/*
    * Copyright 2012 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:
    *
    *   https://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 io.netty.handler.codec.http;
  
  import io.netty.handler.codec.CharSequenceValueConverter;
  import io.netty.handler.codec.DateFormatter;
  import io.netty.handler.codec.DefaultHeaders;
  import io.netty.handler.codec.DefaultHeaders.NameValidator;
  import io.netty.handler.codec.DefaultHeaders.ValueValidator;
  import io.netty.handler.codec.DefaultHeadersImpl;
  import io.netty.handler.codec.HeadersUtils;
  import io.netty.handler.codec.ValueConverter;
  
  import java.util.ArrayList;
  import java.util.Calendar;
  import java.util.Collections;
  import java.util.Date;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.Set;
  
  import static io.netty.util.AsciiString.CASE_INSENSITIVE_HASHER;
  import static io.netty.util.AsciiString.CASE_SENSITIVE_HASHER;
  
  /**
   * Default implementation of {@link HttpHeaders}.
   */
  public class DefaultHttpHeaders extends HttpHeaders {
      private final DefaultHeaders<CharSequence, CharSequence, ?> headers;
  
      /**
       * Create a new, empty HTTP headers object.
       * <p>
       * Header names and values are validated as they are added, to ensure they are compliant with the HTTP protocol.
       */
      public DefaultHttpHeaders() {
          this(nameValidator(true), valueValidator(true));
      }
  
      /**
       * <b>Warning!</b> Setting {@code validate} to {@code false} will mean that Netty won't
       * validate & protect against user-supplied header values that are malicious.
       * This can leave your server implementation vulnerable to
       * <a href="https://cwe.mitre.org/data/definitions/113.html">
       *     CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')
       * </a>.
       * When disabling this validation, it is the responsibility of the caller to ensure that the values supplied
       * do not contain a non-url-escaped carriage return (CR) and/or line feed (LF) characters.
       *
       * @param validate Should Netty validate header values to ensure they aren't malicious.
       * @deprecated Prefer using the {@link #DefaultHttpHeaders()} constructor instead,
       * to always have validation enabled.
       */
      @Deprecated
      public DefaultHttpHeaders(boolean validate) {
          this(nameValidator(validate), valueValidator(validate));
      }
  
      /**
       * Create an HTTP headers object with the given name validator.
       * <p>
       * <b>Warning!</b> It is strongly recommended that the name validator implement validation that is at least as
       * strict as {@link HttpHeaderValidationUtil#validateToken(CharSequence)}.
       * It is also strongly recommended that {@code validateValues} is enabled.
       * <p>
       * Without these validations in place, your code can be susceptible to
       * <a href="https://cwe.mitre.org/data/definitions/113.html">
       *     CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')
       * </a>.
       * It is the responsibility of the caller to ensure that the values supplied
       * do not contain a non-url-escaped carriage return (CR) and/or line feed (LF) characters.
       *
       * @param validateValues Should Netty validate header values to ensure they aren't malicious.
       * @param nameValidator The {@link NameValidator} to use, never {@code null.
       */
      protected DefaultHttpHeaders(boolean validateValues, NameValidator<CharSequence> nameValidator) {
          this(nameValidator, valueValidator(validateValues));
      }
  
      /**
       * Create an HTTP headers object with the given name and value validators.
       * <p>
       * <b>Warning!</b> It is strongly recommended that the name validator implement validation that is at least as
       * strict as {@link HttpHeaderValidationUtil#validateToken(CharSequence)}.
      * And that the value validator is at least as strict as
      * {@link HttpHeaderValidationUtil#validateValidHeaderValue(CharSequence)}.
      * <p>
      * Without these validations in place, your code can be susceptible to
      * <a href="https://cwe.mitre.org/data/definitions/113.html">
      *     CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')
      * </a>.
      * It is the responsibility of the caller to ensure that the values supplied
      * do not contain a non-url-escaped carriage return (CR) and/or line feed (LF) characters.
      *
      * @param nameValidator The {@link NameValidator} to use, never {@code null}.
      * @param valueValidator The {@link ValueValidator} to use, never {@code null}.
      */
     protected DefaultHttpHeaders(
             NameValidator<CharSequence> nameValidator,
             ValueValidator<CharSequence> valueValidator) {
         this(nameValidator, valueValidator, 16);
     }
 
