New synchronize pattern

js/blogger-provider.js

@@ -4,7 +4,6 @@ define(["jquery", "google-helper"], function($, googleHelper) {
 	var core = undefined;
 	
 	var bloggerProvider = {
-		providerType: PROVIDER_TYPE_PUBLISH_FLAG,
 		providerId: PROVIDER_BLOGGER,
 		providerName: "Blogger",
 		defaultPublishFormat: "html"

js/config.js

@@ -12,10 +12,6 @@ var ASYNC_TASK_DEFAULT_TIMEOUT = 30000;
 var ASYNC_TASK_LONG_TIMEOUT = 90000;
 var SYNC_PERIOD = 180000;
 var USER_IDLE_THRESHOLD = 300000;
-var SYNC_PROVIDER_GDRIVE = "sync.gdrive.";
-var SYNC_PROVIDER_DROPBOX = "sync.dropbox.";
-var PROVIDER_TYPE_SYNC_FLAG = 1;
-var PROVIDER_TYPE_PUBLISH_FLAG = 2;
 var PROVIDER_BLOGGER = "blogger";
 var PROVIDER_DROPBOX = "dropbox";
 var PROVIDER_GDRIVE = "gdrive";

js/core.js

@@ -177,7 +177,7 @@ define(
 	
 	// Setting management
 	core.settings = {
-		converterType : "markdown-extra",
+		converterType : "markdown-extra-prettify",
 		layoutOrientation : "horizontal",
 		editorFontSize : 14,
 		commitMsg : "Published by StackEdit.",
@@ -502,6 +502,12 @@ define(
 		
 		// from v1 to v2
 		if(version == "v1") {
+			var gdriveLastChangeId = localStorage["sync.gdrive.lastChangeId"];
+			localStorage["gdrive.lastChangeId"] = gdriveLastChangeId;
+			localStorage.removeItem("sync.gdrive.lastChangeId");
+			var dropboxLastChangeId = localStorage["sync.dropbox.lastChangeId"];
+			localStorage["dropbox.lastChangeId"] = dropboxLastChangeId;
+			localStorage.removeItem("sync.dropbox.lastChangeId");
 			
 			var SYNC_PROVIDER_GDRIVE = "sync." + PROVIDER_GDRIVE + ".";
 			var SYNC_PROVIDER_DROPBOX = "sync." + PROVIDER_DROPBOX + ".";

js/dropbox-helper.js

@@ -108,7 +108,7 @@ define(["jquery", "async-runner"], function($, asyncRunner) {
 		asyncRunner.addTask(task);
 	};
 
-	dropboxHelper.checkUpdates = function(lastChangeId, callback) {
+	dropboxHelper.checkChanges = function(lastChangeId, callback) {
 		callback = callback || core.doNothing;
 		var changes = [];
 		var newChangeId = lastChangeId || 0;
@@ -125,14 +125,7 @@ define(["jquery", "async-runner"], function($, asyncRunner) {
 					// Retrieve success
 					newChangeId = pullChanges.cursor();
 					if(pullChanges.changes !== undefined) {
-						for(var i=0; i<pullChanges.changes.length; i++) {
+						changes = changes.concat(pullChanges.changes);
-							var item = pullChanges.changes[i];
-							var version = localStorage[SYNC_PROVIDER_DROPBOX
-							    + encodeURIComponent(item.path.toLowerCase()) + ".version"];
-							if(version && (item.wasRemoved || item.stat.versionTag != version)) {
-								changes.push(item);
-							}
-						}
 					}
 					if (pullChanges.shouldPullAgain) {
 						task.chain(retrievePageOfChanges);

js/dropbox-provider.js

@@ -5,10 +5,10 @@ define(["jquery", "dropbox-helper"], function($, dropboxHelper) {
 	var fileManager = undefined;
 	
 	var dropboxProvider = {
-		providerType: PROVIDER_TYPE_SYNC_FLAG | PROVIDER_TYPE_PUBLISH_FLAG,
 		providerId: PROVIDER_DROPBOX,
 		providerName: "Dropbox",
-		defaultPublishFormat: "template"
+		defaultPublishFormat: "template",
+		useSync: false
 	};
 	
 	function checkPath(path) {
@@ -110,6 +110,113 @@ define(["jquery", "dropbox-helper"], function($, dropboxHelper) {
 		exportFileToPath(path);
 	};
 	
