/*
 * This file is part of the Meeds project (https://meeds.io/).
 * Copyright (C) 2020 Meeds Association
 * contact@meeds.io
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 * This program 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
 * Lesser General Public License for more details.
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.exoplatform.services.rest.impl.provider;

import org.exoplatform.services.rest.ApplicationContext;
import org.exoplatform.services.rest.impl.ApplicationContextImpl;
import org.exoplatform.services.rest.impl.MultivaluedMapImpl;
import org.exoplatform.services.rest.provider.EntityProvider;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.lang.annotation.Annotation;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.List;
import java.util.Map;

import javax.ws.rs.Consumes;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.Provider;

/**
 * @author <a href="mailto:andrew00x@gmail.com">Andrey Parfonov</a>
 * @version $Id: $
 */
@Provider
@Consumes({MediaType.APPLICATION_FORM_URLENCODED})
@Produces({MediaType.APPLICATION_FORM_URLENCODED})
public class MultivaluedMapEntityProvider implements EntityProvider<MultivaluedMap<String, String>>
{

   /**
    * {@inheritDoc}
    */
   public boolean isReadable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType)
   {
      if (type == MultivaluedMap.class)
      {
         try
         {
            ParameterizedType t = (ParameterizedType)genericType;
            Type[] ta = t.getActualTypeArguments();
            if (ta.length == 2 && ta[0] == String.class && ta[1] == String.class)
               return true;
            return false;
         }
         catch (ClassCastException e)
         {
            return false;
         }
      }
      return false;
   }

   /**
    * {@inheritDoc}
    */
   @SuppressWarnings("unchecked")
   public MultivaluedMap<String, String> readFrom(Class<MultivaluedMap<String, String>> type, Type genericType,
      Annotation[] annotations, MediaType mediaType, MultivaluedMap<String, String> httpHeaders,
      InputStream entityStream) throws IOException
   {
      ApplicationContext context = ApplicationContextImpl.getCurrent();
      Object o = context.getAttributes().get("org.exoplatform.ws.rs.entity.form");
      if (o != null)
         return (MultivaluedMap<String, String>)o;

      MultivaluedMap<String, String> form = new MultivaluedMapImpl();
      int r = -1;
      StringBuffer sb = new StringBuffer();
      try
      {
         while ((r = entityStream.read()) != -1)
         {
            if (r != '&')
            {
               sb.append((char)r);
            }
            else
            {
               addPair(sb.toString().trim(), form);
               sb.setLength(0);
            }
         }
         // keep the last part
         addPair(sb.toString(), form);

         context.getAttributes().put("org.exoplatform.ws.rs.entity.form", form);

         return form;
      }
      catch (UnsupportedEncodingException e)
      {
         throw new IllegalArgumentException(e);
      }
   }

   /**
    * Parse string and add key/value pair in the {@link MultivaluedMap}.
    * 
    * @param s string for processing
    * @param f {@link MultivaluedMap} to add result of parsing
    * @throws UnsupportedEncodingException if supplied string can't be decoded
    */
   private static void addPair(String s, MultivaluedMap<String, String> f) throws UnsupportedEncodingException
   {
      if (s.length() == 0)
         return;
      int eq = s.indexOf('=');
      String name;
      String value;
      if (eq < 0)
      {
         name = URLDecoder.decode(s, "UTF-8");
         value = "";
      }
      else
      {
         name = URLDecoder.decode(s.substring(0, eq), "UTF-8");
         value = URLDecoder.decode(s.substring(eq + 1), "UTF-8");
      }
      f.add(name, value);
   }

   /**
    * {@inheritDoc}
    */
   public long getSize(MultivaluedMap<String, String> t, Class<?> type, Type genericType, Annotation[] annotations,
      MediaType mediaType)
   {
      return -1;
   }

   /**
    * {@inheritDoc}
    */
   public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType)
   {
      return MultivaluedMap.class.isAssignableFrom(type);
   }

   /**
    * {@inheritDoc}
    */
   public void writeTo(MultivaluedMap<String, String> t, Class<?> type, Type genericType, Annotation[] annotations,
      MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) throws IOException
   {
      int i = 0;
      for (Map.Entry<String, List<String>> e : t.entrySet())
      {
         for (String value : e.getValue())
         {
            if (i > 0)
               entityStream.write('&');
            String name = URLEncoder.encode(e.getKey(), "UTF-8");
            entityStream.write(name.getBytes());
            i++;
            if (value != null)
            {
               entityStream.write('=');
               value = URLEncoder.encode(value, "UTF-8");
               entityStream.write(value.getBytes());
            }
         }
      }
   }

}
