package net.minecraft.commands.arguments.item;

import com.mojang.brigadier.StringReader;
import com.mojang.brigadier.arguments.ArgumentType;
import com.mojang.brigadier.context.CommandContext;
import com.mojang.brigadier.exceptions.CommandSyntaxException;
import com.mojang.brigadier.exceptions.DynamicCommandExceptionType;
import com.mojang.datafixers.util.Either;
import com.mojang.datafixers.util.Pair;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Objects;
import net.minecraft.commands.CommandSourceStack;
import net.minecraft.commands.functions.CommandFunction;
import net.minecraft.network.chat.Component;
import net.minecraft.resources.Identifier;

public class FunctionArgument implements ArgumentType<FunctionArgument.Result> {
	private static final Collection<String> EXAMPLES = Arrays.asList("foo", "foo:bar", "#foo");
	private static final DynamicCommandExceptionType ERROR_UNKNOWN_TAG = new DynamicCommandExceptionType(
		tag -> Component.translatableEscape("arguments.function.tag.unknown", tag)
	);
	private static final DynamicCommandExceptionType ERROR_UNKNOWN_FUNCTION = new DynamicCommandExceptionType(
		value -> Component.translatableEscape("arguments.function.unknown", value)
	);

	public static FunctionArgument functions() {
		return new FunctionArgument();
	}

	public FunctionArgument.Result parse(final StringReader reader) throws CommandSyntaxException {
		if (reader.canRead() && reader.peek() == '#') {
			reader.skip();
			final Identifier id = Identifier.read(reader);
			return new FunctionArgument.Result() {
				{
					Objects.requireNonNull(FunctionArgument.this);
				}

				@Override
				public Collection<CommandFunction<CommandSourceStack>> create(final CommandContext<CommandSourceStack> c) throws CommandSyntaxException {
					return FunctionArgument.getFunctionTag(c, id);
				}

				@Override
				public Pair<Identifier, Either<CommandFunction<CommandSourceStack>, Collection<CommandFunction<CommandSourceStack>>>> unwrap(
					final CommandContext<CommandSourceStack> context
				) throws CommandSyntaxException {
					return Pair.of(id, Either.right(FunctionArgument.getFunctionTag(context, id)));
				}

				@Override
				public Pair<Identifier, Collection<CommandFunction<CommandSourceStack>>> unwrapToCollection(final CommandContext<CommandSourceStack> context) throws CommandSyntaxException {
					return Pair.of(id, FunctionArgument.getFunctionTag(context, id));
				}
			};
		} else {
			final Identifier id = Identifier.read(reader);
			return new FunctionArgument.Result() {
				{
					Objects.requireNonNull(FunctionArgument.this);
				}

				@Override
				public Collection<CommandFunction<CommandSourceStack>> create(final CommandContext<CommandSourceStack> c) throws CommandSyntaxException {
					return Collections.singleton(FunctionArgument.getFunction(c, id));
				}

				@Override
				public Pair<Identifier, Either<CommandFunction<CommandSourceStack>, Collection<CommandFunction<CommandSourceStack>>>> unwrap(
					final CommandContext<CommandSourceStack> context
				) throws CommandSyntaxException {
					return Pair.of(id, Either.left(FunctionArgument.getFunction(context, id)));
				}

				@Override
				public Pair<Identifier, Collection<CommandFunction<CommandSourceStack>>> unwrapToCollection(final CommandContext<CommandSourceStack> context) throws CommandSyntaxException {
					return Pair.of(id, Collections.singleton(FunctionArgument.getFunction(context, id)));
				}
			};
		}
	}

	private static CommandFunction<CommandSourceStack> getFunction(final CommandContext<CommandSourceStack> c, final Identifier id) throws CommandSyntaxException {
		return (CommandFunction<CommandSourceStack>)c.getSource().getServer().getFunctions().get(id).orElseThrow(() -> ERROR_UNKNOWN_FUNCTION.create(id.toString()));
	}

	private static Collection<CommandFunction<CommandSourceStack>> getFunctionTag(final CommandContext<CommandSourceStack> c, final Identifier id) throws CommandSyntaxException {
		Collection<CommandFunction<CommandSourceStack>> tag = c.getSource().getServer().getFunctions().getTag(id);
		if (tag == null) {
			throw ERROR_UNKNOWN_TAG.create(id.toString());
		} else {
			return tag;
		}
	}

	public static Collection<CommandFunction<CommandSourceStack>> getFunctions(final CommandContext<CommandSourceStack> context, final String name) throws CommandSyntaxException {
		return context.<FunctionArgument.Result>getArgument(name, FunctionArgument.Result.class).create(context);
	}

	public static Pair<Identifier, Either<CommandFunction<CommandSourceStack>, Collection<CommandFunction<CommandSourceStack>>>> getFunctionOrTag(
		final CommandContext<CommandSourceStack> context, final String name
	) throws CommandSyntaxException {
		return context.<FunctionArgument.Result>getArgument(name, FunctionArgument.Result.class).unwrap(context);
	}

	public static Pair<Identifier, Collection<CommandFunction<CommandSourceStack>>> getFunctionCollection(
		final CommandContext<CommandSourceStack> context, final String name
	) throws CommandSyntaxException {
		return context.<FunctionArgument.Result>getArgument(name, FunctionArgument.Result.class).unwrapToCollection(context);
	}

	@Override
	public Collection<String> getExamples() {
		return EXAMPLES;
	}

	public interface Result {
		Collection<CommandFunction<CommandSourceStack>> create(CommandContext<CommandSourceStack> context) throws CommandSyntaxException;

		Pair<Identifier, Either<CommandFunction<CommandSourceStack>, Collection<CommandFunction<CommandSourceStack>>>> unwrap(
			CommandContext<CommandSourceStack> context
		) throws CommandSyntaxException;

		Pair<Identifier, Collection<CommandFunction<CommandSourceStack>>> unwrapToCollection(CommandContext<CommandSourceStack> context) throws CommandSyntaxException;
	}
}