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	/*
	* 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}<
	* {@link java.lang.String},{@link java.util.List}<{@link java.lang.String}>>.
	* The keys are case-insensitive Strings representing the header names and
	* the value associated with each key is a {@link List}<{@link String}> 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
	* </blockquote></pre>
	* <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
	*/
	@jdk.Exported
	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'));
	} else if (b[0] == '\r' \|\| b[0] == '\n')
	throw new IllegalArgumentException("illegal character in key");

	for (int i=1; i<len; i++) {
	if (b[i] >= 'A' && b[i] <= 'Z') {
	b[i] = (char) (b[i] + ('a' - 'A'));
	} else if (b[i] == '\r' \|\| b[i] == '\n')
	throw new IllegalArgumentException("illegal character in key");
	}
	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) {
	for (String v : value)
	checkValue(v);
	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) {
	checkValue(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);
	}

	private static void checkValue(String value) {
	int len = value.length();
	for (int i=0; i<len; i++) {
	char c = value.charAt(i);
	if (c == '\r') {
	// is allowed if it is followed by \n and a whitespace char
	if (i >= len - 2) {
	throw new IllegalArgumentException("Illegal CR found in header");
	}
	char c1 = value.charAt(i+1);
	char c2 = value.charAt(i+2);
	if (c1 != '\n') {
	throw new IllegalArgumentException("Illegal char found after CR in header");
	}
	if (c2 != ' ' && c2 != '\t') {
	throw new IllegalArgumentException("No whitespace found after CRLF in header");
	}
	i+=2;
	} else if (c == '\n') {
	throw new IllegalArgumentException("Illegal LF found in header");
	}
	}
	}

	/**
	* 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();}
	}

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