feat: add trailing-node extension

packages/extension-utils/src/index.ts

@@ -1,2 +1,3 @@
 export * from './focus.js'
 export * from './selection.js'
+export * from './trailing-node.js'

packages/extension-utils/src/trailing-node.ts

@@ -0,0 +1,84 @@
+import { Extension } from '@tiptap/core'
+import { Node, NodeType } from '@tiptap/pm/model'
+import { Plugin, PluginKey } from '@tiptap/pm/state'
+
+function nodeEqualsType({ types, node }: { types: NodeType | NodeType[]; node: Node | null | undefined }) {
+  return (node && Array.isArray(types) && types.includes(node.type)) || node?.type === types
+}
+
+/**
+ * Extension based on:
+ * - https://github.com/ueberdosis/tiptap/blob/v1/packages/tiptap-extensions/src/extensions/TrailingNode.js
+ * - https://github.com/remirror/remirror/blob/e0f1bec4a1e8073ce8f5500d62193e52321155b9/packages/prosemirror-trailing-node/src/trailing-node-plugin.ts
+ */
+
+export interface TrailingNodeOptions {
+  /**
+   * The node type that should be inserted at the end of the document.
+   * @note the node will always be added to the `notAfter` lists to
+   * prevent an infinite loop.
+   * @default 'paragraph'
+   */
+  node: string;
+  /**
+   * The node types after which the trailing node should not be inserted.
+   * @default ['paragraph']
+   */
+  notAfter?: string | string[];
+}
+
+/**
+ * This extension allows you to add an extra node at the end of the document.
+ * @see https://www.tiptap.dev/api/extensions/trailing-node
+ */
+export const TrailingNode = Extension.create<TrailingNodeOptions>({
+  name: 'trailingNode',
+
+  addOptions() {
+    return {
+      node: 'paragraph',
+      notAfter: [],
+    }
+  },
+
+  addProseMirrorPlugins() {
+    const plugin = new PluginKey(this.name)
+    const disabledNodes = Object.entries(this.editor.schema.nodes)
+      .map(([, value]) => value)
+      .filter(node => (this.options.notAfter || []).concat(this.options.node).includes(node.name))
+
+    return [
+      new Plugin({
+        key: plugin,
+        appendTransaction: (_, __, state) => {
+          const { doc, tr, schema } = state
+          const shouldInsertNodeAtEnd = plugin.getState(state)
+          const endPosition = doc.content.size
+          const type = schema.nodes[this.options.node]
+
+          if (!shouldInsertNodeAtEnd) {
+            return
+          }
+
+          return tr.insert(endPosition, type.create())
+        },
+        state: {
+          init: (_, state) => {
+            const lastNode = state.tr.doc.lastChild
+
+            return !nodeEqualsType({ node: lastNode, types: disabledNodes })
+          },
+          apply: (tr, value) => {
+            if (!tr.docChanged) {
+              return value
+            }
+
+            const lastNode = tr.doc.lastChild
+
+            return !nodeEqualsType({ node: lastNode, types: disabledNodes })
+          },
+        },
+      }),
+    ]
+  },
+})