Added ability to use custom favicon (#202)

* Added ability to change favicon in config

* Turned back version of icon in index.twig

* Added opportunity to upload favicon and route to get saved favicon

* Removed favicon from .codexdocsrc.sample

* Added docs to favicon route

* Replaced uploadFavicon to initiating /favicon route, updated function, added catching errors from uploadFile

* Updated Readme, added info about setting up app

* Updated Readme.md

* Some changes

* Favicon data saves to app.locals, replaced uploading favicon to app.ts

* Changed naming in config, from faviconURL to favicon, changed using app.locals variables

* Renamed uploadFavicon to downLoadFavicon, removed log in locals.ts

* Renamed favicon variable in app.ts

* Added checking favicon before uploading function, removed passing locals to views

* Added timeout for uploading favicon request and writeFileSync changed to writeFile

* Removed passing favicon locals and turned back removed variables

* Turned back variables

* Fixed duplicating os.tmpdir

* Fixed braces in objects, added new lines

* Added default favicon path, if favicon does not exists in config

* Updated docs, fixed using local favicon

src/backend/utils/downloadFavicon.ts

@@ -0,0 +1,85 @@
+import path from 'path';
+import fs from 'fs';
+import fetch from 'node-fetch';
+
+/**
+ * Uploaded favicon data
+ */
+export interface FaviconData {
+  // Uploaded favicon path
+  destination: string;
+
+  // File type
+  type: string;
+}
+
+// Initiate controller for aborting request
+const controller = new AbortController();
+
+/**
+ * Check if string is url
+ *
+ * @param  str - string to check
+ */
+function checkIsUrl(str: string): boolean {
+  const re = new RegExp('https?://');
+
+  return re.test(str);
+}
+
+/**
+ * Upload favicon by url, or get it by path
+ *
+ * @param destination - url or path of favicon
+ * @param faviconFolder - folder to save favicon
+ * @returns { Promise<FaviconData> } - Promise with data about favicon
+ */
+export async function downloadFavicon(destination: string, faviconFolder: string): Promise<FaviconData> {
+  // Check of destination is empty
+  if (!destination) {
+    throw Error('Favicon destination is empty');
+  }
+
+  // Get file name by destination
+  const filename = destination.substring(destination.lastIndexOf('/')+1);
+
+  // Get file format
+  const format = filename.split('.')[1];
+
+  // Check if string is url
+  if (!checkIsUrl(destination)) {
+    return  {
+      destination: `/${filename}`,
+      type: `image/${format}`,
+    } as FaviconData;
+  }
+
+  // Create timeout to abort request
+  const timeoutId = setTimeout(() => {
+    controller.abort();
+    console.log('Favicon request has timed out.');
+  }, 5000);
+
+  // Make get request to url
+  const res = await fetch(destination, { signal: controller.signal });
+  // Get buffer data from response
+  const fileData = await res.buffer();
+
+  // Clear timeout, if data was got
+  clearTimeout(timeoutId);
+
+  // Get file path in temporary directory
+  const filePath = path.join(faviconFolder, `favicon.${format}`);
+
+  // Save file
+  await fs.writeFile(filePath, fileData, (err) => {
+    if (err) {
+      console.log(err);
+    }
+  });
+
+  return {
+    destination: `/favicon/favicon.${format}`,
+    type: `image/${format}`,
+  } as FaviconData;
+}