     /**
      * Create an HTTP headers object with the given name and value validators.
      * <p>
      * <b>Warning!</b> It is strongly recommended that the name validator implement validation that is at least as
      * strict as {@link HttpHeaderValidationUtil#validateToken(CharSequence)}.
      * And that the value validator is at least as strict as
      * {@link HttpHeaderValidationUtil#validateValidHeaderValue(CharSequence)}.
      * <p>
      * Without these validations in place, your code can be susceptible to
      * <a href="https://cwe.mitre.org/data/definitions/113.html">
      *     CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')
      * </a>.
      * It is the responsibility of the caller to ensure that the values supplied
      * do not contain a non-url-escaped carriage return (CR) and/or line feed (LF) characters.
      *
      * @param nameValidator The {@link NameValidator} to use, never {@code null}.
      * @param valueValidator The {@link ValueValidator} to use, never {@code null}.
      * @param sizeHint A hint about the anticipated number of entries.
      */
     protected DefaultHttpHeaders(
             NameValidator<CharSequence> nameValidator,
             ValueValidator<CharSequence> valueValidator,
             int sizeHint) {
         this(new DefaultHeadersImpl<CharSequence, CharSequence>(
                 CASE_INSENSITIVE_HASHER,
                 HeaderValueConverter.INSTANCE,
                 nameValidator,
                 sizeHint,
                 valueValidator));
     }
 
     protected DefaultHttpHeaders(DefaultHeaders<CharSequence, CharSequence, ?> headers) {
         this.headers = headers;
     }
 
     @Override
     public HttpHeaders add(HttpHeaders headers) {
         if (headers instanceof DefaultHttpHeaders) {
             this.headers.add(((DefaultHttpHeaders) headers).headers);
             return this;
         } else {
             return super.add(headers);
         }
     }
 
     @Override
     public HttpHeaders set(HttpHeaders headers) {
         if (headers instanceof DefaultHttpHeaders) {
             this.headers.set(((DefaultHttpHeaders) headers).headers);
             return this;
         } else {
             return super.set(headers);
         }
     }
 
     @Override
     public HttpHeaders add(String name, Object value) {
         headers.addObject(name, value);
         return this;
     }
 
     @Override
     public HttpHeaders add(CharSequence name, Object value) {
         headers.addObject(name, value);
         return this;
     }
 
     @Override
     public HttpHeaders add(String name, Iterable<?> values) {
         headers.addObject(name, values);
         return this;
     }
 
     @Override
     public HttpHeaders add(CharSequence name, Iterable<?> values) {
         headers.addObject(name, values);
         return this;
     }
 
     @Override
     public HttpHeaders addInt(CharSequence name, int value) {
         headers.addInt(name, value);
         return this;
     }
 
     @Override
     public HttpHeaders addShort(CharSequence name, short value) {
         headers.addShort(name, value);
         return this;
     }
 
     @Override
     public HttpHeaders remove(String name) {
         headers.remove(name);
         return this;
     }
 
     @Override
     public HttpHeaders remove(CharSequence name) {
         headers.remove(name);
         return this;
     }
 
     @Override
     public HttpHeaders set(String name, Object value) {
         headers.setObject(name, value);
         return this;
     }
 
     @Override
     public HttpHeaders set(CharSequence name, Object value) {
         headers.setObject(name, value);
         return this;
     }
 
     @Override
     public HttpHeaders set(String name, Iterable<?> values) {
         headers.setObject(name, values);
         return this;
     }
 
     @Override
     public HttpHeaders set(CharSequence name, Iterable<?> values) {
         headers.setObject(name, values);
         return this;
     }
 
     @Override
     public HttpHeaders setInt(CharSequence name, int value) {
         headers.setInt(name, value);
         return this;
     }
 
     @Override
     public HttpHeaders setShort(CharSequence name, short value) {
         headers.setShort(name, value);
         return this;
     }
 
     @Override
     public HttpHeaders clear() {
         headers.clear();
         return this;
     }
 
     @Override
     public String get(String name) {
         return get((CharSequence) name);
     }
 
     @Override
     public String get(CharSequence name) {
         return HeadersUtils.getAsString(headers, name);
     }
 
     @Override
     public Integer getInt(CharSequence name) {
         return headers.getInt(name);
     }
 
     @Override
     public int getInt(CharSequence name, int defaultValue) {
         return headers.getInt(name, defaultValue);
     }
 
     @Override
     public Short getShort(CharSequence name) {
         return headers.getShort(name);
     }
 
