chore: Move editor into codebase (#2930)

shared/editor/plugins/TrailingNode.ts

@@ -0,0 +1,58 @@
+import { NodeType } from "prosemirror-model";
+import { Plugin, PluginKey } from "prosemirror-state";
+import Extension from "../lib/Extension";
+
+export default class TrailingNode extends Extension {
+  get name() {
+    return "trailing_node";
+  }
+
+  get defaultOptions() {
+    return {
+      node: "paragraph",
+      notAfter: ["paragraph", "heading"],
+    };
+  }
+
+  get plugins() {
+    const plugin = new PluginKey(this.name);
+    const disabledNodes = Object.entries(this.editor.schema.nodes)
+      .map(([, value]) => value)
+      .filter((node: NodeType) => this.options.notAfter.includes(node.name));
+
+    return [
+      new Plugin({
+        key: plugin,
+        view: () => ({
+          update: (view) => {
+            const { state } = view;
+            const insertNodeAtEnd = plugin.getState(state);
+
+            if (!insertNodeAtEnd) {
+              return;
+            }
+
+            const { doc, schema, tr } = state;
+            const type = schema.nodes[this.options.node];
+            const transaction = tr.insert(doc.content.size, type.create());
+            view.dispatch(transaction);
+          },
+        }),
+        state: {
+          init: (_, state) => {
+            const lastNode = state.tr.doc.lastChild;
+            return lastNode ? !disabledNodes.includes(lastNode.type) : false;
+          },
+          apply: (tr, value) => {
+            if (!tr.docChanged) {
+              return value;
+            }
+
+            const lastNode = tr.doc.lastChild;
+            return lastNode ? !disabledNodes.includes(lastNode.type) : false;
+          },
+        },
+      }),
+    ];
+  }
+}