Export note with local images

Looks through the note and searches for local images. Copies them to ‘images’ folder in the export path and replaces affected links.

#1261

browser/main/lib/dataApi/exportNote.js

@@ -0,0 +1,67 @@
+import exportImage from 'browser/main/lib/dataApi/exportImage'
+import {findStorage} from 'browser/lib/findStorage'
+
+const fs = require('fs')
+const path = require('path')
+
+/**
+ * Export note together with images
+ *
+ * If images is stored in the storage, creates 'images' subfolder in target directory
+ * and copies images to it. Changes links to images in the content of the note
+ *
+ * @param {String} storageKey
+ * @param {String} noteContent Content to export
+ * @param {String} targetPath Path to exported file
+ * @return {Promise.<*[]>}
+ */
+function exportNote (storageKey, noteContent, targetPath) {
+  const targetStorage = findStorage(storageKey)
+  const storagedImagesRe = /!\[(.*?)\]\(\s*?\/:storage\/(.*\.\S*?)\)/gi
+  const exportTasks = []
+  const images = []
+
+  const exportedData = noteContent.replace(storagedImagesRe, (match, dstFilename, srcFilename) => {
+    if (!path.extname(dstFilename)) {
+      dstFilename += path.extname(srcFilename)
+    }
+    const imagePath = path.join('images', dstFilename)
+
+    exportTasks.push(
+        exportImage(targetStorage.path, srcFilename, path.dirname(targetPath), dstFilename)
+    )
+    images.push(imagePath)
+    return `![${dstFilename}](${imagePath})`
+  })
+
+  exportTasks.push(exportFile(exportedData, targetPath))
+  return Promise.all(exportTasks)
+      .catch((err) => {
+        rollbackExport(images)
+        throw err
+      })
+}
+
+function exportFile (data, filename) {
+  return new Promise((resolve, reject) => {
+    fs.writeFile(filename, data, (err) => {
+      if (err) throw err
+
+      resolve(filename)
+    })
+  })
+}
+
+/**
+ * Remove exported images
+ * @param imagesPaths
+ */
+function rollbackExport (imagesPaths) {
+  imagesPaths.forEach((path) => {
+    if (fs.existsSync(path)) {
+      fs.unlink(path)
+    }
+  })
+}
+
+export default exportNote