Switch code editor to Monaco (#11366)

* Switch code editor to Monaco

This switches out CodeMirror for Monaco which is based on the same code
base as VS code and should work pretty similar to it.

It does add a few async chunks, totalling around 10MB to our build. It
currently supports around 65 languages and in the default configuration,
each language would emit one ugly [number].js chunk, so I opted to
combine them all into a single file for now.

CodeMirror is still being used under the hood by SimpleMDE so it can not
be removed yet.

* inline editorconfig, fix diff, use for markdown, remove more dead code

* refactors, remove jquery usage

* use tab_width

* fix intellisense

* rename function for clarity

* misc tweaks, enable webpack progress display

* only use --progress on dev build

* remove useless borders in arc-green

* fix typo

* remove obsolete comment

* small refactor

* fix file creation and various refactors

* unset useTabStops too when no editorconfig

* small refactor

* disable webpack's [big] warnings

* remove useless await

* fix dark theme check

* rename chunk to 'monaco'

* add to .gitignore and delete webpack dest before build

* increase editor height

* support more editorconfig properties

* remove empty element filter

* rename

Co-authored-by: John Olheiser <john.olheiser@gmail.com>

6 files changed, 184 insertions, 179 deletions

diff --git a/web_src/js/features/codeeditor.js b/web_src/js/features/codeeditor.js
new file mode 100644
index 0000000000..0999d05f05
--- /dev/null
+++ b/web_src/js/features/codeeditor.js
@@ -0,0 +1,104 @@
+import {basename, extname, isObject, isDarkTheme} from '../utils.js';
+
+const languagesByFilename = {};
+const languagesByExt = {};
+
+function getEditorconfig(input) {
+  try {
+    return JSON.parse(input.dataset.editorconfig);
+  } catch (_err) {
+    return null;
+  }
+}
+
+function initLanguages(monaco) {
+  for (const {filenames, extensions, id} of monaco.languages.getLanguages()) {
+    for (const filename of filenames || []) {
+      languagesByFilename[filename] = id;
+    }
+    for (const extension of extensions || []) {
+      languagesByExt[extension] = id;
+    }
+  }
+}
+
+function getLanguage(filename) {
+  return languagesByFilename[filename] || languagesByExt[extname(filename)] || 'plaintext';
+}
+
+function updateEditor(monaco, editor, filenameInput) {
+  const newFilename = filenameInput.value;
+  editor.updateOptions(getOptions(filenameInput));
+  const model = editor.getModel();
+  const language = model.getModeId();
+  const newLanguage = getLanguage(newFilename);
+  if (language !== newLanguage) monaco.editor.setModelLanguage(model, newLanguage);
+}
+
+export async function createCodeEditor(textarea, filenameInput, previewFileModes) {
+  const filename = basename(filenameInput.value);
+  const previewLink = document.querySelector('a[data-tab=preview]');
+  const markdownExts = (textarea.dataset.markdownFileExts || '').split(',');
+  const lineWrapExts = (textarea.dataset.lineWrapExtensions || '').split(',');
+  const isMarkdown = markdownExts.includes(extname(filename));
+
+  if (previewLink) {
+    if (isMarkdown && (previewFileModes || []).includes('markdown')) {
+      previewLink.dataset.url = previewLink.dataset.url.replace(/(.*)\/.*/i, `$1/markdown`);
+      previewLink.style.display = '';
+    } else {
+      previewLink.style.display = 'none';
+    }
+  }
+
+  const monaco = await import(/* webpackChunkName: "monaco" */'monaco-editor');
+  initLanguages(monaco);
+
+  const container = document.createElement('div');
+  container.className = 'monaco-editor-container';
+  textarea.parentNode.appendChild(container);
+
+  const editor = monaco.editor.create(container, {
+    value: textarea.value,
+    language: getLanguage(filename),
+    ...getOptions(filenameInput, lineWrapExts),
+  });
+
+  const model = editor.getModel();
+  model.onDidChangeContent(() => {
+    textarea.value = editor.getValue();
+    textarea.dispatchEvent(new Event('change')); // seems to be needed for jquery-are-you-sure
+  });
+
+  window.addEventListener('resize', () => {
+    editor.layout();
+  });
+
+  filenameInput.addEventListener('keyup', () => {
+    updateEditor(monaco, editor, filenameInput);
+  });
+
+  const loading = document.querySelector('.editor-loading');
+  if (loading) loading.remove();
+
+  return editor;
+}
+
+function getOptions(filenameInput, lineWrapExts) {
+  const ec = getEditorconfig(filenameInput);
+  const theme = isDarkTheme() ? 'vs-dark' : 'vs';
+  const wordWrap = (lineWrapExts || []).includes(extname(filenameInput.value)) ? 'on' : 'off';
+
+  const opts = {theme, wordWrap};
+  if (isObject(ec)) {
+    opts.detectIndentation = !('indent_style' in ec) || !('indent_size' in ec);
+    if ('indent_size' in ec) opts.indentSize = Number(ec.indent_size);
+    if ('tab_width' in ec) opts.tabSize = Number(ec.tab_width) || opts.indentSize;
+    if ('max_line_length' in ec) opts.rulers = [Number(ec.max_line_length)];
+    opts.trimAutoWhitespace = ec.trim_trailing_whitespace === true;
+    opts.insertSpaces = ec.indent_style === 'space';
+    opts.useTabStops = ec.indent_style === 'tab';
+  }
+
+  return opts;
+}
diff --git a/web_src/js/index.js b/web_src/js/index.js
index a74fba34e8..02189a5f13 100644
--- a/web_src/js/index.js
+++ b/web_src/js/index.js
@@ -20,6 +20,7 @@ import createDropzone from './features/dropzone.js';
 import highlight from './features/highlight.js';
 import ActivityTopAuthors from './components/ActivityTopAuthors.vue';
 import {initNotificationsTable, initNotificationCount} from './features/notification.js';
+import {createCodeEditor} from './features/codeeditor.js';
 
