From 65c4f959e807d182f16c8dfd2893e094c1cb8692 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=40Siemienik=20Pawe=C5=82?= <siemienik.pawel@gmail.com>
Date: Mon, 20 Nov 2023 23:14:55 +0100
Subject: [PATCH] Using Proxy to prevent against modification the original view
 model.

Fixes https://github.com/Siemienik/XToolset/issues/137
Fixes https://github.com/Siemienik/XToolset/issues/229
---
 packages/xlsx-renderer/src/Renderer.ts        | 14 +++--------
 packages/xlsx-renderer/src/ViewModel.ts       | 21 ++++++++++++++++
 .../tests/spec/cell-value-type.test.ts        | 25 +++++++++++++++++++
 3 files changed, 50 insertions(+), 10 deletions(-)
 create mode 100644 packages/xlsx-renderer/tests/spec/cell-value-type.test.ts

diff --git a/packages/xlsx-renderer/src/Renderer.ts b/packages/xlsx-renderer/src/Renderer.ts
index 5fb357c..b4c5a0a 100644
--- a/packages/xlsx-renderer/src/Renderer.ts
+++ b/packages/xlsx-renderer/src/Renderer.ts
@@ -2,6 +2,7 @@ import { Workbook } from 'exceljs';
 
 import { Scope } from './Scope';
 import { CellTemplatePool } from './CellTemplatePool';
+import { createVmProxyHandler } from './ViewModel';
 
 export class Renderer {
     constructor(private cellTemplatePool: CellTemplatePool = new CellTemplatePool()) {}
@@ -10,10 +11,7 @@ export class Renderer {
         const template = await templateFactory();
         const output = await templateFactory();
 
-        // todo Temporary fixation for VM mutating problem, @see https://github.com/Siemienik/XToolset/issues/137
-        const vmCopy = JSON.parse(JSON.stringify(vm));
-
-        const scope = new Scope(template, output, vmCopy);
+        const scope = new Scope(template, output, new Proxy(vm, createVmProxyHandler()));
 
         while (!scope.isFinished()) {
             this.cellTemplatePool.match(scope.getCurrentTemplateCell()).apply(scope);
@@ -23,20 +21,16 @@ export class Renderer {
     }
 
     public async renderFromFile(templatePath: string, viewModel: unknown): Promise<Workbook> {
-        const result = await this.render(async () => {
+        return this.render(async () => {
             const template = new Workbook();
             return await template.xlsx.readFile(templatePath);
         }, viewModel);
-
-        return await result;
     }
 
     public async renderFromArrayBuffer(templateArrayBuffer: ArrayBuffer, viewModel: unknown): Promise<Workbook> {
-        const result = await this.render(async () => {
+        return this.render(async () => {
             const template = new Workbook();
             return await template.xlsx.load(templateArrayBuffer);
         }, viewModel);
-
-        return await result;
     }
 }
diff --git a/packages/xlsx-renderer/src/ViewModel.ts b/packages/xlsx-renderer/src/ViewModel.ts
index e5671f0..09481fd 100644
--- a/packages/xlsx-renderer/src/ViewModel.ts
+++ b/packages/xlsx-renderer/src/ViewModel.ts
@@ -1 +1,22 @@
 export type ViewModel = any;
+
+export const createVmProxyHandler = ()=> {
+    const data: Record<string | number, unknown> = {};
+
+    return {
+        get(target: any, p: PropertyKey): any {
+            if (typeof p !== 'string' && typeof p !== 'number') {
+                return;
+            }
+            return p in data ? data[p] : target[p]
+        },
+        set(target: unknown, p: PropertyKey, value: unknown): boolean {
+            if (typeof p !== 'string' && typeof p !== 'number') {
+                return false;
+            }
+            data[p] = value
+
+            return true
+        },
+    }
+}
diff --git a/packages/xlsx-renderer/tests/spec/cell-value-type.test.ts b/packages/xlsx-renderer/tests/spec/cell-value-type.test.ts
new file mode 100644
index 0000000..e8a956d
--- /dev/null
+++ b/packages/xlsx-renderer/tests/spec/cell-value-type.test.ts
@@ -0,0 +1,25 @@
+import * as chai from 'chai';
+import { CellValue, Workbook } from 'exceljs';
+import { ValueType } from 'exceljs';
+import { Renderer } from '../../src/Renderer';
+
+const WS_NAME = 'test ws';
+
+describe('BaseCell unit tests', () => {
+    const factory = async ():Promise<Workbook> =>{
+        const template = new Workbook();
+        template.addWorksheet(WS_NAME).addRow(['## testVar', "#! FINISH"]);
+
+        return template;
+    }
+
+    it('DateTime', async () => {
+        const viewModel = {
+            testVar: new Date(2023, 11, 17, 21, 37)
+        }
+        const renderer = new Renderer();
+        const output = await renderer.render(factory, viewModel)
+
+        chai.expect(output.getWorksheet(WS_NAME)?.getCell('A1').type).equals(ValueType.Date);
+    });
+});