ui: download multiple problems

packages/ui-default/pages/problem_main.page.js

@@ -1,19 +1,38 @@
 import _ from 'lodash';
-
+import { dump } from 'js-yaml';
+import * as streamsaver from 'streamsaver';
 import { NamedPage } from 'vj/misc/Page';
 import Notification from 'vj/components/notification';
 import { ConfirmDialog } from 'vj/components/dialog';
 import Dropdown from 'vj/components/dropdown/Dropdown';
+import { createZipStream } from 'vj/utils/zip';
 import pjax from 'vj/utils/pjax';
 import substitute from 'vj/utils/substitute';
 import request from 'vj/utils/request';
 import tpl from 'vj/utils/tpl';
+import pipeStream from 'vj/utils/pipeStream';
 import delay from 'vj/utils/delay';
 import i18n from 'vj/utils/i18n';
 
 const categories = {};
 const dirtyCategories = [];
 const selections = [];
+// Firefox have no WritableStream
+if (!window.WritableStream) streamsaver.WritableStream = WritableStream;
+if (window.location.protocol === 'https:'
+  || window.location.protocol === 'chrome-extension:'
+  || window.location.hostname === 'localhost') {
+  streamsaver.mitm = '/streamsaver/mitm.html';
+}
+
+let isBeforeUnloadTriggeredByLibrary = !window.isSecureContext;
+function onBeforeUnload(e) {
+  if (isBeforeUnloadTriggeredByLibrary) {
+    isBeforeUnloadTriggeredByLibrary = false;
+    return;
+  }
+  e.returnValue = '';
+}
 
 function setDomSelected($dom, selected) {
   if (selected) {
@@ -202,6 +221,60 @@ async function handleOperation(operation) {
   }
 }
 
+async function handleDownload() {
+  const pids = ensureAndGetSelectedPids();
+  const fileStream = streamsaver.createWriteStream('Export.zip');
+  const targets = [];
+  for (const pid of pids) {
+    const { pdoc } = await request.get(`p/${pid}`);
+    targets.push({ filename: `${pid}/problem.yaml`, content: dump(pdoc) });
+    let { links } = await request.post(`p/${pid}/files`, { operation: 'get_links', files: pdoc.data.map((i) => i.name), type: 'testdata' });
+    for (const filename of Object.keys(links)) {
+      targets.push({ filename: `${pid}/testdata/${filename}`, url: links[filename] });
+    }
+    ({ links } = await request.post(`p/${pid}/files`, {
+      operation: 'get_links', files: pdoc.additional_file.map((i) => i.name), type: 'additional_file',
+    }));
+    for (const filename of Object.keys(links)) {
+      targets.push({ filename: `${pid}/additional_file/${filename}`, url: links[filename] });
+    }
+  }
+  let i = 0;
+  const zipStream = createZipStream({
+    // eslint-disable-next-line consistent-return
+    async pull(ctrl) {
+      if (i === targets.length) return ctrl.close();
+      try {
+        if (targets[i].url) {
+          const response = await fetch(targets[i].url);
+          if (!response.ok) throw response.statusText;
+          ctrl.enqueue({
+            name: targets[i].filename,
+            stream: () => response.body,
+          });
+        } else {
+          ctrl.enqueue({
+            name: targets[i].filename,
+            stream: () => new Blob([targets[i].content], { type: 'application/json' }).stream(),
+          });
+        }
+      } catch (e) {
+        // eslint-disable-next-line no-use-before-define
+        stopDownload();
+        Notification.error(i18n('problem_files.download_as_archive_error', [targets[i].filename, e.toString()]));
+      }
+      i++;
+    },
+  });
+  const abortCallbackReceiver = {};
+  function stopDownload() { abortCallbackReceiver.abort(); }
+  window.addEventListener('unload', stopDownload);
+  window.addEventListener('beforeunload', onBeforeUnload);
+  await pipeStream(zipStream, fileStream, abortCallbackReceiver);
+  window.removeEventListener('unload', stopDownload);
+  window.removeEventListener('beforeunload', onBeforeUnload);
+}
+
 const page = new NamedPage(['problem_main', 'problem_category'], () => {
   const doc = document.documentElement;
   doc.className += ' display-mode';
@@ -216,6 +289,7 @@ const page = new NamedPage(['problem_main', 'problem_category'], () => {
   $('[name="remove_selected_problems"]').on('click', () => handleOperation('delete'));
   $('[name="hide_selected_problems"]').on('click', () => handleOperation('hide'));
   $('[name="unhide_selected_problems"]').on('click', () => handleOperation('unhide'));
+  $('[name="download_selected_problems"]').on('click', handleDownload);
   $('#search').on('click', (ev) => {
     ev.preventDefault();
     updateSelection();