 const {AppSubUrl, StaticUrlPrefix, csrf} = window.config;
 
@@ -28,9 +29,7 @@ function htmlEncode(text) {
 }
 
 let previewFileModes;
-let simpleMDEditor;
 const commentMDEditors = {};
-let codeMirrorEditor;
 
 // Silence fomantic's error logging when tabs are used without a target content element
 $.fn.tab.settings.silent = true;
@@ -1467,62 +1466,6 @@ $.fn.getCursorPosition = function () {
   return pos;
 };
 
-function setSimpleMDE($editArea) {
-  if (codeMirrorEditor) {
-    codeMirrorEditor.toTextArea();
-    codeMirrorEditor = null;
-  }
-
-  if (simpleMDEditor) {
-    return true;
-  }
-
-  simpleMDEditor = new SimpleMDE({
-    autoDownloadFontAwesome: false,
-    element: $editArea[0],
-    forceSync: true,
-    renderingConfig: {
-      singleLineBreaks: false
-    },
-    indentWithTabs: false,
-    tabSize: 4,
-    spellChecker: false,
-    previewRender(plainText, preview) { // Async method
-      setTimeout(() => {
-        // FIXME: still send render request when return back to edit mode
-        $.post($editArea.data('url'), {
-          _csrf: csrf,
-          mode: 'gfm',
-          context: $editArea.data('context'),
-          text: plainText
-        }, (data) => {
-          preview.innerHTML = `<div class="markdown ui segment">${data}</div>`;
-        });
-      }, 0);
-
-      return 'Loading...';
-    },
-    toolbar: ['bold', 'italic', 'strikethrough', '|',
-      'heading-1', 'heading-2', 'heading-3', 'heading-bigger', 'heading-smaller', '|',
-      'code', 'quote', '|',
-      'unordered-list', 'ordered-list', '|',
-      'link', 'image', 'table', 'horizontal-rule', '|',
-      'clean-block', 'preview', 'fullscreen', 'side-by-side', '|',
-      {
-        name: 'revert-to-textarea',
-        action(e) {
-          e.toTextArea();
-        },
-        className: 'fa fa-file',
-        title: 'Revert to simple textarea',
-      },
-    ]
-  });
-  $(simpleMDEditor.codemirror.getInputField()).addClass('js-quick-submit');
-
-  return true;
-}
-
 function setCommentSimpleMDE($editArea) {
   const simplemde = new SimpleMDE({
     autoDownloadFontAwesome: false,
@@ -1569,27 +1512,7 @@ function setCommentSimpleMDE($editArea) {
   return simplemde;
 }
 
