smooth-app/packages/smooth_app/lib/generic_lib/loading_dialog.dart

import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter_svg/flutter_svg.dart';
import 'package:openfoodfacts/openfoodfacts.dart';
import 'package:smooth_app/generic_lib/design_constants.dart';
import 'package:smooth_app/generic_lib/dialogs/smooth_alert_dialog.dart';
import 'package:smooth_app/helpers/app_helper.dart';
import 'package:smooth_app/helpers/launch_url_helper.dart';
import 'package:smooth_app/l10n/app_localizations.dart';

/// Dialog with a stop button, while a future is running.
///
/// Typical use-case: wait during download.
class LoadingDialog<T> {
  LoadingDialog._();

  /// Is the dialog already pop'ed?
  bool _popEd = false;

  /// Runs a future while displaying a stoppable dialog.
  static Future<T?> run<T>({
    required final BuildContext context,
    required final Future<T> future,
    final String? title,
    final bool? dismissible,
  }) {
    final AppLocalizations appLocalizations = AppLocalizations.of(context);
    return LoadingDialog<T>._()._run(
      context: context,
      future: future,
      title: title ?? appLocalizations.loading_dialog_default_title,
      dismissible: dismissible ?? true,
    );
  }

  /// Shows an loading error dialog.
  ///
  /// Typical use-case: when the [run] call failed.
  static Future<void> error({
    required final BuildContext context,
    final String? title,
    final bool shouldOpenNewIssue = false,
  }) async => showDialog<void>(
    context: context,
    builder: (BuildContext context) {
      final AppLocalizations appLocalizations = AppLocalizations.of(context);
      return SmoothAlertDialog(
        body: Column(
          children: <Widget>[
            SvgPicture.asset(
              'assets/misc/error.svg',
              width: MINIMUM_TOUCH_SIZE * 2,
              package: AppHelper.APP_PACKAGE,
            ),
            Padding(
              padding: const EdgeInsets.symmetric(vertical: MEDIUM_SPACE),
              child: Text(
                shouldOpenNewIssue
                    ? appLocalizations.server_error_open_new_issue
                    : title ??
                          appLocalizations.loading_dialog_default_error_message,
                textAlign: TextAlign.center,
              ),
            ),
            if (shouldOpenNewIssue)
              Padding(
                padding: const EdgeInsets.only(bottom: MEDIUM_SPACE),
                child: RichText(
                  textAlign: TextAlign.center,
                  text: TextSpan(
                    style: Theme.of(
                      context,
                    ).textTheme.bodyMedium?.copyWith(color: Colors.blue),
                    text: Status.openNewIssueUrl,
                    recognizer: TapGestureRecognizer()
                      ..onTap = () =>
                          LaunchUrlHelper.launchURL(Status.openNewIssueUrl),
                  ),
                ),
              ),
          ],
        ),
        positiveAction: SmoothActionButton(
          text: appLocalizations.close,
          onPressed: () => Navigator.maybePop(context),
        ),
      );
    },
  );

  /// Displays "downloading" dialog while actually downloading
  Future<T?> _run({
    required final BuildContext context,
    required final Future<T> future,
    required final String title,
    final bool? dismissible,
  }) async => showDialog<T>(
    barrierDismissible: dismissible ?? true,
    context: context,
    builder: (BuildContext context) {
      return _getDialog(context, title, future);
    },
  );

  /// Closes the dialog if relevant, pop'ing the [value]
  void _popDialog(final BuildContext context, final T? value) {
    if (_popEd) {
      return;
    }
    _popEd = true;
    // Here we use the root navigator so that we can pop dialog while using multiple navigators.

    SchedulerBinding.instance.addPostFrameCallback((_) {
      Navigator.of(context, rootNavigator: true).pop(value);
    });
  }

  /// Displayed dialog during future.
  Widget _getDialog(
    final BuildContext context,
    final String title,
    final Future<T> future,
  ) {
    final AppLocalizations appLocalizations = AppLocalizations.of(context);
    return SmoothAlertDialog(
      body: FutureBuilder<T>(
        future: future,
        builder: (BuildContext context, AsyncSnapshot<T> snapshot) {
          if (snapshot.hasError || snapshot.hasData) {
            _popDialog(context, snapshot.data);
          }

          return ListTile(
            leading: const CircularProgressIndicator.adaptive(),
            title: Text(title),
          );
        },
      ),
      positiveAction: SmoothActionButton(
        text: appLocalizations.stop,
        onPressed: () => _popDialog(context, null),
      ),
    );
  }
}