Billing/Billing.Shared/Views/RankPage.xaml.cs

using Billing.Models;
using Billing.Themes;
using Billing.UI;
using Microcharts;
using SkiaSharp;
using SkiaSharp.Views.Forms;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Xamarin.Essentials;
using Xamarin.Forms;
using Resource = Billing.Languages.Resource;

namespace Billing.Views
{
    public partial class RankPage : BillingPage
    {
        private static readonly BindableProperty ChartProperty = Helper.Create<Chart, RankPage>(nameof(Chart));
        private static readonly BindableProperty TopBillsProperty = Helper.Create<IList<UIBill>, RankPage>(nameof(TopBills));
        private static readonly BindableProperty NoResultProperty = Helper.Create<bool, RankPage>(nameof(NoResult));

        public Chart Chart
        {
            get => (Chart)GetValue(ChartProperty);
            set => SetValue(ChartProperty, value);
        }
        public IList<UIBill> TopBills
        {
            get => (IList<UIBill>)GetValue(TopBillsProperty);
            set => SetValue(TopBillsProperty, value);
        }
        public bool NoResult
        {
            get => (bool)GetValue(NoResultProperty);
            set => SetValue(NoResultProperty, value);
        }

        public Command LeftCommand { get; }
        public Command RightCommand { get; }
        public Command FilterCommand { get; }

        private DateTime current;
        private IEnumerable<Bill> bills;
        private CategoryType type = CategoryType.Spending;

        public RankPage()
        {
            LeftCommand = new Command(OnLeftCommand);
            RightCommand = new Command(OnRightCommand);
            InitializeComponent();
        }

        public override void OnLoaded()
        {
            Task.Run(() => SetMonth(DateTime.Today));
        }

        private void OnLeftCommand()
        {
            Task.Run(() =>
            {
                MainThread.BeginInvokeOnMainThread(async () => await scroller.ScrollToAsync(0, 0, true));
                SetMonth(current.AddMonths(-1));
            });
        }

        private void OnRightCommand()
        {
            Task.Run(() =>
            {
                MainThread.BeginInvokeOnMainThread(async () => await scroller.ScrollToAsync(0, 0, true));
                SetMonth(current.AddMonths(1));
            });
        }

        private void SetMonth(DateTime date)
        {
            current = date.AddDays(1 - date.Day);
            var end = current.AddDays(DateTime.DaysInMonth(current.Year, current.Month));

            var format = Resource.DateRangeFormat;
            Title = current.ToString(format) + " ~ " + end.AddDays(-1).ToString(format);

            bills = App.Bills.Where(b => b.CreateTime >= current && b.CreateTime <= end);

            var entries = new List<ChartEntry>();
            var primaryColor = BaseTheme.CurrentPrimaryColor.ToSKColor();
            var textColor = BaseTheme.CurrentSecondaryTextColor.ToSKColor();
            for (var day = current; day <= end; day = day.AddDays(1))
            {
                var daybills = bills.Where(b => Helper.IsSameDay(b.CreateTime, day));
                decimal amount;
                if (type == CategoryType.Income)
                {
                    amount = daybills.Where(b => b.Amount > 0).Sum(b => b.Amount);
                }
                else
                {
                    amount = daybills.Where(b => b.Amount < 0).Sum(b => -b.Amount);
                }
                if (amount > 0)
                {
                    entries.Add(new((float)amount)
                    {
                        Label = day.ToString("MM-dd"),
                        ValueLabel = amount.ToString("#,##0.##"),
                        Color = primaryColor,
                        TextColor = textColor,
                        ValueLabelColor = textColor
                    });
                }
            }

            if (entries.Count > 0)
            {
                NoResult = false;
                Chart = new LineChart
                {
                    BackgroundColor = SKColors.Transparent,
                    LabelTextSize = 24,
                    Entries = entries
                };
                if (type == CategoryType.Income)
                {
                    TopBills = bills.Where(b => b.Amount > 0).OrderByDescending(b => b.Amount).Take(10).Select(b => Helper.WrapBill(b)).ToList();
                }
                else
                {
                    TopBills = bills.Where(b => b.Amount < 0).OrderBy(b => b.Amount).Take(10).Select(b => Helper.WrapBill(b)).ToList();
                }
            }
            else
            {
                NoResult = true;
                Chart = null;
                TopBills = null;
            }
        }
    }
}