Billing/Billing.Shared/Views/BillPage.xaml.cs

using Billing.Models;
using Billing.UI;
using System;
using System.Collections.Generic;
using System.Linq;
using Xamarin.Forms;

namespace Billing.Views
{
    public partial class BillPage : BillingPage
    {
        private static readonly BindableProperty SelectedDateProperty = BindableProperty.Create(nameof(SelectedDate), typeof(DateTime), typeof(BillPage));
        private static readonly BindableProperty BillsProperty = BindableProperty.Create(nameof(Bills), typeof(List<UIBill>), typeof(BillPage));

        public DateTime SelectedDate
        {
            get => (DateTime)GetValue(SelectedDateProperty);
            set => SetValue(SelectedDateProperty, value);
        }
        public List<UIBill> Bills
        {
            get => (List<UIBill>)GetValue(BillsProperty);
            set => SetValue(BillsProperty, value);
        }

        public Command AddBilling { get; }

        public BillPage()
        {
            AddBilling = new Command(OnAddBilling);

            InitializeComponent();

            billingDate.SetDateTime(DateTime.Now);
        }

        private void OnDateSelected(object sender, DateEventArgs e)
        {
            SelectedDate = e.Date;

            var bills = App.Bills.Where(b =>
                b.CreateTime.Year == e.Date.Year &&
                b.CreateTime.Month == e.Date.Month &&
                b.CreateTime.Day == e.Date.Day);
            Bills = new List<UIBill>(bills.Select(b => new UIBill(b)
            {
                Icon = App.Categories.FirstOrDefault(c => c.Id == b.CategoryId)?.Icon ?? BaseModel.ICON_DEFAULT,
                Name = b.Name,
                DateCreation = b.CreateTime,
                Amount = b.Amount,
                Wallet = App.Accounts.FirstOrDefault(a => a.Id == b.WalletId)?.Name
            }));
        }

        private void OnTitleDateLongPressed(object sender, EventArgs e)
        {
            billingDate.SetDateTime(DateTime.Now);
        }

        private async void OnAddBilling()
        {
            if (Tap.IsBusy)
            {
                return;
            }
            using (Tap.Start())
            {
                var page = new AddBillPage(SelectedDate);
                await Navigation.PushAsync(page);
            }
        }
    }

    public class UIBill : BindableObject
    {
        public static readonly BindableProperty IconProperty = BindableProperty.Create(nameof(Icon), typeof(string), typeof(UIBill));
        public static readonly BindableProperty NameProperty = BindableProperty.Create(nameof(Name), typeof(string), typeof(UIBill));
        public static readonly BindableProperty DateCreationProperty = BindableProperty.Create(nameof(DateCreation), typeof(DateTime), typeof(UIBill));
        public static readonly BindableProperty AmountProperty = BindableProperty.Create(nameof(Amount), typeof(decimal), typeof(UIBill));
        public static readonly BindableProperty WalletProperty = BindableProperty.Create(nameof(Wallet), typeof(string), typeof(UIBill));

        public string Icon
        {
            get => (string)GetValue(IconProperty);
            set => SetValue(IconProperty, value);
        }
        public string Name
        {
            get => (string)GetValue(NameProperty);
            set => SetValue(NameProperty, value);
        }
        public DateTime DateCreation
        {
            get => (DateTime)GetValue(DateCreationProperty);
            set => SetValue(DateCreationProperty, value);
        }
        public decimal Amount
        {
            get => (decimal)GetValue(AmountProperty);
            set => SetValue(AmountProperty, value);
        }
        public string Wallet
        {
            get => (string)GetValue(WalletProperty);
            set => SetValue(WalletProperty, value);
        }

        public Bill Bill { get; }

        public UIBill(Bill bill)
        {
            Bill = bill;
        }
    }
}