using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace RealTimeGraphX.Renderers
{
    /// <summary>
    /// Represents a scrolling style graph renderer.
    /// </summary>
    /// <typeparam name="TDataSeries">The type of the graph data series.</typeparam>
    /// <typeparam name="XDataPoint">The type of the x-axis data point.</typeparam>
    /// <typeparam name="YDataPoint">The type of the y-axis data point.</typeparam>
    /// <seealso cref="RealTimeGraphX.GraphRendererBase{XDataPoint, YDataPoint}" />
    public class GraphScrollingRenderer<TDataSeries, XDataPoint, YDataPoint> : GraphRendererBase<TDataSeries, XDataPoint, YDataPoint> where XDataPoint : GraphDataPointBase where YDataPoint : GraphDataPointBase where TDataSeries : IGraphDataSeries
    {
        /// <summary>
        /// Returns an array of absolute graph data points to render.
        /// This method is called per data series.
        /// </summary>
        /// <param name="seriesCollection">A collection of all data series that is currently in the rendering pass.</param>
        /// <param name="series">The current data series to render.</param>
        /// <param name="toRender">Pending data series object to render.</param>
        /// <returns></returns>
        protected override List<GraphPoint> OnRender(IEnumerable<PendingSeries> seriesCollection, TDataSeries series, PendingSeries toRender)
        {
            List<GraphPoint> points = new List<GraphPoint>();

            if (toRender.XX.Count > 0 && toRender.YY.Count > 0)
            {
                XDataPoint min_x = toRender.XX.First();
                XDataPoint max_x = toRender.XX.Last();

                YDataPoint min_y = Input.Range.MinimumY;
                YDataPoint max_y = Input.Range.MaximumY;

                if (Input.Range.AutoY)
                {
                    min_y = _current_min_y;
                    max_y = _current_max_y;
                }

                OnEffectiveRangeXChanged(min_x, max_x);
                OnEffectiveRangeYChanged(min_y, max_y);

                var dxList = toRender.XX.Select(x => x.ComputeRelativePosition(min_x, max_x)).ToList();
                var dyList = toRender.YY.Select(x => x.ComputeRelativePosition(min_y, max_y)).ToList();

                if (max_x - min_x > Input.Range.MaximumX)
                {
                    var offset = ((max_x - min_x) - Input.Range.MaximumX) + min_x;

                    for (int i = 0; i < toRender.XX.Count; i++)
                    {
                        if (toRender.XX[i] < offset)
                        {
                            toRender.XX.RemoveAt(i);
                            toRender.YY.RemoveAt(i);
                            i--;
                        }
                        else
                        {
                            break;
                        }
                    }
                }

                for (int i = 0; i < dxList.Count; i++)
                {
                    float image_x = ConvertXValueToRendererValue(dxList[i]);
                    float image_y = (float)Math.Min(ConvertYValueToRendererValue(dyList[i]), Output.SurfaceHeight - 2);

                    GraphPoint point = new GraphPoint(image_x, image_y);
                    points.Add(point);
                }
            }

            return points;
        }
    }
}