default_page.dart

import 'dart:async';
import 'dart:typed_data';
import 'package:flutter/material.dart';

import '../consts.dart';
import 'loading_page.dart';
import '../widgets/main_layout.dart';
import '../data_classes.dart';
import '../server_requests/fetch_markers.dart';
import '../server_requests/fetch_relation.dart';

class DefaultPage extends StatefulWidget {
  const DefaultPage({Key? key}) : super(key: key);

  @override
  _DefaultPageState createState() => _DefaultPageState();
}

class _DefaultPageState extends State<DefaultPage> {
  late Timer _timer;
  bool showBar = false;
  bool serverConnection = true;
  bool dialogShown = false;

  late Future<List<Measurement>> markerListFuture;
  late Future<Uint8List> relationFuture;

  @override
  void initState() {
    super.initState();
    // Try to fetch measurement data from server
    markerListFuture = fetchMeasurements().then((fetchResult) {
      List<Measurement> measurements = fetchResult.measurements;
      serverConnection = fetchResult.connected;

      // Return the measurements
      return measurements;
    }).catchError((error) {
      serverConnection = false;
      throw Exception("Failed to fetch measurements: $error");
    });

    // Attempt to fetch relation from server if app establishes connection
    if (serverConnection){
      relationFuture = fetchRelation();
    } else { // Read last saved data
      relationFuture =  loadSavedRelation();
    }

    // Schedule fetchMarkerData to run periodically based on fetchInterval
    const Duration interval = Duration(minutes: fetchInterval); // NB fetchInterval value to be determined
    _timer = Timer.periodic(interval, (timer) {
      fetchMeasurements();
    });
  }

  @override
  void dispose() {
    _timer.cancel();
    super.dispose();
  }

  /// Display message to user
  void showConnectionMessage() {
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        actions: [
          TextButton(
            onPressed: () {
              Navigator.of(context).pop();
              },
            child: const Text("Ok"),
          )
        ],
        title: const Center(
          child: Text("No server connection")
        ),
        contentPadding: const EdgeInsets.all(10.0),
        content: const Text(
          "The app may display outdated information. Use with caution!",
          textAlign: TextAlign.center, // Align text center
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.black87,
          leading: IconButton(
            icon: const Icon(
                Icons.menu,
                color: Colors.white54
            ),
            onPressed: () {
              // Not implemented
            },
          ),
          title: Text(
            'Mjøsa',
            style: regTextStyleBig,
          ),
          actions: [
            IconButton(
              icon: const Icon(
                  Icons.search,
                  color: Colors.white54
              ),
              onPressed: () {
                setState(() {
                  showBar = !showBar;
                });
              },
            ),
          ],
        ),
        body: FutureBuilder(
          future: Future.wait([markerListFuture, relationFuture]),
          builder: (BuildContext context, AsyncSnapshot<List<dynamic>> snapshot) {
              List<Measurement> markerList = snapshot.data![0] as List<Measurement>;
              Uint8List relation = snapshot.data![1] as Uint8List;

              return Container( // Return container with list view and background color
                color: const Color(0xff151515),
                child: ListView(
                  children: [
                    MapContainerWidget(
                      markerList: markerList,
                      relation: relation,
                      serverConnection: serverConnection,
                      showSearchBar: showBar,
                    ),
                  ],
                ),
              );
            }
        ),
      ),
    );
  }
}