gateway-topology-simple/src/main/java/org/apache/knox/gateway/topology/simple/ProviderConfigurationParser.java

/*
 * 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.knox.gateway.topology.simple;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

import org.apache.commons.io.FilenameUtils;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;

public class ProviderConfigurationParser {
  private static final JAXBContext jaxbContext = getJAXBContext();

  private static final String EXT_XML  = "xml";
  private static final String EXT_JSON = "json";
  private static final String EXT_YML  = "yml";
  private static final String EXT_YAML = "yaml";

  public static final List<String> SUPPORTED_EXTENSIONS = Collections.unmodifiableList(Arrays.asList(EXT_XML, EXT_JSON, EXT_YML, EXT_YAML));

  private static JAXBContext getJAXBContext() {
    try {
      return JAXBContext.newInstance(XMLProviderConfiguration.class);
    } catch (JAXBException e) {
      throw new IllegalStateException(e);
    }
  }

  public static ProviderConfiguration parse(String path) throws Exception {
    return parse(new File(path));
  }

  public static ProviderConfiguration parse(File file) throws Exception {
    ProviderConfiguration providerConfig = null;

    String extension = FilenameUtils.getExtension(file.getName());
    if (SUPPORTED_EXTENSIONS.contains(extension)) {

      if (isXML(extension)) {
        providerConfig = parseXML(file);
      } else if (isJSON(extension)) {
        providerConfig = parseJSON(file);
      } else if (isYAML(extension)) {
        providerConfig = parseYAML(file);
      }
    } else {
      throw new IllegalArgumentException("Unsupported provider configuration format: " + extension);
    }

    return providerConfig;
  }

  private static boolean isXML(String extension) {
    return EXT_XML.equals(extension);
  }

  private static boolean isJSON(String extension) {
    return EXT_JSON.equals(extension);
  }

  private static boolean isYAML(String extension) {
    return EXT_YAML.equals(extension) || EXT_YML.equals(extension);
  }

  static ProviderConfiguration parseXML(File file) throws Exception {
    return parseXML(Files.newInputStream(file.toPath()));
  }

  static ProviderConfiguration parseXML(InputStream in) throws Exception {
    Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
    XMLProviderConfiguration providerConfig = (XMLProviderConfiguration) jaxbUnmarshaller.unmarshal(in);

    return providerConfig;
  }

  static ProviderConfiguration parseJSON(File file) throws IOException {
    return parseJSON(Files.newInputStream(file.toPath()));
  }

  static ProviderConfiguration parseJSON(InputStream in) throws IOException {
    final ObjectMapper mapper = new ObjectMapper();
    return mapper.readValue(in, JSONProviderConfiguration.class);
  }

  static ProviderConfiguration parseYAML(File file) throws IOException {
    return parseYAML(Files.newInputStream(file.toPath()));
  }

  static ProviderConfiguration parseYAML(InputStream in) throws IOException {
    final ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
    return mapper.readValue(in, JSONProviderConfiguration.class);
  }

}