+	dropboxProvider.syncUp = function(uploadContent, uploadContentCRC, uploadTitle, uploadTitleCRC, syncAttributes, callback) {
+		var syncContentCRC = syncAttributes.contentCRC;
+		// Skip if CRC has not changed
+		if(uploadContentCRC == syncContentCRC) {
+			callback(undefined, false);
+			return;
+		}
+		dropboxHelper.upload(syncAttributes.path, uploadContent, function(error, result) {
+			if(error) {
+				callback(error, true);
+				return;
+			}
+			syncAttributes.version = result.versionTag;
+			syncAttributes.contentCRC = uploadContentCRC;
+			callback(undefined, true);
+		});
+	};
+	
+	function syncDown(callback) {
+		if (dropboxProvider.useSync === false) {
+			callback();
+			return;
+		}
+		var lastChangeId = parseInt(localStorage[PROVIDER_DROPBOX + ".lastChangeId"]);
+		dropboxHelper.checkChanges(lastChangeId, function(error, changes, newChangeId) {
+			if (error) {
+				callback(error);
+				return;
+			}
+			var interestingChanges = [];
+			_.each(changes, function(change) {
+				var syncIndex = "sync." + PROVIDER_DROPBOX + "." + encodeURIComponent(file.path.toLowerCase());
+				var serializedAttributes = localStorage[syncIndex];
+				if(serializedAttributes === undefined) {
+					return;
+				}
+				// Store syncIndex to avoid 2 times formating
+				change.syncIndex = syncIndex;
+				// Delete
+				if(change.wasRemoved === true) {
+					interestingChanges.push(change);
+					return;
+				}
+				// Modify
+				var syncAttributes = JSON.parse(serializedAttributes);
+				if(syncAttributes.version != change.stat.versionTag) {
+					interestingChanges.push(change);
+					// Store syncAttributes to avoid 2 times parsing 
+					change.syncAttributes = syncAttributes;
+				}
+			});
+			dropboxHelper.downloadContent(changes, function(error, changes) {
+				if (error) {
+					callback(error);
+					return;
+				}
+				var updateFileTitles = false;
+				_.each(changes, function(change) {
+					var syncIndex = change.syncIndex;
+					var fileIndex = fileManager.getFileIndexFromSync(syncIndex);
+					// No file corresponding (file may have been deleted locally)
+					if(fileIndex === undefined) {
+						fileManager.removeSync(syncIndex);
+						return;
+					}
+					var localTitle = localStorage[fileIndex + ".title"];
+					// File deleted
+					if (change.wasRemoved === true) {
+						fileManager.removeSync(syncIndex);
+						updateFileTitles = true;
+						core.showMessage('"' + localTitle + '" has been removed from Dropbox.');
+						return;
+					}
+					var syncAttributes = change.syncAttributes;
+					var localContent = localStorage[fileIndex + ".content"];
+					var localContentChanged = syncAttributes.contentCRC != core.crc32(localContent);
+					var file = change.stat;
+					var fileContentChanged = localContent != file.content;
+					// Conflict detection
+					if (fileContentChanged === true && localContentChanged === true) {
+						fileManager.createFile(localTitle + " (backup)", localContent);
+						updateFileTitles = true;
+						core.showMessage('Conflict detected on "' + localTitle + '". A backup has been created locally.');
+					}
+					// If file content changed
+					if(fileContentChanged) {
+						localStorage[fileIndex + ".content"] = file.content;
+						core.showMessage('"' + localTitle + '" has been updated from Dropbox.');
+						if(fileManager.isCurrentFileIndex(fileIndex)) {
+							updateFileTitles = false; // Done by next function
+							fileManager.selectFile(); // Refresh editor
+						}
+					}
+					// Update syncAttributes
+					syncAttributes.version = file.versionTag;
+					syncAttributes.contentCRC = core.crc32(file.content);
+					localStorage[syncIndex] = JSON.stringify(syncAttributes);
+				});
+				if(updateFileTitles) {
+					fileManager.updateFileTitles();
+				}
+				localStorage[PROVIDER_DROPBOX + ".lastChangeId"] = newChangeId;
+				callback();
+			});
+		});
+	}
+	
 	dropboxProvider.publish = function(publishAttributes, title, content, callback) {
 		var path = checkPath(publishAttributes.path);
 		if(path === undefined) {

