Add some handy markdown editor features (#32400)

There were some missing features from EasyMDE:

1. H1 - H3 style
2. Auto add task list
3. Insert a table

And added some tests

7 files changed, 120 insertions, 21 deletions

diff --git a/web_src/css/editor/combomarkdowneditor.css b/web_src/css/editor/combomarkdowneditor.css
index 8a2f4ea416..97a8b70227 100644
--- a/web_src/css/editor/combomarkdowneditor.css
+++ b/web_src/css/editor/combomarkdowneditor.css
@@ -7,17 +7,25 @@
   display: flex;
   align-items: center;
   padding-bottom: 10px;
-  gap: .5rem;
   flex-wrap: wrap;
 }
 
 .combo-markdown-editor .markdown-toolbar-group {
   display: flex;
+  border-left: 1px solid var(--color-secondary);
+  padding: 0 0.5em;
 }
 
+.combo-markdown-editor .markdown-toolbar-group:first-child {
+  border-left: 0;
+  padding-left: 0;
+}
 .combo-markdown-editor .markdown-toolbar-group:last-child {
   flex: 1;
   justify-content: flex-end;
+  border-right: none;
+  border-left: 0;
+  padding-right: 0;
 }
 
 .combo-markdown-editor .markdown-toolbar-button {
@@ -33,6 +41,24 @@
   color: var(--color-primary);
 }
 
+.combo-markdown-editor md-header {
+  position: relative;
+}
+.combo-markdown-editor md-header::after {
+  font-size: 10px;
+  position: absolute;
+  top: 7px;
+}
+.combo-markdown-editor md-header[level="1"]::after {
+  content: "1";
+}
+.combo-markdown-editor md-header[level="2"]::after {
+  content: "2";
+}
+.combo-markdown-editor md-header[level="3"]::after {
+  content: "3";
+}
+
 .ui.form .combo-markdown-editor textarea.markdown-text-editor,
 .combo-markdown-editor textarea.markdown-text-editor {
   display: block;
diff --git a/web_src/css/modules/comment.css b/web_src/css/modules/comment.css
index cda16fdddc..68306686ef 100644
--- a/web_src/css/modules/comment.css
+++ b/web_src/css/modules/comment.css
@@ -21,7 +21,6 @@
   padding: 0.5em 0 0;
   border: none;
   border-top: none;
-  line-height: 1.2;
 }
 
 .edit-content-zone .comment {
diff --git a/web_src/js/features/comp/ComboMarkdownEditor.ts b/web_src/js/features/comp/ComboMarkdownEditor.ts
index d0e122c54a..576c1bccd6 100644
--- a/web_src/js/features/comp/ComboMarkdownEditor.ts
+++ b/web_src/js/features/comp/ComboMarkdownEditor.ts
@@ -15,8 +15,14 @@ import {easyMDEToolbarActions} from './EasyMDEToolbarActions.ts';
 import {initTextExpander} from './TextExpander.ts';
 import {showErrorToast} from '../../modules/toast.ts';
 import {POST} from '../../modules/fetch.ts';
-import {EventEditorContentChanged, initTextareaMarkdown, triggerEditorContentChanged} from './EditorMarkdown.ts';
+import {
+  EventEditorContentChanged,
+  initTextareaMarkdown,
+  textareaInsertText,
+  triggerEditorContentChanged,
+} from './EditorMarkdown.ts';
 import {DropzoneCustomEventReloadFiles, initDropzone} from '../dropzone.ts';
+import {createTippy} from '../../modules/tippy.ts';
 
 let elementIdCounter = 0;
 
@@ -122,8 +128,7 @@ export class ComboMarkdownEditor {
     const monospaceText = monospaceButton.getAttribute(monospaceEnabled ? 'data-disable-text' : 'data-enable-text');
     monospaceButton.setAttribute('data-tooltip-content', monospaceText);
     monospaceButton.setAttribute('aria-checked', String(monospaceEnabled));
-
-    monospaceButton?.addEventListener('click', (e) => {
+    monospaceButton.addEventListener('click', (e) => {
       e.preventDefault();
       const enabled = localStorage?.getItem('markdown-editor-monospace') !== 'true';
       localStorage.setItem('markdown-editor-monospace', String(enabled));
@@ -134,12 +139,14 @@ export class ComboMarkdownEditor {
     });
 
     const easymdeButton = this.container.querySelector('.markdown-switch-easymde');
-    easymdeButton?.addEventListener('click', async (e) => {
+    easymdeButton.addEventListener('click', async (e) => {
       e.preventDefault();
       this.userPreferredEditor = 'easymde';
       await this.switchToEasyMDE();
     });
 
