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>

.eslintrc

@@ -60,6 +60,7 @@ rules:
   no-unused-vars: [2, {args: all, argsIgnorePattern: ^_, varsIgnorePattern: ^_, ignoreRestSiblings: true}]
   no-use-before-define: [0]
   no-var: [2]
+  object-curly-newline: [0]
   object-curly-spacing: [2, never]
   one-var-declaration-per-line: [0]
   one-var: [0]

.gitignore

@@ -77,6 +77,7 @@ coverage.all
 /yarn.lock
 /public/js
 /public/css
+/public/fonts
 /public/fomantic
 /public/img/svg
 /VERSION

Makefile

@@ -88,7 +88,7 @@ GO_PACKAGES ?= $(filter-out code.gitea.io/gitea/integrations/migration-test,$(fi
 WEBPACK_SOURCES := $(shell find web_src/js web_src/less -type f)
 WEBPACK_CONFIGS := webpack.config.js
 WEBPACK_DEST := public/js/index.js public/css/index.css
-WEBPACK_DEST_DIRS := public/js public/css
+WEBPACK_DEST_DIRS := public/js public/css public/fonts
 
 BINDATA_DEST := modules/public/bindata.go modules/options/bindata.go modules/templates/bindata.go
 BINDATA_HASH := $(addsuffix .hash,$(BINDATA_DEST))
@@ -295,7 +295,7 @@ lint-frontend: node_modules
 
 .PHONY: watch-frontend
 watch-frontend: node_modules
-	NODE_ENV=development npx webpack --hide-modules --display-entrypoints=false --watch
+	NODE_ENV=development npx webpack --hide-modules --display-entrypoints=false --watch --progress
 
 .PHONY: test
 test:
@@ -598,6 +598,7 @@ $(FOMANTIC_DEST): $(FOMANTIC_CONFIGS) package-lock.json | node_modules
 webpack: $(WEBPACK_DEST)
 
 $(WEBPACK_DEST): $(WEBPACK_SOURCES) $(WEBPACK_CONFIGS) package-lock.json | node_modules
+	rm -rf $(WEBPACK_DEST_DIRS)
 	npx webpack --hide-modules --display-entrypoints=false
 	@touch $(WEBPACK_DEST)
 

custom/conf/app.ini.sample

@@ -52,7 +52,7 @@ DEFAULT_REPO_UNITS = repo.code,repo.releases,repo.issues,repo.pulls,repo.wiki
 PREFIX_ARCHIVE_FILES = true
 
 [repository.editor]
-; List of file extensions for which lines should be wrapped in the CodeMirror editor
+; List of file extensions for which lines should be wrapped in the Monaco editor
 ; Separate extensions with a comma. To line wrap files without an extension, just put a comma
 LINE_WRAP_EXTENSIONS = .txt,.md,.markdown,.mdown,.mkd,
 ; Valid file modes that have a preview API associated with them, such as api/v1/markdown

