Refactor attachment creation

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/conversation/AttachmentControllerIntegrationTest.java → briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/AttachmentRetrieverIntegrationTest.java

-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.content.res.AssetManager;
 import android.support.test.InstrumentationRegistry;
@@ -21,7 +21,7 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 @RunWith(AndroidJUnit4.class)
-public class AttachmentControllerIntegrationTest {
+public class AttachmentRetrieverIntegrationTest {
 
 	private static final String smallKitten =
 			"https://upload.wikimedia.org/wikipedia/commons/thumb/0/06/Kitten_in_Rizal_Park%2C_Manila.jpg/160px-Kitten_in_Rizal_Park%2C_Manila.jpg";
@@ -47,15 +47,15 @@ public class AttachmentControllerIntegrationTest {
 	);
 	private final MessageId msgId = new MessageId(getRandomId());
 
-	private final AttachmentController controller =
-			new AttachmentController(null, dimensions);
+	private final AttachmentRetriever retriever =
+			new AttachmentRetriever(null, dimensions);
 
 	@Test
 	public void testSmallJpegImage() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(smallKitten);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(160, item.getWidth());
 		assertEquals(240, item.getHeight());
@@ -71,7 +71,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(originalKitten);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(1728, item.getWidth());
 		assertEquals(2592, item.getHeight());
@@ -87,7 +87,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/png");
 		InputStream is = getUrlInputStream(pngKitten);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(737, item.getWidth());
 		assertEquals(510, item.getHeight());
@@ -103,7 +103,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(uberGif);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -118,7 +118,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(lottaPixel);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(64250, item.getWidth());
 		assertEquals(64250, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -133,7 +133,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(imageIoCrash);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1184, item.getWidth());
 		assertEquals(448, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -148,7 +148,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(gimpCrash);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -163,7 +163,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(optiPngAfl);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(32, item.getWidth());
 		assertEquals(32, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -178,7 +178,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(librawError);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertTrue(item.hasError());
 	}
 
@@ -187,7 +187,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated.gif");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(65535, item.getWidth());
 		assertEquals(65535, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -202,7 +202,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated2.gif");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(10000, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -217,7 +217,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("error_large.gif");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(16384, item.getWidth());
 		assertEquals(16384, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -232,7 +232,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("error_high.jpg");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.minWidth, item.getThumbnailWidth());
@@ -247,7 +247,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("error_wide.jpg");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1920, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreationTask.java

+package org.briarproject.briar.android.attachment;
+
+import android.content.ContentResolver;
+import android.net.Uri;
+import android.support.annotation.Nullable;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.briarproject.briar.api.messaging.MessagingManager;
+import org.jsoup.UnsupportedMimeTypeException;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.List;
+import java.util.logging.Logger;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.IoUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+import static org.briarproject.briar.api.messaging.MessagingConstants.IMAGE_MIME_TYPES;
+
+@NotNullByDefault
+class AttachmentCreationTask {
+
+	private static Logger LOG =
+			getLogger(AttachmentCreationTask.class.getName());
+
+	private final MessagingManager messagingManager;
+	private final ContentResolver contentResolver;
+	private final GroupId groupId;
+	private final List<Uri> uris;
+	private final boolean needsSize;
+	@Nullable
+	private AttachmentCreator attachmentCreator;
+
+	private volatile boolean canceled = false;
+
+	AttachmentCreationTask(MessagingManager messagingManager,
+			ContentResolver contentResolver,
+			AttachmentCreator attachmentCreator, GroupId groupId,
+			List<Uri> uris, boolean needsSize) {
+		this.messagingManager = messagingManager;
+		this.contentResolver = contentResolver;
+		this.groupId = groupId;
+		this.uris = uris;
+		this.needsSize = needsSize;
+		this.attachmentCreator = attachmentCreator;
+	}
+
+	public void cancel() {
+		canceled = true;
+		attachmentCreator = null;
+	}
+
+	@IoExecutor
+	public void storeAttachments() {
+		for (Uri uri: uris) processUri(uri);
+		if (!canceled && attachmentCreator != null)
+			attachmentCreator.onAttachmentCreationFinished();
+		attachmentCreator = null;
+	}
+
+	@IoExecutor
+	private void processUri(Uri uri) {
+		if (canceled) return;
+		try {
+			AttachmentHeader h = storeAttachment(uri);
+			if (attachmentCreator != null) {
+				attachmentCreator
+						.onAttachmentHeaderReceived(uri, h, needsSize);
+			}
+		} catch (DbException | IOException e) {
+			logException(LOG, WARNING, e);
+			if (attachmentCreator != null) {
+				attachmentCreator.onAttachmentError(uri, e);
+				canceled = true;
+			}
+		}
+	}
+
+	@IoExecutor
+	private AttachmentHeader storeAttachment(Uri uri)
+			throws IOException, DbException {
+		long start = now();
+		String contentType = contentResolver.getType(uri);
+		if (contentType == null) throw new IOException("null content type");
+		if (!isValidMimeType(contentType))
+			throw new UnsupportedMimeTypeException("", contentType,
+					uri.toString());
+		InputStream is = contentResolver.openInputStream(uri);
+		if (is == null) throw new IOException();
+		long timestamp = System.currentTimeMillis();
+		AttachmentHeader h = messagingManager
+				.addLocalAttachment(groupId, timestamp, contentType, is);
+		tryToClose(is, LOG, WARNING);
+		logDuration(LOG, "Storing attachment", start);
+		return h;
+	}
+
+	private boolean isValidMimeType(@Nullable String mimeType) {
+		if (mimeType == null) return false;
+		for (String supportedType : IMAGE_MIME_TYPES) {
+			if (supportedType.equals(mimeType)) return true;
+		}
+		return false;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreator.java

