aves/lib/widgets/about/licenses.dart

import 'package:aves/utils/constants.dart';
import 'package:aves/widgets/common/icons.dart';
import 'package:aves/widgets/common/menu_row.dart';
import 'package:collection/collection.dart';
import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher.dart';

class Licenses extends StatefulWidget {
  @override
  _LicensesState createState() => _LicensesState();
}

class _LicensesState extends State<Licenses> {
  LicenseSort _sort = LicenseSort.name;
  List<Dependency> _packages;

  @override
  void initState() {
    super.initState();
    _packages = List.of(Constants.packages);
    _sortPackages();
  }

  void _sortPackages() {
    _packages.sort((a, b) {
      switch (_sort) {
        case LicenseSort.license:
          final c = compareAsciiUpperCase(a.license, b.license);
          return c != 0 ? c : compareAsciiUpperCase(a.name, b.name);
        case LicenseSort.name:
        default:
          return compareAsciiUpperCase(a.name, b.name);
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return SliverPadding(
      padding: const EdgeInsets.symmetric(horizontal: 8),
      sliver: SliverList(
        delegate: SliverChildBuilderDelegate(
          (context, index) {
            if (index-- == 0) {
              return _buildHeader();
            }
            return LicenseRow(_packages[index]);
          },
          childCount: _packages.length + 1,
        ),
      ),
    );
  }

  Widget _buildHeader() {
    return Column(
      children: [
        Padding(
          padding: const EdgeInsetsDirectional.only(start: 8),
          child: Row(
            children: [
              Text(
                'Open-source licenses',
                style: Theme.of(context).textTheme.headline6.copyWith(fontFamily: 'Concourse Caps'),
              ),
              const Spacer(),
              PopupMenuButton<LicenseSort>(
                itemBuilder: (context) => [
                  PopupMenuItem(
                    value: LicenseSort.name,
                    child: MenuRow(text: 'Sort by name', checked: _sort == LicenseSort.name),
                  ),
                  PopupMenuItem(
                    value: LicenseSort.license,
                    child: MenuRow(text: 'Sort by license', checked: _sort == LicenseSort.license),
                  ),
                ],
                onSelected: (newSort) {
                  _sort = newSort;
                  _sortPackages();
                  setState(() {});
                },
                tooltip: 'Sort',
                icon: Icon(AIcons.sort),
              ),
            ],
          ),
        ),
        const SizedBox(height: 8),
        const Padding(
          padding: EdgeInsets.symmetric(horizontal: 8),
          child: Text('The following sets forth attribution notices for third party software that may be contained in this application.'),
        ),
      ],
    );
  }
}

class LicenseRow extends StatelessWidget {
  final Dependency package;

  const LicenseRow(this.package);

  static const borderRadius = BorderRadius.all(Radius.circular(8));

  @override
  Widget build(BuildContext context) {
    final textTheme = Theme.of(context).textTheme;
    final bodyTextStyle = textTheme.bodyText2;
    final subColor = bodyTextStyle.color.withOpacity(.6);

    return Padding(
      padding: const EdgeInsets.only(top: 16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          InkWell(
            borderRadius: borderRadius,
            onTap: () => launch(package.sourceUrl),
            child: Padding(
              padding: const EdgeInsets.all(8),
              child: Row(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Text(
                    package.name,
                    style: TextStyle(fontWeight: FontWeight.bold),
                  ),
                  const SizedBox(width: 8),
                  Icon(
                    AIcons.openInNew,
                    size: bodyTextStyle.fontSize,
                  )
                ],
              ),
            ),
          ),
          Padding(
            padding: const EdgeInsetsDirectional.only(start: 16),
            child: InkWell(
              borderRadius: borderRadius,
              onTap: () => launch(package.licenseUrl),
              child: Padding(
                padding: const EdgeInsets.all(8.0),
                child: Row(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Text(
                      package.license,
                      style: TextStyle(color: subColor),
                    ),
                    const SizedBox(width: 8),
                    Icon(
                      AIcons.openInNew,
                      size: bodyTextStyle.fontSize,
                      color: subColor,
                    )
                  ],
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

enum LicenseSort { license, name }