package net.sourceforge.jparam.output;
   
   import java.io.PrintStream;
   import java.lang.reflect.Method;
   import java.util.HashMap;
   import java.util.Map;
   
   import net.sourceforge.jparam.JParamException;
   import net.sourceforge.jparam.util.Utils;
  
  public class SerializerRegistry {
  	private static SerializerRegistry registry = null;
  
  	private Map serializers = new HashMap();
  
  	private ISerializer nullSerializer = new ISerializer() {
  		public void serialize(Object obj, PrintStream out) {
  		    Utils.assert(obj == null, "Null serializer got a non-null object: " + obj);
  
  		    out.print("NULL");
  		}
  
  		public Class getSupportedClass() {
  			return Object.class;
  		}
  	};
  
  	private SerializerRegistry() {
  	}
  
  	public static SerializerRegistry getInstance() {
  		if (registry == null) {
  			registry = new SerializerRegistry();
  		}
  		return registry;
  	}
  
  	public ISerializer getSerializer(Object obj) throws JParamException {
  
  		// check if the object is its own serializer
  		if (obj instanceof ISerializer) {
  			return (ISerializer) obj;
  		}
  
  		if (obj == null) {
  			return nullSerializer;
  		}
  
  		// check if any serializer was registered for this objects class
  		Object serializerObj = serializers.get(obj.getClass());
  		if (serializerObj != null) {
  			return (ISerializer) serializerObj;
  		}
  
  		throw new JParamException("No serializer found for class "
  				+ obj.getClass().getName());
  	}
  
  	public void registerSerializer(Class c, ISerializer s) {
  		Object prevSerializer = serializers.put(c, s);
  		if (prevSerializer != null) {
  			throw new RuntimeException(
  					"A serializer is already registered for: " + c.getName()
  							+ " previous serializer: " + prevSerializer);
  		}
  	}
  
  	public static void clearSingleton() {
  		registry = null;
  	}
  
  	public void registerHelperClass(Class c) {
  		Method[] outputClassMethods = c.getMethods();
  		for (int i = 0; i < outputClassMethods.length; i++) {
  			Method m = outputClassMethods[i];
  
  			ISerializer serializer = null;
  			if (OutputMethodSerializer.isMethodValid(m)) {
  				serializer = new OutputMethodSerializer(m);
  			} else if (SerializeMethodSerializer.isMethodValid(m)) {
  				serializer = new SerializeMethodSerializer(m);
  			}
  
  			if (serializer != null) {
  				registerSerializer(serializer.getSupportedClass(), serializer);
  			}
  		}
  	}
  }