Merge pull request #36 from jb-leger/undo_in_server_part

undo buffer also in server part for redo

README.md

@@ -43,7 +43,7 @@ Result | Windows and Linux | macOS
 ------ | -------------------- | -------
 Clear the whiteboard | Ctrl + Shift + Z | Command + Shift + Z
 Undo your last step | Ctrl + Z | Command + Z
-Redo your last undo | Ctrl + Shift + Z | Command + + Shift + Z
+Redo your last undo | Ctrl + Shift + Z | Command + Shift + Z
 Select an area | Ctrl + X | Command + X
 Take the mouse | Ctrl + M | Command + M
 Take the pen | Ctrl + P | Command + P

s_whiteboard.js

@@ -1,6 +1,7 @@
 //This file is only for saving the whiteboard. (Not to a file, only to RAM atm. Whiteboard is gone after server restart)
 
 var savedBoards = {};
+var savedUndos = {};
 module.exports = {
     handleEventsAndData: function (content) {
         var tool = content["t"]; //Tool witch is used
@@ -8,19 +9,46 @@ module.exports = {
         var username = content["username"];
         if (tool === "clear") { //Clear the whiteboard
             delete savedBoards[wid];
+            delete savedUndos[wid];
         } else if (tool === "undo") { //Undo an action
+            if (!savedUndos[wid]) {
+                savedUndos[wid] = [];
+            }
             if (savedBoards[wid]) {
                 for (var i = savedBoards[wid].length - 1; i >= 0; i--) {
                     if (savedBoards[wid][i]["username"] == username) {
                         var drawId = savedBoards[wid][i]["drawId"];
                         for (var i = savedBoards[wid].length - 1; i >= 0; i--) {
                             if (savedBoards[wid][i]["drawId"] == drawId && savedBoards[wid][i]["username"] == username) {
+                                savedUndos[wid].push(savedBoards[wid][i]);
                                 savedBoards[wid].splice(i, 1);
                             }
                         }
                         break;
                     }
                 }
+                if(savedUndos[wid].length > 1000) {
+                    savedUndos[wid].splice(0, savedUndos[wid].length - 1000);
+                }
+            }
+        } else if (tool === "redo") {
+            if (!savedUndos[wid]) {
+                savedUndos[wid] = [];
+            }
+            if (!savedBoards[wid]) {
+                savedBoards[wid] = [];
+            }
+            for (var i = savedUndos[wid].length - 1; i >= 0; i--) {
+                if (savedUndos[wid][i]["username"] == username) {
+                    var drawId = savedUndos[wid][i]["drawId"];
+                    for (var i = savedUndos[wid].length - 1; i >= 0; i--) {
+                        if (savedUndos[wid][i]["drawId"] == drawId && savedUndos[wid][i]["username"] == username) {
+                            savedBoards[wid].push(savedUndos[wid][i]);
+                            savedUndos[wid].splice(i, 1);
+                        }
+                    }
+                    break;
+                }
             }
         } else if (["line", "pen", "rect", "circle", "eraser", "addImgBG", "recSelect", "eraseRec", "addTextBox", "setTextboxText", "removeTextbox", "setTextboxPosition", "setTextboxFontSize", "setTextboxFontColor"].includes(tool)) { //Save all this actions
             if (!savedBoards[wid]) {