Add basic performer selector

lib/selectors/performer.dart

@@ -0,0 +1,112 @@
+import 'package:flutter/material.dart';
+
+import '../backend.dart';
+import '../database.dart';
+import '../editors/person.dart';
+import '../selectors/role.dart';
+
+class PerformanceModel {
+  final Person person;
+  final Role role;
+
+  PerformanceModel({
+    this.person,
+    this.role,
+  });
+}
+
+// TODO: Allow selecting and adding ensembles.
+// TODO: Allow selecting instruments as roles.
+class PerformerSelector extends StatefulWidget {
+  @override
+  _PerformerSelectorState createState() => _PerformerSelectorState();
+}
+
+class _PerformerSelectorState extends State<PerformerSelector> {
+  Role role;
+
+  @override
+  Widget build(BuildContext context) {
+    final backend = Backend.of(context);
+
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('Select performer'),
+      ),
+      body: Column(
+        children: <Widget>[
+          Material(
+            elevation: 2.0,
+            child: ListTile(
+              title: Text('Role'),
+              subtitle:
+                  Text(role != null ? role.name : 'Select role or instrument'),
+              trailing: IconButton(
+                icon: const Icon(Icons.delete),
+                onPressed: () {
+                  setState(() {
+                    role = null;
+                  });
+                },
+              ),
+              onTap: () async {
+                final Role newRole = await Navigator.push(
+                    context,
+                    MaterialPageRoute(
+                      builder: (context) => RoleSelector(),
+                      fullscreenDialog: true,
+                    ));
+
+                if (newRole != null) {
+                  setState(() {
+                    role = newRole;
+                  });
+                }
+              },
+            ),
+          ),
+          Expanded(
+            child: StreamBuilder(
+              stream: backend.db.allPersons().watch(),
+              builder: (context, snapshot) {
+                if (snapshot.hasData) {
+                  return ListView.builder(
+                    itemCount: snapshot.data.length,
+                    itemBuilder: (context, index) {
+                      final person = snapshot.data[index];
+
+                      return ListTile(
+                        title: Text('${person.lastName}, ${person.firstName}'),
+                        onTap: () => Navigator.pop(context, PerformanceModel(
+                          person: person,
+                          role: role,
+                        )),
+                      );
+                    },
+                  );
+                } else {
+                  return Container();
+                }
+              },
+            ),
+          ),
+        ],
+      ),
+      floatingActionButton: FloatingActionButton(
+        child: const Icon(Icons.add),
+        onPressed: () async {
+          final Person person = await Navigator.push(
+              context,
+              MaterialPageRoute(
+                builder: (context) => PersonEditor(),
+                fullscreenDialog: true,
+              ));
+
+          if (person != null) {
+            Navigator.pop(context, person);
+          }
+        },
+      ),
+    );
+  }
+}