package-lock.json

@@ -4861,6 +4861,27 @@
         "flat-cache": "^2.0.1"
       }
     },
+    "file-loader": {
+      "version": "6.0.0",
+      "resolved": "https://registry.npmjs.org/file-loader/-/file-loader-6.0.0.tgz",
+      "integrity": "sha512-/aMOAYEFXDdjG0wytpTL5YQLfZnnTmLNjn+AIrJ/6HVnTfDqLsVKUUwkDf4I4kgex36BvjuXEn/TX9B/1ESyqQ==",
+      "requires": {
+        "loader-utils": "^2.0.0",
+        "schema-utils": "^2.6.5"
+      },
+      "dependencies": {
+        "loader-utils": {
+          "version": "2.0.0",
+          "resolved": "https://registry.npmjs.org/loader-utils/-/loader-utils-2.0.0.tgz",
+          "integrity": "sha512-rP4F0h2RaWSvPEkD7BLDFQnvSf+nK+wr3ESUjNTyAGobqrijmW92zc+SO6d4p4B1wh7+B/Jg1mkQe5NYUEHtHQ==",
+          "requires": {
+            "big.js": "^5.2.2",
+            "emojis-list": "^3.0.0",
+            "json5": "^2.1.2"
+          }
+        }
+      }
+    },
     "file-uri-to-path": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/file-uri-to-path/-/file-uri-to-path-1.0.0.tgz",
@@ -7903,9 +7924,9 @@
       }
     },
     "jest-worker": {
-      "version": "25.5.0",
+      "version": "26.0.0",
-      "resolved": "https://registry.npmjs.org/jest-worker/-/jest-worker-25.5.0.tgz",
+      "resolved": "https://registry.npmjs.org/jest-worker/-/jest-worker-26.0.0.tgz",
-      "integrity": "sha512-/dsSmUkIy5EBGfv/IjjqmFxrNAUpBERfGs1oHROyD7yxjG/w+t0GOJDX8O1k32ySmd7+a5IhnJU2qQFcJ4n1vw==",
+      "integrity": "sha512-pPaYa2+JnwmiZjK9x7p9BoZht+47ecFCDFA/CJxspHzeDvQcfVBLWzCiWyo+EGrSiQMWZtCFo9iSvMZnAAo8vw==",
       "requires": {
         "merge-stream": "^2.0.0",
         "supports-color": "^7.0.0"
@@ -9255,6 +9276,19 @@
         "minimist": "^1.2.5"
       }
     },
+    "monaco-editor": {
+      "version": "0.20.0",
+      "resolved": "https://registry.npmjs.org/monaco-editor/-/monaco-editor-0.20.0.tgz",
+      "integrity": "sha512-hkvf4EtPJRMQlPC3UbMoRs0vTAFAYdzFQ+gpMb8A+9znae1c43q8Mab9iVsgTcg/4PNiLGGn3SlDIa8uvK1FIQ=="
+    },
+    "monaco-editor-webpack-plugin": {
+      "version": "1.9.0",
+      "resolved": "https://registry.npmjs.org/monaco-editor-webpack-plugin/-/monaco-editor-webpack-plugin-1.9.0.tgz",
+      "integrity": "sha512-tOiiToc94E1sb50BgZ8q8WK/bxus77SRrwCqIpAB5er3cpX78SULbEBY4YPOB8kDolOzKRt30WIHG/D6gz69Ww==",
+      "requires": {
+        "loader-utils": "^1.2.3"
+      }
+    },
     "move-concurrently": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/move-concurrently/-/move-concurrently-1.0.1.tgz",
@@ -13684,13 +13718,13 @@
       }
     },
     "terser-webpack-plugin": {
-      "version": "3.0.0",
+      "version": "3.0.1",
-      "resolved": "https://registry.npmjs.org/terser-webpack-plugin/-/terser-webpack-plugin-3.0.0.tgz",
+      "resolved": "https://registry.npmjs.org/terser-webpack-plugin/-/terser-webpack-plugin-3.0.1.tgz",
-      "integrity": "sha512-gHAVFtJz1gQW5cu0btPtb+5Syo7K9hRj3b0lstgfglaBhbtcOCizsaPTnxOBGmF9iIgwsrSIiraBa2xzuWND7Q==",
+      "integrity": "sha512-eFDtq8qPUEa9hXcUzTwKXTnugIVtlqc1Z/ZVhG8LmRT3lgRY13+pQTnFLY2N7ATB6TKCHuW/IGjoAnZz9wOIqw==",
       "requires": {
         "cacache": "^15.0.3",
         "find-cache-dir": "^3.3.1",
-        "jest-worker": "^25.5.0",
+        "jest-worker": "^26.0.0",
         "p-limit": "^2.3.0",
         "schema-utils": "^2.6.6",
         "serialize-javascript": "^3.0.0",

package.json

@@ -19,6 +19,7 @@
     "domino": "2.1.5",
     "dropzone": "5.7.0",
     "fast-glob": "3.2.2",
+    "file-loader": "6.0.0",
     "fomantic-ui": "2.8.4",
     "highlight.js": "10.0.2",
     "imports-loader": "0.8.0",
@@ -27,6 +28,8 @@
     "jquery.are-you-sure": "1.9.0",
     "less-loader": "6.0.0",
     "mini-css-extract-plugin": "0.9.0",
+    "monaco-editor": "0.20.0",
+    "monaco-editor-webpack-plugin": "1.9.0",
     "optimize-css-assets-webpack-plugin": "5.0.3",
     "postcss-loader": "3.0.0",
     "postcss-preset-env": "6.7.0",
@@ -35,7 +38,7 @@
     "svgo": "1.3.2",
     "svgo-loader": "2.2.1",
     "swagger-ui": "3.25.1",
-    "terser-webpack-plugin": "3.0.0",
+    "terser-webpack-plugin": "3.0.1",
     "vue": "2.6.11",
     "vue-bar-graph": "1.2.0",
     "vue-calendar-heatmap": "0.8.4",

