flutter-examples/expense_planner/lib/example.dart

// Example: Track personal expenses with a chart and a list of transactions.

import 'package:flutter/material.dart';

import './models/transaction.dart';
import './widgets/chart.dart';
import './widgets/new_transaction.dart';
import './widgets/transaction_list.dart';

class Example extends StatefulWidget {
  const Example({super.key});

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

class _ExampleState extends State<Example> {
  final List<Transaction> _userTransactions = [];

  List<Transaction> get _recentTransactions {
    return _userTransactions.where((tx) {
      return tx.date.isAfter(
        DateTime.now().subtract(
          Duration(days: 7),
        ),
      );
    }).toList();
  }

  void _addNewTransaction(
      String txTitle, double txAmount, DateTime chosenDate) {
    final newTx = Transaction(
      title: txTitle,
      amount: txAmount,
      date: chosenDate,
      id: DateTime.now().toString(),
    );

    setState(() {
      _userTransactions.add(newTx);
    });
  }

  void _startAddNewTransaction(BuildContext ctx) {
    showModalBottomSheet(
      context: ctx,
      builder: (_) {
        return GestureDetector(
          onTap: () {},
          behavior: HitTestBehavior.opaque,
          child: NewTransaction(_addNewTransaction),
        );
      },
    );
  }

  void _deleteTransaction(String id) {
    setState(() {
      _userTransactions.removeWhere((tx) => tx.id == id);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          'Personal Expenses',
        ),
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.add),
            onPressed: () => _startAddNewTransaction(context),
          ),
        ],
      ),
      body: SingleChildScrollView(
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            Chart(_recentTransactions),
            TransactionList(_userTransactions, _deleteTransaction),
          ],
        ),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
        onPressed: () => _startAddNewTransaction(context),
      ),
    );
  }
}