js/file-manager.js

@@ -136,19 +136,13 @@ define(["jquery", "google-helper", "dropbox-helper", "github-helper", "synchroni
 			fileManager.setCurrentFileIndex(fileIndex);
 		}
 		
-		var useGoogleDrive = false;
+		synchronizer.resetSyncFlags();
-		var useDropbox = false;
 		function composeTitle(fileIndex) {
 			var result = " " + localStorage[fileIndex + ".title"];
-			var sync = localStorage[fileIndex + ".sync"];
+			var providerIdList = synchronizer.getSyncProvidersFromFile(fileIndex);
-			if (sync.indexOf(";" + SYNC_PROVIDER_DROPBOX) !== -1) {
+			_.each(providerIdList, function(providerId) {
-				useDropbox = true;
+				result = '<i class="icon-' + providerId '"></i>' + result;
-				result = '<i class="icon-dropbox"></i>' + result;
+			});
-			}
-			if (sync.indexOf(";" + SYNC_PROVIDER_GDRIVE) !== -1) {
-				useGoogleDrive = true;
-				result = '<i class="icon-gdrive"></i>' + result;
-			}
 			return result;
 		}
 
@@ -175,8 +169,6 @@ define(["jquery", "google-helper", "dropbox-helper", "github-helper", "synchroni
 			}
 			$("#file-selector").append(li);			
 		});
-		synchronizer.useGoogleDrive = useGoogleDrive;
-		synchronizer.useDropbox = useDropbox;
 	};
 
 	// Remove a syncIndex (synchronized location)

js/gdrive-provider.js

@@ -5,10 +5,10 @@ define(["jquery", "google-helper", "underscore"], function($, googleHelper) {
 	var fileManager = undefined;
 	
 	var gdriveProvider = {
-		providerType: PROVIDER_TYPE_SYNC_FLAG | PROVIDER_TYPE_PUBLISH_FLAG,
 		providerId: PROVIDER_GDRIVE,
 		providerName: "Gdrive",
-		defaultPublishFormat: "template"
+		defaultPublishFormat: "template",
+		useSync: false
 	};
 	
 	function createSyncAttributes(id, etag, content, title) {
@@ -63,7 +63,7 @@ define(["jquery", "google-helper", "underscore"], function($, googleHelper) {
 	};
 	
 	gdriveProvider.exportFile = function(event, title, content, callback) {
-		googleHelper.upload(undefined, undefined, title, content, function(error, result) {
+		googleHelper.upload(undefined, undefined, title, content, undefined, function(error, result) {
 			if (error) {
 				callback(error);
 				return;
@@ -87,7 +87,7 @@ define(["jquery", "google-helper", "underscore"], function($, googleHelper) {
 			callback(true);
 			return;
 		}
-		googleHelper.upload(id, undefined, title, content, function(error, result) {
+		googleHelper.upload(id, undefined, title, content, undefined, function(error, result) {
 			if (error) {
 				callback(error);
 				return;
@@ -97,8 +97,127 @@ define(["jquery", "google-helper", "underscore"], function($, googleHelper) {
 		});
 	};
 	
