/*
 * 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 io.netty.handler.codec.http.cookie;

import static io.netty.handler.codec.http.cookie.CookieUtil.add;
import static io.netty.handler.codec.http.cookie.CookieUtil.addQuoted;
import static io.netty.handler.codec.http.cookie.CookieUtil.stringBuilder;
import static io.netty.handler.codec.http.cookie.CookieUtil.stripTrailingSeparator;
import static io.netty.util.internal.ObjectUtil.checkNotNull;

import io.netty.handler.codec.DateFormatter;
import io.netty.handler.codec.http.HttpConstants;
import io.netty.handler.codec.http.HttpResponse;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

A RFC6265 compliant cookie encoder to be used server side,
so some fields are sent (Version is typically ignored).
As Netty's Cookie merges Expires and MaxAge into one single field, only Max-Age field is sent.
Note that multiple cookies must be sent as separate "Set-Cookie" headers.
// Example HttpResponse res = ...; res.setHeader("Set-Cookie", ServerCookieEncoder.encode("JSESSIONID", "1234")); 
See Also:
ServerCookieDecoder/**
 * A <a href="http://tools.ietf.org/html/rfc6265">RFC6265</a> compliant cookie encoder to be used server side,
 * so some fields are sent (Version is typically ignored).
 *
 * As Netty's Cookie merges Expires and MaxAge into one single field, only Max-Age field is sent.
 *
 * Note that multiple cookies must be sent as separate "Set-Cookie" headers.
 *
 * <pre>
 * // Example
 * {@link HttpResponse} res = ...;
 * res.setHeader("Set-Cookie", {@link ServerCookieEncoder}.encode("JSESSIONID", "1234"));
 * </pre>
 *
 * @see ServerCookieDecoder
 */
public final class ServerCookieEncoder extends CookieEncoder {

    
Strict encoder that validates that name and value chars are in the valid scope
defined in RFC6265, and (for methods that accept multiple cookies) that only
one cookie is encoded with any given name. (If multiple cookies have the same
name, the last one is the one that is encoded.)
/**
     * Strict encoder that validates that name and value chars are in the valid scope
     * defined in RFC6265, and (for methods that accept multiple cookies) that only
     * one cookie is encoded with any given name. (If multiple cookies have the same
     * name, the last one is the one that is encoded.)
     */
    public static final ServerCookieEncoder STRICT = new ServerCookieEncoder(true);

    
Lax instance that doesn't validate name and value, and that allows multiple
cookies with the same name.
/**
     * Lax instance that doesn't validate name and value, and that allows multiple
     * cookies with the same name.
     */
    public static final ServerCookieEncoder LAX = new ServerCookieEncoder(false);

    private ServerCookieEncoder(boolean strict) {
        super(strict);
    }

    
Encodes the specified cookie name-value pair into a Set-Cookie header value.
Params:
name – the cookie name
value – the cookie value
Returns:
a single Set-Cookie header value/**
     * Encodes the specified cookie name-value pair into a Set-Cookie header value.
     *
     * @param name the cookie name
     * @param value the cookie value
     * @return a single Set-Cookie header value
     */
    public String encode(String name, String value) {
        return encode(new DefaultCookie(name, value));
    }

    
Encodes the specified cookie into a Set-Cookie header value.
Params:
cookie – the cookie
Returns:
a single Set-Cookie header value/**
     * Encodes the specified cookie into a Set-Cookie header value.
     *
     * @param cookie the cookie
     * @return a single Set-Cookie header value
     */
    public String encode(Cookie cookie) {
        final String name = checkNotNull(cookie, "cookie").name();
        final String value = cookie.value() != null ? cookie.value() : "";

        validateCookie(name, value);

        StringBuilder buf = stringBuilder();

        if (cookie.wrap()) {
            addQuoted(buf, name, value);
        } else {
            add(buf, name, value);
        }

        if (cookie.maxAge() != Long.MIN_VALUE) {
            add(buf, CookieHeaderNames.MAX_AGE, cookie.maxAge());
            Date expires = new Date(cookie.maxAge() * 1000 + System.currentTimeMillis());
            buf.append(CookieHeaderNames.EXPIRES);
            buf.append((char) HttpConstants.EQUALS);
            DateFormatter.append(expires, buf);
            buf.append((char) HttpConstants.SEMICOLON);
            buf.append((char) HttpConstants.SP);
        }

        if (cookie.path() != null) {
            add(buf, CookieHeaderNames.PATH, cookie.path());
        }

        if (cookie.domain() != null) {
            add(buf, CookieHeaderNames.DOMAIN, cookie.domain());
        }
        if (cookie.isSecure()) {
            add(buf, CookieHeaderNames.SECURE);
        }
        if (cookie.isHttpOnly()) {
            add(buf, CookieHeaderNames.HTTPONLY);
        }

