Internalize the notebook cell executor

package.json

@@ -53,9 +53,16 @@
         "watch:labextension": "jupyter labextension watch ."
     },
     "dependencies": {
-        "@jupyterlab/application": "^4.0.0",
-        "@jupyterlab/coreutils": "^6.0.0",
-        "@jupyterlab/services": "^7.0.0"
+        "@jupyterlab/application": "^4.2.0",
+        "@jupyterlab/apputils": "^4.2.0",
+        "@jupyterlab/cells": "^4.2.0",
+        "@jupyterlab/coreutils": "^6.2.0",
+        "@jupyterlab/notebook": "^4.2.0",
+        "@jupyterlab/outputarea": "^4.2.0",
+        "@jupyterlab/services": "^7.2.0",
+        "@jupyterlab/translation": "^4.2.0",
+        "@lumino/coreutils": "^2.1.0",
+        "@lumino/widgets": "^2.3.0"
     },
     "devDependencies": {
         "@jupyterlab/builder": "^4.0.0",
@@ -95,15 +102,19 @@
     },
     "jupyterlab": {
         "discovery": {
-        "server": {
-            "managers": [
-                "pip"
-            ],
-            "base": {
-                "name": "jupyter_server_nbmodel"
+            "server": {
+                "managers": [
+                    "pip"
+                ],
+                "base": {
+                    "name": "jupyter_server_nbmodel"
+                }
             }
-        }
         },
+        "disabledExtensions": [
+          "@jupyterlab/notebook-extension:cell-executor",
+          "@jupyter/docprovider-extension:notebook-cell-executor"
+        ],
         "extension": true,
         "outputDir": "jupyter_server_nbmodel/labextension"
     },

src/executor.ts

@@ -0,0 +1,326 @@
+import {
+  JupyterFrontEnd,
+  JupyterFrontEndPlugin
+} from '@jupyterlab/application';
+import { Dialog, showDialog } from '@jupyterlab/apputils';
+import {
+  CodeCell,
+  type ICodeCellModel,
+  type MarkdownCell
+} from '@jupyterlab/cells';
+import { URLExt } from '@jupyterlab/coreutils';
+import { INotebookCellExecutor } from '@jupyterlab/notebook';
+import { OutputPrompt, Stdin } from '@jupyterlab/outputarea';
+import { Kernel, ServerConnection } from '@jupyterlab/services';
+import * as KernelMessage from '@jupyterlab/services/lib/kernel/messages';
+import { nullTranslator, type ITranslator } from '@jupyterlab/translation';
+import { PromiseDelegate } from '@lumino/coreutils';
+import { Panel } from '@lumino/widgets';
+
+/**
+ * Polling interval for accepted execution requests.
+ */
+const MAX_POLLING_INTERVAL = 1000;
+
+/**
+ * Notebook cell executor posting a request to the server for execution.
+ */
+export class NotebookCellServerExecutor implements INotebookCellExecutor {
+  private _serverSettings: ServerConnection.ISettings;
+
+  /**
+   * Constructor
+   *
+   * @param options Constructor options; the contents manager, the collaborative drive and optionally the server settings.
+   */
+  constructor(options: { serverSettings?: ServerConnection.ISettings }) {
+    this._serverSettings =
+      options.serverSettings ?? ServerConnection.makeSettings();
+  }
+
+  /**
+   * Execute a given cell of the notebook.
