/*
    * This file is part of ***  M y C o R e  ***
    * See http://www.mycore.de/ for details.
    *
    * MyCoRe is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    *
   * MyCoRe is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with MyCoRe.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  package org.mycore.solr.search;
  
  import static org.mycore.solr.MCRSolrConstants.SOLR_QUERY_PATH;
  import static org.mycore.solr.MCRSolrConstants.SOLR_QUERY_XML_PROTOCOL_VERSION;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.net.URLEncoder;
  import java.nio.charset.StandardCharsets;
  import java.text.MessageFormat;
  import java.util.Locale;
  import java.util.Optional;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.apache.solr.client.solrj.SolrQuery.ORDER;
  import org.apache.solr.client.solrj.impl.HttpSolrClient;
  
  /**
   * Convenience class for holding the parameters for the solr search url.
   *
   * @author shermann
   */
  public class MCRSolrURL {
      private static final Logger LOGGER = LogManager.getLogger(MCRSolrURL.class);
  
      public static final String FIXED_URL_PART = new MessageFormat("?version={0}", Locale.ROOT)
          .format(new Object[] { SOLR_QUERY_XML_PROTOCOL_VERSION });
  
      private HttpSolrClient solrClient;
  
      private String urlQuery, q, sortOptions, wt;
  
      private int start, rows;
  
      boolean returnScore;
  
      private Optional<String> requestHandler;
  
      private MCRSolrURL() {
          requestHandler = Optional.empty();
      }
  
      /**
       * @param solrClient the solr server connection to use
       */
      public MCRSolrURL(HttpSolrClient solrClient) {
          this();
          this.solrClient = solrClient;
          start = 0;
          rows = 10;
          q = null;
          wt = null;
          sortOptions = "";
          returnScore = false;
      }
  
      /**
       * Creates a new solr url using your own url query. Be aware that you cannot
       * use the MCRSolrURL setter methods to edit your request. Only the urlQuery is
       * used.
       *
       * @param solrClient the solr server connection to use
       * @param urlQuery e.g. q=allMeta:Hello&amp;rows=20&amp;defType=edismax
       */
      public MCRSolrURL(HttpSolrClient solrClient, String urlQuery) {
          this();
          this.solrClient = solrClient;
          this.urlQuery = urlQuery;
      }
  
      /**
       * @param solrClient the solr server connection to use
       * @param returnScore specify whether to return the score with results;
       */
      public MCRSolrURL(HttpSolrClient solrClient, boolean returnScore) {
          this(solrClient);
          this.returnScore = returnScore;
      }
 
     /**
      * @return a ready to invoke {@link URL} object or null
      */
     public URL getUrl() {
         try {
             if (this.urlQuery == null) {
                 return new URL(
                     solrClient.getBaseURL() + getRequestHandler() + FIXED_URL_PART + "&q=" + URLEncoder
                         .encode(q, StandardCharsets.UTF_8)
                         + "&start=" + start
                         + "&rows=" + rows + "&sort=" + URLEncoder.encode(sortOptions, StandardCharsets.UTF_8)
                         + (returnScore ? "&fl=*,score" : "")
                         + (wt != null ? "&wt=" + wt : ""));
             } else {
                 return new URL(solrClient.getBaseURL() + getRequestHandler() + FIXED_URL_PART + "&" + urlQuery);
             }
         } catch (Exception urlException) {
             LOGGER.error("Error building solr url", urlException);
         }
 
         return null;
     }
 
     /**
      * Invoke this method to get a {@link URL} referring to the luke interface of a solr server. 
      * Under this URL one can find useful information about the solr schema. 
      *
      * @return a {@link URL} refering to the luke interface or null
      */
     public URL getLukeURL() {
         try {
             return new URL(solrClient.getBaseURL() + "/admin/luke");
         } catch (MalformedURLException e) {
             LOGGER.error("Error building solr luke url", e);
         }
         return null;
     }
 
     /**
      * An abbreviation for getUrl().openStream();
      */
     public InputStream openStream() throws IOException {
         URL url = this.getUrl();
         LOGGER.info(url.toString());
         return url.openStream();
     }
 
     /**
      * Adds a sort option to the solr url.
      *
      * @param sortBy the name of the field to sort by
      * @param order the sort order, one can use {@link ORDER#asc} or {@link ORDER#desc}
      */
     public void addSortOption(String sortBy, String order) {
         if (sortOptions.length() > 0) {
             sortOptions += ",";
         }
         sortOptions += sortBy + " " + (order != null ? order : "desc");
     }
 
     /**
      * Adds a sort option to the solr url
      *
      * @param sort the sort option e.g. 'maintitle desc'
      */
     public void addSortOption(String sort) {
         if (sort == null || sort.equals("")) {
             return;
         }
         if (sortOptions.length() > 0) {
             sortOptions += ",";
         }
         sortOptions += sort;
     }
 
     /**
      * Sets the unencoded query parameter.
      */
     public void setQueryParamter(String query) {
         this.q = query;
     }
 
     /**
      * @return the query parameter
      */
     public String getQueryParamter() {
         return this.q;
     }
 
     /**
      * @return the start parameter
      */
     public int getStart() {
         return start;
     }
 
     /**
      * @return the rows parameter
      */
     public int getRows() {
         return rows;
     }
 
     /**
      * Sets the start parameter.
      */
     public void setStart(int start) {
         this.start = start;
 
     }
 
     /**
      * Sets the rows parameter.
      */
     public void setRows(int rows) {
         this.rows = rows;
     }
 
     public void setReturnScore(boolean yesOrNo) {
         this.returnScore = yesOrNo;
     }
 
     /**
      * The wt (writer type) parameter is used by Solr to determine which QueryResponseWriter should be
      * used to process the request. Valid values are any of the names specified by &lt;queryResponseWriter... /&gt;
      * declarations in solrconfig.xml. The default value is "standard" (xml).
      */
     public void setWriterType(String wt) {
         this.wt = wt;
     }
 
     /**
      * @return true if the score is returned with the results, false otherwise
      */
     public boolean returnsScore() {
         return this.returnScore;
     }
 
     /**
      * Sets the solr request handler.
      *
      * @param requestHandler the name of the request handler to set e.g. /foo
      * */
     public void setRequestHandler(String requestHandler) {
         this.requestHandler = Optional.ofNullable(requestHandler);
     }
 
     /**
      * Returns the current request handler.
      *
      * @return the solr request handler
      * */
     public String getRequestHandler() {
         return this.requestHandler.orElse(SOLR_QUERY_PATH);
     }
 }