Enabling Download of Content 🗃️

.gitignore

@@ -3,3 +3,4 @@ coverage
 reports
 node_modules
 *.code-workspace
+/tmp

.jshintrc

@@ -0,0 +1,3 @@
+{
+  "esversion": 6
+}

src/archive-of-anna.js

@@ -1,4 +1,6 @@
 // Helpers
+const { DOWNLOAD_PATH } = require('./constants');
+const downloadHelper = require('./helpers/download-helper');
 const searchHelper = require('./helpers/search-helper');
 
 // Libraries
@@ -37,11 +39,37 @@ class ArchiveOfAnna {
    * @return {Object} The content of the response.
    * TODO: Fix documentation.
    */
-  static async fetch_by_md5(md5) {
+  static async fetchByMd5(md5) {
     const url = searchHelper.buildFetchUrl(md5);
     const response = await axiosHelper.get(url);
     return searchHelper.getContent(response.data);
   }
+
+  /**
+   * It takes an array of IPFS links and returns a promise that resolves to an array of the same length,
+   * where each element is the file contents of the corresponding IPFS link
+   * @param {Array} ipfsLinks - An array of IPFS links.
+   * @param {String|undefined} name - Name for the file to be saved as.
+   * @param {String} path - Path to save the file to.
+   * @return {File} the result of the downloadHelper.ipfs function.
+   * TODO: Fix Documentation.
+   */
+  static downloadFileViaIpfs(ipfsLinks, name = undefined, path = DOWNLOAD_PATH) {
+    return downloadHelper.ipfs(ipfsLinks, name, path);
+  }
+
+  /**
+   * It takes a list of links to Libgen, and downloads the files
+   * @param {Array} libgenLinks - An array of links to the libgen mirrors.
+   * @param {String|undefined} fork - The fork to download the file from.
+   * @param {String|undefined} name - Name for the file to be saved as.
+   * @param {String} path - Path to save the file to.
+   * @return {File} A promise.
+   * TODO: Fix Documentation
+   */
+  static downloadFileViaLibgen(libgenLinks, fork = undefined, name = undefined, path = DOWNLOAD_PATH) {
+    return downloadHelper.libgenDownload(libgenLinks, fork, name, path);
+  }
 }
 
 module.exports = ArchiveOfAnna;

src/constants.js

@@ -1,5 +1,6 @@
 module.exports = {
   BASE_URI: 'https://annas-archive.org',
+  DOWNLOAD_PATH: './tmp/',
   PATH_PREFIXES: {
     MD5: '/md5/',
   },

src/helpers/download-helper.js

@@ -0,0 +1,55 @@
+const axiosHelper = require('../libraries/axios-helper');
+const fileHelper = require('../libraries/file-helper');
+
+const getSubstringIndicesForFilename = (contentDispositionHeader) => {
+  const filenameHeader = 'filename="';
+  const startIndex = contentDispositionHeader.indexOf(filenameHeader) + filenameHeader.length;
+  const endIndex = contentDispositionHeader.indexOf('"', startIndex);
+
+  return [startIndex, endIndex];
+};
+
+const getFileNameFromHeaders = (response) => {
+  const contentDispositionHeader = response.headers['content-disposition'];
+  const [startIndex, endIndex] = getSubstringIndicesForFilename(contentDispositionHeader);
+
+  return contentDispositionHeader.substring(startIndex, endIndex);
+};
+
+const getFileExtensionFromHeaders = (response) => {
+  const fileName = getFileNameFromHeaders(response);
+  return fileName.substring(fileName.lastIndexOf('.') + 1);
+};
+
+const getCustomFileName = (name) => `${name}.${getFileExtensionFromHeaders(response)}`;
+
+const getFileNameAndContent = async (name, link) => {
+  const response = await axiosHelper.download(link, name);
+  if (response.status != 200) return [null, null];
+
+  const fileName = name ? getCustomFileName(name) : getFileNameFromHeaders(response);
+
+  return [fileName, response.data];
+};
+
+const downloadFileFromGivenLinks = async (links, name, path) => {
+  fileHelper.directorySetup(path); // Setup the download directory if it doesn't exist.
+
+  for (const link of links) {
+    const [fileName, content] = await getFileNameAndContent(name, link);
+
+    if (!content) continue;
+
+    return await fileHelper.writeFileToPath(path, fileName, content);
+  }
+
+  throw new Error('File could not be downloaded due to server error. Please try again later.');
+};
+
+const downloadHelper = {
+  ipfs: async (ipfsLinks, name, path) => await downloadFileFromGivenLinks(ipfsLinks, name, path),
+  libgenDownload: (libgenLinks, fork, name, path) => {},
+  torDownload: () => {}, // TODO: Not in current scope. Need to check if axios can be self-contained for Tor requests.
+};
+
+module.exports = downloadHelper;

src/interface/download-progress.js

@@ -0,0 +1,8 @@
+const store = require('../store');
+
+module.exports = {
+  getProgress: (key) => store.downloadProgress[key],
+  setProgress: (key, progressEvent) => {
+    store.downloadProgress[key] = Math.floor((progressEvent.loaded * 100) / progressEvent.total);
+  },
+};

src/libraries/axios-helper.js

@@ -1,7 +1,22 @@
 const axios = require('axios');
+const { getProgress, setProgress } = require('../interface/download-progress');
+
+const headers = { 'User-Agent': 'PostmanRuntime/7.30.0' };
 
 const axiosHelper = {
-  get: (url) => axios.get(url, { headers: { 'User-Agent': 'PostmanRuntime/7.30.0' } }),
+  get: (url) => axios.get(url, { headers: headers }),
+  download: (url, name = undefined) => {
+    const downloadProgressKey = name || url;
+
+    return axios.get(url, {
+      headers: headers,
+      responseType: 'stream',
+      onDownloadProgress: (progressEvent) => {
+        setProgress(downloadProgressKey, progressEvent);
+        console.log('Current Progress: ' + getProgress(downloadProgressKey) + '%'); // TODO: Remove this console log after setting up hooks.
+      },
+    });
+  },
 };
 
 module.exports = axiosHelper;

src/libraries/file-helper.js

@@ -0,0 +1,24 @@
+const fs = require('fs');
+const util = require('util');
+const stream = require('stream');
+const pipeline = util.promisify(stream.pipeline);
+const nodePath = require('path');
+
+// ? Do I need this as a helper method across the library?
+const pathJoiner = (...paths) => nodePath.join(...paths);
+
+const fileHelper = {
+  writeFileToPath: async (path, fileName, content) => {
+    const writeTo = pathJoiner(path, fileName);
+    const writer = fs.createWriteStream(writeTo);
+
+    await pipeline(content, writer);
+
+    return fs.existsSync(writeTo);
+  },
+  directorySetup: (path) => {
+    fs.existsSync(path) || fs.mkdirSync(path, { recursive: true });
+  },
+};
+
+module.exports = fileHelper;

src/store.js

@@ -0,0 +1,3 @@
+module.exports = {
+  downloadProgress: {},
+};