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 CorentinTh#788

Author: sharevb

src/composable/downloadBase64.ts

@@ -1,8 +1,12 @@
-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,
+};
 
 const commonMimeTypesSignatures = {
   'JVBERi0': 'application/pdf',
@@ -36,30 +40,55 @@ 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 }) {
-  return {
-    download() {
-      if (source.value === '') {
-        throw new Error('Base64 string is empty');
-      }
+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 { mimeType } = getMimeTypeFromBase64({ base64String: source.value });
-      const base64String = mimeType
-        ? source.value
-        : `data:text/plain;base64,${source.value}`;
+  const a = document.createElement('a');
+  a.href = base64String;
+  a.download = cleanFileName;
+  a.click();
+}
 
-      const cleanFileName = filename ?? `file.${getFileExtensionFromMimeType({ mimeType })}`;
+function useDownloadFileFromBase64(
+  { source, filename, extension, fileMimeType }:
+  { source: Ref<string>; filename?: string; extension?: string; fileMimeType?: string }) {
+  return {
+    download() {
+      downloadFromBase64({ sourceValue: source.value, filename, extension, fileMimeType });
+    },
+  };
+}
 
-      const a = document.createElement('a');
-      a.href = base64String;
-      a.download = cleanFileName;
-      a.click();
+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 });
     },
   };
 }

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, 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 +25,16 @@ const base64InputValidation = useValidation({
   ],
 });
 
+watch(
+  base64Input,
+  (newValue, _) => {
+    const { mimeType } = getMimeTypeFromBase64({ base64String: newValue });
+    if (mimeType) {
+      fileExtension.value = getExtensionFromMimeType(mimeType) || fileExtension.value;
+    }
+  },
+);
+
 function downloadFile() {
   if (!base64InputValidation.isValid) {
     return;
@@ -44,6 +61,24 @@ 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