comunicmobile/lib/utils/ui_utils.dart

import 'package:cached_network_image/cached_network_image.dart';
import 'package:comunic/utils/intl_utils.dart';
import 'package:flutter/material.dart';

/// User interface utilities
///
/// @author Pierre HUBERT

/// Build centered progress bar
Widget buildCenteredProgressBar() {
  return Center(
    child: CircularProgressIndicator(),
  );
}

/// Build and return a full loading page
Widget buildLoadingPage() {
  return Scaffold(
    body: buildCenteredProgressBar(),
  );
}

/// Build and return an error card
Widget buildErrorCard(String message, {List<Widget> actions}) {
  return Card(
    elevation: 2.0,
    color: Colors.red,
    child: Padding(
      padding: const EdgeInsets.all(8.0),
      child: Row(
        children: <Widget>[
          Padding(
            padding: const EdgeInsets.only(right: 8.0),
            child: Icon(
              Icons.error,
              color: Colors.white,
            ),
          ),
          Flexible(
            child: Text(
              message,
              style: TextStyle(color: Colors.white),
              maxLines: null,
            ),
          ),
          Row(
            children: actions == null ? <Widget>[] : actions,
          )
        ],
      ),
    ),
  );
}

/// Show an image with a given [url] in full screen
void showImageFullScreen(BuildContext context, String url) {
  Navigator.of(context).push(MaterialPageRoute(builder: (c) {
    // TODO : add better support later
    return CachedNetworkImage(
      imageUrl: url,
    );
  }));
}

/// Show simple snack
void showSimpleSnack(BuildContext context, String message) {
  Scaffold.of(context).showSnackBar(SnackBar(content: Text(message)));
}

/// Show an alert dialog to ask the user to enter a string
///
/// Returns entered string if the dialog is confirmed, null else
Future<String> askUserString({
  @required BuildContext context,
  @required String title,
  @required String message,
  @required String defaultValue,
  @required String hint,
}) async {
  assert(context != null);
  assert(title != null);
  assert(message != null);
  assert(defaultValue != null);
  assert(hint != null);

  TextEditingController controller = TextEditingController(text: defaultValue);

  final confirm = await showDialog<bool>(
      context: context,
      builder: (c) => AlertDialog(
            title: Text(title),
            content: Column(
              children: <Widget>[
                Text(message),
                TextField(
                  controller: controller,
                  maxLines: null,
                  maxLength: 200,
                  keyboardType: TextInputType.text,
                  decoration: InputDecoration(
                    labelText: hint,
                    alignLabelWithHint: true,
                  ),
                )
              ],
            ),
            actions: <Widget>[
              FlatButton(
                child: Text(tr("Cancel").toUpperCase()),
                onPressed: () => Navigator.pop(c, false),
              ),
              FlatButton(
                child: Text(tr("OK")),
                onPressed: () => Navigator.pop(c, true),
              ),
            ],
          ));

  if (confirm == null || !confirm) return null;

  return controller.text;
}

/// Show an alert dialog to get user confirmation for something
///
/// Return value of this function is never null
Future<bool> showConfirmDialog({
  @required BuildContext context,
  String title,
  @required String message,
}) async {
  if (title == null) title = tr("Confirm operation");

  final result = await showDialog<bool>(
      context: context,
      builder: (c) => AlertDialog(
            title: Text(title),
            content: Text(message),
            actions: <Widget>[
              FlatButton(
                onPressed: () => Navigator.pop(context, false),
                child: Text(tr("Cancel").toUpperCase()),
              ),
              FlatButton(
                onPressed: () => Navigator.pop(context, true),
                child: Text(
                  tr("Confirm").toUpperCase(),
                  style: TextStyle(color: Colors.red),
                ),
              ),
            ],
          ));

  return result != null && result;
}

/// Smart [InputCounterWidgetBuilder] that show text limit only when some
/// text has already been entered by the user
Widget smartInputCounterWidgetBuilder(
  BuildContext context, {
  @required int currentLength,
  @required int maxLength,
  @required bool isFocused,
}) =>
    currentLength > 0 ? Text("$currentLength/$maxLength") : Container();