+	gdriveProvider.syncUp = function(uploadContent, uploadContentCRC, uploadTitle, uploadTitleCRC, syncAttributes, callback) {
+		var syncContentCRC = syncAttributes.contentCRC;
+		var syncTitleCRC = syncAttributes.titleCRC;
+		// Skip if CRC has not changed
+		if(uploadContentCRC == syncContentCRC && uploadTitleCRC == syncTitleCRC) {
+			callback(undefined, false);
+			return;
+		}
+		googleHelper.upload(syncAttributes.id, undefined, uploadTitle, uploadContent, syncAttributes.etag, function(error, result) {
+			if(error) {
+				callback(error, true);
+				return;
+			}
+			syncAttributes.etag = result.etag;
+			syncAttributes.contentCRC = uploadContentCRC;
+			syncAttributes.titleCRC = uploadTitleCRC;
+			callback(undefined, true);
+		});
+	};
+	
+	function syncDown(callback) {
+		if (gdriveProvider.useSync === false) {
+			callback();
+			return;
+		}
+		var lastChangeId = parseInt(localStorage[PROVIDER_GDRIVE + ".lastChangeId"]);
+		googleHelper.checkChanges(lastChangeId, function(error, changes, newChangeId) {
+			if (error) {
+				callback(error);
+				return;
+			}
+			var interestingChanges = [];
+			_.each(changes, function(change) {
+				var syncIndex = "sync." + PROVIDER_GDRIVE + "." + file.id;
+				var serializedAttributes = localStorage[syncIndex];
+				if(serializedAttributes === undefined) {
+					return;
+				}
+				// Store syncIndex to avoid 2 times formating
+				change.syncIndex = syncIndex;
+				// Delete
+				if(change.deleted === true) {
+					interestingChanges.push(change);
+					return;
+				}
+				// Modify
+				var syncAttributes = JSON.parse(serializedAttributes);
+				if(syncAttributes.etag != change.file.etag) {
+					interestingChanges.push(change);
+					// Store syncAttributes to avoid 2 times parsing 
+					change.syncAttributes = syncAttributes;
+				}
+			});
+			googleHelper.downloadContent(changes, function(error, changes) {
+				if (error) {
+					callback(error);
+					return;
+				}
+				var updateFileTitles = false;
+				_.each(changes, function(change) {
+					var syncIndex = change.syncIndex;
+					var fileIndex = fileManager.getFileIndexFromSync(syncIndex);
+					// No file corresponding (file may have been deleted locally)
+					if(fileIndex === undefined) {
+						fileManager.removeSync(syncIndex);
+						return;
+					}
+					var localTitle = localStorage[fileIndex + ".title"];
+					// File deleted
+					if (change.deleted === true) {
+						fileManager.removeSync(syncIndex);
+						updateFileTitles = true;
+						core.showMessage('"' + localTitle + '" has been removed from Google Drive.');
+						return;
+					}
+					var syncAttributes = change.syncAttributes;
+					var localTitleChanged = syncAttributes.titleCRC != core.crc32(localTitle);
+					var localContent = localStorage[fileIndex + ".content"];
+					var localContentChanged = syncAttributes.contentCRC != core.crc32(localContent);
+					var file = change.file;
+					var fileTitleChanged = localTitle != file.title;
+					var fileContentChanged = localContent != file.content;
+					// Conflict detection
+					if ((fileTitleChanged === true && localTitleChanged === true)
+						|| (fileContentChanged === true && localContentChanged === true)) {
+						fileManager.createFile(localTitle + " (backup)", localContent);
+						updateFileTitles = true;
+						core.showMessage('Conflict detected on "' + localTitle + '". A backup has been created locally.');
+					}
+					// If file title changed
+					if(fileTitleChanged) {
+						localStorage[fileIndex + ".title"] = file.title;
+						updateFileTitles = true;
+						core.showMessage('"' + localTitle + '" has been renamed to "' + file.title + '" on Google Drive.');
+					}
+					// If file content changed
+					if(fileContentChanged) {
+						localStorage[fileIndex + ".content"] = file.content;
+						core.showMessage('"' + file.title + '" has been updated from Google Drive.');
+						if(fileManager.isCurrentFileIndex(fileIndex)) {
+							updateFileTitles = false; // Done by next function
+							fileManager.selectFile(); // Refresh editor
+						}
+					}
+					// Update syncAttributes
+					syncAttributes.etag = file.etag;
+					syncAttributes.contentCRC = core.crc32(file.content);
+					syncAttributes.titleCRC = core.crc32(file.title);
+					localStorage[syncIndex] = JSON.stringify(syncAttributes);
+				});
+				if(updateFileTitles) {
+					fileManager.updateFileTitles();
+				}
+				localStorage[PROVIDER_GDRIVE + ".lastChangeId"] = newChangeId;
+				callback();
+			});
+		});
+	}
+	
 	gdriveProvider.publish = function(publishAttributes, title, content, callback) {
-		googleHelper.upload(publishAttributes.fileId, undefined, title, content, callback);
+		googleHelper.upload(publishAttributes.fileId, undefined, title, content, undefined, callback);
 	};
 
