# Decision.java

    /*
    ** Module   : Decision.java
    ** Abstract : Helpers to manage/search cached access decisions.
    **
    ** Copyright (c) 2004-2021, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --JPRM-- ----------------------------------Description-----------------------------------
    ** 001 NVS 20050322   @20454 Created the initial version. This class represents cached access decisions.
    ** 002 ECF 20080704   @39142 Minor memory optimization. Use Boolean constants instead of instantiating new
    **                           Boolean objects.
    ** 003 GES 20210917          Removed dead code, implemented generics, improved documentation, encapsulated
    **                           the cache itself.
    */

    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program is distributed in the hope that it will be useful,
    ** but WITHOUT ANY WARRANTY; without even the implied warranty of
    ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ** GNU Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
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    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
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    **     Corporation or FWD.  All modified versions must contain the notices of
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    */

    package com.goldencode.p2j.security;

    import java.util.*;

    /**
     * Cache and helpers to lookup cached decisions.  Each decision associates a resource instance name, access
     * mode (the rights being requested, which is an integer) and the resulting access decision (a boolean).
     * This allows repeated accesses to reuse the previously calculated decisions.
     * <p>
     * Access decisions are cached in maps. The top level map contains second level maps and has the instance
     * name for the key. Second level maps have access mode as the key and contain a boolean value bearing the
     * decision.  Instances of this cache are specific to a given resource type and are held by the respective
     * security contexts.
     */
    class Decision
    {
       /** Cache storage. */
       private Map<String, Map<Integer, Boolean>> cache = new HashMap<String, Map<Integer, Boolean>>();

       /**
        * Searches the instance's cached decisions to find the decision for the requested access mode.
        *
        * @param    instance
        *           The resource instance name.
        * @param    mode
        *           The requested access mode (rights level).
        *
        * @return   The cached decision or {@code null} if no matching decision exists.
        */
       Boolean search(String instance, int mode)
       {
          Map<Integer, Boolean> internal = cache.get(instance);

          if (internal == null)
          {
             return null;
          }

          return internal.get(mode);
       }

       /**
        * Removes the access decision from the cache.
        *
        * @param    instance
        *           The resource instance name.
        * @param    mode
        *           The requested access mode (rights level).
        */
       void remove(String instance, int mode)
       {
          Map<Integer, Boolean> internal = cache.get(instance);

          if (internal == null)
          {
             return;
          }

          internal.remove(mode);
       }

       /**
        * Puts the access decision into the cache.
        *
        * @param    instance
        *           The resource instance name.
        * @param    mode
        *           The requested access mode (rights level).
        * @param    decision
        *           The value to cache.
        */
       void cache(String instance, int mode, boolean decision)
       {
          Map<Integer, Boolean> internal = cache.get(instance);

          if (internal == null)
          {
             internal = new HashMap<Integer, Boolean>();
             cache.put(instance, internal);
          }

          internal.put(mode, (decision ? Boolean.TRUE : Boolean.FALSE));
       }
    }