+package org.briarproject.briar.android.attachment;
+
+
+import android.app.Application;
+import android.arch.lifecycle.LiveData;
+import android.arch.lifecycle.MutableLiveData;
+import android.net.Uri;
+import android.support.annotation.Nullable;
+import android.support.annotation.UiThread;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.R;
+import org.briarproject.briar.api.messaging.Attachment;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.briarproject.briar.api.messaging.FileTooBigException;
+import org.briarproject.briar.api.messaging.MessagingManager;
+import org.jsoup.UnsupportedMimeTypeException;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_IMAGE_SIZE;
+
+@NotNullByDefault
+public class AttachmentCreator {
+
+	private static Logger LOG = getLogger(AttachmentCreator.class.getName());
+
+	private final Application app;
+	@IoExecutor
+	private final Executor ioExecutor;
+	private final MessagingManager messagingManager;
+	private final AttachmentRetriever controller;
+
+	private final Map<Uri, AttachmentItem> unsentItems =
+			new ConcurrentHashMap<>();
+	private final Map<Uri, MutableLiveData<AttachmentItemResult>>
+			liveDataResult = new ConcurrentHashMap<>();
+
+	@Nullable
+	private MutableLiveData<Boolean> liveDataFinished = null;
+	@Nullable
+	private AttachmentCreationTask task;
+
+	public AttachmentCreator(Application app, @IoExecutor Executor ioExecutor,
+			MessagingManager messagingManager,
+			AttachmentRetriever controller) {
+		this.app = app;
+		this.ioExecutor = ioExecutor;
+		this.messagingManager = messagingManager;
+		this.controller = controller;
+	}
+
+	@UiThread
+	public AttachmentResult storeAttachments(GroupId groupId,
+			Collection<Uri> uris) {
+		if (task != null && !isStoring()) throw new AssertionError();
+		List<LiveData<AttachmentItemResult>> itemResults = new ArrayList<>();
+		List<Uri> urisToStore = new ArrayList<>();
+		for (Uri uri : uris) {
+			MutableLiveData<AttachmentItemResult> liveData =
+					new MutableLiveData<>();
+			itemResults.add(liveData);
+			liveDataResult.put(uri, liveData);
+			if (unsentItems.containsKey(uri)) {
+				// This can happen due to configuration changes.
+				// So don't create a new attachment, if we have one already.
+				AttachmentItem item = requireNonNull(unsentItems.get(uri));
+				AttachmentItemResult result =
+						new AttachmentItemResult(uri, item);
+				liveData.setValue(result);
+			} else {
+				urisToStore.add(uri);
+			}
+		}
+		boolean needsSize = uris.size() == 1;
+		task = new AttachmentCreationTask(messagingManager,
+				app.getContentResolver(), this, groupId, urisToStore,
+				needsSize);
+		ioExecutor.execute(() -> task.storeAttachments());
+		liveDataFinished = new MutableLiveData<>();
+		return new AttachmentResult(itemResults, liveDataFinished);
+	}
+
+	@IoExecutor
+	void onAttachmentHeaderReceived(Uri uri, AttachmentHeader h,
+			boolean needsSize) {
+		// get and cache AttachmentItem for ImagePreview
+		try {
+			Attachment a = controller.getMessageAttachment(h);
