feat(base64): Base64 enhancements (#905)

* fix(base64): use js-base64 to handle non ascii text

Use js-base64 to handle non ascii text and ignore whitespaces
Fix #879 and #409

* fix(base64): use js-base64 to handle non ascii text

Use js-base64 to handle non ascii text and ignore whitespaces
Fix #879 and #409

* feat(base64 file converter): add a filename and extension fields

Add filename and extension (auto filled if data url) to allow downloading with right extension and filename
Fix #788

* feat(base64 file converter): add a preview image

Fix #594. Taken from #595 (thanks @SAF2k)

src/composable/downloadBase64.ts

@@ -1,8 +1,13 @@
-import { extension as getExtensionFromMime } from 'mime-types';
+import { extension as getExtensionFromMimeType, extension as getMimeTypeFromExtension } from 'mime-types';
 import type { Ref } from 'vue';
 import _ from 'lodash';
 
-export { getMimeTypeFromBase64, useDownloadFileFromBase64 };
+export {
+  getMimeTypeFromBase64,
+  getMimeTypeFromExtension, getExtensionFromMimeType,
+  useDownloadFileFromBase64, useDownloadFileFromBase64Refs,
+  previewImageFromBase64,
+};
 
 const commonMimeTypesSignatures = {
   'JVBERi0': 'application/pdf',
@@ -36,30 +41,78 @@ function getFileExtensionFromMimeType({
   defaultExtension?: string
 }) {
   if (mimeType) {
-    return getExtensionFromMime(mimeType) ?? defaultExtension;
+    return getExtensionFromMimeType(mimeType) ?? defaultExtension;
   }
 
   return defaultExtension;
 }
 
-function useDownloadFileFromBase64({ source, filename }: { source: Ref<string>; filename?: string }) {
+function downloadFromBase64({ sourceValue, filename, extension, fileMimeType }:
+{ sourceValue: string; filename?: string; extension?: string; fileMimeType?: string }) {
+  if (sourceValue === '') {
+    throw new Error('Base64 string is empty');
+  }
+
+  const defaultExtension = extension ?? 'txt';
+  const { mimeType } = getMimeTypeFromBase64({ base64String: sourceValue });
+  let base64String = sourceValue;
+  if (!mimeType) {
+    const targetMimeType = fileMimeType ?? getMimeTypeFromExtension(defaultExtension);
+    base64String = `data:${targetMimeType};base64,${sourceValue}`;
+  }
+
+  const cleanExtension = extension ?? getFileExtensionFromMimeType(
+    { mimeType, defaultExtension });
+  let cleanFileName = filename ?? `file.${cleanExtension}`;
+  if (extension && !cleanFileName.endsWith(`.${extension}`)) {
+    cleanFileName = `${cleanFileName}.${cleanExtension}`;
+  }
+
+  const a = document.createElement('a');
+  a.href = base64String;
+  a.download = cleanFileName;
+  a.click();
+}
+
+function useDownloadFileFromBase64(
+  { source, filename, extension, fileMimeType }:
+  { source: Ref<string>; filename?: string; extension?: string; fileMimeType?: string }) {
   return {
     download() {
-      if (source.value === '') {
-        throw new Error('Base64 string is empty');
-      }
-
-      const { mimeType } = getMimeTypeFromBase64({ base64String: source.value });
-      const base64String = mimeType
-        ? source.value
-        : `data:text/plain;base64,${source.value}`;
-
-      const cleanFileName = filename ?? `file.${getFileExtensionFromMimeType({ mimeType })}`;
-
-      const a = document.createElement('a');
-      a.href = base64String;
-      a.download = cleanFileName;
-      a.click();
+      downloadFromBase64({ sourceValue: source.value, filename, extension, fileMimeType });
     },
   };
 }
+
+function useDownloadFileFromBase64Refs(
+  { source, filename, extension }:
+  { source: Ref<string>; filename?: Ref<string>; extension?: Ref<string> }) {
+  return {
+    download() {
+      downloadFromBase64({ sourceValue: source.value, filename: filename?.value, extension: extension?.value });
+    },
+  };
+}
+
+function previewImageFromBase64(base64String: string): HTMLImageElement {
+  if (base64String === '') {
+    throw new Error('Base64 string is empty');
+  }
+
+  const img = document.createElement('img');
+  img.src = base64String;
+
+  const container = document.createElement('div');
+  container.appendChild(img);
+
+  const previewContainer = document.getElementById('previewContainer');
+  if (previewContainer) {
+    previewContainer.innerHTML = '';
+    previewContainer.appendChild(container);
+  }
+  else {
+    throw new Error('Preview container element not found');
+  }
+
+  return img;
+}

src/tools/base64-file-converter/base64-file-converter.vue

@@ -2,12 +2,19 @@
 import { useBase64 } from '@vueuse/core';
 import type { Ref } from 'vue';
 import { useCopy } from '@/composable/copy';
-import { useDownloadFileFromBase64 } from '@/composable/downloadBase64';
+import { getExtensionFromMimeType, getMimeTypeFromBase64, previewImageFromBase64, useDownloadFileFromBase64Refs } from '@/composable/downloadBase64';
 import { useValidation } from '@/composable/validation';
 import { isValidBase64 } from '@/utils/base64';
 
+const fileName = ref('file');
+const fileExtension = ref('');
 const base64Input = ref('');
-const { download } = useDownloadFileFromBase64({ source: base64Input });
+const { download } = useDownloadFileFromBase64Refs(
+  {
+    source: base64Input,
+    filename: fileName,
+    extension: fileExtension,
+  });
 const base64InputValidation = useValidation({
   source: base64Input,
   rules: [
@@ -18,6 +25,35 @@ const base64InputValidation = useValidation({
   ],
 });
 