routers/repo/editor.go

@@ -5,6 +5,7 @@
 package repo
 
 import (
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"path"
@@ -146,11 +147,24 @@ func editFile(ctx *context.Context, isNewFile bool) {
 	ctx.Data["MarkdownFileExts"] = strings.Join(setting.Markdown.FileExtensions, ",")
 	ctx.Data["LineWrapExtensions"] = strings.Join(setting.Repository.Editor.LineWrapExtensions, ",")
 	ctx.Data["PreviewableFileModes"] = strings.Join(setting.Repository.Editor.PreviewableFileModes, ",")
-	ctx.Data["EditorconfigURLPrefix"] = fmt.Sprintf("%s/api/v1/repos/%s/editorconfig/", setting.AppSubURL, ctx.Repo.Repository.FullName())
+	ctx.Data["Editorconfig"] = GetEditorConfig(ctx, treePath)
 
 	ctx.HTML(200, tplEditFile)
 }
 
+// GetEditorConfig returns a editorconfig JSON string for given treePath or "null"
+func GetEditorConfig(ctx *context.Context, treePath string) string {
+	ec, err := ctx.Repo.GetEditorconfig()
+	if err == nil {
+		def, err := ec.GetDefinitionForFilename(treePath)
+		if err == nil {
+			jsonStr, _ := json.Marshal(def)
+			return string(jsonStr)
+		}
+	}
+	return "null"
+}
+
 // EditFile render edit file page
 func EditFile(ctx *context.Context) {
 	editFile(ctx, false)
@@ -186,6 +200,7 @@ func editFilePost(ctx *context.Context, form auth.EditRepoFileForm, isNewFile bo
 	ctx.Data["MarkdownFileExts"] = strings.Join(setting.Markdown.FileExtensions, ",")
 	ctx.Data["LineWrapExtensions"] = strings.Join(setting.Repository.Editor.LineWrapExtensions, ",")
 	ctx.Data["PreviewableFileModes"] = strings.Join(setting.Repository.Editor.PreviewableFileModes, ",")
+	ctx.Data["Editorconfig"] = GetEditorConfig(ctx, form.TreePath)
 
 	if ctx.HasError() {
 		ctx.HTML(200, tplEditFile)

templates/base/head.tmpl

@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<html lang="{{.Language}}">
+<html lang="{{.Language}}" class="theme-{{.SignedUser.Theme}}">
 <head data-suburl="{{AppSubUrl}}">
 	<meta charset="utf-8">
 	<meta name="viewport" content="width=device-width, initial-scale=1">

templates/pwa/serviceworker_js.tmpl

@@ -45,7 +45,17 @@ var urlsToCache = [
   '{{StaticUrlPrefix}}/vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-regular.woff2',
   '{{StaticUrlPrefix}}/vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-italic.woff2',
   '{{StaticUrlPrefix}}/vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-700.woff2',
-  '{{StaticUrlPrefix}}/vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-700italic.woff2'
+  '{{StaticUrlPrefix}}/vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-700italic.woff2',
+
+  // monaco
+  '{{StaticUrlPrefix}}/css/monaco.css',
+  '{{StaticUrlPrefix}}/fonts/codicon.ttf',
+  '{{StaticUrlPrefix}}/js/monaco-css.worker.js',
+  '{{StaticUrlPrefix}}/js/monaco-editor.worker.js',
+  '{{StaticUrlPrefix}}/js/monaco-html.worker.js',
+  '{{StaticUrlPrefix}}/js/monaco-json.worker.js',
+  '{{StaticUrlPrefix}}/js/monaco.js',
+  '{{StaticUrlPrefix}}/js/monaco-ts.worker.js'
 ];
 
 self.addEventListener('install', function (event) {

templates/repo/editor/diff_preview.tmpl

@@ -1,6 +1,6 @@
 <div class="diff-file-box">
 	<div class="ui attached table segment">
-		<div class="file-body file-code code-view code-diff">
+		<div class="file-body file-code code-view code-diff-unified">
 			<table>
 				<tbody>
 					{{template "repo/diff/section_unified" dict "file" .File "root" $}}