 	gdriveProvider.newPublishAttributes = function(event) {
@@ -122,7 +241,7 @@ define(["jquery", "google-helper", "underscore"], function($, googleHelper) {
 		state = JSON.parse(state);
 		if (state.action == "create") {
 			googleHelper.upload(undefined, state.folderId, GDRIVE_DEFAULT_FILE_TITLE,
-				"", function(error, file) {
+				"", undefined, function(error, file) {
 				if(error) {
 					return;
 				}

js/github-provider.js

@@ -4,7 +4,6 @@ define(["jquery", "github-helper"], function($, githubHelper) {
 	var core = undefined;
 	
 	var githubProvider = {
-		providerType: PROVIDER_TYPE_PUBLISH_FLAG,
 		providerId: PROVIDER_GITHUB,
 		providerName: "GitHub"
 	};

js/google-helper.js

@@ -76,7 +76,7 @@ define(["jquery", "async-runner"], function($, asyncRunner) {
 		});
 	}
 
-	googleHelper.upload = function(fileId, parentId, title, content, callback) {
+	googleHelper.upload = function(fileId, parentId, title, content, etag, callback) {
 		callback = callback || core.doNothing;
 		var result = undefined;
 		var task = asyncRunner.createTask();
@@ -95,13 +95,10 @@ define(["jquery", "async-runner"], function($, asyncRunner) {
 			}
 			var path = '/upload/drive/v2/files';
 			var method = 'POST';
-			var etag = undefined;
 			if (fileId !== undefined) {
 				// If it's an update
 				path += "/" + fileId;
 				method = 'PUT';
-				etag = localStorage[SYNC_PROVIDER_GDRIVE
-										+ fileId + ".etag"];
 			}
 			var headers = { 'Content-Type' : 'multipart/mixed; boundary="'
 				+ boundary + '"', };
@@ -155,7 +152,7 @@ define(["jquery", "async-runner"], function($, asyncRunner) {
 		asyncRunner.addTask(task);
 	};
 
-	googleHelper.checkUpdates = function(lastChangeId, callback) {
+	googleHelper.checkChanges = function(lastChangeId, callback) {
 		callback = callback || core.doNothing;
 		var changes = [];
 		var newChangeId = lastChangeId || 0;
@@ -185,15 +182,7 @@ define(["jquery", "async-runner"], function($, asyncRunner) {
 					newChangeId = response.largestChangeId;
 					nextPageToken = response.nextPageToken;
 					if (response.items !== undefined) {
-						for ( var i = 0; i < response.items.length; i++) {
+						changes = changes.concat(response.items);
-							var item = response.items[i];
-							var etag = localStorage[SYNC_PROVIDER_GDRIVE
-								+ item.fileId + ".etag"];
-							if (etag
-								&& (item.deleted === true || item.file.etag != etag)) {
-								changes.push(item);
-							}
-						}
 					}
 					if (nextPageToken !== undefined) {
 						task.chain(retrievePageOfChanges);

js/publisher.js

@@ -9,7 +9,7 @@ define(["jquery", "github-provider", "blogger-provider", "dropbox-provider", "gd
 	// Create a map with providerName: providerObject
 	var providerMap = _.chain(arguments)
 		.map(function(argument) {
-			return argument && argument.providerType & PROVIDER_TYPE_PUBLISH_FLAG && [argument.providerId, argument];
+			return argument && argument.providerId && [argument.providerId, argument];
 		}).compact().object().value();
 
