3 files changed, 138 insertions, 4 deletions

diff --git a/src/client/util/DragManager.ts b/src/client/util/DragManager.ts
index 337ec855a..eb4b3aeaa 100644
--- a/src/client/util/DragManager.ts
+++ b/src/client/util/DragManager.ts
@@ -1,3 +1,4 @@
+import { DocumentDecorations } from "../views/DocumentDecorations";
 
 export namespace DragManager {
     export function Root() {
@@ -43,6 +44,7 @@ export namespace DragManager {
         drop: (e: Event, de: DropEvent) => void;
     }
 
+
     export function MakeDropTarget(element: HTMLElement, options: DropOptions): DragDropDisposer {
         if ("canDrop" in element.dataset) {
             throw new Error("Element is already droppable, can't make it droppable again");
@@ -59,10 +61,8 @@ export namespace DragManager {
         };
     }
 
-
-    let _lastPointerX: number = 0;
-    let _lastPointerY: number = 0;
     export function StartDrag(ele: HTMLElement, dragData: { [id: string]: any }, options: DragOptions) {
+        DocumentDecorations.Instance.Hidden = true;
         if (!dragDiv) {
             dragDiv = document.createElement("div");
             DragManager.Root().appendChild(dragDiv);
@@ -131,5 +131,6 @@ export namespace DragManager {
             }
         }));
         options.handlers.dragComplete({});
+        DocumentDecorations.Instance.Hidden = false;
     }
 }
\ No newline at end of file
diff --git a/src/client/util/Scripting.ts b/src/client/util/Scripting.ts
index 6bc5fa412..befb9df4c 100644
--- a/src/client/util/Scripting.ts
+++ b/src/client/util/Scripting.ts
@@ -6,7 +6,7 @@ import { NumberField as NumberFieldImport, NumberField } from "../../fields/Numb
 import { ImageField as ImageFieldImport } from "../../fields/ImageField";
 import { TextField as TextFieldImport, TextField } from "../../fields/TextField";
 import { RichTextField as RichTextFieldImport } from "../../fields/RichTextField";
-import { KeyStore as KeyStoreImport } from "../../fields/Key";
+import { KeyStore as KeyStoreImport } from "../../fields/KeyStore";
 
 export interface ExecutableScript {
     (): any;
diff --git a/src/client/util/UndoManager.ts b/src/client/util/UndoManager.ts
new file mode 100644
index 000000000..46ad558f3
--- /dev/null
+++ b/src/client/util/UndoManager.ts
@@ -0,0 +1,133 @@
+import { observable, action } from "mobx";
+
+function propertyDecorator(target: any, key: string | symbol) {
+    Object.defineProperty(target, key, {
+        configurable: true,
+        enumerable: false,
+        get: function () {
+            return 5;
+        },
+        set: function (value: any) {
+            Object.defineProperty(this, key, {
+                enumerable: false,
+                writable: true,
+                configurable: true,
+                value: function (...args: any[]) {
+                    try {
+                        UndoManager.StartBatch();
+                        return value.apply(this, args);
+                    } finally {
+                        UndoManager.EndBatch();
+                    }
+                }
+            })
+        }
+    })
+}
+export function undoBatch(target: any, key: string | symbol, descriptor?: TypedPropertyDescriptor<any>): any {
+    if (!descriptor) {
+        propertyDecorator(target, key);
+        return;
+    }
+    const oldFunction = descriptor.value;
+
+    descriptor.value = function (...args: any[]) {
+        try {
+            UndoManager.StartBatch()
+            return oldFunction.apply(this, args)
+        } finally {
+            UndoManager.EndBatch()
+        }
+    }
+
+    return descriptor;
+}
+
+export namespace UndoManager {
+    export interface UndoEvent {
+        undo: () => void;
+        redo: () => void;
+    }
+    type UndoBatch = UndoEvent[];
+
+    let undoStack: UndoBatch[] = observable([]);
+    let redoStack: UndoBatch[] = observable([]);
+    let currentBatch: UndoBatch | undefined;
+    let batchCounter = 0;
+    let undoing = false;
+
+    export function AddEvent(event: UndoEvent): void {
+        if (currentBatch && batchCounter && !undoing) {
+            currentBatch.push(event);
+        }
+    }
+
+    export function CanUndo(): boolean {
+        return undoStack.length > 0;
+    }
+
+    export function CanRedo(): boolean {
+        return redoStack.length > 0;
+    }
+
+    export function StartBatch(): void {
+        batchCounter++;
+        if (batchCounter > 0) {
+            currentBatch = [];
+        }
+    }
+
+    export const EndBatch = action(() => {
+        batchCounter--;
+        if (batchCounter === 0 && currentBatch && currentBatch.length) {
+            undoStack.push(currentBatch);
+            redoStack.length = 0;
+            currentBatch = undefined;
+        }
+    })
+
+    export function RunInBatch(fn: () => void) {
+        StartBatch();
+        fn();
+        EndBatch();
+    }
+
+    export const Undo = action(() => {
+        if (undoStack.length === 0) {
+            return;
+        }
+
+        let commands = undoStack.pop();
+        if (!commands) {
+            return;
+        }
+
+        undoing = true;
+        for (let i = commands.length - 1; i >= 0; i--) {
+            commands[i].undo();
+        }
+        undoing = false;
+
+        redoStack.push(commands);
+    })
+
+    export const Redo = action(() => {
+        if (redoStack.length === 0) {
+            return;
+        }
+
+        let commands = redoStack.pop();
+        if (!commands) {
+            return;
+        }
+
+        undoing = true;
+        for (let i = 0; i < commands.length; i++) {
+            commands[i].redo();
+        }
+        undoing = false;
+
+        undoStack.push(commands);
+    })
+
+}
\ No newline at end of file