+    this.initMarkdownButtonTableAdd();
+
     initTextareaMarkdown(this.textarea);
     initTextareaEvents(this.textarea, this.dropzone);
   }
@@ -219,6 +226,42 @@ export class ComboMarkdownEditor {
     });
   }
 
+  generateMarkdownTable(rows: number, cols: number): string {
+    const tableLines = [];
+    tableLines.push(
+      `| ${'Header '.repeat(cols).trim().split(' ').join(' | ')} |`,
+      `| ${'--- '.repeat(cols).trim().split(' ').join(' | ')} |`,
+    );
+    for (let i = 0; i < rows; i++) {
+      tableLines.push(`| ${'Cell '.repeat(cols).trim().split(' ').join(' | ')} |`);
+    }
+    return tableLines.join('\n');
+  }
+
+  initMarkdownButtonTableAdd() {
+    const addTableButton = this.container.querySelector('.markdown-button-table-add');
+    const addTablePanel = this.container.querySelector('.markdown-add-table-panel');
+    // here the tippy can't attach to the button because the button already owns a tippy for tooltip
+    const addTablePanelTippy = createTippy(addTablePanel, {
+      content: addTablePanel,
+      trigger: 'manual',
+      placement: 'bottom',
+      hideOnClick: true,
+      interactive: true,
+      getReferenceClientRect: () => addTableButton.getBoundingClientRect(),
+    });
+    addTableButton.addEventListener('click', () => addTablePanelTippy.show());
+
+    addTablePanel.querySelector('.ui.button.primary').addEventListener('click', () => {
+      let rows = parseInt(addTablePanel.querySelector<HTMLInputElement>('[name=rows]').value);
+      let cols = parseInt(addTablePanel.querySelector<HTMLInputElement>('[name=cols]').value);
+      rows = Math.max(1, Math.min(100, rows));
+      cols = Math.max(1, Math.min(100, cols));
+      textareaInsertText(this.textarea, `\n${this.generateMarkdownTable(rows, cols)}\n\n`);
+      addTablePanelTippy.hide();
+    });
+  }
+
   switchTabToEditor() {
     this.tabEditor.click();
   }
diff --git a/web_src/js/features/comp/EditorMarkdown.test.ts b/web_src/js/features/comp/EditorMarkdown.test.ts
new file mode 100644
index 0000000000..acd496bed6
--- /dev/null
+++ b/web_src/js/features/comp/EditorMarkdown.test.ts
@@ -0,0 +1,27 @@
+import {initTextareaMarkdown} from './EditorMarkdown.ts';
+
+test('EditorMarkdown', () => {
+  const textarea = document.createElement('textarea');
+  initTextareaMarkdown(textarea);
+
+  const testInput = (value, expected) => {
+    textarea.value = value;
+    textarea.setSelectionRange(value.length, value.length);
+    const e = new KeyboardEvent('keydown', {key: 'Enter', cancelable: true});
+    textarea.dispatchEvent(e);
+    if (!e.defaultPrevented) textarea.value += '\n';
+    expect(textarea.value).toEqual(expected);
+  };
+
+  testInput('-', '-\n');
+  testInput('1.', '1.\n');
+
+  testInput('- ', '');
+  testInput('1. ', '');
+
+  testInput('- x', '- x\n- ');
+  testInput('- [ ]', '- [ ]\n- ');
+  testInput('- [ ] foo', '- [ ] foo\n- [ ] ');
+  testInput('* [x] foo', '* [x] foo\n* [ ] ');
+  testInput('1. [x] foo', '1. [x] foo\n1. [ ] ');
+});
diff --git a/web_src/js/features/comp/EditorMarkdown.ts b/web_src/js/features/comp/EditorMarkdown.ts
index deee561dab..2af003ccb0 100644
--- a/web_src/js/features/comp/EditorMarkdown.ts
+++ b/web_src/js/features/comp/EditorMarkdown.ts
@@ -4,6 +4,16 @@ export function triggerEditorContentChanged(target) {
   target.dispatchEvent(new CustomEvent(EventEditorContentChanged, {bubbles: true}));
 }
 
+export function textareaInsertText(textarea, value) {
+  const startPos = textarea.selectionStart;
+  const endPos = textarea.selectionEnd;
+  textarea.value = textarea.value.substring(0, startPos) + value + textarea.value.substring(endPos);
+  textarea.selectionStart = startPos;
+  textarea.selectionEnd = startPos + value.length;
+  textarea.focus();
+  triggerEditorContentChanged(textarea);
+}
+
 function handleIndentSelection(textarea, e) {
   const selStart = textarea.selectionStart;
   const selEnd = textarea.selectionEnd;
@@ -46,7 +56,7 @@ function handleIndentSelection(textarea, e) {
   triggerEditorContentChanged(textarea);
 }
 
