/*
    * #%L
    * wcm.io
    * %%
    * Copyright (C) 2015 wcm.io
    * %%
    * 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.
   * #L%
   */
  package io.wcm.caravan.io.http.impl.servletclient;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.text.SimpleDateFormat;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Date;
  import java.util.List;
  import java.util.Locale;
  import java.util.TimeZone;
  
  import javax.servlet.ServletOutputStream;
  import javax.servlet.http.Cookie;
  import javax.servlet.http.HttpServletResponse;
  
  import com.google.common.base.Charsets;
  import com.google.common.collect.HashMultimap;
  import com.google.common.collect.Lists;
  import com.google.common.collect.Multimap;
  
  import io.wcm.caravan.io.http.response.CaravanHttpResponse;
  import io.wcm.caravan.io.http.response.CaravanHttpResponseBuilder;
  
  /**
   * Mapper from {@link CaravanHttpResponse} to {@link HttpServletResponse}.
   */
  public class HttpServletResponseMapper implements HttpServletResponse {
  
    private String characterEncoding = Charsets.UTF_8.toString();
    private String contentType;
    private ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    private int bufferSize = 4096;
    private Locale locale;
    private final List<Cookie> cookies = Lists.newArrayList();
    private final Multimap<String, String> headers = HashMultimap.create();
    private int status = HttpServletResponse.SC_OK;
    private String reason = "OK";
  
    @Override
    public String getCharacterEncoding() {
      return characterEncoding;
    }
  
    @Override
    public String getContentType() {
      return contentType;
    }
  
    @Override
    public ServletOutputStream getOutputStream() throws IOException {
  
      return new ServletOutputStream() {
  
        @Override
        public void write(int b) throws IOException {
          outputStream.write(b);
        }
      };
    }
  
    @Override
    public PrintWriter getWriter() throws IOException {
      return new PrintWriter(outputStream);
    }
  
    @Override
    public void setCharacterEncoding(String charset) {
      characterEncoding = charset;
    }
  
    @Override
    public void setContentLength(int len) {
      setIntHeader("Content-Length", len);
  
      // if the content length is known in advance then resize the ByteArrayOutputSteram accordingly
      // (but only if nothing has yet been written to the output stream)
      if (len > 0 && outputStream.size() == 0) {
        outputStream = new ByteArrayOutputStream(len);
     }
   }
 
   @Override
   public void setContentType(String type) {
     contentType = type;
   }
 
   @Override
   public void setBufferSize(int size) {
     bufferSize = size;
   }
 
   @Override
   public int getBufferSize() {
     return bufferSize;
   }
 
   @Override
   public void flushBuffer() throws IOException {
     outputStream.flush();
   }
 
   @Override
   public void resetBuffer() {
     outputStream.reset();
   }
 
   @Override
   public boolean isCommitted() {
     return false;
   }
 
   @Override
   public void reset() {
     resetBuffer();
     this.characterEncoding = null;
     this.contentType = null;
     this.locale = null;
     this.cookies.clear();
     this.headers.clear();
     this.status = HttpServletResponse.SC_OK;
     this.reason = null;
   }
 
   @Override
   public void setLocale(Locale loc) {
     locale = loc;
   }
 
   @Override
   public Locale getLocale() {
     return locale;
   }
 
   @Override
   public void addCookie(Cookie cookie) {
     cookies.add(cookie);
   }
 
   @Override
   public boolean containsHeader(String name) {
     return headers.containsKey(name);
   }
 
   @Override
   public String encodeURL(String url) {
     return url;
   }
 
   @Override
   public String encodeRedirectURL(String url) {
     return encodeURL(url);
   }
 
   @Override
   public String encodeUrl(String url) {
     return encodeURL(url);
   }
 
   @Override
   public String encodeRedirectUrl(String url) {
     return encodeRedirectURL(url);
   }
 
   @Override
   public void sendError(int sc, String msg) throws IOException {
     status = sc;
     reason = msg;
   }
 
   @Override
   public void sendError(int sc) throws IOException {
     status = sc;
   }
 
   @Override
   public void sendRedirect(String location) throws IOException {
     setHeader("Location", location);
     setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
   }
 
   @Override
   public void setDateHeader(String name, long date) {
     String value = formatDate(date);
     setHeader(name, value);
   }
 
   private String formatDate(long date) {
     SimpleDateFormat dateFormat = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss zzz", Locale.US);
     dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
     return dateFormat.format(new Date(date));
   }
 
   @Override
   public void addDateHeader(String name, long date) {
     String value = formatDate(date);
     addHeader(name, value);
   }
 
   @Override
   public void setHeader(String name, String value) {
     headers.replaceValues(name, Collections.singletonList(value));
   }
 
   @Override
   public void addHeader(String name, String value) {
     headers.put(name, value);
   }
 
   @Override
   public void setIntHeader(String name, int value) {
     setHeader(name, String.valueOf(value));
   }
 
   @Override
   public void addIntHeader(String name, int value) {
     addHeader(name, String.valueOf(value));
   }
 
   @Override
   public void setStatus(int sc) {
     status = sc;
   }
 
   @Override
   public void setStatus(int sc, String sm) {
     setStatus(sc);
     reason = sm;
   }
 
   @Override
   public int getStatus() {
     return status;
   }
 
   @Override
   public String getHeader(String name) {
     Collection<String> values = headers.get(name);
     return values.isEmpty() ? null : values.iterator().next();
   }
 
   @Override
   public Collection<String> getHeaders(String name) {
     return headers.get(name);
   }
 
   @Override
   public Collection<String> getHeaderNames() {
     return headers.keySet();
   }
 
   public CaravanHttpResponse getResponse() {
     return new CaravanHttpResponseBuilder()
     .body(outputStream.toByteArray())
     .headers(headers)
     .reason(reason)
     .status(status)
     .build();
   }
 
 }