Added quick reports (at this moment only one) to campaign statistics page.

server/lib/report-helpers.js

@@ -1,6 +1,8 @@
 'use strict';
 
 const path = require('path');
+const csvStringify = require('csv-stringify');
+const stream = require('stream');
 
 function nameToFileName(name) {
     return name.
@@ -25,10 +27,51 @@ function getReportOutputFile(report) {
     return getReportFileBase(report) + '.err';
 }
 
+async function renderCsvFromStream(readable, writable, opts, transform) {
+    const finished = new Promise((success, fail) => {
+        let lastReadable = readable;
+
+        const stringifier = csvStringify(opts);
+
+        stringifier.on('finish', () => success());
+        stringifier.on('error', err => fail(err));
+
+        if (transform) {
+            const rowTransform = new stream.Transform({
+                objectMode: true,
+                transform(row, encoding, callback) {
+                    async function performTransform() {
+                        try {
+                            const newRow = await transform(row, encoding);
+                            callback(null, newRow);
+                        } catch (err) {
+                            callback(err);
+                        }
+                    }
+
+                    // noinspection JSIgnoredPromiseFromCall
+                    performTransform();
+                }
+            });
+
+            lastReadable.on('error', err => fail(err));
+            lastReadable.pipe(rowTransform);
+
+            lastReadable = rowTransform;
+        }
+
+        stringifier.pipe(writable);
+        lastReadable.pipe(stringifier);
+    });
+
+    await finished;
+}
+
 
 module.exports = {
     getReportContentFile,
     getReportOutputFile,
     nameToFileName,
-    reportFilesDir
+    reportFilesDir,
+    renderCsvFromStream
 };