-function handleNewline(textarea, e) {
+function handleNewline(textarea: HTMLTextAreaElement, e: Event) {
   const selStart = textarea.selectionStart;
   const selEnd = textarea.selectionEnd;
   if (selEnd !== selStart) return; // do not process when there is a selection
@@ -66,9 +76,9 @@ function handleNewline(textarea, e) {
   const indention = /^\s*/.exec(line)[0];
   line = line.slice(indention.length);
 
-  // parse the prefixes: "1. ", "- ", "* ", "[ ] ", "[x] "
+  // parse the prefixes: "1. ", "- ", "* ", there could also be " [ ] " or " [x] " for task lists
   // there must be a space after the prefix because none of "1.foo" / "-foo" is a list item
-  const prefixMatch = /^([0-9]+\.|[-*]|\[ \]|\[x\])\s/.exec(line);
+  const prefixMatch = /^([0-9]+\.|[-*])(\s\[([ x])\])?\s/.exec(line);
   let prefix = '';
   if (prefixMatch) {
     prefix = prefixMatch[0];
@@ -85,8 +95,9 @@ function handleNewline(textarea, e) {
   } else {
     // start a new line with the same indention and prefix
     let newPrefix = prefix;
-    if (newPrefix === '[x]') newPrefix = '[ ]';
-    if (/^\d+\./.test(newPrefix)) newPrefix = `1. `; // a simple approach, otherwise it needs to parse the lines after the current line
+    // a simple approach, otherwise it needs to parse the lines after the current line
+    if (/^\d+\./.test(prefix)) newPrefix = `1. ${newPrefix.slice(newPrefix.indexOf('.') + 2)}`;
+    newPrefix = newPrefix.replace('[x]', '[ ]');
     const newLine = `\n${indention}${newPrefix}`;
     textarea.value = value.slice(0, selStart) + newLine + value.slice(selEnd);
     textarea.setSelectionRange(selStart + newLine.length, selStart + newLine.length);
diff --git a/web_src/js/features/comp/EditorUpload.ts b/web_src/js/features/comp/EditorUpload.ts
index 582639a817..b1f49cbe92 100644
--- a/web_src/js/features/comp/EditorUpload.ts
+++ b/web_src/js/features/comp/EditorUpload.ts
@@ -1,7 +1,7 @@
 import {imageInfo} from '../../utils/image.ts';
 import {replaceTextareaSelection} from '../../utils/dom.ts';
 import {isUrl} from '../../utils/url.ts';
-import {triggerEditorContentChanged} from './EditorMarkdown.ts';
+import {textareaInsertText, triggerEditorContentChanged} from './EditorMarkdown.ts';
 import {
   DropzoneCustomEventRemovedFile,
   DropzoneCustomEventUploadDone,
@@ -41,14 +41,7 @@ class TextareaEditor {
   }
 
   insertPlaceholder(value) {
-    const editor = this.editor;
-    const startPos = editor.selectionStart;
-    const endPos = editor.selectionEnd;
-    editor.value = editor.value.substring(0, startPos) + value + editor.value.substring(endPos);
-    editor.selectionStart = startPos;
-    editor.selectionEnd = startPos + value.length;
-    editor.focus();
-    triggerEditorContentChanged(editor);
+    textareaInsertText(this.editor, value);
   }
 
   replacePlaceholder(oldVal, newVal) {
diff --git a/web_src/js/modules/tippy.ts b/web_src/js/modules/tippy.ts
index 375d816c6b..d75015f69e 100644
--- a/web_src/js/modules/tippy.ts
+++ b/web_src/js/modules/tippy.ts
@@ -11,7 +11,7 @@ type TippyOpts = {
 const visibleInstances = new Set<Instance>();
 const arrowSvg = `<svg width="16" height="7"><path d="m0 7 8-7 8 7Z" class="tippy-svg-arrow-outer"/><path d="m0 8 8-7 8 7Z" class="tippy-svg-arrow-inner"/></svg>`;
 
-export function createTippy(target: Element, opts: TippyOpts = {}) {
+export function createTippy(target: Element, opts: TippyOpts = {}): Instance {
   // the callback functions should be destructured from opts,
   // because we should use our own wrapper functions to handle them, do not let the user override them
   const {onHide, onShow, onDestroy, role, theme, arrow, ...other} = opts;