// Copyright 2016 The Domain Registry Authors. All Rights Reserved.
//
// Licensed 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 com.google.domain.registry.flows;

import static com.google.domain.registry.flows.EppController.handleEppCommand;
import static java.nio.charset.StandardCharsets.UTF_8;
import static javax.servlet.http.HttpServletResponse.SC_BAD_REQUEST;
import static javax.servlet.http.HttpServletResponse.SC_OK;

import com.google.common.net.MediaType;
import com.google.domain.registry.util.FormattingLogger;

import java.io.IOException;
import java.io.OutputStream;

import javax.servlet.http.HttpServletResponse;

/** Utility methods for Epp servlet classes. */
public final class EppServletUtils {

  public static final MediaType APPLICATION_EPP_XML_UTF8 =
      MediaType.create("application", "epp+xml").withCharset(UTF_8);

  private static final FormattingLogger logger = FormattingLogger.getLoggerForCallerClass();

  /**
   * Handle an EPP request and write out a servlet response.
   *
   * @throws IOException upon failure writing to {@code rsp}
   */
  static void handleEppCommandAndWriteResponse(
      byte[] inputXmlBytes, HttpServletResponse rsp, SessionMetadata sessionMetadata)
          throws IOException {
    byte[] response;
    try {
      response = handleEppCommand(inputXmlBytes, sessionMetadata);
    } catch (Exception e) {
      logger.warning(e, "handleEppCommand general exception");
      rsp.setStatus(SC_BAD_REQUEST);
      return;
    }
    // Note that we always return 200 (OK) even if the EppController returns an error response.
    // This is because returning an non-OK HTTP status code will cause the proxy server to
    // silently close the connection without returning any data. The only time we will ever return
    // a non-OK status (400) is if we fail to muster even an EPP error response message. In that
    // case it's better to close the connection than to return garbage.
    rsp.setStatus(SC_OK);
    rsp.setContentType(APPLICATION_EPP_XML_UTF8.toString());
    try (OutputStream output = rsp.getOutputStream()) {
      output.write(response);
    }
  }

  private EppServletUtils() {}
}