/**
    * 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.ws.security.validate;
  
  import java.util.List;
  
  import org.apache.ws.security.WSSecurityException;
  import org.apache.ws.security.handler.RequestData;
  import org.apache.ws.security.saml.SAMLKeyInfo;
  import org.apache.ws.security.saml.ext.AssertionWrapper;
  import org.apache.ws.security.saml.ext.OpenSAMLUtil;
  import org.joda.time.DateTime;
  import org.opensaml.common.SAMLVersion;
  import org.opensaml.xml.validation.ValidationException;
  import org.opensaml.xml.validation.ValidatorSuite;
  
  /**
   * This class validates a SAML Assertion, which is wrapped in an "AssertionWrapper" instance.
   * It assumes that the AssertionWrapper instance has already verified the signature on the
   * assertion (done by the SAMLTokenProcessor). It verifies trust in the signature, and also
   * checks that the Subject contains a KeyInfo (and processes it) for the holder-of-key case,
   * and verifies that the Assertion is signed as well for holder-of-key. 
   */
  public class SamlAssertionValidator extends SignatureTrustValidator {
      
      private static final org.apache.commons.logging.Log LOG = 
          org.apache.commons.logging.LogFactory.getLog(SamlAssertionValidator.class);
      
      /**
       * The time in seconds in the future within which the NotBefore time of an incoming 
       * Assertion is valid. The default is 60 seconds.
       */
      private int futureTTL = 60;
      
      /**
       * Whether to validate the signature of the Assertion (if it exists) against the 
       * relevant profile. Default is true.
       */
      private boolean validateSignatureAgainstProfile = true;
      
      /**
       * Set the time in seconds in the future within which the NotBefore time of an incoming 
       * Assertion is valid. The default is 60 seconds.
       */
      public void setFutureTTL(int newFutureTTL) {
          futureTTL = newFutureTTL;
      }
      
      /**
       * Validate the credential argument. It must contain a non-null AssertionWrapper. 
       * A Crypto and a CallbackHandler implementation is also required to be set.
       * 
       * @param credential the Credential to be validated
       * @param data the RequestData associated with the request
       * @throws WSSecurityException on a failed validation
       */
      public Credential validate(Credential credential, RequestData data) throws WSSecurityException {
          if (credential == null || credential.getAssertion() == null) {
              throw new WSSecurityException(WSSecurityException.FAILURE, "noCredential");
          }
          AssertionWrapper assertion = credential.getAssertion();
          
          // Check HOK requirements
          String confirmMethod = null;
          List<String> methods = assertion.getConfirmationMethods();
          if (methods != null && methods.size() > 0) {
              confirmMethod = methods.get(0);
          }
          if (OpenSAMLUtil.isMethodHolderOfKey(confirmMethod)) {
              if (assertion.getSubjectKeyInfo() == null) {
                  LOG.debug("There is no Subject KeyInfo to match the holder-of-key subject conf method");
                  throw new WSSecurityException(WSSecurityException.FAILURE, "noKeyInSAMLToken");
              }
              // The assertion must have been signed for HOK
              if (!assertion.isSigned()) {
                  LOG.debug("A holder-of-key assertion must be signed");
                  throw new WSSecurityException(WSSecurityException.FAILURE, "invalidSAMLsecurity");
              }
          }
          
          // Check conditions
          checkConditions(assertion);
         
         // Validate the assertion against schemas/profiles
         validateAssertion(assertion);
 
         // Verify trust on the signature
         if (assertion.isSigned()) {
             verifySignedAssertion(assertion, data);
         }
         return credential;
     }
     
     /**
      * Verify trust in the signature of a signed Assertion. This method is separate so that
      * the user can override if if they want.
      * @param assertion The signed Assertion
      * @param data The RequestData context
      * @return A Credential instance
      * @throws WSSecurityException
      */
     protected Credential verifySignedAssertion(
         AssertionWrapper assertion,
         RequestData data
     ) throws WSSecurityException {
         Credential trustCredential = new Credential();
         SAMLKeyInfo samlKeyInfo = assertion.getSignatureKeyInfo();
         trustCredential.setPublicKey(samlKeyInfo.getPublicKey());
         trustCredential.setCertificates(samlKeyInfo.getCerts());
         return super.validate(trustCredential, data);
     }
     
