package ca.uhn.hl7v2.hoh.api;
   
   import java.util.Collections;
   import java.util.HashMap;
   import java.util.Map;
   
   public abstract class AbstractReceivable<T> implements IReceivable<T> {
   	private final Map<String, Object> myMetadata = new HashMap<>();
   
  	/**
  	 * Add a metadata value
  	 * 
  	 * @param theKey The key
  	 * @param theValue The value
  	 * @throws NullPointerException If theKey is null
  	 */
  	public void addMetadata(String theKey, Object theValue) {
  		if (theKey == null) {
  			throw new NullPointerException("Key may not be null");
  		}
  		
  		if (theValue != null) {
  			if (MessageMetadataKeys.keyStringSet().contains(theKey)) {
  				Class<?> valueType = MessageMetadataKeys.valueOf(theKey).getValueType();
  				if (!valueType.isAssignableFrom(theValue.getClass())) {
  					throw new IllegalArgumentException("Value for key \"" + theKey + "\" must be of type: " + valueType.getName());
  				}
  			}
  		}
  		
  		myMetadata.put(theKey, theValue);
  	}
  	
  	/**
  	 * {@inheritDoc}
  	 */
  	public Map<String, Object> getMetadata() {
  		return Collections.unmodifiableMap(myMetadata);
  	}
  
  
  }