Implement plugin

src/mathcommand.js

@@ -0,0 +1,36 @@
+import Command from '@ckeditor/ckeditor5-core/src/command';
+import { getSelectedMathModelWidget } from './utils';
+
+export default class MathCommand extends Command {
+	execute( equation ) {
+		const model = this.editor.model;
+		const selection = model.document.selection;
+		const selectedElement = selection.getSelectedElement();
+
+		model.change( writer => {
+			let mathtex;
+			if ( selectedElement && selectedElement.is( 'mathtex' ) ) {
+				// Update selected element
+				const mode = selectedElement.getAttribute( 'mode' );
+				const display = selectedElement.getAttribute( 'display' );
+				mathtex = writer.createElement( 'mathtex', { equation, mode, display } );
+			} else {
+				// Create new model element
+				mathtex = writer.createElement( 'mathtex', { equation, mode: 'script', display: true } );
+			}
+			model.insertContent( mathtex );
+			writer.setSelection( mathtex, 'on' );
+		} );
+	}
+
+	refresh() {
+		const model = this.editor.model;
+		const selection = model.document.selection;
+
+		const isAllowed = model.schema.checkChild( selection.focus.parent, 'mathtex' );
+		this.isEnabled = isAllowed;
+
+		const selectedEquation = getSelectedMathModelWidget( selection );
+		this.value = selectedEquation ? selectedEquation.getAttribute( 'equation' ) : null;
+	}
+}