import {
  JupyterFrontEnd,
  JupyterFrontEndPlugin
} from '@jupyterlab/application';
import { INotebookTracker, NotebookPanel } from '@jupyterlab/notebook';
import { ToolbarButton, MainAreaWidget } from '@jupyterlab/apputils';
import { ISettingRegistry } from '@jupyterlab/settingregistry';
import { saveIcon } from '@jupyterlab/ui-components';

import { requestAPI } from './request';
import { registerCommands, CommandIDs } from './commands';
import { SnapshotModel } from './model';
import { SnapshotPanel } from './widgets/SnapshotPanel';
import { DiffWidget } from './widgets/DiffWidget';
import { INotebook } from './diff';

/**
 * Initialization data for the snapshot extension.
 */
const plugin: JupyterFrontEndPlugin<void> = {
  id: 'snapshot:plugin',
  description: 'Notebook version snapshot extension (manual commit, name + description).',
  autoStart: true,
  requires: [INotebookTracker],
  optional: [ISettingRegistry],
  activate: (
    app: JupyterFrontEnd,
    tracker: INotebookTracker,
    settingRegistry: ISettingRegistry | null
  ) => {
    console.log('JupyterLab extension snapshot is activated!');

    if (settingRegistry) {
      settingRegistry
        .load(plugin.id)
        .then(settings => {
          console.log('snapshot settings loaded:', settings.composite);
        })
        .catch(reason => {
          console.error('Failed to load settings for snapshot.', reason);
        });
    }

    const serverSettings = app.serviceManager.serverSettings;
    const model = new SnapshotModel(serverSettings);

    const openDiff = (newNb: INotebook, oldNb: INotebook, name: string) => {
      const widget = new DiffWidget({ newNb, oldNb });
      widget.title.label = name && name.trim() ? name : '快照对比';
      widget.title.closable = true;
      const host = new MainAreaWidget({ content: widget });
      app.shell.add(host, 'main', { mode: 'split-right' });
    };

    const panel = new SnapshotPanel({
      model,
      app,
      tracker,
      serverSettings,
      onOpenDiff: openDiff
    });
    panel.id = 'snapshot:panel';
    // Icon-only panel tab: the title text becomes a hover caption so the
    // sidebar stays compact. saveIcon is reused for visual consistency with
    // the commit toolbar button (both signal "save" semantics).
    panel.title.icon = saveIcon;
    panel.title.caption = '快照历史';
    app.shell.add(panel, 'left', { rank: 200 });

    // Keep the model in sync with the current notebook.
    const syncPath = () => {
      const current = tracker.currentWidget;
      model.setPath(current?.context.path ?? '');
    };
    tracker.widgetAdded.connect(() => syncPath());
    tracker.currentChanged.connect(() => syncPath());
    syncPath();

    registerCommands(app, tracker, model);

    // Add an icon-only "保存快照" button to every notebook panel's toolbar.
    // The tooltip on hover carries the full description.
    // NOTE: docRegistry.addWidgetExtension('Notebook', ...) places its
    // returned widget in the *main area* (a new tab), not on the toolbar.
    // The toolbar wants panel.toolbar.addItem directly.
    const addCommitButton = (panelHost: NotebookPanel) => {
      const button = new ToolbarButton({
        icon: saveIcon,
        tooltip: '保存当前 notebook 为快照',
        onClick: () => {
          void app.commands.execute(CommandIDs.commit);
        }
      });
      button.addClass('jp-snapshot-toolbar-button');
      panelHost.toolbar.addItem('snapshot:commit', button);
    };
    // Add to panels that are already open at activation time.
    tracker.forEach(addCommitButton);
    // Add to any panel that opens later.
    tracker.widgetAdded.connect((_, panelHost) => addCommitButton(panelHost));

    // Keep the unused import alive for the build (requestAPI is part of
    // the public surface and re-used by the api module).
    void requestAPI;
  }
};

export default plugin;