OpenMRS

/**
 * The contents of this file are subject to the OpenMRS Public License
 * Version 1.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://license.openmrs.org
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
 * License for the specific language governing rights and limitations
 * under the License.
 *
 * Copyright (C) OpenMRS, LLC.  All Rights Reserved.
 */
package org.openmrs.logic;

import java.util.Map;
import java.util.Set;

import org.openmrs.Patient;
import org.openmrs.logic.result.Result;
import org.openmrs.logic.result.Result.Datatype;
import org.openmrs.logic.rule.RuleParameterInfo;

/**
 * 
 * Base class for all logic rules.
 * 
 */
public interface Rule {

    /**
     * 
     * Evaluate rule for a given patient and applying the given criteria.
     * 
     * @param patient a patient for whom rule is to be calculated
     * @return result of the rule for the given patient with given criteria
     *         applied
     * @throws LogicException TODO
     */
    public Result eval(LogicContext context, Patient patient,
            Map<String, Object> parameters) throws LogicException;

    /**
     * Returns the list of arguments.
     * 
     * @return list of arguments or null if no arguments
     */
    public Set<RuleParameterInfo> getParameterList();

    /**
     * 
     * Returns a list of dependencies (tokens for rules upon which this rule may
     * depend).
     * 
     * @return tokens for all rules that may be called by this rule
     * 
     */
    // TODO: it would be better to be able to query for dependency on both rules
    // and/or data source keys
    public String[] getDependencies();

    /**
     * 
     * Gets the time (in seconds) during which the Rule's results are considered
     * to be valid. This is used to prevent the use of invalid (old) items from
     * a cache
     * 
     * @return duration (in seconds) the results are considered valid for this
     *         rule
     */
    public int getTTL();

    /**
     * 
     * Gets the default datatype that the rule returns, when supplied with a
     * given token. While results are loosely typed, this method allows rules to
     * declare a default datatype to simplify user interfaces and defaults when
     * working with rules.
     * 
     * @return datatype
     */
    public Datatype getDefaultDatatype();

}