+   *
+   * @param options Execution options
+   * @returns Execution success status
+   */
+  async runCell({
+    cell,
+    notebook,
+    notebookConfig,
+    onCellExecuted,
+    onCellExecutionScheduled,
+    sessionContext,
+    sessionDialogs,
+    translator
+  }: INotebookCellExecutor.IRunCellOptions): Promise<boolean> {
+    translator = translator ?? nullTranslator;
+    const trans = translator.load('jupyterlab');
+
+    switch (cell.model.type) {
+      case 'markdown':
+        (cell as MarkdownCell).rendered = true;
+        cell.inputHidden = false;
+        onCellExecuted({ cell, success: true });
+        break;
+      case 'code':
+        if (sessionContext) {
+          if (sessionContext.isTerminating) {
+            await showDialog({
+              title: trans.__('Kernel Terminating'),
+              body: trans.__(
+                'The kernel for %1 appears to be terminating. You can not run any cell for now.',
+                sessionContext.session?.path
+              ),
+              buttons: [Dialog.okButton()]
+            });
+            break;
+          }
+          if (sessionContext.pendingInput) {
+            await showDialog({
+              title: trans.__('Cell not executed due to pending input'),
+              body: trans.__(
+                'The cell has not been executed to avoid kernel deadlock as there is another pending input! Submit your pending input and try again.'
+              ),
+              buttons: [Dialog.okButton()]
+            });
+            return false;
+          }
+          if (sessionContext.hasNoKernel) {
+            const shouldSelect = await sessionContext.startKernel();
+            if (shouldSelect && sessionDialogs) {
+              await sessionDialogs.selectKernel(sessionContext);
+            }
+          }
+
+          if (sessionContext.hasNoKernel) {
+            cell.model.sharedModel.transact(() => {
+              (cell.model as ICodeCellModel).clearExecution();
+            });
+            return true;
+          }
+
+          const kernelId = sessionContext?.session?.kernel?.id;
+          const apiURL = URLExt.join(
+            this._serverSettings.baseUrl,
+            `api/kernels/${kernelId}/execute`
+          );
+          const cellId = cell.model.sharedModel.getId();
+          const documentId = notebook.sharedModel.getState('document_id');
+
+          const init = {
+            method: 'POST',
+            body: JSON.stringify({ cell_id: cellId, document_id: documentId })
+          };
+          onCellExecutionScheduled({ cell });
+          let success = false;
+          try {
+            // FIXME quid of deletedCells and timing record
+            const response = await requestServer(
+              cell as CodeCell,
+              apiURL,
+              init,
+              this._serverSettings,
+              translator
+            );
+            const data = await response.json();
+            success = data['status'] === 'ok';
+          } catch (error: unknown) {
+            onCellExecuted({
+              cell,
+              success: false
+            });
+            if (cell.isDisposed) {
+              return false;
+            } else {
+              throw error;
+            }
+          }
+
+          onCellExecuted({ cell, success });
+
+          return true;
+        }
+        cell.model.sharedModel.transact(() => {
+          (cell.model as ICodeCellModel).clearExecution();
+        }, false);
+        break;
+      default:
+        break;
+    }
+    return Promise.resolve(true);
+  }
+}
+
+async function requestServer(
+  cell: CodeCell,
+  url: string,
+  init: RequestInit,
+  settings: ServerConnection.ISettings,
+  translator?: ITranslator,
+  interval = 100
+): Promise<Response> {
+  const promise = new PromiseDelegate<Response>();
+  ServerConnection.makeRequest(url, init, settings)
+    .then(async response => {
+      if (!response.ok) {
+        if (response.status === 300) {
+          let replyUrl = response.headers.get('Location') || '';
+
+          if (!replyUrl.startsWith(settings.baseUrl)) {
+            replyUrl = URLExt.join(settings.baseUrl, replyUrl);
+          }
+          const { parent_header, input_request } = await response.json();
+          // TODO only the client sending the snippet will be prompted for the input
+          // we can have a deadlock if its connection is lost.
+          const panel = new Panel();
+          panel.addClass('jp-OutputArea-child');
+          panel.addClass('jp-OutputArea-stdin-item');
+
+          const prompt = new OutputPrompt();
+          prompt.addClass('jp-OutputArea-prompt');
+          panel.addWidget(prompt);
+
+          const input = new Stdin({
+            future: Object.freeze({
+              sendInputReply: (
+                content: KernelMessage.IInputReply,
+                parent_header: KernelMessage.IHeader<'input_request'>
+              ) => {
+                ServerConnection.makeRequest(
+                  replyUrl,
+                  {
+                    method: 'POST',
+                    body: JSON.stringify({ input: content.value })
+                  },
+                  settings
+                ).catch(error => {
+                  console.error(
+                    `Failed to set input to ${JSON.stringify(content)}.`,
+                    error
+                  );
+                });
+              }
+            }) as Kernel.IShellFuture,
+            parent_header,
+            password: input_request.password,
+            prompt: input_request.prompt,
+            translator
+          });
+          input.addClass('jp-OutputArea-output');
+          panel.addWidget(input);
+
+          // Get the input node to ensure focus after updating the model upon user reply.