-function setCodeMirror($editArea) {
-  if (simpleMDEditor) {
-    simpleMDEditor.toTextArea();
-    simpleMDEditor = null;
-  }
-
-  if (codeMirrorEditor) {
-    return true;
-  }
-
-  codeMirrorEditor = CodeMirror.fromTextArea($editArea[0], {
-    lineNumbers: true
-  });
-  codeMirrorEditor.on('change', (cm, _change) => {
-    $editArea.val(cm.getValue());
-  });
-
-  return true;
-}
-
-function initEditor() {
+async function initEditor() {
   $('.js-quick-pull-choice-option').on('change', function () {
     if ($(this).val() === 'commit-to-new-branch') {
       $('.quick-pull-branch-name').show();
@@ -1650,89 +1573,7 @@ function initEditor() {
   const $editArea = $('.repository.editor textarea#edit_area');
   if (!$editArea.length) return;
 
-  const markdownFileExts = $editArea.data('markdown-file-exts').split(',');
-  const lineWrapExtensions = $editArea.data('line-wrap-extensions').split(',');
-
-  $editFilename.on('keyup', () => {
-    const val = $editFilename.val();
-    let mode, spec, extension, extWithDot, dataUrl, apiCall;
-
-    extension = extWithDot = '';
-    const m = /.+\.([^.]+)$/.exec(val);
-    if (m) {
-      extension = m[1];
-      extWithDot = `.${extension}`;
-    }
-
-    const info = CodeMirror.findModeByExtension(extension);
-    const previewLink = $('a[data-tab=preview]');
-    if (info) {
-      mode = info.mode;
-      spec = info.mime;
-      apiCall = mode;
-    } else {
-      apiCall = extension;
-    }
-
-    if (previewLink.length && apiCall && previewFileModes && previewFileModes.length && previewFileModes.includes(apiCall)) {
-      dataUrl = previewLink.data('url');
-      previewLink.data('url', dataUrl.replace(/(.*)\/.*/i, `$1/${mode}`));
-      previewLink.show();
-    } else {
-      previewLink.hide();
-    }
-
-    // If this file is a Markdown extensions, we will load that editor and return
-    if (markdownFileExts.includes(extWithDot)) {
-      if (setSimpleMDE($editArea)) {
-        return;
-      }
-    }
-
-    // Else we are going to use CodeMirror
-    if (!codeMirrorEditor && !setCodeMirror($editArea)) {
-      return;
-    }
-
-    if (mode) {
-      codeMirrorEditor.setOption('mode', spec);
-      CodeMirror.autoLoadMode(codeMirrorEditor, mode);
-    }
-
-    if (lineWrapExtensions.includes(extWithDot)) {
-      codeMirrorEditor.setOption('lineWrapping', true);
-    } else {
-      codeMirrorEditor.setOption('lineWrapping', false);
-    }
-
-    // get the filename without any folder
-    let value = $editFilename.val();
-    if (value.length === 0) {
-      return;
-    }
-    value = value.split('/');
-    value = value[value.length - 1];
-
-    $.getJSON($editFilename.data('ec-url-prefix') + value, (editorconfig) => {
-      if (editorconfig.indent_style === 'tab') {
-        codeMirrorEditor.setOption('indentWithTabs', true);
-        codeMirrorEditor.setOption('extraKeys', {});
-      } else {
-        codeMirrorEditor.setOption('indentWithTabs', false);
-        // required because CodeMirror doesn't seems to use spaces correctly for {"indentWithTabs": false}:
-        // - https://github.com/codemirror/CodeMirror/issues/988
-        // - https://codemirror.net/doc/manual.html#keymaps
-        codeMirrorEditor.setOption('extraKeys', {
-          Tab(cm) {
-            const spaces = new Array(parseInt(cm.getOption('indentUnit')) + 1).join(' ');
-            cm.replaceSelection(spaces);
-          }
-        });
-      }
-      codeMirrorEditor.setOption('indentUnit', editorconfig.indent_size || 4);
-      codeMirrorEditor.setOption('tabSize', editorconfig.tab_width || 4);
-    });
-  }).trigger('keyup');
+  await createCodeEditor($editArea[0], $editFilename[0], previewFileModes);
 