 	// Used to know if the current file has publications

js/synchronizer.js

@@ -8,7 +8,7 @@ define(["jquery", "google-helper", "dropbox-helper", "dropbox-provider", "gdrive
 	// Create a map with providerName: providerObject
 	var providerMap = _.chain(arguments)
 		.map(function(argument) {
-			return argument && argument.providerType & PROVIDER_TYPE_SYNC_FLAG && [argument.providerId, argument];
+			return argument && argument.providerId && [argument.providerId, argument];
 		}).compact().object().value();
 
 	// Used to know the providers we are connected to 
@@ -59,51 +59,32 @@ define(["jquery", "google-helper", "dropbox-helper", "dropbox-provider", "gdrive
 		
 		// Dequeue a synchronized location
 		var syncIndex = uploadFileSyncIndexList.pop();
-		var syncAttributes = JSON.parse(localStorage[fileSyncIndex]);
+		var syncAttributes = JSON.parse(localStorage[syncIndex]);
-		=
+		// Use the specified provider to perform the upload
-		var syncContentCRC = localStorage[fileSyncIndex + ".contentCRC"];
+		providerMap[syncAttributes.provider].syncUp(
-		var syncTitleCRC = localStorage[fileSyncIndex + ".titleCRC"];
+			uploadContent,
-		// Skip if CRC has not changed
+			uploadContentCRC,
-		if(uploadContentCRC == syncContentCRC && (syncTitleCRC === undefined || uploadTitleCRC == syncTitleCRC)) {
+			uploadTitle,
-			locationUp(callback);
+			uploadTitleCRC,
-			return;
+			syncAttributes,
-		}
+			function(error, uploadFlag) {
-		
+				if(uploadFlag === true) {
-		// If upload is going to run, go for an other upload cycle at the end
+					// If uploadFlag is true, request another upload cycle
 					uploadCycle = true;
-		// When page is refreshed, this flag is false but should be true here
+					// When page is refreshed, this flag is false but should be true
 					uploadPending = true;
-
+				}
-		// Try to find the provider
-		if (fileSyncIndex.indexOf(SYNC_PROVIDER_GDRIVE) === 0) {
-			var id = fileSyncIndex.substring(SYNC_PROVIDER_GDRIVE.length);
-			googleHelper.upload(id, undefined, uploadTitle, uploadContent, function(error, result) {
 				if(error) {
-					// If error we abort the synchronization (retry later)
 					callback(error);
 					return;
 				}
-				localStorage[fileSyncIndex + ".contentCRC"] = uploadContentCRC;
+				if(uploadFlag) {
-				localStorage[fileSyncIndex + ".titleCRC"] = uploadTitleCRC;
+					// Update syncAttributes in localStorage
-				locationUp(callback);
+					localStorage[syncIndex] = JSON.stringify(syncAttributes);
-			});
-		} else if (fileSyncIndex.indexOf(SYNC_PROVIDER_DROPBOX) === 0) {
-			var path = fileSyncIndex.substring(SYNC_PROVIDER_DROPBOX.length);
-			path = decodeURIComponent(path);
-			dropboxHelper.upload(path, uploadContent, function(error, result) {
-				if (error) {
-					// If error we abort the synchronization (retry later)
-					callback(error);
-					return;
 				}
-				localStorage[fileSyncIndex + ".contentCRC"] = uploadContentCRC;
 				locationUp(callback);
-			});
-		} else {
-			// This should never happen
-			console.error("Invalid fileSyncIndex: " + fileSyncIndex);
-			callback("error");
 			}
+		);
 	}
 
 	// Recursive function to upload multiple files
@@ -119,7 +100,7 @@ define(["jquery", "google-helper", "dropbox-helper", "dropbox-provider", "gdrive
 		// Dequeue a fileIndex
 		var fileIndex = uploadFileIndexList.pop();
 		var fileSyncIndexes = localStorage[fileIndex + ".sync"];
-		if(!fileIndex || fileSyncIndexes.length === 1) {
+		if(fileSyncIndexes.length === 1) {
 			fileUp(callback);
 			return;
 		}
@@ -141,7 +122,7 @@ define(["jquery", "google-helper", "dropbox-helper", "dropbox-provider", "gdrive
 		if(uploadCycle === true) {
 			// New upload cycle
 			uploadCycle = false;
-			uploadFileIndexList = localStorage["file.list"].split(";");
+			uploadFileIndexList = _.compact(localStorage["file.list"].split(";"));
 			fileUp(callback);
 		}
 		else {
@@ -149,157 +130,25 @@ define(["jquery", "google-helper", "dropbox-helper", "dropbox-provider", "gdrive
 		} 
 	}
 
