package org.kuali.rice.krms.api.engine;
   
   import java.util.Collections;
   import java.util.HashMap;
   import java.util.Map;
   
   import org.joda.time.DateTime;
   
   public final class SelectionCriteria {
  
  	private final Long effectiveExecutionTime;
  	private final String eventName;
  	private final Map<String, String> contextQualifiers;
  	private final Map<String, String> agendaQualifiers;
  	
  	private SelectionCriteria(String eventName, DateTime effectiveDate) {
  		if (eventName == null || "".equals(eventName.trim())) {
  			throw new IllegalArgumentException("Event name must not be null or empty.");
  		}
  		this.eventName = eventName;
  		
  		if (effectiveDate != null) {
  			this.effectiveExecutionTime = effectiveDate.getMillis();
  		} else {
  			this.effectiveExecutionTime = null;
  		}
  		
  		this.contextQualifiers = new HashMap<String, String>();
  		this.agendaQualifiers = new HashMap<String, String>();
  	}
  	
  	/**
  	 * This static factory method creates a SelectionCriteria used to select an Agenda to execute.
  	 * 
  	 * @param eventName the event that is triggering rule execution.  Must not be null.
  	 * @param effectiveExecutionTime the time that the rule is being executed at.  If null, the time of engine execution will be used.
  	 * @param contextQualifiers qualifiers used to select the context
  	 * @param agendaQualifiers qualifiers used to select the agenda from the context
  	 * @return the {@link SelectionCriteria}
  	 */
  	public static SelectionCriteria createCriteria(String eventName, DateTime effectiveExecutionTime, Map<String, String> contextQualifiers, Map<String, String> agendaQualifiers) {
  		SelectionCriteria criteria = new SelectionCriteria(eventName, effectiveExecutionTime);
          if (contextQualifiers != null) {
  		    criteria.contextQualifiers.putAll(contextQualifiers);
          }
          if (agendaQualifiers != null) {
  		    criteria.agendaQualifiers.putAll(agendaQualifiers);
          }
  		return criteria;
  	}
  
  	public String getEventName() {
  		return eventName;
  	}
  	
  	/**
  	 * This method gets the effective date/time in epoch time, suitable for 
  	 * converting to a {@link java.util.Date} via {@link java.util.Date#Date(long)}
  	 * @return the epoch time for effective execution, or null 
  	 * (which defers to the {@link Engine} but implies that the actual time when execution begins will be used).
  	 */
  	public Long getEffectiveExecutionTime() {
  		return effectiveExecutionTime;
  	}
  
  	public Map<String, String> getContextQualifiers() {
  		return Collections.unmodifiableMap(contextQualifiers);
  	}
  
  	public Map<String, String> getAgendaQualifiers() {
  		return Collections.unmodifiableMap(agendaQualifiers);
  	}
  
  }