feat: protect pdf

src/lib/ghostscript/background-worker.js

@@ -1,10 +1,12 @@
+import { COMPRESS_ACTION, PROTECT_ACTION } from './worker-init';
+
 function loadScript() {
   import('./gs-worker.js');
 }
 
 var Module;
 
-function _GSPS2PDF(dataStruct, responseCallback) {
+function compressPdf(dataStruct, responseCallback) {
   const compressionLevel = dataStruct.compressionLevel || 'medium';
 
   // Set PDF settings based on compression level
@@ -44,7 +46,11 @@ function _GSPS2PDF(dataStruct, responseCallback) {
           });
           var blob = new Blob([uarray], { type: 'application/octet-stream' });
           var pdfDataURL = self.URL.createObjectURL(blob);
-          responseCallback({ pdfDataURL: pdfDataURL, url: dataStruct.url });
+          responseCallback({
+            pdfDataURL: pdfDataURL,
+            url: dataStruct.url,
+            type: COMPRESS_ACTION
+          });
         }
       ],
       arguments: [
@@ -76,6 +82,77 @@ function _GSPS2PDF(dataStruct, responseCallback) {
   xhr.send();
 }
 
+function protectPdf(dataStruct, responseCallback) {
+  const password = dataStruct.password || '';
+
+  // Validate password
+  if (!password) {
+    responseCallback({
+      error: 'Password is required for encryption',
+      url: dataStruct.url
+    });
+    return;
+  }
+  var xhr = new XMLHttpRequest();
+  xhr.open('GET', dataStruct.psDataURL);
+  xhr.responseType = 'arraybuffer';
+  xhr.onload = function () {
+    console.log('onload');
+    // release the URL
+    self.URL.revokeObjectURL(dataStruct.psDataURL);
+    //set up EMScripten environment
+    Module = {
+      preRun: [
+        function () {
+          self.Module.FS.writeFile('input.pdf', new Uint8Array(xhr.response));
+        }
+      ],
+      postRun: [
+        function () {
+          var uarray = self.Module.FS.readFile('output.pdf', {
+            encoding: 'binary'
+          });
+          var blob = new Blob([uarray], { type: 'application/octet-stream' });
+          var pdfDataURL = self.URL.createObjectURL(blob);
+          responseCallback({
+            pdfDataURL: pdfDataURL,
+            url: dataStruct.url,
+            type: PROTECT_ACTION
+          });
+        }
+      ],
+      arguments: [
+        '-sDEVICE=pdfwrite',
+        '-dCompatibilityLevel=1.4',
+        `-sOwnerPassword=${password}`,
+        `-sUserPassword=${password}`,
+        // Permissions (prevent copying/printing/etc)
+        '-dEncryptionPermissions=-4',
+        '-DNOPAUSE',
+        '-dQUIET',
+        '-dBATCH',
+        '-sOutputFile=output.pdf',
+        'input.pdf'
+      ],
+      print: function (text) {},
+      printErr: function (text) {},
+      totalDependencies: 0,
+      noExitRuntime: 1
+    };
+    // Module.setStatus("Loading Ghostscript...");
+    if (!self.Module) {
+      self.Module = Module;
+      loadScript();
+    } else {
+      self.Module['calledRun'] = false;
+      self.Module['postRun'] = Module.postRun;
+      self.Module['preRun'] = Module.preRun;
+      self.Module.callMain();
+    }
+  };
+  xhr.send();
+}
+
 self.addEventListener('message', function ({ data: e }) {
   console.log('message', e);
   // e.data contains the message sent to the worker.
@@ -83,7 +160,14 @@ self.addEventListener('message', function ({ data: e }) {
     return;
   }
   console.log('Message received from main script', e.data);
-  _GSPS2PDF(e.data, ({ pdfDataURL }) => self.postMessage(pdfDataURL));
+  const responseCallback = ({ pdfDataURL, type }) => {
+    self.postMessage(pdfDataURL);
+  };
+  if (e.data.type === COMPRESS_ACTION) {
+    compressPdf(e.data, responseCallback);
+  } else if (e.data.type === PROTECT_ACTION) {
+    protectPdf(e.data, responseCallback);
+  }
 });
 
 console.log('Worker ready');