仅保存20条记录, ctrl+s, ctrl+e时保存历史记录. 自动保存时不添加到历史记录中

https://github.com/leanote/desktop-app/issues/70

node_modules/note.js

@@ -43,7 +43,7 @@ type NoteOrContent struct {
 // 笔记服务
 var Note = {
 	// 更新笔记
-	updateNoteOrContent: function(noteOrContent, callback) {
+	updateNoteOrContent: function(noteOrContent, callback, needAddToHistory) {
 		var me = this;
 
 		// Web.alertWeb(process.type); // render
@@ -153,7 +153,11 @@ var Note = {
 							callback && callback(noteOrContent);
 
 							if('Content' in updates) {
-								me.addNoteHistory(noteOrContent.NoteId, noteOrContent.Content);
+
+								// 需要添加到历史记录中才加
+								if (needAddToHistory) {
+									me.addNoteHistory(noteOrContent.NoteId, noteOrContent.Content);
+								}
 							}
 						}
 					});
@@ -207,18 +211,29 @@ var Note = {
 	addNoteHistory: function(noteId, content) {
 		var me = this;
 		db.noteHistories.loadDB(function (ok) {
+			if (!ok) {
+				return;
+			}
 			// 先判断是否存在, 不存在则新建之
 			db.noteHistories.findOne({_id: noteId}, function(err, history) {
+				var now = new Date();
 				// 新建之
 				if(!history) {
-					db.noteHistories.insert({_id: noteId, Histories: [content], "UpdatedTime": new Date()});
+					db.noteHistories.insert({_id: noteId, Histories: [{Content: content, "UpdatedTime": now}], "UpdatedTime": now});
 				}
 				// 更新之
 				else {
 					var histories = history.Histories;
-					histories.push({Content: content, UpdatedTime: new Date()});
+					histories.push({Content: content, UpdatedTime: now});
 
-					// 不能多了, 多了有麻烦
+					// 不能多了, 多了有麻烦, 20个最多
+					var max = 20;
+					var len = histories.length;
+					if (len > max) {
+						for (var i = 0; i < len - max; ++i) {
+							histories.shift();
+						}
+					}
 
 					db.noteHistories.update({_id: noteId}, {$set: {Histories: histories}});
 				}
@@ -241,7 +256,7 @@ var Note = {
 			}
 			db.noteHistories.findOne({_id: noteId}, function(err, doc) {
 				if(err || !doc) {
-					callback(false);
+					callback([]);
 				}
 				else {
 					var histories = [];