/*
 * 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;

import java.net.URI;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;

import javax.ws.rs.core.CacheControl;
import javax.ws.rs.core.EntityTag;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.NewCookie;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Variant;

/**
 * @author <a href="mailto:andrew00x@gmail.com">Andrey Parfonov</a>
 * @version $Id: $
 */
public final class ResponseImpl extends Response
{

   /**
    * HTTP status.
    */
   private final int status;

   /**
    * Entity. Entity will be written as response message body. 
    */
   private final Object entity;

   /**
    * HTTP headers. 
    */
   private final MultivaluedMap<String, Object> headers;

   /**
    * Construct Response with supplied status, entity and headers.
    * 
    * @param status HTTP status
    * @param entity an entity
    * @param headers HTTP headers
    */
   ResponseImpl(int status, Object entity, MultivaluedMap<String, Object> headers)
   {
      this.status = status;
      this.entity = entity;
      this.headers = headers;
   }

   /**
    * {@inheritDoc}
    */
   @Override
   public Object getEntity()
   {
      return entity;
   }

   /**
    * {@inheritDoc}
    */
   @Override
   public MultivaluedMap<String, Object> getMetadata()
   {
      return headers;
   }

   /**
    * {@inheritDoc}
    */
   @Override
   public int getStatus()
   {
      return status;
   }

   // ResponseBuilder

   /**
    * @see ResponseBuilder
    */
   public static final class ResponseBuilderImpl extends ResponseBuilder
   {

      /**
       * HTTP headers which can't be multivalued.
       */
      private enum HEADERS {
         /**
          * Cache control. 
          */
         CACHE_CONTROL,
         /**
          * Content-Language.
          */
         CONTENT_LANGUAGE,
         /**
          * Content-Location.
          */
         CONTENT_LOCATION,
         /**
          * Content-Type.
          */
         CONTENT_TYPE,
         /**
          * Content-length. 
          */
         CONTENT_LENGTH,
         /**
          * ETag.
          */
         ETAG,
         /**
          * Expires.
          */
         EXPIRES,
         /**
          * Last-Modified.
          */
         LAST_MODIFIED,
         /**
          * Location.
          */
         LOCATION
      }

      /**
       * HTTP headers which can't be multivalued.
       */
      private static final Map<HEADERS, String> HEADERS_MAP = new HashMap<HEADERS, String>();

      static
      {
         HEADERS_MAP.put(HEADERS.CACHE_CONTROL, HttpHeaders.CACHE_CONTROL);
         HEADERS_MAP.put(HEADERS.CONTENT_LANGUAGE, HttpHeaders.CONTENT_LANGUAGE);
         HEADERS_MAP.put(HEADERS.CONTENT_LOCATION, HttpHeaders.CONTENT_LOCATION);
         HEADERS_MAP.put(HEADERS.CONTENT_TYPE, HttpHeaders.CONTENT_TYPE);
         HEADERS_MAP.put(HEADERS.CONTENT_LENGTH, HttpHeaders.CONTENT_LENGTH);
         HEADERS_MAP.put(HEADERS.ETAG, HttpHeaders.ETAG);
         HEADERS_MAP.put(HEADERS.LAST_MODIFIED, HttpHeaders.LAST_MODIFIED);
         HEADERS_MAP.put(HEADERS.LOCATION, HttpHeaders.LOCATION);
         HEADERS_MAP.put(HEADERS.EXPIRES, HttpHeaders.EXPIRES);
      }

      /**
       * Default HTTP status, No-content, 204.
       */
      private static final int DEFAULT_HTTP_STATUS = Response.Status.NO_CONTENT.getStatusCode();

      /**
       * Default HTTP status.
       */
      private int status = DEFAULT_HTTP_STATUS;

      /**
       * Entity. Entity will be written as response message body.
       */
      private Object entity;

      /**
       * Not multivalued HTTP headers.
       */
      private Map<String, Object> headers = new HashMap<String, Object>();

      /**
       * Multivalued HTTP headers.
       */
      private List<Object> headerValues;

      /**
       * HTTP cookies, Set-Cookie header.
       */
      private Map<String, NewCookie> cookies;

      /**
       * See {@link ResponseBuilder}.
       */
      ResponseBuilderImpl()
      {
      }

      /**
       * Useful for clone method.
       * @param other other ResponseBuilderImpl
       * @see #clone()
       */
      private ResponseBuilderImpl(ResponseBuilderImpl other)
      {
         this.status = other.status;
         this.entity = other.entity;
         this.headers.putAll(other.headers);
         this.cookies.putAll(other.cookies);
         this.headerValues.addAll(other.headerValues);
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public Response build()
      {
         MultivaluedMap<String, Object> m = new OutputHeadersMap();
         // following headers can't be multivalued
         for (Map.Entry<String, Object> e : headers.entrySet())
         {
            if (e.getValue() != null)
               m.putSingle(e.getKey(), e.getValue());
         }

         // following headers can be multivalued
         if (headerValues != null)
         {
            Iterator<Object> i = headerValues.iterator();
            while (i.hasNext())
               m.add((String)i.next(), i.next());
         }

