feat(test): add comprehensive test suite and testing infrastructure

- Add vitest configuration with coverage reporting
- Create test setup file with DOM mocks
- Add tests for state management, helpers, and tool configurations
- Update tsconfig and package.json for testing support
- Clean up unused comments and improve code style

src/js/logic/change-permissions.ts

@@ -7,7 +7,6 @@ import blobStream from 'blob-stream';
 import * as pdfjsLib from "pdfjs-dist";
 
 export async function changePermissions() {
-    // --- 1. GATHER INPUTS FROM THE NEW UI ---
     const currentPassword = (document.getElementById('current-password') as HTMLInputElement).value;
     const newUserPassword = (document.getElementById('new-user-password') as HTMLInputElement).value;
     const newOwnerPassword = (document.getElementById('new-owner-password') as HTMLInputElement).value;
@@ -24,7 +23,6 @@ export async function changePermissions() {
         const file = state.files[0];
         const pdfData = await readFileAsArrayBuffer(file);
         
-        // --- 2. UNLOCK PDF WITH CURRENT PASSWORD ---
         let pdf;
         try {
             pdf = await pdfjsLib.getDocument({ 
@@ -38,10 +36,9 @@ export async function changePermissions() {
                 showAlert('Incorrect Password', 'The current password you entered is incorrect.');
                 return;
             }
-            throw e; // Re-throw other errors
+            throw e; 
         }
         
-        // --- 3. RASTERIZE PAGES (UNCHANGED LOGIC) ---
         const numPages = pdf.numPages;
         const pageImages = [];
 
@@ -63,7 +60,6 @@ export async function changePermissions() {
 
         document.getElementById('loader-text').textContent = 'Applying new permissions...';
         
-        // --- 4. GATHER ALL PERMISSION CHECKBOX VALUES ---
         const allowPrinting = (document.getElementById('allow-printing') as HTMLInputElement).checked;
         const allowCopying = (document.getElementById('allow-copying') as HTMLInputElement).checked;
         const allowModifying = (document.getElementById('allow-modifying') as HTMLInputElement).checked;
@@ -72,10 +68,10 @@ export async function changePermissions() {
         const allowContentAccessibility = (document.getElementById('allow-content-accessibility') as HTMLInputElement).checked;
         const allowDocumentAssembly = (document.getElementById('allow-document-assembly') as HTMLInputElement).checked;
 
-        // --- 5. CREATE NEW PDF WITH PDFKIT USING ALL NEW SETTINGS ---
+
         const doc = new PDFDocument({
             size: [pageImages[0].width, pageImages[0].height],
-            pdfVersion: '1.7ext3', // Use 256-bit AES encryption
+            pdfVersion: '1.7ext3', // Uses 256-bit AES encryption
             
             // Apply the new, separate user and owner passwords
             userPassword: newUserPassword,
@@ -104,8 +100,6 @@ export async function changePermissions() {
         }
         
         doc.end();
-
-        // --- 6. FINALIZE AND DOWNLOAD (UNCHANGED LOGIC) ---
         stream.on('finish', function () {
             const blob = stream.toBlob('application/pdf');
             downloadFile(blob, `permissions-changed-${file.name}`);

src/js/logic/cropper.ts

@@ -169,8 +169,6 @@ async function performMetadataCrop(pdfToModify: any, cropData: any) {
     }
 }
 
-// FILE: js/logic/cropper.js
-
 /**
  * Performs a destructive crop by flattening the selected area to an image.
  */
@@ -179,8 +177,6 @@ async function performFlatteningCrop(cropData: any) {
     
     // Load the original PDF with pdf-lib to copy un-cropped pages from
     const sourcePdfDocForCopying = await PDFLibDocument.load(cropperState.originalPdfBytes);
-
-    // CORRECTED: Use .numPages from the pdf.js document object
     const totalPages = cropperState.pdfDoc.numPages;
 
     for (let i = 0; i < totalPages; i++) {
@@ -217,7 +213,6 @@ async function performFlatteningCrop(cropData: any) {
             const newPage = newPdfDoc.addPage([finalWidth, finalHeight]);
             newPage.drawImage(embeddedImage, { x: 0, y: 0, width: finalWidth, height: finalHeight });
         } else {
-            // Correctly copy the page from the source pdf-lib document
             const [copiedPage] = await newPdfDoc.copyPages(sourcePdfDocForCopying, [i]);
             newPdfDoc.addPage(copiedPage);
         }
@@ -225,9 +220,7 @@ async function performFlatteningCrop(cropData: any) {
     return newPdfDoc;
 }
 
-/**
- * Main function to set up the Cropper tool.
- */
+
 export async function setupCropperTool() {
     if (state.files.length === 0) return;
 
@@ -237,16 +230,12 @@ export async function setupCropperTool() {
     const arrayBuffer = await readFileAsArrayBuffer(state.files[0]);
     cropperState.originalPdfBytes = arrayBuffer;
     const arrayBufferForPdfJs = (arrayBuffer as ArrayBuffer).slice(0);
-
-
-    // pdfjsLib.GlobalWorkerOptions.workerSrc = `https://cdnjs.cloudflare.com/ajax/libs/pdf.js/2.16.105/pdf.worker.min.js`;
     pdfjsLib.GlobalWorkerOptions.workerSrc = new URL(
         'pdfjs-dist/build/pdf.worker.min.mjs',
         import.meta.url
     ).toString();
 
     try {
-        // const loadingTask = pdfjsLib.getDocument({ data: cropperState.originalPdfBytes });
         const loadingTask = pdfjsLib.getDocument({ data: arrayBufferForPdfJs }); 
 
         cropperState.pdfDoc = await loadingTask.promise;

src/js/logic/invert-colors.ts

@@ -1,4 +1,3 @@
-// FILE: js/logic/invert-colors.js
 import { showLoader, hideLoader, showAlert } from '../ui.js';
 import { downloadFile } from '../utils/helpers.js';
 import { state } from '../state.js';