+          const inputNode = input.node.getElementsByTagName('input')[0];
+
+          void input.value.then(value => {
+            panel.addClass('jp-OutputArea-stdin-hiding');
+
+            // FIXME this is not great as the model should not be modified on the client.
+            // Use stdin as the stream so it does not get combined with stdout.
+            // Note: because it modifies DOM it may (will) shift focus away from the input node.
+            cell.outputArea.model.add({
+              output_type: 'stream',
+              name: 'stdin',
+              text: value + '\n'
+            });
+            // Refocus the input node after it lost focus due to update of the model.
+            inputNode.focus();
+
+            // Keep the input in view for a little while; this (along refocusing)
+            // ensures that we can avoid the cell editor stealing the focus, and
+            // leading to user inadvertently modifying editor content when executing
+            // consecutive commands in short succession.
+            window.setTimeout(async () => {
+              // Tack currently focused element to ensure that it remains on it
+              // after disposal of the panel with the old input
+              // (which modifies DOM and can lead to focus jump).
+              const focusedElement = document.activeElement;
+              // Dispose the old panel with no longer needed input box.
+              panel.dispose();
+              // Refocus the element that was focused before.
+              if (focusedElement && focusedElement instanceof HTMLElement) {
+                focusedElement.focus();
+              }
+
+              try {
+                const response = await requestServer(
+                  cell,
+                  url,
+                  init,
+                  settings,
+                  translator
+                );
+                promise.resolve(response);
+              } catch (error) {
+                promise.reject(error);
+              }
+            }, 500);
+          });
+
+          cell.outputArea.layout.addWidget(panel);
+        } else {
+          promise.reject(await ServerConnection.ResponseError.create(response));
+        }
+      } else if (response.status === 202) {
+        let redirectUrl = response.headers.get('Location') || url;
+
+        if (!redirectUrl.startsWith(settings.baseUrl)) {
+          redirectUrl = URLExt.join(settings.baseUrl, redirectUrl);
+        }
+
+        setTimeout(
+          async (
+            cell: CodeCell,
+            url: string,
+            init: RequestInit,
+            settings: ServerConnection.ISettings,
+            translator?: ITranslator,
+            interval?: number
+          ) => {
+            try {
+              const response = await requestServer(
+                cell,
+                url,
+                init,
+                settings,
+                translator,
+                interval
+              );
+              promise.resolve(response);
+            } catch (error) {
+              promise.reject(error);
+            }
+          },
+          interval,
+          cell,
+          redirectUrl,
+          { method: 'GET' },
+          settings,
+          translator,
+          // Evanescent interval
+          Math.min(MAX_POLLING_INTERVAL, interval * 2)
+        );
+      } else {
+        promise.resolve(response);
+      }
+    })
+    .catch(reason => {
+      promise.reject(new ServerConnection.NetworkError(reason));
+    });
+  return promise.promise;
+}
+
+export const notebookCellExecutor: JupyterFrontEndPlugin<INotebookCellExecutor> =
+  {
+    id: 'jupyter-server-nbmodel:notebook-cell-executor',
+    description:
+      'Add notebook cell executor that uses REST API instead of kernel protocol over WebSocket.',
+    autoStart: true,
+    provides: INotebookCellExecutor,
+    activate: (app: JupyterFrontEnd): INotebookCellExecutor => {
+      return new NotebookCellServerExecutor({
+        serverSettings: app.serviceManager.serverSettings
+      });
+    }
+  };