package ie.dcu.segment.options;

/**
 * A segmentation algorithm parameter that can assume one of a set of predefined
 * values.
 * 
 * @author Kevin McGuinness
 */
public class EnumOption<T extends Enum<T>> extends AbstractOption<T> {
	private Class<T> clazz;


	/**
	 * Create an enum option.
	 * 
	 * @param clazz
	 *        The class of the enum.
	 * @param name
	 *        The option name.
	 * @param description
	 *        The option description.
	 * @param def
	 *        The default value.
	 */
	public EnumOption(Class<T> clazz, String name, String description, T def) {
		super(OptionType.Enumeration, name, description, def);
		this.clazz = clazz;
	}


	public T[] values() {
		return clazz.getEnumConstants();
	}


	public Conversion<T> convert(Object value) {
		if (clazz.isInstance(value)) {
			return valid(clazz.cast(value));
		} else if (value != null) {
			
			String str = value.toString().trim();
			Conversion<T> conv;
			try {
				conv = valid(Enum.valueOf(clazz, str));
			} catch (IllegalArgumentException e) {
				conv = invalid("Invalid value \"%s\" for %s", value, getName());
			}
			
			if (!conv.isOk()) {
				// Try convert from an integer
				try {
					int x = Integer.parseInt(str);
					T[] v = values();
					if (x > 0 && x < v.length) {
						return valid(v[x]);
					}
					
				} catch (NumberFormatException e) {
					// Ignore .. we already have an error message from the string conversion
				}
			}
		}
		return invalid("%s is null", getName());
	}
}