/*
 * %W% %E%
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.net;

import java.util.Map;
import java.util.List;
import java.util.Collections;
import java.util.Comparator;
import java.io.IOException;

/**
 * CookieManager provides a concrete implementation of {@link CookieHandler},
 * which separates the storage of cookies from the policy surrounding accepting
 * and rejecting cookies. A CookieManager is initialized with a {@link CookieStore}
 * which manages storage, and a {@link CookiePolicy} object, which makes
 * policy decisions on cookie acceptance/rejection.
 *
 * <p> The HTTP cookie management in java.net package looks like:
 * <blockquote>
 * <pre>
 *                  use
 * CookieHandler <------- HttpURLConnection
 *       ^
 *       | impl
 *       |         use
 * CookieManager -------> CookiePolicy
 *             |   use
 *             |--------> HttpCookie
 *             |              ^
 *             |              | use
 *             |   use        |
 *             |--------> CookieStore
 *                            ^
 *                            | impl
 *                            |
 *                  Internal in-memory implementation
 * </pre>
 * <ul>
 *   <li>
 *     CookieHandler is at the core of cookie management. User can call
 *     CookieHandler.setDefault to set a concrete CookieHanlder implementation
 *     to be used.
 *   </li>
 *   <li>
 *     CookiePolicy.shouldAccept will be called by CookieManager.put to see whether
 *     or not one cookie should be accepted and put into cookie store. User can use
 *     any of three pre-defined CookiePolicy, namely ACCEPT_ALL, ACCEPT_NONE and
 *     ACCEPT_ORIGINAL_SERVER, or user can define his own CookiePolicy implementation
 *     and tell CookieManager to use it.
 *   </li>
 *   <li>
 *     CookieStore is the place where any accepted HTTP cookie is stored in.
 *     If not specified when created, a CookieManager instance will use an internal
 *     in-memory implementation. Or user can implements one and tell CookieManager
 *     to use it.
 *   </li>
 *   <li>
 *     Currently, only CookieStore.add(URI, HttpCookie) and CookieStore.get(URI)
 *     are used by CookieManager. Others are for completeness and might be needed
 *     by a more sophisticated CookieStore implementation, e.g. a NetscapeCookieSotre.
 *   </li>
 * </ul>
 * </blockquote>
 *
 * <p>There're various ways user can hook up his own HTTP cookie management behavior, e.g.
 * <blockquote>
 * <ul>
 *   <li>Use CookieHandler.setDefault to set a brand new {@link CookieHandler} implementation
 *   <li>Let CookieManager be the default {@link CookieHandler} implementation,
 *       but implement user's own {@link CookieStore} and {@link CookiePolicy}
 *       and tell default CookieManager to use them:
 *     <blockquote><pre>
 *       // this should be done at the beginning of an HTTP session
 *       CookieHandler.setDefault(new CookieManager(new MyCookieStore(), new MyCookiePolicy()));
 *     </pre></blockquote>
 *   <li>Let CookieManager be the default {@link CookieHandler} implementation, but
 *       use customized {@link CookiePolicy}:
 *     <blockquote><pre>
 *       // this should be done at the beginning of an HTTP session
 *       CookieHandler.setDefault(new CookieManager());
 *       // this can be done at any point of an HTTP session
 *       ((CookieManager)CookieHandler.getDefault()).setCookiePolicy(new MyCookiePolicy());
 *     </pre></blockquote>
 * </ul>
 * </blockquote>
 *
 * <p>The implementation conforms to RFC 2965, section 3.3.
 *
 * @version %I%, %E%
 * @author Edward Wang
 * @since 1.6
 */
public class CookieManager extends CookieHandler
{
    /* ---------------- Fields -------------- */
    
    private CookiePolicy policyCallback;


    private CookieStore cookieJar = null;


    /* ---------------- Ctors -------------- */
    
    /**
     * Create a new cookie manager.
     *
     * <p>This constructor will create new cookie manager with default
     * cookie store and accept policy. The effect is same as
     * <tt>CookieManager(null, null)</tt>.
     */
    public CookieManager() {
        this(null, null);
    }


    /**
     * Create a new cookie manager with specified cookie store and cookie policy.
     *
     * @param store     a <tt>CookieStore</tt> to be used by cookie manager.
     *                  if <tt>null</tt>, cookie manager will use a default one,
     *                  which is an in-memory CookieStore implmentation.
     * @param cookiePolicy      a <tt>CookiePolicy</tt> instance
     *                          to be used by cookie manager as policy callback.
     *                          if <tt>null</tt>, ACCEPT_ORIGINAL_SERVER will
     *                          be used.
     */
    public CookieManager(CookieStore store,
                         CookiePolicy cookiePolicy)
    {
        // use default cookie policy if not specify one
        policyCallback = (cookiePolicy == null) ? CookiePolicy.ACCEPT_ORIGINAL_SERVER
                                                : cookiePolicy;
        
        // if not specify CookieStore to use, use default one
        if (store == null) {
            cookieJar = new sun.net.www.protocol.http.InMemoryCookieStore();
        } else {
            cookieJar = store;
        }
    }