-	// Used to download file changes from Google Drive
+	// Recursive function to download changes from multiple providers
-	function syncDownGdrive(callback) {
+	var providerList = [];
-		if (synchronizer.useGoogleDrive === false) {
+	function providerDown(callback) {
+		if(providerList.length === 0) {
 			callback();
-			return;
 		}
-		var lastChangeId = parseInt(localStorage[SYNC_PROVIDER_GDRIVE
+		var provider = providerList.pop();
-			+ "lastChangeId"]);
+		provider.syncDown(function(error) {
-		googleHelper.checkUpdates(lastChangeId, function(error, changes, newChangeId) {
+			if(error) {
-			if (error) {
 				callback(error);
 				return;
 			}
-			googleHelper.downloadContent(changes, function(error, changes) {
+			providerDown(callback);
-				if (error) {
-					callback(error);
-					return;
-				}
-				var updateFileTitles = false;
-				for ( var i = 0; i < changes.length; i++) {
-					var change = changes[i];
-					var fileSyncIndex = SYNC_PROVIDER_GDRIVE + change.fileId;
-					var fileIndex = fileManager.getFileIndexFromSync(fileSyncIndex);
-					// No file corresponding (file may have been deleted locally)
-					if(fileIndex === undefined) {
-						fileManager.removeSync(fileSyncIndex);
-						continue;
-					}
-					var localTitle = localStorage[fileIndex + ".title"];
-					// File deleted
-					if (change.deleted === true) {
-						fileManager.removeSync(fileSyncIndex);
-						updateFileTitles = true;
-						core.showMessage('"' + localTitle + '" has been removed from Google Drive.');
-						continue;
-					}
-					var localTitleChanged = localStorage[fileSyncIndex + ".titleCRC"] != core.crc32(localTitle);
-					var localContent = localStorage[fileIndex + ".content"];
-					var localContentChanged = localStorage[fileSyncIndex + ".contentCRC"] != core.crc32(localContent);
-					var file = change.file;
-					var fileTitleChanged = localTitle != file.title;
-					var fileContentChanged = localContent != file.content;
-					// Conflict detection
-					if ((fileTitleChanged === true && localTitleChanged === true)
-						|| (fileContentChanged === true && localContentChanged === true)) {
-						fileManager.createFile(localTitle + " (backup)", localContent);
-						updateFileTitles = true;
-						core.showMessage('Conflict detected on "' + localTitle + '". A backup has been created locally.');
-					}
-					// If file title changed
-					if(fileTitleChanged) {
-						localStorage[fileIndex + ".title"] = file.title;
-						updateFileTitles = true;
-						core.showMessage('"' + localTitle + '" has been renamed to "' + file.title + '" on Google Drive.');
-					}
-					// If file content changed
-					if(fileContentChanged) {
-						localStorage[fileIndex + ".content"] = file.content;
-						core.showMessage('"' + file.title + '" has been updated from Google Drive.');
-						if(fileManager.isCurrentFileIndex(fileIndex)) {
-							updateFileTitles = false; // Done by next function
-							fileManager.selectFile(); // Refresh editor
-						}
-					}
-					// Update file etag and CRCs
-					localStorage[fileSyncIndex + ".etag"] = file.etag;
-					localStorage[fileSyncIndex + ".contentCRC"] = core.crc32(file.content);
-					localStorage[fileSyncIndex + ".titleCRC"] = core.crc32(file.title);
-				}
-				if(updateFileTitles) {
-					fileManager.updateFileTitles();
-				}
-				localStorage[SYNC_PROVIDER_GDRIVE
-				 			+ "lastChangeId"] = newChangeId;
-				callback();
-			});
-		});
-	}
-
-	// Used to download file changes from Dropbox
-	function syncDownDropbox(callback) {
-		if (synchronizer.useDropbox === false) {
-			callback();
-			return;
-		}
-		var lastChangeId = localStorage[SYNC_PROVIDER_DROPBOX + "lastChangeId"];
-		dropboxHelper.checkUpdates(lastChangeId, function(error, changes, newChangeId) {
-			if (error) {
-				callback(error);
-				return;
-			}
-			dropboxHelper.downloadContent(changes, function(error, changes) {
-				if (error) {
-					callback(error);
-					return;
-				}
-				var updateFileTitles = false;
-				for ( var i = 0; i < changes.length; i++) {
-					var change = changes[i];
-					var fileSyncIndex = SYNC_PROVIDER_DROPBOX + encodeURIComponent(change.path.toLowerCase());
-					var fileIndex = fileManager.getFileIndexFromSync(fileSyncIndex);
-					// No file corresponding (file may have been deleted locally)
-					if(fileIndex === undefined) {
-						fileManager.removeSync(fileSyncIndex);
-						continue;
-					}
-					var localTitle = localStorage[fileIndex + ".title"];
-					// File deleted
-					if (change.wasRemoved === true) {
-						fileManager.removeSync(fileSyncIndex);
-						updateFileTitles = true;
-						core.showMessage('"' + localTitle + '" has been removed from Dropbox.');
-						continue;
-					}
-					var localContent = localStorage[fileIndex + ".content"];
-					var localContentChanged = localStorage[fileSyncIndex + ".contentCRC"] != core.crc32(localContent);
-					var file = change.stat;
-					var fileContentChanged = localContent != file.content;
-					// Conflict detection
-					if (fileContentChanged === true && localContentChanged === true) {
-						fileManager.createFile(localTitle + " (backup)", localContent);
-						updateFileTitles = true;
-						core.showMessage('Conflict detected on "' + localTitle + '". A backup has been created locally.');
-					}
-					// If file content changed
-					if(fileContentChanged) {
-						localStorage[fileIndex + ".content"] = file.content;
-						core.showMessage('"' + localTitle + '" has been updated from Dropbox.');
-						if(fileManager.isCurrentFileIndex(fileIndex)) {
-							updateFileTitles = false; // Done by next function
-							fileManager.selectFile(); // Refresh editor
-						}
-					}
-					// Update file version and CRC
-					localStorage[fileSyncIndex + ".version"] = file.versionTag;
-					localStorage[fileSyncIndex + ".contentCRC"] = core.crc32(file.content);
-				}
-				if(updateFileTitles) {
-					fileManager.updateFileTitles();
-				}
-				localStorage[SYNC_PROVIDER_DROPBOX
-				             + "lastChangeId"] = newChangeId;
-				callback();
-			});
 		});
 	}
 	
