/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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.apache.shiro.web.tags;

 import java.beans.BeanInfo;

 import java.beans.Introspector;

 import java.beans.PropertyDescriptor;

 import java.io.IOException;

 import javax.servlet.jsp.JspException;

 import javax.servlet.jsp.JspTagException;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 /**

  * <p>Tag used to print out the String value of a user's default principal,

  * or a specific principal as specified by the tag's attributes.</p>

  *

  * <p> If no attributes are specified, the tag prints out the <tt>toString()</tt>

  * value of the user's default principal.  If the <tt>type</tt> attribute

  * is specified, the tag looks for a principal with the given type.  If the

  * <tt>property</tt> attribute is specified, the tag prints the string value of

  * the specified property of the principal.  If no principal is found or the user

  * is not authenticated, the tag displays nothing unless a <tt>defaultValue</tt>

  * is specified.</p>

  *

  * @since 0.2

  */

 public class PrincipalTag extends SecureTag {

     //TODO - complete JavaDoc

     /*--------------------------------------------

     |             C O N S T A N T S             |

     ============================================*/

     /*--------------------------------------------

     |    I N S T A N C E   V A R I A B L E S    |

     ============================================*/

     private static final Logger log = LoggerFactory.getLogger(PrincipalTag.class);

     /**

      * The type of principal to be retrieved, or null if the default principal should be used.

      */

     private String type;

     /**

      * The property name to retrieve of the principal, or null if the <tt>toString()</tt> value should be used.

      */

     private String property;

     /**

      * The default value that should be displayed if the user is not authenticated, or no principal is found.

      */

     private String defaultValue;

     /*--------------------------------------------

     |         C O N S T R U C T O R S           |

     ============================================*/

     /*--------------------------------------------

     |  A C C E S S O R S / M O D I F I E R S    |

     ============================================*/

     public String getType() {

         return type;

     }

     public void setType(String type) {

         this.type = type;

     }

     public String getProperty() {

         return property;

     }

     public void setProperty(String property) {

         this.property = property;

     }

     public String getDefaultValue() {

         return defaultValue;

     }

     public void setDefaultValue(String defaultValue) {

         this.defaultValue = defaultValue;

     }

     /*--------------------------------------------

     |               M E T H O D S               |

     ============================================*/

     @SuppressWarnings({"unchecked"})

     public int onDoStartTag() throws JspException {

         String strValue = null;

         if (getSubject() != null) {

             // Get the principal to print out

             Object principal;

             if (type == null) {

                 principal = getSubject().getPrincipal();

             } else {

                 principal = getPrincipalFromClassName();

             }

             // Get the string value of the principal

             if (principal != null) {

                 if (property == null) {

                     strValue = principal.toString();

                 } else {

                     strValue = getPrincipalProperty(principal, property);

                 }

             }

         }

         // Print out the principal value if not null

         if (strValue != null) {

             try {

                 pageContext.getOut().write(strValue);

             } catch (IOException e) {

                 throw new JspTagException("Error writing [" + strValue + "] to JSP.", e);

             }

         }

         return SKIP_BODY;

     }

     @SuppressWarnings({"unchecked"})

     private Object getPrincipalFromClassName() {

         Object principal = null;

         try {

             Class cls = Class.forName(type);

             principal = getSubject().getPrincipals().oneByType(cls);

         } catch (ClassNotFoundException e) {

             if (log.isErrorEnabled()) {

                 log.error("Unable to find class for name [" + type + "]");

             }

         }

         return principal;

     }

     private String getPrincipalProperty(Object principal, String property) throws JspTagException {

         String strValue = null;

         try {

             BeanInfo bi = Introspector.getBeanInfo(principal.getClass());

             // Loop through the properties to get the string value of the specified property

             boolean foundProperty = false;

             for (PropertyDescriptor pd : bi.getPropertyDescriptors()) {

                 if (pd.getName().equals(property)) {

                     Object value = pd.getReadMethod().invoke(principal, (Object[]) null);

                     strValue = String.valueOf(value);

                     foundProperty = true;

                     break;

                 }

             }

             if (!foundProperty) {

                 final String message = "Property [" + property + "] not found in principal of type [" + principal.getClass().getName() + "]";

                 if (log.isErrorEnabled()) {

                     log.error(message);

                 }

                 throw new JspTagException(message);

             }

         } catch (Exception e) {

             final String message = "Error reading property [" + property + "] from principal of type [" + principal.getClass().getName() + "]";

             if (log.isErrorEnabled()) {

                 log.error(message, e);

             }

             throw new JspTagException(message, e);

         }

         return strValue;

     }

 }