/*
 * Copyright 2005-2010 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ 
package org.wamblee.security.authorization;

import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;
import javax.persistence.Version;

import org.wamblee.usermgt.UserAccessor;

/**
 * Service to determine if access to a certain resource is allowed.
 * 
 * @author Erik Brakkee
 */
@Entity
@Table(name = "SEC_AUTH_SVC")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "TYPE")
@NamedQueries( 
    @NamedQuery(name = AuthorizationService.QUERY_FIND_BY_NAME, 
        query = "select s from AuthorizationService s where s.name = :" +
        AuthorizationService.NAME_PARAM)
        )
public abstract class AuthorizationService {
 
    public static final String QUERY_FIND_BY_NAME = "AuthorizationService.findByName";
    public static final String NAME_PARAM = "name";
    
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long primaryKey;

    @Version
    private int version;
    
    public AuthorizationService() { 
        // Empty. 
    }
    
    public AuthorizationService(AuthorizationService aSvc) { 
        primaryKey = aSvc.primaryKey;
        version = aSvc.version;
    }
    
    /**
     * Checks whether an operation is allowed on a resource.
     * 
     * @param aResource
     *            Resource.
     * @param aOperation
     *            Operation.
     * 
     * @return Checks whether the operation is allowed on a resource.
     */
    public abstract boolean isAllowed(Object aResource, Operation aOperation);

    public abstract <T> T check(T aResource, Operation aOperation);

    /**
     * Gets the authorization rules.
     * 
     * @return Rules.
     */
    public abstract AuthorizationRule[] getRules();

    /**
     * Appends a new authorization rule to the end.
     * 
     * @param aRule
     *            Rule to append.
     */
    public abstract void appendRule(AuthorizationRule aRule);

    /**
     * Removes a rule.
     * 
     * @param aIndex
     *            Index of the rule to remove.
     */
    public abstract void removeRule(int aIndex);

    /**
     * Inserts a rule.
     * 
     * @param aIndex
     *            Index of the position of the rule after insertion.
     * @param aRule
     *            Rule to insert.
     */
    public abstract void insertRuleAfter(int aIndex, AuthorizationRule aRule);

    /**
     * Sets the user accessor so that the authorization service can get access to the logged in 
     * user. 
     * @param aUserAccessor User accessor.
     */
    public abstract void setUserAccessor(UserAccessor aUserAccessor);
}