/*
 * Minecraft Forge, Patchwork Project
 * Copyright (c) 2016-2020, 2019-2020
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation version 2.1
 * of the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

package net.minecraftforge.fml;

import java.util.Iterator;
import java.util.Spliterator;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ConcurrentMap;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

public class InterModComms {
	public static final class IMCMessage {
		private final String modId;
		private final String method;
		private final String senderModId;
		private final Supplier<?> thing;

		IMCMessage(String senderModId, String modId, String method, Supplier<?> thing) {
			this.senderModId = senderModId;
			this.modId = modId;
			this.method = method;
			this.thing = thing;
		}

		/**
		 * @return The modid of the sender. This is supplied by the caller, or by the active mod container context.
		 * Consider it unreliable.
		 */
		public String getSenderModId() {
			return this.senderModId;
		}

		/**
		 * @return The modid being sent to.
		 */
		public String getModId() {
			return this.modId;
		}

		/**
		 * @return The method being sent to.
		 */
		public String getMethod() {
			return this.method;
		}

		/**
		 * @param <T> The type of the message.
		 * @return A {@link Supplier} of the message.
		 */
		@SuppressWarnings("unchecked")
		public <T> Supplier<T> getMessageSupplier() {
			return (Supplier<T>) this.thing;
		}
	}

	private static ConcurrentMap<String, ConcurrentLinkedQueue<IMCMessage>> containerQueues = new ConcurrentHashMap<>();

	/**
	 * Send IMC to remote. Sender will default to the active modcontainer, or minecraft if not.
	 *
	 * @param modId the mod id to send to
	 * @param method the method name to send
	 * @param thing the thing associated with the method name
	 * @return true if the message was enqueued for sending (the target modid is loaded)
	 */
	public static boolean sendTo(final String modId, final String method, final Supplier<?> thing) {
		if (!ModList.get().isLoaded(modId)) {
			return false;
		}

		containerQueues.computeIfAbsent(modId, k -> new ConcurrentLinkedQueue<>()).add(new IMCMessage(ModLoadingContext.get().getActiveContainer().getModId(), modId, method, thing));
		return true;
	}

	/**
	 * Send IMC to remote.
	 *
	 * @param senderModId the mod id you are sending from
	 * @param modId the mod id to send to
	 * @param method the method name to send
	 * @param thing the thing associated with the method name
	 * @return true if the message was enqueued for sending (the target modid is loaded)
	 */
	public static boolean sendTo(final String senderModId, final String modId, final String method, final Supplier<?> thing) {
		if (!ModList.get().isLoaded(modId)) {
			return false;
		}

		containerQueues.computeIfAbsent(modId, k -> new ConcurrentLinkedQueue<>()).add(new IMCMessage(senderModId, modId, method, thing));
		return true;
	}

	/**
	 * Retrieve pending messages for your modid. Use the predicate to filter the method name.
	 *
	 * @param modId the modid you are querying for
	 * @param methodMatcher a predicate for the method you are interested in
	 * @return All messages passing the supplied method predicate
	 */
	public static Stream<IMCMessage> getMessages(final String modId, final Predicate<String> methodMatcher) {
		ConcurrentLinkedQueue<IMCMessage> queue = containerQueues.get(modId);

		if (queue == null) {
			return Stream.empty();
		}

		return StreamSupport.stream(new QueueFilteringSpliterator(queue, methodMatcher), false);
	}

	/**
	 * Retrieve all message for your modid.
	 *
	 * @param modId the modid you are querying for
	 * @return All messages
	 */
	public static Stream<IMCMessage> getMessages(final String modId) {
		return getMessages(modId, s -> Boolean.TRUE);
	}

	private static class QueueFilteringSpliterator implements Spliterator<IMCMessage> {
		private final ConcurrentLinkedQueue<IMCMessage> queue;
		private final Predicate<String> methodFilter;
		private final Iterator<IMCMessage> iterator;

		private QueueFilteringSpliterator(final ConcurrentLinkedQueue<IMCMessage> queue, final Predicate<String> methodFilter) {
			this.queue = queue;
			this.iterator = queue.iterator();
			this.methodFilter = methodFilter;
		}

		@Override
		public int characteristics() {
			return Spliterator.CONCURRENT | Spliterator.NONNULL | Spliterator.ORDERED;
		}

		@Override
		public long estimateSize() {
			return queue.size();
		}

		@Override
		public boolean tryAdvance(final Consumer<? super IMCMessage> action) {
			if (!iterator.hasNext()) {
				return false;
			}

			IMCMessage next = iterator.next();

			while (iterator.hasNext() && !methodFilter.test(next.method)) {
				next = iterator.next();
			}

			action.accept(next);
			this.iterator.remove();
			return true;
		}

		@Override
		public Spliterator<IMCMessage> trySplit() {
			throw new UnsupportedOperationException("forge behavior is return null, report this to Patchwork!");
		}
	}
}