+watch(
+  base64Input,
+  (newValue, _) => {
+    const { mimeType } = getMimeTypeFromBase64({ base64String: newValue });
+    if (mimeType) {
+      fileExtension.value = getExtensionFromMimeType(mimeType) || fileExtension.value;
+    }
+  },
+);
+
+function previewImage() {
+  if (!base64InputValidation.isValid) {
+    return;
+  }
+  try {
+    const image = previewImageFromBase64(base64Input.value);
+    image.style.maxWidth = '100%';
+    image.style.maxHeight = '400px';
+    const previewContainer = document.getElementById('previewContainer');
+    if (previewContainer) {
+      previewContainer.innerHTML = '';
+      previewContainer.appendChild(image);
+    }
+  }
+  catch (_) {
+    //
+  }
+}
+
 function downloadFile() {
   if (!base64InputValidation.isValid) {
     return;
@@ -44,6 +80,24 @@ async function onUpload(file: File) {
 
 <template>
   <c-card title="Base64 to file">
+    <n-grid cols="3" x-gap="12">
+      <n-gi span="2">
+        <c-input-text
+          v-model:value="fileName"
+          label="File Name"
+          placeholder="Download filename"
+          mb-2
+        />
+      </n-gi>
+      <n-gi>
+        <c-input-text
+          v-model:value="fileExtension"
+          label="Extension"
+          placeholder="Extension"
+          mb-2
+        />
+      </n-gi>
+    </n-grid>
     <c-input-text
       v-model:value="base64Input"
       multiline
@@ -53,7 +107,14 @@ async function onUpload(file: File) {
       mb-2
     />
 
-    <div flex justify-center>
+    <div flex justify-center py-2>
+      <div id="previewContainer" />
+    </div>
+
+    <div flex justify-center gap-3>
+      <c-button :disabled="base64Input === '' || !base64InputValidation.isValid" @click="previewImage()">
+        Preview image
+      </c-button>
       <c-button :disabled="base64Input === '' || !base64InputValidation.isValid" @click="downloadFile()">
         Download file
       </c-button>

src/utils/base64.test.ts

@@ -38,7 +38,8 @@ describe('base64 utils', () => {
 
     it('should throw for incorrect base64 string', () => {
       expect(() => base64ToText('a')).to.throw('Incorrect base64 string');
-      expect(() => base64ToText(' ')).to.throw('Incorrect base64 string');
+      // should not really be false because trimming of space is now implied
+      // expect(() => base64ToText(' ')).to.throw('Incorrect base64 string');
       expect(() => base64ToText('é')).to.throw('Incorrect base64 string');
       // missing final '='
       expect(() => base64ToText('bG9yZW0gaXBzdW0')).to.throw('Incorrect base64 string');
@@ -56,17 +57,17 @@ describe('base64 utils', () => {
 
     it('should return false for incorrect base64 string', () => {
       expect(isValidBase64('a')).to.eql(false);
-      expect(isValidBase64(' ')).to.eql(false);
       expect(isValidBase64('é')).to.eql(false);
       expect(isValidBase64('data:text/plain;notbase64,YQ==')).to.eql(false);
       // missing final '='
       expect(isValidBase64('bG9yZW0gaXBzdW0')).to.eql(false);
     });
 
-    it('should return false for untrimmed correct base64 string', () => {
-      expect(isValidBase64('bG9yZW0gaXBzdW0= ')).to.eql(false);
-      expect(isValidBase64(' LTE=')).to.eql(false);
-      expect(isValidBase64(' YQ== ')).to.eql(false);
+    it('should return true for untrimmed correct base64 string', () => {
+      expect(isValidBase64('bG9yZW0gaXBzdW0= ')).to.eql(true);
+      expect(isValidBase64(' LTE=')).to.eql(true);
+      expect(isValidBase64(' YQ== ')).to.eql(true);
+      expect(isValidBase64(' ')).to.eql(true);
     });
   });
 

src/utils/base64.ts

@@ -1,7 +1,9 @@
+import { Base64 } from 'js-base64';
+
 export { textToBase64, base64ToText, isValidBase64, removePotentialDataAndMimePrefix };
 
 function textToBase64(str: string, { makeUrlSafe = false }: { makeUrlSafe?: boolean } = {}) {
-  const encoded = window.btoa(str);
+  const encoded = Base64.encode(str);
   return makeUrlSafe ? makeUriSafe(encoded) : encoded;
 }
 
@@ -16,7 +18,7 @@ function base64ToText(str: string, { makeUrlSafe = false }: { makeUrlSafe?: bool
   }
 
   try {
-    return window.atob(cleanStr);
+    return Base64.decode(cleanStr);
   }
   catch (_) {
     throw new Error('Incorrect base64 string');
@@ -34,10 +36,11 @@ function isValidBase64(str: string, { makeUrlSafe = false }: { makeUrlSafe?: boo
   }
 
   try {
+    const reEncodedBase64 = Base64.fromUint8Array(Base64.toUint8Array(cleanStr));
     if (makeUrlSafe) {
-      return removePotentialPadding(window.btoa(window.atob(cleanStr))) === cleanStr;
+      return removePotentialPadding(reEncodedBase64) === cleanStr;
     }
-    return window.btoa(window.atob(cleanStr)) === cleanStr;
+    return reEncodedBase64 === cleanStr.replace(/\s/g, '');
   }
   catch (err) {
     return false;