     /**
      * Check the Conditions of the Assertion.
      */
     protected void checkConditions(AssertionWrapper assertion) throws WSSecurityException {
         DateTime validFrom = null;
         DateTime validTill = null;
         if (assertion.getSamlVersion().equals(SAMLVersion.VERSION_20)
             && assertion.getSaml2().getConditions() != null) {
             validFrom = assertion.getSaml2().getConditions().getNotBefore();
             validTill = assertion.getSaml2().getConditions().getNotOnOrAfter();
         } else if (assertion.getSamlVersion().equals(SAMLVersion.VERSION_11)
             && assertion.getSaml1().getConditions() != null) {
             validFrom = assertion.getSaml1().getConditions().getNotBefore();
             validTill = assertion.getSaml1().getConditions().getNotOnOrAfter();
         }
         
         if (validFrom != null) {
             DateTime currentTime = new DateTime();
             currentTime = currentTime.plusSeconds(futureTTL);
             if (validFrom.isAfter(currentTime)) {
                 LOG.debug("SAML Token condition (Not Before) not met");
                 throw new WSSecurityException(WSSecurityException.FAILURE, "invalidSAMLsecurity");
             }
         }
 
         if (validTill != null && validTill.isBeforeNow()) {
             LOG.debug("SAML Token condition (Not On Or After) not met");
             throw new WSSecurityException(WSSecurityException.FAILURE, "invalidSAMLsecurity");
         }
     }
     
     /**
      * Validate the assertion against schemas/profiles
      */
     protected void validateAssertion(AssertionWrapper assertion) throws WSSecurityException {
         if (validateSignatureAgainstProfile) {
             assertion.validateSignatureAgainstProfile();
         }
         
         if (assertion.getSaml1() != null) {
             ValidatorSuite schemaValidators = 
                 org.opensaml.Configuration.getValidatorSuite("saml1-schema-validator");
             ValidatorSuite specValidators = 
                 org.opensaml.Configuration.getValidatorSuite("saml1-spec-validator");
             try {
                 schemaValidators.validate(assertion.getSaml1());
                 specValidators.validate(assertion.getSaml1());
             } catch (ValidationException e) {
                 LOG.debug("Saml Validation error: " + e.getMessage(), e);
                 throw new WSSecurityException(
                     WSSecurityException.FAILURE, "invalidSAMLsecurity", null, e
                 );
             }
         } else if (assertion.getSaml2() != null) {
             ValidatorSuite schemaValidators = 
                 org.opensaml.Configuration.getValidatorSuite("saml2-core-schema-validator");
             ValidatorSuite specValidators = 
                 org.opensaml.Configuration.getValidatorSuite("saml2-core-spec-validator");
             try {
                 schemaValidators.validate(assertion.getSaml2());
                 specValidators.validate(assertion.getSaml2());
             } catch (ValidationException e) {
                 LOG.debug("Saml Validation error: " + e.getMessage(), e);
                 throw new WSSecurityException(
                     WSSecurityException.FAILURE, "invalidSAMLsecurity", null, e
                 );
             }
         }
     }
 
     /**
      * Whether to validate the signature of the Assertion (if it exists) against the 
      * relevant profile. Default is true.
      */
     public boolean isValidateSignatureAgainstProfile() {
         return validateSignatureAgainstProfile;
     }
 
     /**
      * Whether to validate the signature of the Assertion (if it exists) against the 
      * relevant profile. Default is true.
      */
     public void setValidateSignatureAgainstProfile(boolean validateSignatureAgainstProfile) {
         this.validateSignatureAgainstProfile = validateSignatureAgainstProfile;
     }
     
 }