Add about tab

lib/models/advanced_group_info.dart

@@ -45,4 +45,9 @@ class AdvancedGroupInfo extends Group implements LikeElement {
 
   @override
   LikesType likeType = LikesType.GROUP;
+
+  get hasURL => url != null && url.isNotEmpty && url != "null";
+
+  get hasDescription =>
+      description != null && description.isNotEmpty && description != "null";
 }

lib/ui/screens/authorized_group_page_screen.dart

@@ -1,5 +1,6 @@
 import 'package:comunic/models/advanced_group_info.dart';
 import 'package:comunic/ui/routes/main_route/main_route.dart';
+import 'package:comunic/ui/screens/group_sections/about_group_section.dart';
 import 'package:comunic/ui/screens/group_sections/group_members_screen.dart';
 import 'package:comunic/ui/screens/group_sections/group_posts_section.dart';
 import 'package:comunic/ui/screens/group_settings_screen.dart';
@@ -51,6 +52,12 @@ class _AuthorizedGroupPageScreenState
           widget: GroupPostsSection(group: _group),
           label: tr("Posts"),
         ),
+
+        // About the group
+        _GroupPageTab(
+          widget: AboutGroupSection(group: _group),
+          label: tr("About"),
+        )
       ]..addAll(_group.isAtLeastModerator
           ? [
               _GroupPageTab(

lib/ui/screens/group_sections/about_group_section.dart

@@ -0,0 +1,93 @@
+import 'package:comunic/models/advanced_group_info.dart';
+import 'package:comunic/models/group.dart';
+import 'package:comunic/utils/date_utils.dart';
+import 'package:comunic/utils/intl_utils.dart';
+import 'package:flutter/material.dart';
+import 'package:url_launcher/url_launcher.dart';
+
+/// About group section
+///
+/// @author Pierre Hubert
+
+class AboutGroupSection extends StatelessWidget {
+  final AdvancedGroupInfo group;
+
+  const AboutGroupSection({
+    Key key,
+    @required this.group,
+  })  : assert(group != null),
+        super(key: key);
+
+  @override
+  Widget build(BuildContext context) => ListView(
+        children: [
+          // URL, if any
+          group.hasURL
+              ? ListTile(
+                  leading: Icon(Icons.link),
+                  title: Text(tr("URL")),
+                  subtitle: Text(group.url),
+                  onTap: () => launch(group.url),
+                )
+              : Container(),
+
+          // Description, if any
+          group.hasDescription
+              ? ListTile(
+                  leading: Icon(Icons.note),
+                  title: Text(tr("Description")),
+                  subtitle: Text(group.description),
+                  onTap: () => launch(group.description),
+                )
+              : Container(),
+
+          // Time create
+          ListTile(
+            leading: Icon(Icons.access_time),
+            title: Text("Created"),
+            subtitle: Text(diffTimeFromNowToStr(group.timeCreate)),
+          ),
+
+          // Number of members
+          ListTile(
+            leading: Icon(Icons.group),
+            title: Text(tr("Members")),
+            subtitle: Text(
+                tr("%1% members", args: {"1": group.numberMembers.toString()})),
+          ),
+
+          // Who can create posts
+          ListTile(
+            leading: Icon(Icons.add),
+            title: Text(tr("Who can create posts")),
+            subtitle: Text(
+                group.postCreationLevel == GroupPostCreationLevel.MEMBERS
+                    ? tr("Every members")
+                    : tr("Only moderators and administrators")),
+          ),
+
+          // Registration process
+          ListTile(
+            leading: Icon(Icons.login),
+            title: Text(tr("Registration process")),
+            subtitle: Text(group.registrationLevel ==
+                    GroupRegistrationLevel.CLOSED
+                ? tr("On invitation only")
+                : (group.registrationLevel == GroupRegistrationLevel.MODERATED
+                    ? tr("A moderator has to approve requests")
+                    : tr("Anyone can join the group without approval"))),
+          ),
+
+          // Group visibility
+          ListTile(
+            leading: Icon(Icons.remove_red_eye),
+            title: Text(tr("Visibility")),
+            subtitle: Text(group.visibilityLevel == GroupVisibilityLevel.SECRETE
+                ? tr("Secrete group")
+                : (group.visibilityLevel == GroupVisibilityLevel.PRIVATE
+                    ? tr("Private group")
+                    : tr("Open group"))),
+          ),
+        ],
+      );
+}