     @Override
     public short getShort(CharSequence name, short defaultValue) {
         return headers.getShort(name, defaultValue);
     }
 
     @Override
     public Long getTimeMillis(CharSequence name) {
         return headers.getTimeMillis(name);
     }
 
     @Override
     public long getTimeMillis(CharSequence name, long defaultValue) {
         return headers.getTimeMillis(name, defaultValue);
     }
 
     @Override
     public List<String> getAll(String name) {
         return getAll((CharSequence) name);
     }
 
     @Override
     public List<String> getAll(CharSequence name) {
         return HeadersUtils.getAllAsString(headers, name);
     }
 
     @Override
     public List<Entry<String, String>> entries() {
         if (isEmpty()) {
             return Collections.emptyList();
         }
         List<Entry<String, String>> entriesConverted = new ArrayList<Entry<String, String>>(
                 headers.size());
         for (Entry<String, String> entry : this) {
             entriesConverted.add(entry);
         }
         return entriesConverted;
     }
 
     @Deprecated
     @Override
     public Iterator<Map.Entry<String, String>> iterator() {
         return HeadersUtils.iteratorAsString(headers);
     }
 
     @Override
     public Iterator<Entry<CharSequence, CharSequence>> iteratorCharSequence() {
         return headers.iterator();
     }
 
     @Override
     public Iterator<String> valueStringIterator(CharSequence name) {
         final Iterator<CharSequence> itr = valueCharSequenceIterator(name);
         return new Iterator<String>() {
             @Override
             public boolean hasNext() {
                 return itr.hasNext();
             }
 
             @Override
             public String next() {
                 return itr.next().toString();
             }
 
             @Override
             public void remove() {
                 itr.remove();
             }
         };
     }
 
     @Override
     public Iterator<CharSequence> valueCharSequenceIterator(CharSequence name) {
         return headers.valueIterator(name);
     }
 
     @Override
     public boolean contains(String name) {
         return contains((CharSequence) name);
     }
 
     @Override
     public boolean contains(CharSequence name) {
         return headers.contains(name);
     }
 
     @Override
     public boolean isEmpty() {
         return headers.isEmpty();
     }
 
     @Override
     public int size() {
         return headers.size();
     }
 
     @Override
     public boolean contains(String name, String value, boolean ignoreCase) {
         return contains((CharSequence) name, (CharSequence) value, ignoreCase);
     }
 
     @Override
     public boolean contains(CharSequence name, CharSequence value, boolean ignoreCase) {
         return headers.contains(name, value, ignoreCase ? CASE_INSENSITIVE_HASHER : CASE_SENSITIVE_HASHER);
     }
 
     @Override
     public Set<String> names() {
         return HeadersUtils.namesAsString(headers);
     }
 
     @Override
     public boolean equals(Object o) {
         return o instanceof DefaultHttpHeaders
                 && headers.equals(((DefaultHttpHeaders) o).headers, CASE_SENSITIVE_HASHER);
     }
 
     @Override
     public int hashCode() {
         return headers.hashCode(CASE_SENSITIVE_HASHER);
     }
 
     @Override
     public HttpHeaders copy() {
         return new DefaultHttpHeaders(headers.copy());
     }
 
     static ValueConverter<CharSequence> valueConverter() {
         return HeaderValueConverter.INSTANCE;
     }
 
     static ValueValidator<CharSequence> valueValidator(boolean validate) {
         return validate ? DefaultHttpHeadersFactory.headersFactory().getValueValidator() :
                 DefaultHttpHeadersFactory.headersFactory().withValidation(false).getValueValidator();
     }
 
     static NameValidator<CharSequence> nameValidator(boolean validate) {
         return validate ? DefaultHttpHeadersFactory.headersFactory().getNameValidator() :
                 DefaultHttpHeadersFactory.headersFactory().withNameValidation(false).getNameValidator();
     }
 
     private static class HeaderValueConverter extends CharSequenceValueConverter {
         static final HeaderValueConverter INSTANCE = new HeaderValueConverter();
 
         @Override
         public CharSequence convertObject(Object value) {
             if (value instanceof CharSequence) {
                 return (CharSequence) value;
             }
             if (value instanceof Date) {
                 return DateFormatter.format((Date) value);
             }
             if (value instanceof Calendar) {
                 return DateFormatter.format(((Calendar) value).getTime());
             }
             return value.toString();
         }
     }
 }