   // Using events from https://github.com/codedance/jquery.AreYouSure#advanced-usage
   // to enable or disable the commit button
diff --git a/web_src/js/utils.js b/web_src/js/utils.js
index b000c1af77..b511c9981d 100644
--- a/web_src/js/utils.js
+++ b/web_src/js/utils.js
@@ -1,3 +1,25 @@
+// retrieve a HTML string for given SVG icon name and size in pixels
 export function svg(name, size) {
   return `<svg class="svg ${name}" width="${size}" height="${size}" aria-hidden="true"><use xlink:href="#${name}"/></svg>`;
 }
+
+// transform /path/to/file.ext to file.ext
+export function basename(path = '') {
+  return path ? path.replace(/^.*\//, '') : '';
+}
+
+// transform /path/to/file.ext to .ext
+export function extname(path = '') {
+  const [_, ext] = /.+(\.[^.]+)$/.exec(path) || [];
+  return ext || '';
+}
+
+// test whether a variable is an object
+export function isObject(obj) {
+  return Object.prototype.toString.call(obj) === '[object Object]';
+}
+
+// returns whether a dark theme is enabled
+export function isDarkTheme() {
+  return document.documentElement.classList.contains('theme-arc-green');
+}
diff --git a/web_src/less/_editor.less b/web_src/less/_editor.less
index 714d41649a..d8ba1467e9 100644
--- a/web_src/less/_editor.less
+++ b/web_src/less/_editor.less
@@ -32,3 +32,40 @@
 .editor-toolbar i.separator {
     border-left: none;
 }
+
+.editor-loading {
+    padding: 1rem;
+    text-align: center;
+}
+
+.edit-diff {
+    padding: 0 !important;
+}
+
+.edit-diff > div > .ui.table {
+    border-top: none !important;
+    border-bottom: none !important;
+    border-left: 1px solid #d4d4d5 !important;
+    border-right: 1px solid #d4d4d5 !important;
+}
+
+#edit_area {
+    display: none;
+}
+
+.monaco-editor-container {
+    width: 100%;
+    min-height: 200px;
+    height: 90vh;
+}
+
+/* overwrite conflicting styles from fomantic */
+.monaco-editor-container .inputarea {
+    min-height: 0 !important;
+    margin: 0 !important;
+    padding: 0 !important;
+    resize: none !important;
+    border: none !important;
+    color: transparent !important;
+    background-color: transparent !important;
+}
diff --git a/web_src/less/_repository.less b/web_src/less/_repository.less
index 863f2bad8e..6fb089636a 100644
--- a/web_src/less/_repository.less
+++ b/web_src/less/_repository.less
@@ -1555,14 +1555,6 @@
                         text-align: center;
                     }
 
-                    .removed-code {
-                        background-color: #ff9999;
-                    }
-
-                    .added-code {
-                        background-color: #99ff99;
-                    }
-
                     [data-line-num]::before {
                         content: attr(data-line-num);
                         text-align: right;
@@ -2865,3 +2857,11 @@ td.blob-excerpt {
     height: 48px;
     overflow: hidden;
 }
+
+.removed-code {
+    background-color: #ff9999;
+}
+
+.added-code {
+    background-color: #99ff99;
+}
diff --git a/web_src/less/themes/theme-arc-green.less b/web_src/less/themes/theme-arc-green.less
index d56b7b8eeb..19689d107b 100644
--- a/web_src/less/themes/theme-arc-green.less
+++ b/web_src/less/themes/theme-arc-green.less
@@ -576,10 +576,6 @@ a.ui.basic.green.label:hover {
 
 .repository.file.editor.edit,
 .repository.wiki.new .CodeMirror {
-    border-right: 1px solid rgba(187, 187, 187, .6);
-    border-left: 1px solid rgba(187, 187, 187, .6);
-    border-bottom: 1px solid rgba(187, 187, 187, .6);
-
     .editor-preview,
     .editor-preview-side,
     & + .editor-preview-side {
@@ -751,7 +747,11 @@ a.ui.basic.green.label:hover {
     border-color: #314a37 !important;
 }
 
-.repository .diff-file-box .code-diff tbody tr .added-code {
+.removed-code {
+    background-color: #5f3737;
+}
+
+.added-code {
     background-color: #3a523a;
 }
 
@@ -766,10 +766,6 @@ a.ui.basic.green.label:hover {
     color: #8ab398;
 }
 
-.repository .diff-file-box .code-diff tbody tr .removed-code {
-    background-color: #5f3737;
-}
-
 .tag-code,
 .tag-code td {
     background: #242637 !important;
@@ -1300,6 +1296,11 @@ a.ui.labels .label:hover {
     border-color: #7f98ad;
 }
 
+.edit-diff > div > .ui.table {
+    border-left-color: #404552 !important;
+    border-right-color: #404552 !important;
+}
+
 .editor-toolbar a {
     color: #87ab63 !important;
 }