templates/repo/editor/edit.tmpl

@@ -15,7 +15,7 @@
 						{{range $i, $v := .TreeNames}}
 							<div class="divider"> / </div>
 							{{if eq $i $l}}
-								<input id="file-name" value="{{$v}}" placeholder="{{$.i18n.Tr "repo.editor.name_your_file"}}" data-ec-url-prefix="{{$.EditorconfigURLPrefix}}" required autofocus>
+								<input id="file-name" value="{{$v}}" placeholder="{{$.i18n.Tr "repo.editor.name_your_file"}}" data-editorconfig="{{$.Editorconfig}}" required autofocus>
 								<span class="poping up" data-content="{{$.i18n.Tr "repo.editor.filename_help"}}" data-position="bottom center" data-variation="tiny inverted">{{svg "octicon-info" 16}}</span>
 							{{else}}
 								<span class="section"><a href="{{EscapePound $.BranchLink}}/{{index $.TreePaths $i | EscapePound}}">{{$v}}</a></span>
@@ -41,11 +41,14 @@
 						data-markdown-file-exts="{{.MarkdownFileExts}}"
 						data-line-wrap-extensions="{{.LineWrapExtensions}}">
 {{.FileContent}}</textarea>
+					<div class="editor-loading">
+						{{.i18n.Tr "loading"}}
+					</div>
 				</div>
 				<div class="ui bottom attached tab segment markdown" data-tab="preview">
 					{{.i18n.Tr "loading"}}
 				</div>
-				<div class="ui bottom attached tab segment diff" data-tab="diff">
+				<div class="ui bottom attached tab segment diff edit-diff" data-tab="diff">
 					{{.i18n.Tr "loading"}}
 				</div>
 			</div>

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;
+}

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($editArea) {
+async function initEditor() {
-  if (simpleMDEditor) {
-    simpleMDEditor.toTextArea();
-    simpleMDEditor = null;
-  }
-
-  if (codeMirrorEditor) {
-    return true;
-  }
-
-  codeMirrorEditor = CodeMirror.fromTextArea($editArea[0], {
-    lineNumbers: true
-  });
-  codeMirrorEditor.on('change', (cm, _change) => {
-    $editArea.val(cm.getValue());
-  });
-
-  return true;
-}
-
-function initEditor() {
   $('.js-quick-pull-choice-option').on('change', function () {
     if ($(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 = $editArea.data('markdown-file-exts').split(',');
+  await createCodeEditor($editArea[0], $editFilename[0], previewFileModes);
-  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');
 
   // Using events from https://github.com/codedance/jquery.AreYouSure#advanced-usage
   // to enable or disable the commit button

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');
+}

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;
+}

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;
+}

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;
 }

webpack.config.js

@@ -2,6 +2,7 @@ const cssnano = require('cssnano');
 const fastGlob = require('fast-glob');
 const FixStyleOnlyEntriesPlugin = require('webpack-fix-style-only-entries');
 const MiniCssExtractPlugin = require('mini-css-extract-plugin');
+const MonacoWebpackPlugin = require('monaco-editor-webpack-plugin');
 const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
 const PostCSSPresetEnv = require('postcss-preset-env');
 const PostCSSSafeParser = require('postcss-safe-parser');
@@ -76,6 +77,14 @@ module.exports = {
     splitChunks: {
       chunks: 'async',
       name: (_, chunks) => chunks.map((item) => item.name).join('-'),
+      cacheGroups: {
+        // this bundles all monaco's languages into one file instead of emitting 1-65.js files
+        monaco: {
+          test: /monaco-editor/,
+          name: 'monaco',
+          chunks: 'async'
+        }
+      }
     }
   },
   module: {
@@ -91,6 +100,7 @@ module.exports = {
       },
       {
         test: /\.worker\.js$/,
+        exclude: /monaco/,
         use: [
           {
             loader: 'worker-loader',
@@ -149,7 +159,10 @@ module.exports = {
             loader: 'css-loader',
             options: {
               importLoaders: 2,
-              url: false,
+              url: (_url, resourcePath) => {
+                // only resolve URLs for dependencies
+                return resourcePath.includes('node_modules');
+              },
             }
           },
           {
@@ -187,6 +200,19 @@ module.exports = {
           },
         ],
       },
+      {
+        test: /\.(ttf|woff2?)$/,
+        use: [
+          {
+            loader: 'file-loader',
+            options: {
+              name: '[name].[ext]',
+              outputPath: 'fonts/',
+              publicPath: (url) => `../fonts/${url}`, // seems required for monaco's font
+            },
+          },
+        ],
+      },
     ],
   },
   plugins: [
@@ -209,9 +235,14 @@ module.exports = {
     new SpriteLoaderPlugin({
       plainSprite: true,
     }),
+    new MonacoWebpackPlugin({
+      filename: 'js/monaco-[name].worker.js',
+    }),
   ],
   performance: {
     hints: false,
+    maxEntrypointSize: Infinity,
+    maxAssetSize: Infinity,
   },
   resolve: {
     symlinks: false,
@@ -224,4 +255,7 @@ module.exports = {
       'node_modules/**',
     ],
   },
+  stats: {
+    children: false,
+  },
 };