TF-EssentialsX/Essentials/src/com/earth2me/essentials/signs/SignGameMode.java

package com.earth2me.essentials.signs;

import com.earth2me.essentials.ChargeException;
import static com.earth2me.essentials.I18n.tl;
import com.earth2me.essentials.Trade;
import com.earth2me.essentials.User;
import java.util.Locale;
import net.ess3.api.IEssentials;
import org.bukkit.GameMode;
import org.bukkit.entity.Player;


public class SignGameMode extends EssentialsSign
{
	public SignGameMode()
	{
		super("GameMode");
	}

	@Override
	protected boolean onSignCreate(final ISign sign, final User player, final String username, final IEssentials ess) throws SignException
	{
		final String gamemode = sign.getLine(1);
		if (gamemode.isEmpty())
		{
			sign.setLine(1, "Survival");
		}

		validateTrade(sign, 2, ess);

		return true;
	}

	@Override
	protected boolean onSignInteract(final ISign sign, final User player, final String username, final IEssentials ess) throws SignException, ChargeException
	{
		final Trade charge = getTrade(sign, 2, ess);
		final String mode = sign.getLine(1).trim();

		if (mode.isEmpty())
		{
			throw new SignException(tl("invalidSignLine", 2));
		}

		charge.isAffordableFor(player);

		performSetMode(mode.toLowerCase(Locale.ENGLISH), player.getBase());
		player.sendMessage(tl("gameMode", tl(player.getBase().getGameMode().toString().toLowerCase(Locale.ENGLISH)), player.getDisplayName()));
		Trade.log("Sign", "gameMode", "Interact", username, null, username, charge, sign.getBlock().getLocation(), ess);
		charge.charge(player);
		return true;
	}

	private void performSetMode(String mode, Player player) throws SignException
	{
		if (mode.contains("survi") || mode.equalsIgnoreCase("0"))
		{
			player.setGameMode(GameMode.SURVIVAL);
		}
		else if (mode.contains("creat") || mode.equalsIgnoreCase("1"))
		{
			player.setGameMode(GameMode.CREATIVE);
		}
		else if (mode.contains("advent") || mode.equalsIgnoreCase("2"))
		{
			player.setGameMode(GameMode.ADVENTURE);
		}
		else
		{
			throw new SignException(tl("invalidSignLine", 2));
		}
	}
}