/*
 * Copyright (c) 2022 MarkLogic Corporation
 *
 * 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.marklogic.client.io;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

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

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.marklogic.client.MarkLogicBindingException;
import com.marklogic.client.MarkLogicIOException;
import com.marklogic.client.impl.ValuesListBuilder;
import com.marklogic.client.io.marker.OperationNotSupported;
import com.marklogic.client.io.marker.ValuesListReadHandle;
import com.marklogic.client.query.ValuesListResults;

import java.nio.charset.StandardCharsets;
import java.util.HashMap;

/**
 * A ValuesListHandle represents a list of available named lexicon configurations
 * from saved query options.
 */
public class ValuesListHandle
  extends BaseHandle<InputStream, OperationNotSupported>
  implements ValuesListReadHandle, ValuesListResults
{
  static final private Logger logger = LoggerFactory.getLogger(ValuesListHandle.class);

  private ValuesListBuilder.ValuesList valuesHolder;
  private Unmarshaller unmarshaller;

  String optionsName = null;

  /**
   * The constructor.
   */
  public ValuesListHandle() {
    super();
    super.setFormat(Format.XML);

    try {
      JAXBContext jc = JaxbContextLoader.CACHED_CONTEXT;
      unmarshaller = jc.createUnmarshaller();
    } catch (JAXBException e) {
      throw new MarkLogicBindingException(e);
    } catch (NoClassDefFoundError ncdfe) {
      throw new MarkLogicBindingException(new JAXBException("JAXB context initialization failed"));
    }
  }

  /**
   * Sets the format associated with this handle.
   *
   * This handle only supports XML.
   *
   * @param format The format, which must be Format.XML or an exception will be raised.
   */
  @Override
  public void setFormat(Format format) {
    if (format != Format.XML)
      throw new IllegalArgumentException("ValuesListHandle supports the XML format only");
  }

  /**
   * Fluent setter for the format associated with this handle.
   *
   * This handle only supports XML.
   *
   * @param format The format, which must be Format.XML or an exception will be raised.
   * @return The QueryOptionsListHandle instance on which this method was called.
   */
  public ValuesListHandle withFormat(Format format) {
    setFormat(format);
    return this;
  }

  /**
   * Returns the name of the query options used for this query.
   * @return The options name.
   */
  public String getOptionsName() {
    return optionsName;
  }

  /**
   * Sets the name of the query options to be used for this query.
   *
   * If no query options node with the specified name exists, the query will fail.
   *
   * @param name The name of the saved query options node on the server.
   */
  public void setOptionsName(String name) {
    optionsName = name;
  }

  @Override
  protected Class<InputStream> receiveAs() {
    return InputStream.class;
  }

  @Override
  protected void receiveContent(InputStream content) {
    try {
      valuesHolder = (ValuesListBuilder.ValuesList) unmarshaller.unmarshal(
        new InputStreamReader(content, StandardCharsets.UTF_8)
      );
    } catch (JAXBException e) {
      logger.error("Failed to unmarshall values list",e);
      throw new MarkLogicIOException(e);
    } finally {
      try {
        content.close();
      } catch (IOException e) {
        // ignore.
      }
    }

  }

  /**
   * Returns a HashMap of the named lexicon configurations.
   *
   * The keys are the names of the lexicons, the values are the corresponding URIs on the server.
   *
   * @return The map of names to URIs.
   */
  @Override
  public HashMap<String, String> getValuesMap() {
    return valuesHolder.getValuesMap();
  }

  /**
   * Initialization-on-demand holder for {@link ValuesListHandle}'s JAXB context.
   */
  private static class JaxbContextLoader {

    private static final JAXBContext CACHED_CONTEXT;

    static {
      try {
        CACHED_CONTEXT = JAXBContext.newInstance(ValuesListBuilder.ValuesList.class);
      } catch (JAXBException e) {
        throw new MarkLogicBindingException(e);
      }
    }
  }
}