         // add cookies
         if (cookies != null)
         {
            for (NewCookie c : cookies.values())
               m.add(HttpHeaders.SET_COOKIE, c);
         }

         Response r = new ResponseImpl(status, entity, m);
         reset();

         return r;
      }

      /**
       * Set ResponseBuilder to default state.
       */
      private void reset()
      {
         status = DEFAULT_HTTP_STATUS;
         entity = null;
         headers.clear();
         headerValues = null;
         cookies = null;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder cacheControl(CacheControl cacheControl)
      {
         headers.put(HEADERS_MAP.get(HEADERS.CACHE_CONTROL), cacheControl);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder clone()
      {
         return new ResponseBuilderImpl(this);
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder contentLocation(URI location)
      {
         headers.put(HEADERS_MAP.get(HEADERS.CONTENT_LOCATION), location);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder cookie(NewCookie... cookies)
      {
         if (cookies == null && this.cookies != null)
         {
            this.cookies.clear();
         }
         else if (cookies != null)
         {
            if (this.cookies == null)
               this.cookies = new HashMap<String, NewCookie>();
            // new cookie overwrite old ones with the same name
            for (NewCookie c : cookies)
               this.cookies.put(c.getName(), c);
         }

         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder entity(Object entity)
      {
         this.entity = entity;
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder expires(Date expires)
      {
         headers.put(HEADERS_MAP.get(HEADERS.EXPIRES), expires);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder header(String name, Object value)
      {
         for (Map.Entry<HEADERS, String> e : HEADERS_MAP.entrySet())
         {
            if (e.getValue().equalsIgnoreCase(name))
            {
               headers.put(e.getValue(), value);
               return this;
            }
         }
         if (value != null)
            add(name, value);
         else
            remove(name);

         return this;
      }

      /**
       * Add header with supplied name and Object as header value.
       * 
       * @param name a header name
       * @param value a header value
       */
      private void add(String name, Object value)
      {
         if (headerValues == null)
            headerValues = new ArrayList<Object>();

         headerValues.add(name);
         headerValues.add(value);
      }

      /**
       * Remove header with supplied name.
       * @param name a header name 
       */
      private void remove(String name)
      {
         if (headerValues == null || headerValues.isEmpty())
            return;

         Iterator<Object> i = headerValues.iterator();
         while (i.hasNext())
         {
            String n = i.next().toString();
            if (n.equalsIgnoreCase(name))
            {
               i.remove(); // remove name
               i.next();
               i.remove(); // remove value
            }
            else
            {
               i.next(); // skip next Object in iterator
            }
         }
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder language(String language)
      {
         headers.put(HEADERS_MAP.get(HEADERS.CONTENT_LANGUAGE), language);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder language(Locale language)
      {
         headers.put(HEADERS_MAP.get(HEADERS.CONTENT_LANGUAGE), language);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder lastModified(Date lastModified)
      {
         headers.put(HEADERS_MAP.get(HEADERS.LAST_MODIFIED), lastModified);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder location(URI location)
      {
         headers.put(HEADERS_MAP.get(HEADERS.LOCATION), location);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder status(int status)
      {
         this.status = status;
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder tag(EntityTag tag)
      {
         headers.put(HEADERS_MAP.get(HEADERS.ETAG), tag);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder tag(String tag)
      {
         headers.put(HEADERS_MAP.get(HEADERS.ETAG), tag);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder type(MediaType type)
      {
         headers.put(HEADERS_MAP.get(HEADERS.CONTENT_TYPE), type);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder type(String type)
      {
         headers.put(HEADERS_MAP.get(HEADERS.CONTENT_TYPE), type);
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder variant(Variant variant)
      {
         type(variant.getMediaType());
         language(variant.getLanguage());
         if (variant.getEncoding() != null)
            header(HttpHeaders.CONTENT_ENCODING, variant.getEncoding());
         return this;
      }

      /**
       * {@inheritDoc}
       */
      @Override
      public ResponseBuilder variants(List<Variant> variants)
      {
         if (variants.isEmpty())
            return this;

         boolean acceptMediaType = variants.get(0).getMediaType() != null;
         boolean acceptLanguage = variants.get(0).getLanguage() != null;
         boolean acceptEncoding = variants.get(0).getEncoding() != null;

         for (Variant v : variants)
         {
            acceptMediaType |= v.getMediaType() != null;
            acceptLanguage |= v.getLanguage() != null;
            acceptEncoding |= v.getEncoding() != null;
         }

         StringBuffer sb = new StringBuffer();
         if (acceptMediaType)
            sb.append(HttpHeaders.ACCEPT);
         if (acceptLanguage)
         {
            if (sb.length() > 0)
               sb.append(',');
            sb.append(HttpHeaders.ACCEPT_LANGUAGE);
         }
         if (acceptEncoding)
         {
            if (sb.length() > 0)
               sb.append(',');
            sb.append(HttpHeaders.ACCEPT_ENCODING);
         }

         if (sb.length() > 0)
            header(HttpHeaders.VARY, sb.toString());

         return this;
      }

   }

}
