using System;
using System.Collections.ObjectModel;
using System.Globalization;
using CommunityToolkit.Mvvm.ComponentModel;
using CryptoPortfolio_Tracker.Models;
using LiveChartsCore;
using LiveChartsCore.Defaults;
using LiveChartsCore.SkiaSharpView;
using LiveChartsCore.SkiaSharpView.Painting;
using SkiaSharp;

namespace CryptoPortfolio_Tracker.ViewModels;

public partial class CryptoChartViewModel : ViewModelBase
{
    [ObservableProperty] public partial string CryptocurrencyName { get; set; } = null!;
    [ObservableProperty] public partial decimal CurrentPrice { get; set; }
    [ObservableProperty] public partial decimal PriceChangePercentage24H { get; set; }
    [ObservableProperty] public partial decimal PriceChange24H { get; set; }
    [ObservableProperty] public partial decimal? MarketCap { get; set; }
    [ObservableProperty] public partial decimal? Volume24H { get; set; }
    [ObservableProperty] public partial bool IsPositive { get; set; }
    [ObservableProperty] public partial bool IsNegative { get; set; }
    [ObservableProperty] public partial DateTime StartDate { get; set; }
    [ObservableProperty] public partial DateTime EndDate { get; set; }

    public ObservableCollection<DateTimePoint> PriceHistory7D { get; } = [];

    public TimeSpan UnitWidth { get; } = TimeSpan.FromHours(1);

    public Func<DateTime, string> DateFormatter { get; } =
        date => date.ToString("dd.MM HH:mm");

    public Func<double, string> PriceFormatter { get; } =
        FormatPrice;

    public SolidColorPaint GridPaint { get; } =
        new(new SKColor(255, 255, 255, 25));

    public SolidColorPaint ChartStroke { get; } =
        new(new SKColor(0x3B, 0xB3, 0x46));

    public ISeries[] Series { get; private set; } = [];

    public CryptoChartViewModel(Cryptocurrency cryptocurrency)
    {
        CryptocurrencyName = cryptocurrency.Name;
        CurrentPrice = cryptocurrency.CurrentPriceUsd;
        PriceChangePercentage24H = cryptocurrency.PriceChangePercentage24H ?? 0;
        PriceChange24H = cryptocurrency.PriceChange24H ?? 0;
        MarketCap = cryptocurrency.MarketCapUsd;
        Volume24H = cryptocurrency.Volume24HUsd;

        IsPositive = cryptocurrency.PriceChangePercentage24H > 0;
        IsNegative = cryptocurrency.PriceChangePercentage24H < 0;

        foreach (var point in cryptocurrency.PriceHistory7D)
        {
            PriceHistory7D.Add(point);
        }

        if (PriceHistory7D.Count > 0)
        {
            StartDate = PriceHistory7D[0].DateTime;
            EndDate = PriceHistory7D[^1].DateTime;
        }

        UpdateSeries();
    }

    partial void OnStartDateChanged(DateTime value)
    {
        UpdateSeries();
    }

    partial void OnEndDateChanged(DateTime value)
    {
        UpdateSeries();
    }

    private void UpdateSeries()
    {
        ObservableCollection<DateTimePoint> visiblePoints = [];

        foreach (var point in PriceHistory7D)
        {
            if (point.DateTime >= StartDate &&
                point.DateTime <= EndDate)
            {
                visiblePoints.Add(point);
            }
        }

        if (visiblePoints.Count == 0)
        {
            Series = [];
            OnPropertyChanged(nameof(Series));
            return;
        }

        LineSeries<DateTimePoint> lineSeries =
            new()
            {
                Values = visiblePoints,
                GeometrySize = 0,
                Fill = null,
                GeometryFill = null,
                GeometryStroke = null,
                Stroke = ChartStroke,
                LineSmoothness = 0.2
            };

        Series =
        [
            lineSeries
        ];

        OnPropertyChanged(nameof(Series));
    }

    private static string FormatPrice(double price)
    {
        return price switch
        {
            >= 1000 => price.ToString("N0", CultureInfo.InvariantCulture),
            >= 1 => price.ToString("N2", CultureInfo.InvariantCulture),
            >= 0.01 => price.ToString("N4", CultureInfo.InvariantCulture),
            _ => price.ToString("0.########", CultureInfo.InvariantCulture)
        };
    }
}