michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: package org.mozilla.gecko.background.fxa;
michael@0: 
michael@0: import java.net.URI;
michael@0: import java.net.URISyntaxException;
michael@0: import java.util.HashMap;
michael@0: 
michael@0: import org.mozilla.gecko.background.common.log.Logger;
michael@0: import org.mozilla.gecko.sync.net.Resource;
michael@0: 
michael@0: import ch.boye.httpclientandroidlib.Header;
michael@0: import ch.boye.httpclientandroidlib.HttpHeaders;
michael@0: import ch.boye.httpclientandroidlib.HttpResponse;
michael@0: import ch.boye.httpclientandroidlib.impl.cookie.DateParseException;
michael@0: import ch.boye.httpclientandroidlib.impl.cookie.DateUtils;
michael@0: 
michael@0: public class SkewHandler {
michael@0:   private static final String LOG_TAG = "SkewHandler";
michael@0:   protected volatile long skewMillis = 0L;
michael@0:   protected final String hostname;
michael@0: 
michael@0:   private static final HashMap<String, SkewHandler> skewHandlers = new HashMap<String, SkewHandler>();
michael@0: 
michael@0:   public static SkewHandler getSkewHandlerForResource(final Resource resource) {
michael@0:     return getSkewHandlerForHostname(resource.getHostname());
michael@0:   }
michael@0: 
michael@0:   public static SkewHandler getSkewHandlerFromEndpointString(final String url) throws URISyntaxException {
michael@0:     if (url == null) {
michael@0:       throw new IllegalArgumentException("url must not be null.");
michael@0:     }
michael@0:     URI u = new URI(url);
michael@0:     return getSkewHandlerForHostname(u.getHost());
michael@0:   }
michael@0: 
michael@0:   public static synchronized SkewHandler getSkewHandlerForHostname(final String hostname) {
michael@0:     SkewHandler handler = skewHandlers.get(hostname);
michael@0:     if (handler == null) {
michael@0:       handler = new SkewHandler(hostname);
michael@0:       skewHandlers.put(hostname, handler);
michael@0:     }
michael@0:     return handler;
michael@0:   }
michael@0: 
michael@0:   public static synchronized void clearSkewHandlers() {
michael@0:     skewHandlers.clear();
michael@0:   }
michael@0: 
michael@0:   public SkewHandler(final String hostname) {
michael@0:     this.hostname = hostname;
michael@0:   }
michael@0: 
michael@0:   public boolean updateSkewFromServerMillis(long millis, long now) {
michael@0:     skewMillis = millis - now;
michael@0:     Logger.debug(LOG_TAG, "Updated skew: " + skewMillis + "ms for hostname " + this.hostname);
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   public boolean updateSkewFromHTTPDateString(String date, long now) {
michael@0:     try {
michael@0:       final long millis = DateUtils.parseDate(date).getTime();
michael@0:       return updateSkewFromServerMillis(millis, now);
michael@0:     } catch (DateParseException e) {
michael@0:       Logger.warn(LOG_TAG, "Unexpected: invalid Date header from " + this.hostname);
michael@0:       return false;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   public boolean updateSkewFromDateHeader(Header header, long now) {
michael@0:     String date = header.getValue();
michael@0:     if (null == date) {
michael@0:       Logger.warn(LOG_TAG, "Unexpected: null Date header from " + this.hostname);
michael@0:       return false;
michael@0:     }
michael@0:     return updateSkewFromHTTPDateString(date, now);
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Update our tracked skew value to account for the local clock differing from
michael@0:    * the server's.
michael@0:    * 
michael@0:    * @param response
michael@0:    *          the received HTTP response.
michael@0:    * @param now
michael@0:    *          the current time in milliseconds.
michael@0:    * @return true if the skew value was updated, false otherwise.
michael@0:    */
michael@0:   public boolean updateSkew(HttpResponse response, long now) {
michael@0:     Header header = response.getFirstHeader(HttpHeaders.DATE);
michael@0:     if (null == header) {
michael@0:       Logger.warn(LOG_TAG, "Unexpected: missing Date header from " + this.hostname);
michael@0:       return false;
michael@0:     }
michael@0:     return updateSkewFromDateHeader(header, now);
michael@0:   }
michael@0: 
michael@0:   public long getSkewInMillis() {
michael@0:     return skewMillis;
michael@0:   }
michael@0: 
michael@0:   public long getSkewInSeconds() {
michael@0:     return skewMillis / 1000;
michael@0:   }
michael@0: 
michael@0:   public void resetSkew() {
michael@0:     skewMillis = 0L;
michael@0:   }
michael@0: }