen");
    }

    void validateWrite(ResourceKey<T> key)
    {
        if (this.frozen)
            throw new IllegalStateException("Registry is already frozen (trying to add key " + key + ")");
    }

    Holder.Reference<T> getOrCreateHolderOrThrow(ResourceKey<T> key)
    {
        return this.holdersByName.computeIfAbsent(key.location(), k -> {
            if (this.intrusiveHolderCallback != null)
            {
                throw new IllegalStateException("This registry can't create new holders without value");
            }
            else
            {
                this.validateWrite(key);
                return Holder.Reference.createStandAlone(this.holderOwner(), key);
            }
        });
    }

    @Override
    public Optional<Holder.Reference<T>> getRandom(RandomSource rand)
    {
        return Util.getRandomSafe(this.getSortedHolders(), rand);
    }

    @Override
    public Stream<Holder.Reference<T>> holders()
    {
        return this.getSortedHolders().stream();
    }

    @Override
    public Stream<Pair<TagKey<T>, HolderSet.Named<T>>> getTags()
    {
        return this.tags.entrySet().stream().map(e -> Pair.of(e.getKey(), e.getValue()));
    }

    @Override
    public HolderSet.Named<T> getOrCreateTag(TagKey<T> name)
    {
        HolderSet.Named<T> named = this.tags.get(name);
        if (named == null)
        {
            named = createTag(name);
            // They use volatile and set it this way to not have the performance penalties of synced read access. But this makes a lot of new maps.. We need to look into performance alternatives.
            Map<TagKey<T>, HolderSet.Named<T>> map = new IdentityHashMap<>(this.tags);
            map.put(name, named);
            this.tags = map;
        }

        return named;
    }

    void addOptionalTag(TagKey<T> name, @NotNull Set<? extends Supplier<T>> defaults)
    {
        this.optionalTags.putAll(name, defaults);
    }

    @Override
    public Stream<TagKey<T>> getTagNames()
    {
        return this.tags.keySet().stream();
    }

    //TODO: Move this to ValidateCallback?
    @Override
    public Registry<T> freeze()
    {
        this.frozen = true;
        List<ResourceLocation> unregistered = this.holdersByName.entrySet().stream()
                .filter(e -> !e.getValue().isBound())
                .map(Map.Entry::getKey).sorted().toList();

        if (!unregistered.isEmpty())
            throw new IllegalStateException("Unbound values in registry " + this.key() + ": " + unregistered.stream().map(ResourceLocation::toString).collect(Collectors.joining(", \n\t")));

        if (this.unregisteredIntrusiveHolders != null && this.unregisteredIntrusiveHolders.values().stream().anyMatch(r -> !r.isBound() && r.getType() == Holder.Reference.Type.INTRUSIVE)) {
            throw new IllegalStateException("Some intrusive holders were not registered: " + this.unregisteredIntrusiveHolders.values() + " Hint: Did you register all your registry objects? Registry stage: " + stage.getName());
        }

        return this;
    }

    @Override
    public Holder.Reference<T> createIntrusiveHolder(T value)
    {
        if (this.intrusiveHolderCallback == null)
            throw new IllegalStateException("This registry can't create intrusive holders");

        this.validateWrite();

        return super.createIntrusiveHolder(value);
    }

    @Override
    public Optional<HolderSet.Named<T>> getTag(TagKey<T> name)
    {
        return Optional.ofNullable(this.tags.get(name));
    }

    @Override
    public void bindTags(Map<TagKey<T>, List<Holder<T>>> newTags)
    {
        Map<Holder.Reference<T>, List<TagKey<T>>> holderToTag = new IdentityHashMap<>();
        this.holdersByName.values().forEach(v -> holderToTag.put(v, new ArrayList<>()));
        newTags.forEach((name, values) -> values.forEach(holder -> addTagToHolder(holderToTag, name, holder)));

        Set<TagKey<T>> set = new HashSet<>(Sets.difference(this.tags.keySet(), newTags.keySet()));
        set.removeAll(this.optionalTags.keySet());
        if (!set.isEmpty())
            LOGGER.warn("Not all defined tags for registry {} are present in data pack: {}", this.key(), set.stream().map(k -> k.location().toString()).sorted()
                    .collect(Collectors.joining(", \n\t")));

        Map<TagKey<T>, HolderSet.Named<T>> tmpTags = new IdentityHashMap<>(this.tags);
        newTags.forEach((k, v) -> tmpTags.computeIfAbsent(k, this::createTag).bind(v));