+			AttachmentItem item = controller.getAttachmentItem(h, a, needsSize);
+			if (item.hasError()) throw new IOException();
+			unsentItems.put(uri, item);
+			MutableLiveData<AttachmentItemResult> result =
+					liveDataResult.get(uri);
+			if (result != null) {  // might have been cleared on UiThread
+				result.postValue(new AttachmentItemResult(uri, item));
+			}
+		} catch (IOException | DbException e) {
+			logException(LOG, WARNING, e);
+			onAttachmentError(uri, e);
+		}
+	}
+
+	@IoExecutor
+	void onAttachmentError(Uri uri, Throwable t) {
+		String errorMsg;
+		if (t instanceof UnsupportedMimeTypeException) {
+			String mimeType = ((UnsupportedMimeTypeException) t).getMimeType();
+			errorMsg = app.getString(
+					R.string.image_attach_error_invalid_mime_type, mimeType);
+		} else if (t instanceof FileTooBigException) {
+			int mb = MAX_IMAGE_SIZE / 1024 / 1024;
+			errorMsg = app.getString(R.string.image_attach_error_too_big, mb);
+		} else {
+			errorMsg = null; // generic error
+		}
+		MutableLiveData<AttachmentItemResult> result = liveDataResult.get(uri);
+		if (result != null)
+			result.postValue(new AttachmentItemResult(errorMsg));
+		// expect to receive a cancel from the UI
+	}
+
+	@IoExecutor
+	void onAttachmentCreationFinished() {
+		if (liveDataFinished != null) liveDataFinished.postValue(true);
+	}
+
+	@UiThread
+	public List<AttachmentHeader> getAttachmentHeadersForSending() {
+		List<AttachmentHeader> headers =
+				new ArrayList<>(unsentItems.values().size());
+		for (AttachmentItem item : unsentItems.values()) {
+			headers.add(item.getHeader());
+		}
+		return headers;
+	}
+
+	/**
+	 * Marks the attachments as sent and adds the items to the cache for display
+	 *
+	 * @param id The MessageId of the sent message.
+	 */
+	public void onAttachmentsSent(MessageId id) {
+		controller.cachePut(id, new ArrayList<>(unsentItems.values()));
+		resetState();
+	}
+
+	@UiThread
+	public void cancel() {
+		if (task == null) throw new AssertionError();
+		task.cancel();
+		// let observers know that they can remove themselves
+		for (MutableLiveData<AttachmentItemResult> liveData : liveDataResult
+				.values()) {
+			if (liveData.getValue() == null) {
+				liveData.setValue(null);
+			}
+		}
+		if (liveDataFinished != null) liveDataFinished.setValue(false);
+		deleteUnsentAttachments();
+		resetState();
+	}
+
+	@UiThread
+	private void resetState() {
+		task = null;
+		liveDataResult.clear();
+		liveDataFinished = null;
+		unsentItems.clear();
+	}
+
+	@UiThread
+	public void deleteUnsentAttachments() {
+		List<AttachmentItem> itemsToDelete =
+				new ArrayList<>(unsentItems.values());
+		ioExecutor.execute(() -> {
+			for (AttachmentItem item : itemsToDelete) {
+				try {
+					messagingManager.removeAttachment(item.getHeader());
+				} catch (DbException e) {
+					logException(LOG, WARNING, e);
+				}
+			}
+		});
+	}
+
+	private boolean isStoring() {
+		return liveDataFinished != null;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentDimensions.java → briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentDimensions.java

