[WO-382] Lazy loading for attachments

src/js/controller/read.js

@@ -117,7 +117,7 @@ define(function(require) {
             var email = $scope.state.mailList.selected;
 
             emailDao.getAttachment({
-                path: folder.path,
+                folder: folder.path,
                 uid: email.uid,
                 attachment: attachment
             }, function(err) {

src/js/dao/email-dao.js

@@ -306,9 +306,19 @@ define(function(require) {
 
                 var localMessage = localMessages[0];
 
+                // treat attachment and non-attachment body parts separately:
+                // we need to fetch the content for non-attachment body parts (encrypted, signed, text, html)
+                // but we spare the effort and fetch attachment content later upon explicit user request.
+                var contentParts = localMessage.bodyParts.filter(function(bodyPart) {
+                    return bodyPart.type !== "attachment";
+                });
+                var attachmentParts = localMessage.bodyParts.filter(function(bodyPart) {
+                    return bodyPart.type === "attachment";
+                });
+
                 // do we need to fetch content from the imap server?
                 var needsFetch = false;
-                localMessage.bodyParts.forEach(function(part) {
+                contentParts.forEach(function(part) {
                     needsFetch = (typeof part.content === 'undefined');
                 });
 
@@ -324,15 +334,16 @@ define(function(require) {
                 self._emailSync._getBodyParts({
                     folder: folder,
                     uid: localMessage.uid,
-                    bodyParts: localMessage.bodyParts
+                    bodyParts: contentParts
                 }, function(err, parsedBodyParts) {
                     if (err) {
                         done(err);
                         return;
                     }
 
-                    message.bodyParts = parsedBodyParts;
-                    localMessage.bodyParts = parsedBodyParts;
+                    // piece together the parsed bodyparts and the empty attachments which have not been parsed
+                    message.bodyParts = parsedBodyParts.concat(attachmentParts);
+                    localMessage.bodyParts = parsedBodyParts.concat(attachmentParts);
 
                     // persist it to disk
                     self._emailSync._localStoreMessages({
@@ -384,6 +395,22 @@ define(function(require) {
         }
     };
 
+    EmailDAO.prototype.getAttachment = function(options, callback) {
+        this._emailSync._getBodyParts({
+            folder: options.folder,
+            uid: options.uid,
+            bodyParts: [options.attachment]
+        }, function(err, parsedBodyParts) {
+            if (err) {
+                callback(err);
+                return;
+            }
+
+            options.attachment.content = parsedBodyParts[0].content;
+            callback(err, err ? undefined : options.attachment);
+        });
+    };
+
     EmailDAO.prototype.decryptBody = function(options, callback) {
         var self = this,
             message = options.message;

src/js/dao/email-sync.js

@@ -447,6 +447,13 @@ define(function(require) {
                                     return;
                                 }
 
+                                // this enables us to already show the attachment clip in the message list ui
+                                messages.forEach(function(message) {
+                                    message.attachments = message.bodyParts.filter(function(bodyPart) {
+                                        return bodyPart.type === 'attachment';
+                                    });
+                                });
+
                                 // if persisting worked, add them to the messages array
                                 folder.messages = folder.messages.concat(messages);
                                 self.onIncomingMessage(messages);

test/new-unit/email-dao-test.js

@@ -866,6 +866,63 @@ define(function(require) {
             });
         });
 
+        describe('getAttachment', function() {
+            var folder = 'asdasdasdasdasd',
+                uid = 1234,
+                imapGetStub;
+
+            beforeEach(function() {
+                imapGetStub = sinon.stub(emailSync, '_getBodyParts');
+            });
+
+            afterEach(function() {
+                emailSync._getBodyParts.restore();
+            });
+
+            it('should fetch an attachment from imap', function(done) {
+                var attmt = {};
+
+                imapGetStub.withArgs({
+                    folder: folder,
+                    uid: uid,
+                    bodyParts: [attmt]
+                }).yieldsAsync(null, [{
+                    content: 'CONTENT!!!'
+                }]);
+
+                dao.getAttachment({
+                    folder: folder,
+                    uid: uid,
+                    attachment: attmt
+                }, function(err, fetchedAttmt) {
+                    expect(err).to.not.exist;
+                    expect(fetchedAttmt).to.equal(attmt);
+                    expect(attmt.content).to.not.be.empty;
+                    expect(imapGetStub.calledOnce).to.be.true;
+
+                    done();
+                });
+            });
+
+            it('should error during fetch', function(done) {
+                var attmt = {};
+
+                imapGetStub.yieldsAsync({});
+
+                dao.getAttachment({
+                    folder: folder,
+                    uid: uid,
+                    attachment: attmt
+                }, function(err, fetchedAttmt) {
+                    expect(err).to.exist;
+                    expect(fetchedAttmt).to.not.exist;
+                    expect(imapGetStub.calledOnce).to.be.true;
+
+                    done();
+                });
+            });
+        });
+
         describe('decryptBody', function() {
             it('should do nothing when the message is not encrypted', function() {
                 var message = {