/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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.opencastproject.security.aai.api;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.beans.factory.InitializingBean;
  import org.springframework.expression.Expression;
  import org.springframework.expression.ExpressionParser;
  import org.springframework.expression.spel.standard.SpelExpressionParser;
  import org.springframework.util.Assert;
  import org.springframework.util.CollectionUtils;
  
  import java.util.HashMap;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import javax.servlet.http.HttpServletRequest;
  /**
   * Generic AAI Attribute mapper using Spring Expression language mappings.
   *
   */
  public class AttributeMapper implements InitializingBean {
  
    /** The logging facility */
    private static final Logger logger = LoggerFactory.getLogger(AttributeMapper.class);
  
    /** List of all attributes that should be fetched */
    private List<String> aaiAttributes;
  
    /**
     * Map of List of expressions. Key is a mapping name, value a list of
     * expressions
     */
    private Map<String, List<String>> attributeMap;
  
    /** Use HTTP Header or environment attributes */
    private boolean useHeader = true;
  
    /** The delimiter for multivalue attributes */
    private String multiValueDelimiter = ";";
  
    public void afterPropertiesSet() throws Exception {
      Assert.notNull(attributeMap, "attributeMap must be set");
    }
  
    /**
     * Apply all expressions on the sourceAttributes
     *
     * @param sourceAttributes
     *    Key is attribute name, value a list of split AAI attribute values
     * @param mappingId
     *    The mapping list to use
     * @return
     */
    public List<String> getMappedAttributes(
        Map<String, List<String>> sourceAttributes, String mappingId) {
      Set<String> mappedAttributes = new LinkedHashSet<String>();
      ExpressionParser parser = new SpelExpressionParser();
  
      List<String> expressions = attributeMap.get(mappingId);
  
      if (expressions == null) {
        throw new IllegalArgumentException("No mapping for \"" + mappingId
            + "\" specified. Did you forget to configure a <util:map id=\""
            + mappingId + "\" ...?");
      }
  
      for (String expression : expressions) {
        Expression exp = null;
        try {
          exp = parser.parseExpression(expression);
          Object res = exp.getValue(sourceAttributes);
          logger.debug("Mapping {} to {}", exp.getExpressionString(), res);
          if (res == null) {
            continue;
          }
          if (res instanceof String) {
            mappedAttributes.add((String) res);
         } else if (res instanceof List<?>) {
           for (Object resListItem : (List<?>) res) {
             if (resListItem instanceof String) {
               mappedAttributes.add((String) resListItem);
             }
           }
         }
       } catch (Exception e) {
         logger.warn("Mapping for '{}' with expression {} exp.getExpressionString() failed: {}",
             mappingId, exp.getExpressionString(), e.getMessage());
       }
     }
 
     return CollectionUtils.arrayToList(mappedAttributes.toArray());
   }
 
   /**
    *
    * @param request
    *    The current HttpServletRequest
    * @param mappingId
    *    The mapping list to use
    * @return
    */
   public List<String> getMappedAttributes(HttpServletRequest request,
       String mappingId) {
     Assert
         .notNull(
             aaiAttributes,
             "aaiAttributes must be set. Did you forget to configure <util:list id=\"aaiAttribute\"?");
     Assert.isTrue(aaiAttributes.size() > 0,
             "At least one aaiAttribute must be set. Did you forget to configure some in "
                     + "<util:list id=\"aaiAttribute\"?");
 
     Map<String, List<String>> sourceAttributes = new HashMap<String, List<String>>();
 
     for (String aaiAttribute : aaiAttributes) {
       String value = null;
       if (this.isUseHeader()) {
         value = request.getHeader(aaiAttribute);
         if (value == null) {
           logger.warn("No header '{}' found in request.", aaiAttribute);
           continue;
         }
       } else {
         value = (String) request.getAttribute(aaiAttribute);
         if (value == null) {
           logger.warn("No attribute '{}' found in request.", aaiAttribute);
           continue;
         }
       }
       sourceAttributes.put(aaiAttribute,
           CollectionUtils.arrayToList(value.split(multiValueDelimiter)));
     }
     return this.getMappedAttributes(sourceAttributes, mappingId);
   }
 
   public Map<String, List<String>> getAttributeMap() {
     return attributeMap;
   }
 
   public void setAttributeMap(Map<String, List<String>> attributeMap) {
     this.attributeMap = attributeMap;
   }
 
   public List<String> getAaiAttributes() {
     return aaiAttributes;
   }
 
   public void setAaiAttributes(List<String> aaiAttributes) {
     this.aaiAttributes = aaiAttributes;
   }
 
   public boolean isUseHeader() {
     return useHeader;
   }
 
   public void setUseHeader(boolean useHeader) {
     this.useHeader = useHeader;
   }
 
   public String getMultiValueDelimiter() {
     return multiValueDelimiter;
   }
 
   public void setMultiValueDelimiter(String multiValueDelimiter) {
     this.multiValueDelimiter = multiValueDelimiter;
   }
 
 }