        Set<TagKey<T>> defaultedTags = Sets.difference(this.optionalTags.keySet(), newTags.keySet());
        defaultedTags.forEach(name -> {
            List<Holder<T>> defaults = this.optionalTags.get(name).stream()
                    .map(valueSupplier -> getHolder(valueSupplier.get()).orElse(null))
                    .filter(Objects::nonNull)
                    .distinct()
                    .toList();
            defaults.forEach(holder -> addTagToHolder(holderToTag, name, holder));
            tmpTags.computeIfAbsent(name, this::createTag).bind(defaults);
        });

        holderToTag.forEach(Holder.Reference::bindTags);
        this.tags = tmpTags;

        this.delegate.onBindTags(this.tags, defaultedTags);
    }

    private void addTagToHolder(Map<Holder.Reference<T>, List<TagKey<T>>> holderToTag, TagKey<T> name, Holder<T> holder)
    {
        if (!holder.canSerializeIn(this.holderOwner()))
            throw new IllegalStateException("Can't create named set " + name + " containing value " + holder + " from outside registry " + this);

        if (!(holder instanceof Holder.Reference<T>))
            throw new IllegalStateException("Found direct holder " + holder + " value in tag " + name);

        holderToTag.get((Holder.Reference<T>) holder).add(name);
    }

    @Override
    public void resetTags()
    {
        this.tags.values().forEach(t -> t.bind(List.of()));
        this.holders.values().forEach(v -> v.bindTags(Set.of()));
    }

    @Override
    public void unfreeze()
    {
        this.frozen = false;
    }

    boolean isFrozen()
    {
        return this.frozen;
    }

    boolean isIntrusive()
    {
        return this.intrusiveHolderCallback != null;
    }

    @Nullable
    Holder.Reference<T> onAdded(RegistryManager stage, int id, ResourceKey<T> key, T newValue, T oldValue)
    {
        if (stage != RegistryManager.ACTIVE && (this.intrusiveHolderCallback == null || !stage.isStaging()))  // Intrusive handlers need updating in staging.
            return null; // Only do holder shit on the active registries, not pending or snapshots.

        //Holder.Reference<T> oldHolder = oldValue == null ? null : getHolder(key, oldValue);
        // Do we need to do anything with the old holder? We cant update its pointer unless its non-intrusive...
        // And if thats the case, then we *should* get its reference in newHolder

        Holder.Reference<T> newHolder = getHolder(key, newValue);

        this.holdersById.size(Math.max(this.holdersById.size(), id + 1));
        this.holdersById.set(id, newHolder);
        this.holdersByName.put(key.location(), newHolder);
        this.holders.put(newValue, newHolder);
        if (this.unregisteredIntrusiveHolders != null)
        {
            this.unregisteredIntrusiveHolders.remove(newValue);
            newHolder.bindKey(key);
        }
        newHolder.bindValue(newValue);
        this.holdersSorted = null;

        return newHolder;
    }

    @SuppressWarnings("deprecation")
    private HolderSet.Named<T> createTag(TagKey<T> name)
    {
        return HolderSet.emptyNamed(this.holderOwner(), name);
    }

    private Holder.Reference<T> getHolder(ResourceKey<T> key, T value)
    {
        if (this.intrusiveHolderCallback != null)
            return this.intrusiveHolderCallback.apply(value);

        return this.holdersByName.computeIfAbsent(key.location(), k -> Holder.Reference.createStandAlone(this.holderOwner(), key));
    }

    private List<Holder.Reference<T>> getSortedHolders()
    {
        if (this.holdersSorted == null)
            this.holdersSorted = this.holdersById.stream().filter(Objects::nonNull).toList();

        return this.holdersSorted;
    }

    public static class Factory<V> implements IForgeRegistry.CreateCallback<V>, IForgeRegistry.AddCallback<V>
    {
        public static final ResourceLocation ID = new ResourceLocation("forge", "registry_defaulted_wrapper");

        @Override
        public void onCreate(IForgeRegistryInternal<V> owner, RegistryManager stage)
        {
            ForgeRegistry<V> fowner = (ForgeRegistry<V>) owner;
            owner.setSlaveMap(ID, new NamespacedWrapper<V>(fowner, fowner.getBuilder().getIntrusiveHolderCallback(), stage));
        }

        @Override
        @SuppressWarnings("unchecked")
        public void onAdd(IForgeRegistryInternal<V> owner, RegistryManager stage, int id, ResourceKey<V> key, V value, V oldValue)
        {
            owner.getSlaveMap(ID, NamespacedWrapper.class).onAdded(stage, id, key, value, oldValue);
        }
    }
}