 	function syncDown(callback) {
-		syncDownGdrive(function() {
+		providerList = _.values(providerMap);
-			syncDownDropbox(callback);
+		providerDown(callback);
-		});
 	};
 		
 	var syncRunning = false;
@@ -316,6 +165,7 @@ define(["jquery", "google-helper", "dropbox-helper", "dropbox-provider", "gdrive
 		
 		function isError(error) {
 			if(error !== undefined) {
+				console.error(error);
 				syncRunning = false;
 				synchronizer.updateSyncButton();
 				return true;
@@ -369,6 +219,24 @@ define(["jquery", "google-helper", "dropbox-helper", "dropbox-provider", "gdrive
 		});
 	};
 	
+	synchronizer.resetSyncFlags = function() {
+		_.each(providerMap, function(provider) {
+			provider.useSync = false;
+		});		
+	};
+	
+	synchronizer.getSyncProvidersFromFile = function(fileIndex) {
+		var sync = localStorage[fileIndex + ".sync"];
+		var providerIdList = [];
+		_.each(providerMap, function(provider) {
+			if (sync.indexOf(";sync." + provider.providerId + ".") !== -1) {
+				provider.useSync = true;
+				providerIdList.push(provider.providerId);
+			}
+		});
+		return providerIdList;
+	};
+	
 	synchronizer.init = function(coreModule, fileManagerModule) {
 		core = coreModule;
 		fileManager = fileManagerModule;