/*
    * ====================================================================
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.hc.client5.http.validator;
  
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.Internal;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HttpHeaders;
  import org.apache.hc.core5.http.MessageHeaders;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.CharArrayBuffer;
  import org.apache.hc.core5.util.LangUtils;
  import org.apache.hc.core5.util.Tokenizer;
  
  /**
   * Represents ETag value.
   *
   * @since 5.4
   */
  @Contract(threading = ThreadingBehavior.IMMUTABLE)
  public final class ETag {
  
      private final String value;
      private final ValidatorType type;
  
      public ETag(final String value, final ValidatorType type) {
          this.value = Args.notNull(value, "Value");
          this.type = Args.notNull(type, "Validator type");
      }
  
      public ETag(final String value) {
          this(value, ValidatorType.STRONG);
      }
  
      public ValidatorType getType() {
          return type;
      }
  
      public String getValue() {
          return value;
      }
  
      public static boolean strongCompare(final ETag t1, final ETag t2) {
          if (t1 == null || t2 == null) {
              return false;
          }
          return t1.type == ValidatorType.STRONG && t1.type == t2.type && t1.value.equals(t2.value);
      }
  
      public static boolean weakCompare(final ETag t1, final ETag t2) {
          if (t1 == null || t2 == null) {
              return false;
          }
          return t1.value.equals(t2.value);
      }
  
      static ETag parse(final CharSequence buf, final Tokenizer.Cursor cursor) {
          final Tokenizer tokenizer = Tokenizer.INSTANCE;
          tokenizer.skipWhiteSpace(buf, cursor);
  
          ValidatorType type = ValidatorType.STRONG;
  
          if (!cursor.atEnd() && buf.charAt(cursor.getPos()) == 'W') {
              cursor.updatePos(cursor.getPos() + 1);
              if (!cursor.atEnd() && buf.charAt(cursor.getPos()) == '/') {
                  type = ValidatorType.WEAK;
                  cursor.updatePos(cursor.getPos() + 1);
              } else {
                  return null;
              }
          }
  
          String value = null;
         if (!cursor.atEnd() && buf.charAt(cursor.getPos()) == '"') {
             cursor.updatePos(cursor.getPos() + 1);
             final StringBuilder sb = new StringBuilder();
             for (;;) {
                 if (cursor.atEnd()) {
                     return null;
                 }
                 final char ch = buf.charAt(cursor.getPos());
                 cursor.updatePos(cursor.getPos() + 1);
                 if (ch == '"') {
                     break;
                 } else {
                     sb.append(ch);
                 }
             }
             value = sb.toString();
         }
 
         tokenizer.skipWhiteSpace(buf, cursor);
         if (!cursor.atEnd()) {
             return null;
         }
 
         return new ETag(value, type);
     }
 
     public static ETag parse(final String s) {
         if (s == null) {
             return null;
         }
         final Tokenizer.Cursor cursor = new Tokenizer.Cursor(0, s.length());
         return parse(s, cursor);
     }
 
     public static ETag parse(final Header h) {
         if (h == null) {
             return null;
         }
         final String value = h.getValue();
         if (value == null) {
             return null;
         }
         return parse(value);
     }
 
     public static ETag get(final MessageHeaders message) {
         if (message == null) {
             return null;
         }
         return parse(message.getFirstHeader(HttpHeaders.ETAG));
     }
 
     @Internal
     public void format(final CharArrayBuffer buf) {
         if (buf == null) {
             return;
         }
         if (type == ValidatorType.WEAK) {
             buf.append("W/");
         }
         buf.append('"');
         buf.append(value);
         buf.append('"');
     }
 
     @Override
     public boolean equals(final Object o) {
         if (this == o) {
             return true;
         }
         if (o instanceof ETag) {
             final ETag that = (ETag) o;
             return this.type == that.type && this.value.equals(that.value);
         }
         return false;
     }
 
     @Override
     public int hashCode() {
         int hash = LangUtils.HASH_SEED;
         hash = LangUtils.hashCode(hash, type);
         hash = LangUtils.hashCode(hash, value);
         return hash;
     }
 
     @Override
     public String toString() {
         final CharArrayBuffer buf = new CharArrayBuffer(64);
         format(buf);
         return buf.toString();
     }
 
 }