/*
    * 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.frontend;
  
  import java.net.MalformedURLException;
  import java.net.URI;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  /**
   * 
   * @author Matthias Eichner
   */
  public class MCRURL {
  
      static Logger LOGGER = LogManager.getLogger(MCRURL.class);
  
      private URL url;
  
      private Map<String, List<String>> parameterMap;
  
      public MCRURL(String url) throws MalformedURLException {
          this.url = new URL(url);
      }
  
      public Map<String, List<String>> getParameterMap() {
          if (this.parameterMap == null) {
              this.parameterMap = buildParameterMap(this.url);
          }
          return parameterMap;
      }
  
      private Map<String, List<String>> buildParameterMap(URL url) {
          Map<String, List<String>> p = new HashMap<>();
          String queryString = url.getQuery();
          if (queryString == null) {
              return p;
          }
          for (String pair : queryString.split("&")) {
              int eq = pair.indexOf("=");
              String key = eq >= 0 ? pair.substring(0, eq) : pair;
              String value = eq >= 0 ? pair.substring(eq + 1) : "";
              if (p.containsKey(key)) {
                  p.get(key).add(value);
              } else {
                  List<String> valueList = new ArrayList<>();
                  valueList.add(value);
                  p.put(key, valueList);
              }
          }
          return p;
      }
  
      private String buildQueryString(Map<String, List<String>> parameterMap) {
          StringBuilder queryBuilder = new StringBuilder();
          for (Entry<String, List<String>> entrySet : parameterMap.entrySet()) {
              String name = entrySet.getKey();
              for (String value : entrySet.getValue()) {
                  queryBuilder.append(name).append("=").append(value).append("&");
              }
          }
          String queryString = queryBuilder.toString();
          return queryString.length() > 0 ? queryString.substring(0, queryString.length() - 1) : "";
      }
  
      private void rebuild() {
          String query = buildQueryString(this.parameterMap);
          try {
              URI uri = this.url.toURI();
              StringBuilder urlBuffer = new StringBuilder();
              urlBuffer.append(
                  new URI(uri.getScheme(), uri.getUserInfo(), uri.getHost(), uri.getPort(), uri.getPath(), null, null));
              if (query != null) {
                  urlBuffer.append("?").append(query);
              }
              if (uri.getFragment() != null) {
                 urlBuffer.append("#").append(uri.getFragment());
             }
             this.url = new URL(urlBuffer.toString());
             if (this.parameterMap != null) {
                 // rebuild parameter map
                 this.parameterMap = buildParameterMap(this.url);
             }
         } catch (Exception exc) {
             LOGGER.error("unable to rebuild url {}", this.url);
         }
     }
 
     public String getParameter(String name) {
         List<String> valueList = getParameterMap().get(name);
         return valueList != null ? valueList.get(0) : null;
     }
 
     public List<String> getParameterValues(String name) {
         List<String> valueList = getParameterMap().get(name);
         return valueList != null ? valueList : new ArrayList<>();
     }
 
     public MCRURL addParameter(String name, String value) {
         StringBuilder urlBuffer = new StringBuilder(this.url.toString());
         urlBuffer.append(this.url.getQuery() == null ? "?" : "&");
         urlBuffer.append(name).append("=").append(value);
         try {
             this.url = new URL(urlBuffer.toString());
             if (this.parameterMap != null) {
                 // rebuild parameter map
                 this.parameterMap = buildParameterMap(this.url);
             }
         } catch (MalformedURLException exc) {
             LOGGER.error("unable to add parameter ({}={}) to url{}", name, value, this.url);
         }
         return this;
     }
 
     public MCRURL removeParameter(String name) {
         this.getParameterMap().remove(name);
         rebuild();
         return this;
     }
 
     public MCRURL removeParameterValue(String name, String value) {
         List<String> values = this.getParameterMap().get(name);
         if (values != null) {
             boolean removed = false;
             while (values.remove(value)) {
                 removed = true;
             }
             if (removed) {
                 rebuild();
             }
         }
         return this;
     }
 
     public URL getURL() {
         return this.url;
     }
 
     @Override
     public String toString() {
         return this.url.toString();
     }
 
 }