/*

 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.net.httpserver;

import java.util.*;

/**

 * HTTP request and response headers are represented by this class which implements

 * the interface

 * {@link java.util.Map}{@literal <}{@link java.lang.String}, {@link java.util.List}

 * {@literal <}{@link java.lang.String}{@literal >>}.

 * The keys are case-insensitive Strings representing the header names and

 * the value associated with each key is

 * a {@link List}{@literal <}{@link String}{@literal >} with one

 * element for each occurrence of the header name in the request or response.

 * <p>

 * For example, if a response header instance contains

 * one key "HeaderName" with two values "value1 and value2"

 * then this object is output as two header lines:

 * <blockquote><pre>

 * HeaderName: value1

 * HeaderName: value2

 * </pre></blockquote>

 * <p>

 * All the normal {@link java.util.Map} methods are provided, but the following

 * additional convenience methods are most likely to be used:

 * <ul>

 * <li>{@link #getFirst(String)} returns a single valued header or the first value of

 * a multi-valued header.</li>

 * <li>{@link #add(String,String)} adds the given header value to the list for the given key</li>

 * <li>{@link #set(String,String)} sets the given header field to the single value given

 * overwriting any existing values in the value list.

 * </ul><p>

 * All methods in this class accept <code>null</code> values for keys and values. However, null

 * keys will never will be present in HTTP request headers, and will not be output/sent in response headers.

 * Null values can be represented as either a null entry for the key (i.e. the list is null) or

 * where the key has a list, but one (or more) of the list's values is null. Null values are output

 * as a header line containing the key but no associated value.

 * @since 1.6

 */

public class Headers implements Map<String,List<String>> {

        HashMap<String,List<String>> map;

        public Headers () {map = new HashMap<String,List<String>>(32);}

        /* Normalize the key by converting to following form.

         * First char upper case, rest lower case.

         * key is presumed to be ASCII

         */

        private String normalize (String key) {

            if (key == null) {

                return null;

            }

            int len = key.length();

            if (len == 0) {

                return key;

            }

            char[] b = key.toCharArray();

            if (b[0] >= 'a' && b[0] <= 'z') {

                b[0] = (char)(b[0] - ('a' - 'A'));

            }

            for (int i=1; i<len; i++) {

                if (b[i] >= 'A' && b[i] <= 'Z') {

                    b[i] = (char) (b[i] + ('a' - 'A'));

                }

            }

            return new String(b);

        }

        public int size() {return map.size();}

        public boolean isEmpty() {return map.isEmpty();}

        public boolean containsKey(Object key) {

            if (key == null) {

                return false;

            }

            if (!(key instanceof String)) {

                return false;

            }

            return map.containsKey (normalize((String)key));

        }

        public boolean containsValue(Object value) {

            return map.containsValue(value);

        }

        public List<String> get(Object key) {

            return map.get(normalize((String)key));

        }

        /**

         * returns the first value from the List of String values

         * for the given key (if at least one exists).

         * @param key the key to search for

         * @return the first string value associated with the key

         */

        public String getFirst (String key) {

            List<String> l = map.get(normalize(key));

            if (l == null) {

                return null;

            }

            return l.get(0);

        }

        public List<String> put(String key, List<String> value) {

            return map.put (normalize(key), value);

        }

        /**

         * adds the given value to the list of headers

         * for the given key. If the mapping does not

         * already exist, then it is created

         * @param key the header name

         * @param value the header value to add to the header

         */

        public void add (String key, String value) {

            String k = normalize(key);

            List<String> l = map.get(k);

            if (l == null) {

                l = new LinkedList<String>();

                map.put(k,l);

            }

            l.add (value);

        }

        /**

         * sets the given value as the sole header value

         * for the given key. If the mapping does not

         * already exist, then it is created

         * @param key the header name

         * @param value the header value to set.

         */

        public void set (String key, String value) {

            LinkedList<String> l = new LinkedList<String>();

            l.add (value);

            put (key, l);

        }

        public List<String> remove(Object key) {

            return map.remove(normalize((String)key));

        }

        public void putAll(Map<? extends String,? extends List<String>> t)  {

            map.putAll (t);

        }

        public void clear() {map.clear();}

        public Set<String> keySet() {return map.keySet();}

        public Collection<List<String>> values() {return map.values();}

        public Set<Map.Entry<String, List<String>>> entrySet() {

            return map.entrySet();

        }

        public boolean equals(Object o) {return map.equals(o);}

        public int hashCode() {return map.hashCode();}

    }