/*
    * Copyright 2015 The Netty Project
    *
    * The Netty Project licenses this file to you 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.
   */
  package org.jboss.netty.handler.codec.http.cookie;
  
  import org.jboss.netty.handler.codec.http.HttpHeaderDateFormat;
  
  import java.text.ParsePosition;
  import java.util.Date;
  
  /**
   * A <a href="http://tools.ietf.org/html/rfc6265">RFC6265</a> compliant cookie decoder to be used client side.
   *
   * It will store the way the raw value was wrapped in {@link Cookie#setWrap(boolean)} so it can be
   * eventually sent back to the Origin server as is.
   *
   * @see ClientCookieEncoder
   */
  public final class ClientCookieDecoder extends CookieDecoder {
  
      /**
       * Strict encoder that validates that name and value chars are in the valid scope
       * defined in RFC6265
       */
      public static final ClientCookieDecoder STRICT = new ClientCookieDecoder(true);
  
      /**
       * Lax instance that doesn't validate name and value
       */
      public static final ClientCookieDecoder LAX = new ClientCookieDecoder(false);
  
      private ClientCookieDecoder(boolean strict) {
          super(strict);
      }
  
      /**
       * Decodes the specified Set-Cookie HTTP header value into a {@link Cookie}.
       *
       * @return the decoded {@link Cookie}
       */
      public Cookie decode(String header) {
          if (header == null) {
              throw new NullPointerException("header");
          }
          final int headerLen = header.length();
  
          if (headerLen == 0) {
              return null;
          }
  
          CookieBuilder cookieBuilder = null;
  
          loop: for (int i = 0;;) {
  
              // Skip spaces and separators.
              for (;;) {
                  if (i == headerLen) {
                      break loop;
                  }
                  char c = header.charAt(i);
                  if (c == ',') {
                      // Having multiple cookies in a single Set-Cookie header is
                      // deprecated, modern browsers only parse the first one
                      break loop;
  
                  } else if (c == '\t' || c == '\n' || c == 0x0b || c == '\f'
                          || c == '\r' || c == ' ' || c == ';') {
                      i++;
                      continue;
                  }
                  break;
              }
  
              int nameBegin = i;
              int nameEnd = i;
              int valueBegin = -1;
              int valueEnd = -1;
  
              if (i != headerLen) {
                  keyValLoop: for (;;) {
  
                      char curChar = header.charAt(i);
                      if (curChar == ';') {
                          // NAME; (no value till ';')
                          nameEnd = i;
                          valueBegin = valueEnd = -1;
                          break keyValLoop;
 
                     } else if (curChar == '=') {
                         // NAME=VALUE
                         nameEnd = i;
                         i++;
                         if (i == headerLen) {
                             // NAME= (empty value, i.e. nothing after '=')
                             valueBegin = valueEnd = 0;
                             break keyValLoop;
                         }
 
                         valueBegin = i;
                         // NAME=VALUE;
                         int semiPos = header.indexOf(';', i);
                         valueEnd = i = semiPos > 0 ? semiPos : headerLen;
                         break keyValLoop;
                     } else {
                         i++;
                     }
 
                     if (i == headerLen) {
                         // NAME (no value till the end of string)
                         nameEnd = headerLen;
                         valueBegin = valueEnd = -1;
                         break;
                     }
                 }
             }
 
             if (valueEnd > 0 && header.charAt(valueEnd - 1) == ',') {
                 // old multiple cookies separator, skipping it
                 valueEnd--;
             }
 
             if (cookieBuilder == null) {
                 // cookie name-value pair
                 DefaultCookie cookie = initCookie(header, nameBegin, nameEnd, valueBegin, valueEnd);
 