    
    /* ---------------- Public operations -------------- */
    
    /**
     * To set the cookie policy of this cookie manager.
     *
     * <p> A instance of <tt>CookieManager</tt> will have
     * cookie policy ACCEPT_ORIGINAL_SERVER by default. Users always
     * can call this method to set another cookie policy.
     *
     * @param cookiePolicy      the cookie policy. Can be <tt>null</tt>, which
     *                          has no effects on current cookie policy.
     */
    public void setCookiePolicy(CookiePolicy cookiePolicy) {
        if (cookiePolicy != null) policyCallback = cookiePolicy;
    }
    
    
    /**
     * To retrieve current cookie store.
     *
     * @return  the cookie store currently used by cookie manager.
     */
    public CookieStore getCookieStore() {
        return cookieJar;
    }


    public Map<String, List<String>>
        get(URI uri, Map<String, List<String>> requestHeaders)
        throws IOException
    {
        // pre-condition check
        if (uri == null || requestHeaders == null) {
            throw new IllegalArgumentException("Argument is null");
        }
        
        Map<String, List<String>> cookieMap =
                        new java.util.HashMap<String, List<String>>();
        // if there's no default CookieStore, no way for us to get any cookie
        if (cookieJar == null)
            return Collections.unmodifiableMap(cookieMap);
        
        List<HttpCookie> cookies = new java.util.ArrayList<HttpCookie>();
        for (HttpCookie cookie : cookieJar.get(uri)) {
            // apply path-matches rule (RFC 2965 sec. 3.3.4)
            if (pathMatches(uri.getPath(), cookie.getPath())) {
                cookies.add(cookie);
            }
        }
        
        // apply sort rule (RFC 2965 sec. 3.3.4)
        List<String> cookieHeader = sortByPath(cookies);
        
        cookieMap.put("Cookie", cookieHeader);
        return Collections.unmodifiableMap(cookieMap);
    }
    
    
    public void
        put(URI uri, Map<String, List<String>> responseHeaders)
        throws IOException
    {
        // pre-condition check
        if (uri == null || responseHeaders == null) {
            throw new IllegalArgumentException("Argument is null");
        }
        
        
        // if there's no default CookieStore, no need to remember any cookie
        if (cookieJar == null)
            return;
        
        for (String headerKey : responseHeaders.keySet()) {
            // RFC 2965 3.2.2, key must be 'Set-Cookie2'
            // we also accept 'Set-Cookie' here for backward compatibility
            if (headerKey == null
                || !(headerKey.equalsIgnoreCase("Set-Cookie2")
                     || headerKey.equalsIgnoreCase("Set-Cookie")
                    )
                )
            {
                continue;
            }
            
            for (String headerValue : responseHeaders.get(headerKey)) {
                try {
                    List<HttpCookie> cookies = HttpCookie.parse(headerValue);
                    for (HttpCookie cookie : cookies) {
                        if (shouldAcceptInternal(uri, cookie)) {
                            cookieJar.add(uri, cookie);
                        }
                    }
                } catch (IllegalArgumentException e) {
                    // invalid set-cookie header string
                    // no-op
                }
            }
        }
    }


    /* ---------------- Private operations -------------- */
    
    // to determine whether or not accept this cookie
    private boolean shouldAcceptInternal(URI uri, HttpCookie cookie) {
        try {
            return policyCallback.shouldAccept(uri, cookie);
        } catch (Exception ignored) { // pretect against malicious callback
            return false;
        }
    }
    
    
    /*
     * path-matches algorithm, as defined by RFC 2965
     */
    private boolean pathMatches(String path, String pathToMatchWith) {
        if (path == pathToMatchWith)
            return true;
        if (path == null || pathToMatchWith == null)
            return false;
        if (path.startsWith(pathToMatchWith))
            return true;
        
        return false;
    }
    
    
    /*
     * sort cookies with respect to their path: those with more specific Path attributes
     * precede those with less specific, as defined in RFC 2965 sec. 3.3.4
     */
    private List<String> sortByPath(List<HttpCookie> cookies) {
        Collections.sort(cookies, new CookiePathComparator());

        List<String> cookieHeader = new java.util.ArrayList<String>();
        for (HttpCookie cookie : cookies) {
            // Netscape cookie spec and RFC 2965 have different format of Cookie
            // header; RFC 2965 requires a leading $Version="1" string while Netscape
            // does not.
            // The workaround here is to add a $Version="1" string in advance
            if (cookies.indexOf(cookie) == 0 && cookie.getVersion() > 0) {
                cookieHeader.add("$Version=\"1\"");
            }

            cookieHeader.add(cookie.toString());
        }
        return cookieHeader;
    }


    static class CookiePathComparator implements Comparator<HttpCookie> {
        public int compare(HttpCookie c1, HttpCookie c2) {
            if (c1 == c2) return 0;
            if (c1 == null) return -1;
            if (c2 == null) return 1;
            
            // path rule only applies to the cookies with same name
            if (!c1.getName().equals(c2.getName())) return 0;
            
            // those with more specific Path attributes precede those with less specific
            if (c1.getPath().startsWith(c2.getPath()))
                return -1;
            else if (c2.getPath().startsWith(c1.getPath()))
                return 1;
            else
                return 0;
        }
    }
}