using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using Newtonsoft.Json;
using SkiaSharp;
using UnityEngine;
using UnityEngine.UIElements;


namespace BITKit.UX
{
    public class SkiaChart : VisualElement
    {
        public new class UxmlTraits : VisualElement.UxmlTraits
        {
            private readonly UxmlStringAttributeDescription m_JsonAttribute = new ()
            {
                name = "Json"
            };
            private readonly UxmlBoolAttributeDescription m_allowWarningsAttribute = new ()
            {
                name = "allowWarnings",
                defaultValue = false
            };
            public override void Init(VisualElement ve, IUxmlAttributes bag, CreationContext cc)
            {
                base.Init(ve, bag, cc);
                var x = (SkiaChart)ve;
                x.Json = m_JsonAttribute.GetValueFromBag(bag, cc);
                x.AllowWarning = m_allowWarningsAttribute.GetValueFromBag(bag, cc);
        
            }
        }
        public new class UxmlFactory : UxmlFactory<SkiaChart, UxmlTraits> { }
        public SkiaChart()
        {
			RegisterCallback<GeometryChangedEvent>(x =>
			{
				if (visible)
				{
					Rebuild();
				}
			});	RegisterCallback<CustomStyleResolvedEvent>(OnCustomStyleResolved);
			
			style.flexDirection = FlexDirection.Row;
			_dataContainer = this.Create<VisualElement>();
			_chartContainer = this.Create<VisualElement>();
			_chartContainer.style.flexGrow = 1;
			
			_dataContainer.style.justifyContent = Justify.SpaceBetween;

			_dataContainer.name = "Data";
			_chartContainer.name = "Chart";
        }

        private void OnCustomStyleResolved(CustomStyleResolvedEvent evt)
        {
	        if(evt.customStyle.TryGetValue(new CustomStyleProperty<Color>("--chart-secondary-color"), out var helpLineColor))
	        {
		        _secondaryColor = helpLineColor;
	        }
	        Rebuild();
        }

        public string Json
        {
            get => _json;
            set
            {
                _json = value;
                Rebuild();
            }
        }
        private string _json;
        public bool AllowWarning { get; set; }
        public Color SecondaryColor
        {
	        get => _secondaryColor;
	        set
	        {
		        _secondaryColor = value;
		        Rebuild();
	        }
		}
        private Color _secondaryColor;

        private readonly VisualElement _dataContainer;
        private readonly VisualElement _chartContainer;
        private void Rebuild()
        {
	        var data = Array.Empty<float>();
	        try
	        {
		        data = JsonConvert.DeserializeObject<float[]>(Json);
	        }
	        catch (Exception e)
	        {
		        if (AllowWarning)
			        Debug.LogException(e);
		        return;
	        }
	
	        if(float.IsNaN(layout.width) || float.IsNaN(layout.height))
		        return;
	        
	        if (data is null or { Length: 0 }) return;
	        
	   

	        _dataContainer.Clear();
	        _chartContainer.Clear();
	        
	        var max = data.Max();
	        var min = data.Min();
	        //假如min是x,max是y,将中间的差用data.Length划分

	        _dataContainer.style.flexDirection = FlexDirection.ColumnReverse;
	        for (var i = 0; i < data.Length; i++)
	        {
		        var label = _dataContainer.Create<Label>();
		        
		        var value = (max - min) / (data.Length - 1) * i + min;
		        label.text = value.ToString();
	        }

	        
	        if(_chartContainer.layout.width is float.NaN or <10 || _chartContainer.layout.height is float.NaN or <10)
		        return;
	        var info = new SKImageInfo(
				width: (int)_chartContainer.layout.width,
				height: (int)_chartContainer.layout.height,
				colorType: SKColorType.Rgba8888,
				alphaType: SKAlphaType.Premul
			);
	  
			using var surface = SKSurface.Create(info);
	  
			using var canvas = surface.Canvas;
	  
			using var linePaint = new SKPaint();
			linePaint.Color = resolvedStyle.color.ToSKColor();
			linePaint.StrokeWidth = resolvedStyle.unityTextOutlineWidth;
			linePaint.IsAntialias = true;
			linePaint.Style = SKPaintStyle.Stroke;
	  
			using var helpLinePaint = new SKPaint();
			helpLinePaint.Color = resolvedStyle.unityTextOutlineColor.ToSKColor();
			helpLinePaint.StrokeWidth = 1;
			helpLinePaint.Style = SKPaintStyle.Stroke;
			
			using var fillPaint = new SKPaint();
			fillPaint.Color = new SKColor(200, 200, 200, 200);
			fillPaint.Style=SKPaintStyle.Fill;
	  
			DoubleBuffer<SKPoint> buffer = new();
			
			var path = new SKPath { FillType = SKPathFillType.EvenOdd };
			
			path.MoveTo(0,0);
			path.LineTo(0,0);
			
			for (var i = 0; i < data.Length; i++)
			{
				var value = data[i];
				var posX = (float)info.Width / (data.Length - 1) * (i);
				var d = max - min;
				var p = (value - min) / d;
				var poxY = info.Height * p;
	  
				var currentPoint = new SKPoint(posX, poxY);
				if (buffer.TryGetRelease(out var previousPoint))
				{
					canvas.DrawLine(previousPoint, currentPoint, linePaint);
				}
	  
				var label = _chartContainer.Create<Label>();
				label.text = value.ToString(CultureInfo.InvariantCulture);
				label.style.position = Position.Absolute;
				label.style.left = posX;//-label.layout.width/2;
				label.style.bottom = poxY;//- label.layout.height/2; 
				
				canvas.DrawLine(posX, 0, posX, poxY, helpLinePaint);
				
				path.LineTo(posX,poxY);
				
				buffer.Release(currentPoint);
			}
			
			path.LineTo(info.Width,0);
			path.Close();
			
			
			//canvas.DrawPath(path,filePaint);
	  
			var texture = info.ToTexture2D(surface);
			
			_chartContainer.style.backgroundImage = texture;
        }
    }
}