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.sync;
michael@0: 
michael@0: import java.util.concurrent.CountDownLatch;
michael@0: import java.util.concurrent.TimeUnit;
michael@0: 
michael@0: import org.mozilla.gecko.background.common.log.Logger;
michael@0: import org.mozilla.gecko.sync.delegates.JSONRecordFetchDelegate;
michael@0: import org.mozilla.gecko.sync.net.AuthHeaderProvider;
michael@0: import org.mozilla.gecko.sync.net.SyncStorageRecordRequest;
michael@0: import org.mozilla.gecko.sync.net.SyncStorageRequestDelegate;
michael@0: import org.mozilla.gecko.sync.net.SyncStorageResponse;
michael@0: 
michael@0: /**
michael@0:  * An object which fetches a chunk of JSON from a URI, using certain credentials,
michael@0:  * and informs its delegate of the result.
michael@0:  */
michael@0: public class JSONRecordFetcher {
michael@0:   private static final long DEFAULT_AWAIT_TIMEOUT_MSEC = 2 * 60 * 1000;   // Two minutes.
michael@0:   private static final String LOG_TAG = "JSONRecordFetcher";
michael@0: 
michael@0:   protected final AuthHeaderProvider authHeaderProvider;
michael@0:   protected final String uri;
michael@0:   protected JSONRecordFetchDelegate delegate;
michael@0: 
michael@0:   public JSONRecordFetcher(final String uri, final AuthHeaderProvider authHeaderProvider) {
michael@0:     if (uri == null) {
michael@0:       throw new IllegalArgumentException("uri must not be null");
michael@0:     }
michael@0:     this.uri = uri;
michael@0:     this.authHeaderProvider = authHeaderProvider;
michael@0:   }
michael@0: 
michael@0:   protected String getURI() {
michael@0:     return this.uri;
michael@0:   }
michael@0: 
michael@0:   private class JSONFetchHandler implements SyncStorageRequestDelegate {
michael@0: 
michael@0:     // SyncStorageRequestDelegate methods for fetching.
michael@0:     @Override
michael@0:     public AuthHeaderProvider getAuthHeaderProvider() {
michael@0:       return authHeaderProvider;
michael@0:     }
michael@0: 
michael@0:     public String ifUnmodifiedSince() {
michael@0:       return null;
michael@0:     }
michael@0: 
michael@0:     public void handleRequestSuccess(SyncStorageResponse response) {
michael@0:       if (response.wasSuccessful()) {
michael@0:         try {
michael@0:           delegate.handleSuccess(response.jsonObjectBody());
michael@0:         } catch (Exception e) {
michael@0:           handleRequestError(e);
michael@0:         }
michael@0:         return;
michael@0:       }
michael@0:       handleRequestFailure(response);
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void handleRequestFailure(SyncStorageResponse response) {
michael@0:       delegate.handleFailure(response);
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void handleRequestError(Exception ex) {
michael@0:       delegate.handleError(ex);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   public void fetch(final JSONRecordFetchDelegate delegate) {
michael@0:     this.delegate = delegate;
michael@0:     try {
michael@0:       final SyncStorageRecordRequest r = new SyncStorageRecordRequest(this.getURI());
michael@0:       r.delegate = new JSONFetchHandler();
michael@0:       r.get();
michael@0:     } catch (Exception e) {
michael@0:       delegate.handleError(e);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   private class LatchedJSONRecordFetchDelegate implements JSONRecordFetchDelegate {
michael@0:     public ExtendedJSONObject body = null;
michael@0:     public Exception exception = null;
michael@0:     private CountDownLatch latch;
michael@0: 
michael@0:     public LatchedJSONRecordFetchDelegate(CountDownLatch latch) {
michael@0:       this.latch = latch;
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void handleFailure(SyncStorageResponse response) {
michael@0:       this.exception = new HTTPFailureException(response);
michael@0:       latch.countDown();
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void handleError(Exception e) {
michael@0:       this.exception = e;
michael@0:       latch.countDown();
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void handleSuccess(ExtendedJSONObject body) {
michael@0:       this.body = body;
michael@0:       latch.countDown();
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Fetch the info record, blocking until it returns.
michael@0:    * @return the info record.
michael@0:    */
michael@0:   public ExtendedJSONObject fetchBlocking() throws HTTPFailureException, Exception {
michael@0:     CountDownLatch latch = new CountDownLatch(1);
michael@0:     LatchedJSONRecordFetchDelegate delegate = new LatchedJSONRecordFetchDelegate(latch);
michael@0:     this.delegate = delegate;
michael@0:     this.fetch(delegate);
michael@0: 
michael@0:     // Sanity wait: the resource itself will time out and throw after two
michael@0:     // minutes, so we just want to avoid coding errors causing us to block
michael@0:     // endlessly.
michael@0:     if (!latch.await(DEFAULT_AWAIT_TIMEOUT_MSEC, TimeUnit.MILLISECONDS)) {
michael@0:       Logger.warn(LOG_TAG, "Interrupted fetching info record.");
michael@0:       throw new InterruptedException("info fetch timed out.");
michael@0:     }
michael@0: 
michael@0:     if (delegate.body != null) {
michael@0:       return delegate.body;
michael@0:     }
michael@0: 
michael@0:     if (delegate.exception != null) {
michael@0:       throw delegate.exception;
michael@0:     }
michael@0: 
michael@0:     throw new Exception("Unknown error.");
michael@0:   }
michael@0: }