                 if (cookie == null) {
                     return null;
                 }
 
                 cookieBuilder = new CookieBuilder(cookie);
             } else {
                 // cookie attribute
                 String attrValue = valueBegin == -1 ? null : header.substring(valueBegin, valueEnd);
                 cookieBuilder.appendAttribute(header, nameBegin, nameEnd, attrValue);
             }
         }
         return cookieBuilder.cookie();
     }
 
     private static class CookieBuilder {
 
         private final DefaultCookie cookie;
         private String domain;
         private String path;
         private int maxAge = Integer.MIN_VALUE;
         private String expires;
         private boolean secure;
         private boolean httpOnly;
 
         public CookieBuilder(DefaultCookie cookie) {
             this.cookie = cookie;
         }
 
         private int mergeMaxAgeAndExpire(int maxAge, String expires) {
             // max age has precedence over expires
             if (maxAge != Integer.MIN_VALUE) {
                 return maxAge;
             } else if (expires != null) {
                 Date expiresDate = HttpHeaderDateFormat.get().parse(expires, new ParsePosition(0));
                 if (expiresDate != null) {
                     long maxAgeMillis = expiresDate.getTime() - System.currentTimeMillis();
                     return (int) (maxAgeMillis / 1000 + (maxAgeMillis % 1000 != 0 ? 1 : 0));
                 }
             }
             return Integer.MIN_VALUE;
         }
 
         public Cookie cookie() {
             cookie.setDomain(domain);
             cookie.setPath(path);
             cookie.setMaxAge(mergeMaxAgeAndExpire(maxAge, expires));
             cookie.setSecure(secure);
             cookie.setHttpOnly(httpOnly);
             return cookie;
         }
 
         /**
          * Parse and store a key-value pair. First one is considered to be the
          * cookie name/value. Unknown attribute names are silently discarded.
          *
          * @param header
          *            the HTTP header
          * @param keyStart
          *            where the key starts in the header
          * @param keyEnd
          *            where the key ends in the header
          * @param value
          *            the decoded value
          */
         public void appendAttribute(String header, int keyStart, int keyEnd,
                 String value) {
             setCookieAttribute(header, keyStart, keyEnd, value);
         }
 
         private void setCookieAttribute(String header, int keyStart,
                 int keyEnd, String value) {
             int length = keyEnd - keyStart;
 
             if (length == 4) {
                 parse4(header, keyStart, value);
             } else if (length == 6) {
                 parse6(header, keyStart, value);
             } else if (length == 7) {
                 parse7(header, keyStart, value);
             } else if (length == 8) {
                 parse8(header, keyStart, value);
             }
         }
 
         private void parse4(String header, int nameStart, String value) {
             if (header.regionMatches(true, nameStart, CookieHeaderNames.PATH, 0, 4)) {
                 path = value;
             }
         }
 
         private void parse6(String header, int nameStart, String value) {
             if (header.regionMatches(true, nameStart, CookieHeaderNames.DOMAIN, 0, 5)) {
                 domain = value.length() > 0 ? value.toString() : null;
             } else if (header.regionMatches(true, nameStart, CookieHeaderNames.SECURE, 0, 5)) {
                 secure = true;
             }
         }
 
         private void setExpire(String value) {
             expires = value;
         }
 
         private void setMaxAge(String value) {
             try {
                 maxAge = Math.max(Integer.valueOf(value), 0);
             } catch (NumberFormatException e1) {
                 // ignore failure to parse -> treat as session cookie
             }
         }
 
         private void parse7(String header, int nameStart, String value) {
             if (header.regionMatches(true, nameStart, CookieHeaderNames.EXPIRES, 0, 7)) {
                 setExpire(value);
             } else if (header.regionMatches(true, nameStart, CookieHeaderNames.MAX_AGE, 0, 7)) {
                 setMaxAge(value);
             }
         }
 
         private void parse8(String header, int nameStart, String value) {
             if (header.regionMatches(true, nameStart, CookieHeaderNames.HTTPONLY, 0, 8)) {
                 httpOnly = true;
             }
         }
     }
 }