-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.content.res.Resources;
 import android.support.annotation.VisibleForTesting;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 
-class AttachmentDimensions {
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class AttachmentDimensions {
 
 	final int defaultSize;
 	final int minWidth, maxWidth;
@@ -21,7 +26,7 @@ class AttachmentDimensions {
 		this.maxHeight = maxHeight;
 	}
 
-	static AttachmentDimensions getAttachmentDimensions(Resources res) {
+	public static AttachmentDimensions getAttachmentDimensions(Resources res) {
 		int defaultSize =
 				res.getDimensionPixelSize(R.dimen.message_bubble_image_default);
 		int minWidth = res.getDimensionPixelSize(
@@ -33,7 +38,7 @@ class AttachmentDimensions {
 		int maxHeight = res.getDimensionPixelSize(
 				R.dimen.message_bubble_image_max_height);
 		return new AttachmentDimensions(defaultSize, minWidth, maxWidth,
-				minHeight, minHeight);
+				minHeight, maxHeight);
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentItem.java → briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentItem.java

-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.os.Parcel;
 import android.os.Parcelable;
@@ -12,6 +12,8 @@ import java.util.concurrent.atomic.AtomicLong;
 
 import javax.annotation.concurrent.Immutable;
 
+import static java.util.Objects.requireNonNull;
+
 @Immutable
 @NotNullByDefault
 public class AttachmentItem implements Parcelable {
@@ -57,8 +59,8 @@ public class AttachmentItem implements Parcelable {
 		MessageId messageId = new MessageId(messageIdByte);
 		width = in.readInt();
 		height = in.readInt();
-		String mimeType = in.readString();
-		extension = in.readString();
+		String mimeType = requireNonNull(in.readString());
+		extension = requireNonNull(in.readString());
 		thumbnailWidth = in.readInt();
 		thumbnailHeight = in.readInt();
 		hasError = in.readByte() != 0;
@@ -82,27 +84,27 @@ public class AttachmentItem implements Parcelable {
 		return height;
 	}
 
-	String getMimeType() {
+	public String getMimeType() {
 		return header.getContentType();
 	}
 
-	String getExtension() {
+	public String getExtension() {
 		return extension;
 	}
 
-	int getThumbnailWidth() {
+	public int getThumbnailWidth() {
 		return thumbnailWidth;
 	}
 
-	int getThumbnailHeight() {
+	public int getThumbnailHeight() {
 		return thumbnailHeight;
 	}
 
-	boolean hasError() {
+	public boolean hasError() {
 		return hasError;
 	}
 
-	String getTransitionName() {
+	public String getTransitionName() {
 		return String.valueOf(instanceId);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/AttachmentResult.java → briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentItemResult.java

-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.net.Uri;
 
@@ -9,7 +9,7 @@ import javax.annotation.concurrent.Immutable;
 
 @Immutable
 @NotNullByDefault
-public class AttachmentResult {
+public class AttachmentItemResult {
 
 	@Nullable
 	private final Uri uri;
@@ -18,13 +18,13 @@ public class AttachmentResult {
 	@Nullable
 	private final String errorMsg;
 
-	public AttachmentResult(Uri uri, AttachmentItem item) {
+	public AttachmentItemResult(Uri uri, AttachmentItem item) {
 		this.uri = uri;
 		this.item = item;
 		this.errorMsg = null;
 	}
 
-	public AttachmentResult(@Nullable String errorMsg) {
+	public AttachmentItemResult(@Nullable String errorMsg) {
 		this.uri = null;
 		this.item = null;
 		this.errorMsg = errorMsg;

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentManager.java

+package org.briarproject.briar.android.attachment;
+
+import android.net.Uri;
+import android.support.annotation.UiThread;
+
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+
+import java.util.Collection;
+import java.util.List;
+
+@UiThread
+public interface AttachmentManager{
+
+	AttachmentResult storeAttachments(Collection<Uri> uri);
+
+	List<AttachmentHeader> getAttachmentHeadersForSending();
+
+	void cancel();
+
+}

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentResult.java

+package org.briarproject.briar.android.attachment;
+
+import android.arch.lifecycle.LiveData;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.Collection;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class AttachmentResult {
+
+	private final Collection<LiveData<AttachmentItemResult>> itemResults;
+	private final LiveData<Boolean> finished;
+
+	public AttachmentResult(
+			Collection<LiveData<AttachmentItemResult>> itemResults,
+			LiveData<Boolean> finished) {
+		this.itemResults = itemResults;
+		this.finished = finished;
+	}
+
+	public Collection<LiveData<AttachmentItemResult>> getItemResults() {
+		return itemResults;
+	}
+
+	public LiveData<Boolean> getFinished() {