/*
 * Copyright 2017 Graz University of Technology EAAF-Core Components has been developed in a
 * cooperation between EGIZ, A-SIT Plus, A-SIT, and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.2 or - as soon they will be approved by the European
 * Commission - subsequent versions of the EUPL (the "Licence"); You may not use this work except in
 * compliance with the Licence. You may obtain a copy of the Licence at:
 * https://joinup.ec.europa.eu/news/understanding-eupl-v12
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the Licence
 * is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the Licence for the specific language governing permissions and limitations under
 * the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text file for details on the
 * various modules and licenses. The "NOTICE" text file is part of the distribution. Any derivative
 * works that you distribute must include a readable copy of the "NOTICE" text file.
*/

package at.gv.egiz.eaaf.modules.pvp2.impl.utils;

import java.io.IOException;
import java.util.List;

import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.dom.DOMSource;
import javax.xml.validation.Schema;
import javax.xml.validation.Validator;

import org.apache.commons.lang3.StringUtils;
import org.opensaml.common.xml.SAMLSchemaBuilder;
import org.opensaml.saml2.core.Attribute;
import org.opensaml.saml2.core.Status;
import org.opensaml.saml2.core.StatusCode;
import org.opensaml.saml2.metadata.AssertionConsumerService;
import org.opensaml.saml2.metadata.SPSSODescriptor;
import org.opensaml.ws.soap.soap11.Body;
import org.opensaml.ws.soap.soap11.Envelope;
import org.opensaml.xml.XMLObject;
import org.opensaml.xml.XMLObjectBuilderFactory;
import org.opensaml.xml.io.Marshaller;
import org.opensaml.xml.io.MarshallingException;
import org.opensaml.xml.schema.XSString;
import org.opensaml.xml.schema.impl.XSStringBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;

import at.gv.egiz.eaaf.core.impl.utils.Random;
import at.gv.egiz.eaaf.modules.pvp2.PvpConstants;
import at.gv.egiz.eaaf.modules.pvp2.api.reqattr.EaafRequestedAttribute;

public class Saml2Utils {
  private static final Logger log = LoggerFactory.getLogger(Saml2Utils.class);

  private static DocumentBuilder builder;

  static {
    final DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    factory.setNamespaceAware(true);

    try {
      builder = factory.newDocumentBuilder();

    } catch (final ParserConfigurationException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }

  /**
   * Create a SAML2 object.
   *
   * @param       <T> SAML2 object class
   * @param clazz object class
   * @return SAML2 object
   */
  public static <T> T createSamlObject(final Class<T> clazz) {
    try {
      final XMLObjectBuilderFactory builderFactory =
          org.opensaml.xml.Configuration.getBuilderFactory();

      final QName defaultElementName =
          (QName) clazz.getDeclaredField("DEFAULT_ELEMENT_NAME").get(null);
      @SuppressWarnings("unchecked")
      final T object =
          (T) builderFactory.getBuilder(defaultElementName).buildObject(defaultElementName);
      return object;
    } catch (final Throwable e) {
      e.printStackTrace();
      return null;
    }
  }

  /**
   * Get a new SAML2 conform random value.
   *
   * @return
   */
  public static String getSecureIdentifier() {
    return "_".concat(Random.nextHexRandom16());

  }

  /**
   * Transform SAML2 Object to Element.
   *
   * @param object SAML2 object
   * @return Element
   * @throws IOException          In case of an transformation error
   * @throws MarshallingException In case of an transformation error
   * @throws TransformerException In case of an transformation error
   */
  public static Document asDomDocument(final XMLObject object)
      throws IOException, MarshallingException, TransformerException {
    final Document document = builder.newDocument();
    final Marshaller out =
        org.opensaml.xml.Configuration.getMarshallerFactory().getMarshaller(object);
    out.marshall(object, document);
    return document;
  }

  /**
   * Build success status element.
   *
   * @return
   */
  public static Status getSuccessStatus() {
    final Status status = Saml2Utils.createSamlObject(Status.class);
    final StatusCode statusCode = Saml2Utils.createSamlObject(StatusCode.class);
    statusCode.setValue(StatusCode.SUCCESS_URI);
    status.setStatusCode(statusCode);
    return status;
  }

  /**
   * Get AssertionConsumerService Index from metadata element.
   *
   * @param spSsoDescriptor metadata element
   * @return
   */
  public static int getDefaultAssertionConsumerServiceIndex(final SPSSODescriptor spSsoDescriptor) {

    final List<AssertionConsumerService> assertionConsumerList =
        spSsoDescriptor.getAssertionConsumerServices();

    for (final AssertionConsumerService el : assertionConsumerList) {
      if (el.isDefault()) {
        return el.getIndex();
      }

    }

    return 0;
  }

  /**
   * Build SOAP11 body from SAML2 object.
   *
   * @param payload SAML2 object
   * @return
   */
  public static Envelope buildSoap11Envelope(final XMLObject payload) {
    final XMLObjectBuilderFactory bf = org.opensaml.xml.Configuration.getBuilderFactory();
    final Envelope envelope = (Envelope) bf.getBuilder(Envelope.DEFAULT_ELEMENT_NAME)
        .buildObject(Envelope.DEFAULT_ELEMENT_NAME);
    final Body body =
        (Body) bf.getBuilder(Body.DEFAULT_ELEMENT_NAME).buildObject(Body.DEFAULT_ELEMENT_NAME);

    body.getUnknownXMLObjects().add(payload);
    envelope.setBody(body);

    return envelope;
  }

  /**
   * Generate EAAF specific requested attribute.
   *
   * @param attr       SAML2 attribute definition
   * @param isRequired is-mandatory flag
   * @param value      Attribute value
   * @return
   */
  public static EaafRequestedAttribute generateReqAuthnAttributeSimple(final Attribute attr,
      final boolean isRequired, final String value) {
    final EaafRequestedAttribute requested =
        Saml2Utils.createSamlObject(EaafRequestedAttribute.class);
    requested.setName(attr.getName());
    requested.setNameFormat(attr.getNameFormat());
    requested.setFriendlyName(attr.getFriendlyName());
    requested.setIsRequired(String.valueOf(isRequired));
    final List<XMLObject> attributeValues = requested.getAttributeValues();
    if (StringUtils.isNotEmpty(value)) {
      final XMLObject attributeValueForRequest =
          createAttributeValue(PvpConstants.EIDAS_REQUESTED_ATTRIBUTE_VALUE_TYPE, value);
      attributeValues.add(attributeValueForRequest);
    }
    return requested;

  }

  /**
   * Perform XML schema-validation on SAML2 object.
   *
   * @param xmlObject SAML2 object
   * @throws Exception In case of a validation error
   */
  public static void schemeValidation(final XMLObject xmlObject) throws Exception {
    try {
      final Schema test = SAMLSchemaBuilder.getSAML11Schema();
      final Validator val = test.newValidator();
      final DOMSource source = new DOMSource(xmlObject.getDOM());
      val.validate(source);
      log.debug("SAML2 Scheme validation successful");
      return;

    } catch (final Exception e) {
      log.warn("SAML2 scheme validation FAILED.", e);
      throw e;

    }
  }

  private static XMLObject createAttributeValue(final QName attributeValueType,
      final String value) {
    final XSStringBuilder stringBuilder = (XSStringBuilder) org.opensaml.xml.Configuration
        .getBuilderFactory().getBuilder(XSString.TYPE_NAME);
    final XSString stringValue = stringBuilder.buildObject(attributeValueType, XSString.TYPE_NAME);
    stringValue.setValue(value);
    return stringValue;

  }
}