/*
 * #!
 * Ontopia Navigator
 * #-
 * Copyright (C) 2001 - 2013 The Ontopia Project
 * #-
 * 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 net.ontopia.topicmaps.nav2.taglibs.TMvalue;

import java.util.HashSet;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import javax.servlet.jsp.JspTagException;

import net.ontopia.topicmaps.core.TopicIF;
import net.ontopia.topicmaps.core.AssociationIF;
import net.ontopia.topicmaps.core.AssociationRoleIF;
import net.ontopia.utils.DeciderIF;

import net.ontopia.topicmaps.nav2.utils.NavigatorUtils;
import net.ontopia.topicmaps.nav2.core.NavigatorRuntimeException;
import net.ontopia.topicmaps.nav2.taglibs.value.BaseScopedTag;

/**
 * INTERNAL: Value Producing Tag for finding all the association
 * roles of all the topics and associations in a collection.
 */
public class RolesTag extends BaseScopedTag {

  // constants
  public static final String BINARY = "binary";
  public static final String NARY   = "nary";  

  // tag attributes
  private String cardinality = null;
  private String varRemoveColl = null;
  
  public Collection process(Collection tmObjects) throws JspTagException {
    // find all base names of all tmObjects in collection
    // avoid duplicate type entries therefore use a HashSet
    if (tmObjects == null || tmObjects.isEmpty())
      return Collections.EMPTY_SET;
    else {
      HashSet assocRoles = new HashSet();
      // retrieve collection which should be subtracted
      Collection excludedTopics = (varRemoveColl == null ? null : contextTag.getContextManager().getValue(varRemoveColl));

      DeciderIF scopeDecider = null;
      // setup scope filter for user context filtering
      if (useUserContextFilter)
        scopeDecider = getScopeDecider(SCOPE_ASSOCIATIONS);
      
      // loop over input collection
      Iterator iter = tmObjects.iterator();
      Object obj = null;
      while (iter.hasNext()) {
        obj = iter.next();
        // --- for topic objects
        if (obj instanceof TopicIF) {
          TopicIF topic = (TopicIF) obj;
          // System.out.println("RolesTag for topic " + topic );
          Collection _roles = topic.getRoles();
          if (checkCardinality(_roles.size())) {
            Iterator itRoles = _roles.iterator();
            while (itRoles.hasNext()) {
              AssociationRoleIF assocRole = (AssociationRoleIF) itRoles.next();
              if (scopeDecider != null && !scopeDecider.ok(assocRole.getAssociation()))
                continue;
              if (excludedTopics == null || !excludedTopics.contains(assocRole.getPlayer()))
                assocRoles.add( assocRole );
            }
          }
        }
        // --- for association objects
        else if (obj instanceof AssociationIF) {
          AssociationIF assoc = (AssociationIF) obj;
          // System.out.println("RolesTag for assoc " + assoc );
          Collection _roles = assoc.getRoles();
          if (checkCardinality(_roles.size())) {
            Iterator itRoles = _roles.iterator();
            while (itRoles.hasNext()) {
              AssociationRoleIF assocRole = (AssociationRoleIF) itRoles.next();
              if (scopeDecider != null && !scopeDecider.ok(assocRole.getAssociation()))
                continue;
              if (excludedTopics == null || !excludedTopics.contains(assocRole.getPlayer()))
                assocRoles.add( assocRole );
            }
          }
        } else {
          String msg = "RolesTag: only support instances of TopicIF or " +
            "AssociationIF, but got " + obj.getClass().getName();
          throw new NavigatorRuntimeException(msg);
        }
      } // while iter      
      return assocRoles;
    }
  }

  /**
   * INTERNAL: returns true if claimed cardinality is kept, otherwise
   * false.
   */
  private final boolean checkCardinality(int nrOfPlayers) {
    if (cardinality == null)
      return true;
    if (cardinality.equals(BINARY))
      return (nrOfPlayers == 2);
    if (cardinality.equals(NARY))
      return (nrOfPlayers > 2);
    return false;
  }
  
  // -------------------------------------------------------
  // set methods for tag attributes
  // -------------------------------------------------------
  
  /**
   * Sets the variable name of an input collection consisting of one
   * or more topics that will removed from the retrieved list of
   * association role players.
   */
  public void setRemove(String varRemoveTopicColl) {
    this.varRemoveColl = varRemoveTopicColl;
  }

  /**
   * Specify in which cardinality you are interested. This filters out
   * the association roles retrieved for the input collection
   * (consisting of TopicIF and AssociationIF objects). If not
   * specified any kind of cardinality is returned. Allowed values
   * are "binary", "nary" (means at least trenary).
   */
  public void setCardinality(String cardinality) {
    // FIXME: Should support "unary" as well.
    if (cardinality.equals(BINARY) || cardinality.equals(NARY))
      this.cardinality = cardinality;
    else
      throw new IllegalArgumentException("RolesTag: not allowed value specified" +
                                         " for attribute 'cardinality'.");
  }
  
}