/*
 * 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.opensaml;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Writer;

import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.opensaml.messaging.context.MessageContext;
import org.opensaml.messaging.encoder.MessageEncodingException;
import org.opensaml.saml.saml2.binding.encoding.impl.HTTPPostEncoder;

import at.gv.egiz.eaaf.core.api.gui.IVelocityGuiBuilderConfiguration;
import at.gv.egiz.eaaf.core.api.gui.IVelocityGuiFormBuilder;
import at.gv.egiz.eaaf.core.impl.gui.velocity.VelocityProvider;
import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;
import net.shibboleth.shared.servlet.HttpServletSupport;


/**
 * OpenSAML2 Post-Binding encoder that uses dynamic loaded templates.
 *
 * @author tlenz
 *
 */
@Slf4j
public class HttpPostEncoderWithOwnTemplate extends HTTPPostEncoder {

  private final IVelocityGuiBuilderConfiguration guiConfig;
  private final IVelocityGuiFormBuilder guiBuilder;

  /**
   * Own Post-Binding encoder.
   *
   * @param guiConfig  GUI configuration
   * @param guiBuilder GUI builder implementation
   * @throws Exception In case of a {@link Velocity} initialization error
   */
  public HttpPostEncoderWithOwnTemplate(final IVelocityGuiBuilderConfiguration guiConfig,
      final IVelocityGuiFormBuilder guiBuilder) throws Exception {
    this.guiConfig = guiConfig;
    this.guiBuilder = guiBuilder;

    setVelocityEngine(VelocityProvider.getClassPathVelocityEngine());

  }

  /**
   * Base64 and POST encodes the out-bound message and writes it to the out-bound
   * transport.
   *
   * @param messageContext current message context
   *
   * @throws MessageEncodingException thrown if there is a problem encoding the
   *                                  message
   */
  @Override
  protected void postEncode(final MessageContext messageContext, final String endpointUrl)
      throws MessageEncodingException {
    log.debug("Invoking Velocity template to create POST body");
    InputStream is = null;
    try {
      // build Velocity Context from GUI input paramters
      final VelocityContext context =
          guiBuilder.generateVelocityContextFromConfiguration(guiConfig);

      // load template
      is = guiBuilder.getTemplateInputStream(guiConfig);

      populateVelocityContext(context, messageContext, endpointUrl);

      final HttpServletResponse response = getHttpServletResponse();

      HttpServletSupport.addNoCacheHeaders(response);
      HttpServletSupport.setUTF8Encoding(response);
      HttpServletSupport.setContentType(response, "text/html");

      final Writer out = new OutputStreamWriter(response.getOutputStream(), "UTF-8");
      getVelocityEngine().evaluate(context, out, "SAML2_POST_BINDING",
          new BufferedReader(new InputStreamReader(is, "UTF-8")));
      out.flush();

    } catch (final Exception e) {
      log.error("Error invoking Velocity template", e);
      throw new MessageEncodingException("Error creating output document", e);

    } finally {
      if (is != null) {
        try {
          is.close();

        } catch (final IOException e) {
          log.error("Can NOT close GUI-Template InputStream.", e);
        }
      }

    }
  }

}