checker/lib/screens/return.dart

import 'dart:convert';

import 'package:checker/base/base_screen.dart';
import 'package:checker/base/base_state.dart';
import 'package:checker/db.dart';
import 'package:checker/strings.dart';
import 'package:flutter/material.dart';
import 'package:checker/network.dart';
import 'package:http/http.dart';
import 'package:intl/intl.dart';

class ReturnScreen extends BaseScreen {
  final int userId;
  final int bonus;

  ReturnScreen(SqliteHelper helper, String app, this.userId, this.bonus) : super(helper, app);

  @override
  _ReturnScreenState createState() => _ReturnScreenState<ReturnScreen>(helper, app);
}

class _ReturnScreenState<T> extends BaseState<ReturnScreen> {
  static DateFormat dateFormat = DateFormat('d MMM yy');

  ScrollController _controller;
  List _purchases = [];
  int _bonus;
  int _page = 1;
  bool _fullLoaded = false;
  bool _loading = false;


  _ReturnScreenState(SqliteHelper helper, String app) : super(helper, app);

  bool isAutomaticallyImplyLeading() => true;

  @override
  Widget getScreenContent() => ListView.separated(
    itemBuilder: (context, index) {
      final TextStyle style =  Theme.of(context).textTheme.subhead;
      if(index > 0) {
        final item = _purchases[index - 1];
        final DateTime date = DateTime.parse(item['date']);
        final String formattedDate = dateFormat.format(date);
        return GestureDetector(
          child: Padding(
            padding: const EdgeInsets.all(16),
            child: Row(
              children: <Widget>[
                Expanded(
                  child: Text(formattedDate, style: style),
                ),
                Expanded(
                  child: Text(item['sum_total'], style: style),
                ),
                Expanded(
                  child: Text(item['sum_bonus'].toString(), style: style),
                )
              ],
            ),
          ),
          onTap: () => _confirmReturnPurchase(item, formattedDate),
        );
      } else {
        final TextStyle headerStyle = style.copyWith(color: Colors.grey);
        return Padding(
          padding: const EdgeInsets.all(16),
          child: Row(
            children: <Widget>[
              Expanded(
                child: Container(),
              ),
              Expanded(
                child: Text(StringsLocalization.sum(), style: headerStyle),
              ),
              Expanded(
                child: Text(StringsLocalization.points(), style: headerStyle),
              )
            ],
          ),
        );
      }
    },
    separatorBuilder: (_, index) => index == 0
      ? Container()
      : Padding(
        padding: const EdgeInsets.symmetric(horizontal: 16),
        child: Divider(height: 1,),
      ),
    itemCount: _purchases.length > 0 ? _purchases.length + 1 : _purchases.length,
    controller: _controller);

  @override
  Widget build(BuildContext context) => getMainWidget();

  @override
  String getTitle() => StringsLocalization.returnLabel();

  @override
  void initState() {
    super.initState();
    setState(() {
      loading = true;
    });
    _loadUserPurchases();
    _bonus = widget.bonus;
    _controller = ScrollController();
    _controller.addListener(_scrollListener);
  }

  void _scrollListener() {
    if (_controller.offset >= _controller.position.maxScrollExtent &&
        !_controller.position.outOfRange) {
      _loadUserPurchases();
    }
  }
  
  void _loadUserPurchases() async {
    if(!_fullLoaded && !_loading) {
      _loading = true;
      setState(() => loading = true);
      String token = await helper.getToken();
      Response response = await getUserPurchases(token, widget.userId, _page);
      final responseJson = json.decode(response.body);
      List purchases = responseJson['results'];
      _fullLoaded = _page == responseJson['pages'];
      setState(() {
        loading = false;
        _purchases.addAll(purchases);
      });
      _page++;
      _loading = false;
      setState(() => loading = false);
    }
  }

  num extractReturnPoints(Map purchase) {
    final returnPoints = purchase['sum_bonus'];
    if(returnPoints is num) {
      return returnPoints;
    } else if(returnPoints is String) {
      final RegExp returnPattern = RegExp(r"(\d+)");
      final List<Match> digits = returnPattern.allMatches(returnPoints).toList();
      return int.parse(digits[0].group(0)) - int.parse(digits[1].group(1));
    } else {
      return 0;
    }
  }

  void _confirmReturnPurchase(Map purchase, String formattedDate) {
    final num totalReturn = extractReturnPoints(purchase);
    showDialog(
      context: context,
      builder: (context) =>
        AlertDialog(
          title: Text(StringsLocalization.confirmation()),
          content: Text(StringsLocalization.returnConfirmation(
            purchase['sum_total'], formattedDate, _bonus - totalReturn)),
          actions: <Widget>[
            FlatButton(
              child: Text(StringsLocalization.no()),
              onPressed: () => Navigator.pop(context),
            ),
            FlatButton(
              child: Text(StringsLocalization.yes()),
              onPressed: () {
                Navigator.pop(context);
                _returnPurchase(purchase, formattedDate, totalReturn);
              }
            )
          ],
        )
    );
  }

  void _returnPurchase(Map purchase, String formattedDate, num totalReturn) async {
    String token = await helper.getToken();
    final Response response = await returnPurchase(token, widget.userId, purchase['id']);
    if(response.statusCode == 204) {
      _bonus += totalReturn;
      setState(() {
        _purchases.removeWhere((p) => p['id'] == purchase['id']);
      });
      showDialog(
        context: context,
        builder: (context) =>
          AlertDialog(
            title: Text(StringsLocalization.returnConfirmed()),
            content: Text(StringsLocalization.returnConfirmedContent(purchase['sum_total'], formattedDate)),
            actions: <Widget>[
              FlatButton(
                child: Text(StringsLocalization.yes()),
                onPressed: () => Navigator.pop(context)
              )
            ],
          )
      );
    }
  }
}