package net.minecraft.server.commands;

import com.mojang.brigadier.CommandDispatcher;
import com.mojang.brigadier.exceptions.CommandSyntaxException;
import com.mojang.brigadier.exceptions.DynamicCommandExceptionType;
import com.mojang.brigadier.exceptions.SimpleCommandExceptionType;
import net.minecraft.commands.CommandSourceStack;
import net.minecraft.commands.Commands;
import net.minecraft.commands.arguments.EntityArgument;
import net.minecraft.network.chat.Component;
import net.minecraft.server.level.ServerPlayer;
import net.minecraft.world.entity.Entity;
import org.jspecify.annotations.Nullable;

public class SpectateCommand {
	private static final SimpleCommandExceptionType ERROR_SELF = new SimpleCommandExceptionType(Component.translatable("commands.spectate.self"));
	private static final DynamicCommandExceptionType ERROR_NOT_SPECTATOR = new DynamicCommandExceptionType(
		s -> Component.translatableEscape("commands.spectate.not_spectator", s)
	);
	private static final DynamicCommandExceptionType ERROR_CANNOT_SPECTATE = new DynamicCommandExceptionType(
		s -> Component.translatableEscape("commands.spectate.cannot_spectate", s)
	);

	public static void register(final CommandDispatcher<CommandSourceStack> dispatcher) {
		dispatcher.register(
			Commands.literal("spectate")
				.requires(Commands.hasPermission(Commands.LEVEL_GAMEMASTERS))
				.executes(c -> spectate(c.getSource(), null, c.getSource().getPlayerOrException()))
				.then(
					Commands.argument("target", EntityArgument.entity())
						.executes(c -> spectate(c.getSource(), EntityArgument.getEntity(c, "target"), c.getSource().getPlayerOrException()))
						.then(
							Commands.argument("player", EntityArgument.player())
								.executes(c -> spectate(c.getSource(), EntityArgument.getEntity(c, "target"), EntityArgument.getPlayer(c, "player")))
						)
				)
		);
	}

	private static int spectate(final CommandSourceStack source, @Nullable final Entity target, final ServerPlayer player) throws CommandSyntaxException {
		if (player == target) {
			throw ERROR_SELF.create();
		} else if (!player.isSpectator()) {
			throw ERROR_NOT_SPECTATOR.create(player.getDisplayName());
		} else if (target != null && target.getType().clientTrackingRange() == 0) {
			throw ERROR_CANNOT_SPECTATE.create(target.getDisplayName());
		} else {
			player.setCamera(target);
			if (target != null) {
				source.sendSuccess(() -> Component.translatable("commands.spectate.success.started", target.getDisplayName()), false);
			} else {
				source.sendSuccess(() -> Component.translatable("commands.spectate.success.stopped"), false);
			}

			return 1;
		}
	}
}