package foundation.variant.provider;

import java.util.Calendar;
import java.util.Date;
import java.util.HashSet;
import java.util.Set;

public class GlobalVariantProvider implements IVariantsProvider {
	
	public static String ProviderName = "globalVariant";
	public static Set<String> VariantNames;
	private static GlobalVariantProvider instance;

	
	static {
		VariantNames = new HashSet<String>();
		initVariantNames();
	}
	
	private GlobalVariantProvider() {
		
	}
	
	public static GlobalVariantProvider getInstance() {
		if (instance == null) {
			instance = new GlobalVariantProvider();
		}
		
		return instance;
	}
	
	@Override
	public String getProviderName() {
		return ProviderName;
	}

	@Override
	public VariantProviderType getProviderType() {
		return VariantProviderType.Persist;
	}

	@Override
	public Set<String> getVariantNames() {
		return VariantNames;
	}

	@Override
	public boolean containsVariant(String name) {
		if (name == null) {
			return false;
		}
		
		name = name.toLowerCase();
		return VariantNames.contains(name);
	}

	@Override
	public Object getVariantValue(DataEvent dataEvent, String name) {
		if ("newdate".equals(name)) {
			return new Date();
		}
		else if ("newdatetime".equals(name)) {
			return new Date();
		}
		else if ("current.year".equals(name)) {
			Calendar calendar = Calendar.getInstance();
			return String.valueOf(calendar.get(Calendar.YEAR));
		}
		else if ("current.month".equals(name)) {
			Calendar calendar = Calendar.getInstance();
			return String.valueOf(calendar.get(Calendar.MONTH) + 1);
		}
		
		return null;
	}
	
	public static void initVariantNames() {
		addOneVariantName("newDate");
		addOneVariantName("newDateTime");
		addOneVariantName("current.year");
		addOneVariantName("current.month");
	}
	
	public static void addOneVariantName(String name) {
		VariantNames.add(name.toLowerCase());
	}
}