package geniusweb.issuevalue;

import java.io.IOException;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.deser.std.StdDeserializer;

/**
 * A possible value for an Issue. Must be immutable and thread safe. Supported
 * values are {@link NumberValue} and {@link DiscreteValue}. All values are just
 * strings, a custom deserializer is used to determine which type it is.
 * 
 * Value must be de-serializable all by itself, because it can occur plain in a
 * Bid eg Bid["fte":0.8]
 */
@JsonDeserialize(using = ValueDeserializer.class)
public interface Value {
	/**
	 * @return the contained value (String, BigDecimal)
	 */
	public Object getValue();

}

/**
 * Deserializes a Value. Special deserializer is needed because by default
 * jackson deserializes numbers as double and thus cause rounding errors.
 */
@SuppressWarnings("serial")
class ValueDeserializer extends StdDeserializer<Value> {

	public ValueDeserializer() {
		this(null);
	}

	public ValueDeserializer(Class<?> vc) {
		super(vc);
	}

	@Override
	public Value deserialize(JsonParser jp, DeserializationContext ctxt)
			throws IOException, JsonProcessingException {
		String text = jp.getText();
		switch (jp.currentToken()) {
		case VALUE_NUMBER_FLOAT:
		case VALUE_NUMBER_INT:
			return new NumberValue(text);
		case VALUE_STRING:
			return new DiscreteValue(text);
		default:
			throw new IOException(
					"Expected number of double quoted string but found " + text
							+ " of type " + jp.currentToken());
		}

	}

}