added some test stuff for gui elements

lib/entities/PlannedPizza.dart

@@ -0,0 +1,7 @@
+
+class PlannedPizza {
+  final String name;
+  final DateTime dateTime;
+
+  PlannedPizza(this.name, this.dateTime);
+}

lib/pages/PlannedPizzasPage.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
+import 'package:pizzaplanner/entities/PlannedPizza.dart';
 
 class PlannedPizzasPage extends StatefulWidget {
   @override
@@ -7,27 +9,67 @@ class PlannedPizzasPage extends StatefulWidget {
 }
 
 class PlannedPizzasState extends State<PlannedPizzasPage> {
+  final List<PlannedPizza> plannedPizzas = <PlannedPizza>[
+    PlannedPizza("Movie Night", DateTime(2021, 6, 30)),
+    PlannedPizza("Birthday Pizza", DateTime(2021, 7, 14)),
+    PlannedPizza("Something else", DateTime(2021, 9, 3)),
+  ];
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
         title: Text("Planned Pizzas"),
       ),
-      body: ListView(
+      body: ListView.separated(
         padding: const EdgeInsets.all(8),
-        children: <Widget>[
-          Container(
+          itemCount: plannedPizzas.length,
+          itemBuilder: (BuildContext context, int i) {
+            return Container(
               height: 100,
               color: Colors.blueAccent,
-            child: const Center(child: Text("Pizza!"))
-          )
-        ],
-      ),
-      floatingActionButton: FloatingActionButton(
-        onPressed: () => null,
-        tooltip: "Add Pizza",
-        child: Icon(Icons.add)
+              child: PlannedPizzaWidget(plannedPizzas[i])
+            );
+          },
+          separatorBuilder: (BuildContext context, int i) => const Divider(),
       ),
     );
   }
 }
+
+class PlannedPizzaWidget extends StatelessWidget {
+  final DateFormat dateFormatter = DateFormat("yyyy-MM-dd");
+  final PlannedPizza plannedPizza;
+
+  PlannedPizzaWidget(this.plannedPizza);
+
+  @override
+  Widget build(BuildContext context){
+    return Container(
+      height: 100,
+      color: Colors.blueAccent,
+      child: Column(
+        children: <Widget>[
+          Text(plannedPizza.name),
+          Text(dateFormatter.format(plannedPizza.dateTime)),
+          Text(this.getTimeRemainingString())
+        ]
+      )
+    );
+  }
+
+  String getTimeRemainingString(){
+    DateTime now = DateTime.now();
+    Duration duration = plannedPizza.dateTime.difference(now);
+    if (duration.inHours <= 0) {
+      return "In ${duration.inMinutes} minutes!";
+    }
+    if (duration.inDays <= 0) {
+      return "In ${duration.inHours} hours";
+    }
+    if (duration.inDays <= 31) {
+      return "In ${duration.inDays} days";
+    }
+    return "In ${(duration.inDays / 7).floor()} weeks";
+  }
+}