        return stripTrailingSeparator(buf);
    }

    
Deduplicate a list of encoded cookies by keeping only the last instance with a given name.
Params:
encoded – The list of encoded cookies.
nameToLastIndex – A map from cookie name to index of last cookie instance.
Returns:
The encoded list with all but the last instance of a named cookie./** Deduplicate a list of encoded cookies by keeping only the last instance with a given name.
     *
     * @param encoded The list of encoded cookies.
     * @param nameToLastIndex A map from cookie name to index of last cookie instance.
     * @return The encoded list with all but the last instance of a named cookie.
     */
    private static List<String> dedup(List<String> encoded, Map<String, Integer> nameToLastIndex) {
        boolean[] isLastInstance = new boolean[encoded.size()];
        for (int idx : nameToLastIndex.values()) {
            isLastInstance[idx] = true;
        }
        List<String> dedupd = new ArrayList<String>(nameToLastIndex.size());
        for (int i = 0, n = encoded.size(); i < n; i++) {
            if (isLastInstance[i]) {
                dedupd.add(encoded.get(i));
            }
        }
        return dedupd;
    }

    
Batch encodes cookies into Set-Cookie header values.
Params:
cookies – a bunch of cookies
Returns:
the corresponding bunch of Set-Cookie headers/**
     * Batch encodes cookies into Set-Cookie header values.
     *
     * @param cookies a bunch of cookies
     * @return the corresponding bunch of Set-Cookie headers
     */
    public List<String> encode(Cookie... cookies) {
        if (checkNotNull(cookies, "cookies").length == 0) {
            return Collections.emptyList();
        }

        List<String> encoded = new ArrayList<String>(cookies.length);
        Map<String, Integer> nameToIndex = strict && cookies.length > 1 ? new HashMap<String, Integer>() : null;
        boolean hasDupdName = false;
        for (int i = 0; i < cookies.length; i++) {
            Cookie c = cookies[i];
            encoded.add(encode(c));
            if (nameToIndex != null) {
                hasDupdName |= nameToIndex.put(c.name(), i) != null;
            }
        }
        return hasDupdName ? dedup(encoded, nameToIndex) : encoded;
    }

    
Batch encodes cookies into Set-Cookie header values.
Params:
cookies – a bunch of cookies
Returns:
the corresponding bunch of Set-Cookie headers/**
     * Batch encodes cookies into Set-Cookie header values.
     *
     * @param cookies a bunch of cookies
     * @return the corresponding bunch of Set-Cookie headers
     */
    public List<String> encode(Collection<? extends Cookie> cookies) {
        if (checkNotNull(cookies, "cookies").isEmpty()) {
            return Collections.emptyList();
        }

        List<String> encoded = new ArrayList<String>(cookies.size());
        Map<String, Integer> nameToIndex = strict && cookies.size() > 1 ? new HashMap<String, Integer>() : null;
        int i = 0;
        boolean hasDupdName = false;
        for (Cookie c : cookies) {
            encoded.add(encode(c));
            if (nameToIndex != null) {
                hasDupdName |= nameToIndex.put(c.name(), i++) != null;
            }
        }
        return hasDupdName ? dedup(encoded, nameToIndex) : encoded;
    }

    
Batch encodes cookies into Set-Cookie header values.
Params:
cookies – a bunch of cookies
Returns:
the corresponding bunch of Set-Cookie headers/**
     * Batch encodes cookies into Set-Cookie header values.
     *
     * @param cookies a bunch of cookies
     * @return the corresponding bunch of Set-Cookie headers
     */
    public List<String> encode(Iterable<? extends Cookie> cookies) {
        Iterator<? extends Cookie> cookiesIt = checkNotNull(cookies, "cookies").iterator();
        if (!cookiesIt.hasNext()) {
            return Collections.emptyList();
        }

        List<String> encoded = new ArrayList<String>();
        Cookie firstCookie = cookiesIt.next();
        Map<String, Integer> nameToIndex = strict && cookiesIt.hasNext() ? new HashMap<String, Integer>() : null;
        int i = 0;
        encoded.add(encode(firstCookie));
        boolean hasDupdName = nameToIndex != null && nameToIndex.put(firstCookie.name(), i++) != null;
        while (cookiesIt.hasNext()) {
            Cookie c = cookiesIt.next();
            encoded.add(encode(c));
            if (nameToIndex != null) {
                hasDupdName |= nameToIndex.put(c.name(), i++) != null;
            }
        }
        return hasDupdName ? dedup(encoded, nameToIndex) : encoded;
    }
}