/*
 * 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.zeppelin.utils;

import java.net.InetAddress;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.UnknownHostException;
import java.util.Locale;
import org.apache.zeppelin.conf.ZeppelinConfiguration;

public class CorsUtils {

  private CorsUtils() {
    // Helper Class
  }

  public static final String HEADER_ORIGIN = "Origin";
  public static boolean isValidOrigin(String sourceHost, ZeppelinConfiguration zConf)
      throws UnknownHostException, URISyntaxException {

    String sourceUriHost = "";

    if (sourceHost != null && !sourceHost.isEmpty()) {
      sourceUriHost = new URI(sourceHost).getHost();
      sourceUriHost = (sourceUriHost == null) ? "" : sourceUriHost.toLowerCase(Locale.ROOT);
    }

    String currentHost = InetAddress.getLocalHost().getHostName().toLowerCase(Locale.ROOT);
    // getAllowedOrigins() returns lowercased entries; normalize sourceHost the same way
    // before the membership check so case differences in the Origin header do not produce
    // false rejections of explicitly configured origins.
    String normalizedOrigin =
        sourceHost == null ? "" : sourceHost.toLowerCase(Locale.ROOT);

    return zConf.getAllowedOrigins().contains("*")
        || currentHost.equals(sourceUriHost)
        || "localhost".equals(sourceUriHost)
        || zConf.getAllowedOrigins().contains(normalizedOrigin);
  }
}
