using System;
using System.Collections.Generic;
using System.Drawing;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using bbiwarg.Recognition.TouchRecognition;
using bbiwarg.Utility;
using bbiwarg.Input.InputHandling;

namespace bbiwarg.Output.DebugOutput
{
    /// <summary>
    /// Provides an image showing touch events.
    /// </summary>
    class TouchEventVisualizer
    {
        /// <summary>
        /// used to prevent the simultaneous access to <see cref="handleNewFrameData"/> and <see cref="getOutputImage"/> from different threads
        /// </summary>
        private Object sync;

        /// <summary>
        /// used to store the relative time at which the touch events occured
        /// </summary>
        private Stopwatch timer;


        /// <summary>
        /// all touch events starting at the last TouchDown, indexed by a unique id
        /// </summary>
        private Dictionary<int, List<Vector2D>> activeTouches;

        /// <summary>
        /// old touch events which are stored for a limited time, indexed by a unique id
        /// </summary>
        private Dictionary<int, List<Vector2D>> oldTouches;

        /// <summary>
        /// relative times of last frame updates which are stored for a limited time, indexed by a unique id
        /// </summary>
        private Dictionary<int, long> lastUpdates;

        /// <summary>
        /// the next free id, used as a unique id for the dictionaries
        /// </summary>
        private int nextFreeID;


        /// <summary>
        /// Creates a TouchEventVisualizer.
        /// </summary>
        public TouchEventVisualizer()
        {
            sync = new object();
            reset();
        }

        /// <summary>
        /// Resets the touch events and the timer.
        /// </summary>
        public void reset()
        {
            timer = new Stopwatch();
            timer.Start();

            nextFreeID = 1;
            activeTouches = new Dictionary<int, List<Vector2D>>();
            oldTouches = new Dictionary<int, List<Vector2D>>();
            lastUpdates = new Dictionary<int, long>();

        }

        /// <summary>
        /// Handles the event that a new frame is finished processing by updating the touch events.
        /// </summary>
        /// <param name="sender">event sender</param>
        /// <param name="e">event arguments</param>
        public void handleNewFrameData(object sender, NewProcessedFrameEventArgs e)
        {
            FrameData frameData = e.FrameData;
            lock (frameData) lock (sync) 
                {
                    if (frameData.ResetFlag)
                        reset();

                    foreach (TouchEvent te in frameData.TouchEvents)
                    {
                        switch (te.Type)
                        {
                            case TouchEventType.Down:
                                activeTouches.Add(te.Touch.TrackID, new List<Vector2D>());
                                activeTouches[te.Touch.TrackID].Add(te.Touch.RelativePosition);
                                break;
                            case TouchEventType.Move:
                                activeTouches[te.Touch.TrackID].Add(te.Touch.RelativePosition);
                                break;
                            case TouchEventType.Up:
                                activeTouches[te.Touch.TrackID].Add(te.Touch.RelativePosition);

                                oldTouches.Add(nextFreeID, activeTouches[te.Touch.TrackID]);
                                lastUpdates.Add(nextFreeID, timer.ElapsedMilliseconds);

                                activeTouches.Remove(te.Touch.TrackID);
                                nextFreeID++;
                                break;
                        }
                    }
                }
        }

        /// <summary>
        /// Returns an output image showing the touch events.
        /// </summary>
        /// <param name="imageSize">output image size</param>
        /// <param name="numRows">number of rows in the palm grid</param>
        /// <param name="numColumns">number columns in the palm grid</param>
        /// <returns>image showing touch events</returns>
        public OutputImage getOutputImage(ImageSize imageSize, int numRows, int numColumns)
        {
            lock (sync)
            {
                long currentTime = timer.ElapsedMilliseconds;
                removeOldPositions(currentTime - Parameters.TouchEventVisualizerFadeOutTime);

                OutputImage outputImage = new OutputImage(imageSize);
                int imageWidth = imageSize.Width;
                int imageHeight = imageSize.Height;

                // border
                outputImage.drawBorder(Parameters.TouchEventVisualizerGridColor);

                // draw grid
                int widthPerColumn = imageWidth / numColumns;
                int heightPerRow = imageHeight / numRows;

                // find active blocks
                bool[,] activeBlocks = new bool[numRows, numColumns];
                if (numRows * numColumns > 1)
                {
                    foreach (List<Vector2D> positions in activeTouches.Values)
                    {
                        Vector2D lastPosition = positions.Last();
                        int activeRow = (int)Math.Min(lastPosition.Y * numRows, numRows - 1);
                        int activeCol = (int)Math.Min(lastPosition.X * numColumns, numColumns - 1);
                        activeBlocks[activeRow, activeCol] = true;
                    }
                }

                // draw blocks
                int index = 1;
                for (int row = 0; row < numRows; row++)
                {
                    for (int col = 0; col < numColumns; col++)
                    {
                        if (activeBlocks[row, col])
                            outputImage.fillRectangle(new Rectangle(col * widthPerColumn, row * heightPerRow, widthPerColumn, heightPerRow), Parameters.TouchEventVisualizerActiveBlockColor);

                        int x = (int)((col + 0.5f) * widthPerColumn) - 5;
                        int y = (int)((row + 0.5f) * heightPerRow) + 5;
                        outputImage.drawText(new Point(x,y), index.ToString(), Parameters.TouchEventVisualizerTextColor);
                        index++;
                    }
                }

                // draw grid
                for (int i = 0; i <= numColumns; i++)
                    outputImage.drawLineSegment(new LineSegment2D(new Vector2D(i * widthPerColumn, 0), new Vector2D(i * widthPerColumn, imageHeight - 1)), Parameters.TouchEventVisualizerGridColor);
                for (int i = 0; i <= numRows; i++)
                    outputImage.drawLineSegment(new LineSegment2D(new Vector2D(0, i * heightPerRow), new Vector2D(imageWidth - 1, i * heightPerRow)), Parameters.TouchEventVisualizerGridColor);

                // draw active touches
                foreach (List<Vector2D> positions in activeTouches.Values)
                    outputImage.drawTouchGesture(positions, imageSize.MaxPixel);

                // draw old touches (fade out)
                foreach (int id in oldTouches.Keys)
                {
                    List<Vector2D> positions = oldTouches[id];
                    long lastUpdate = lastUpdates[id];
                    float opacity = 1 - ((currentTime - lastUpdate) / (float)Parameters.TouchEventVisualizerFadeOutTime);
                    outputImage.drawTouchGesture(positions, imageSize.MaxPixel, opacity);
                }

                return outputImage;
            }
        }

        /// <summary>
        /// Removes old touch events and update times.
        /// </summary>
        /// <param name="breakTime">every touch event which occured before breakTime is removed</param>
        private void removeOldPositions(long breakTime)
        {
            List<int> ids = new List<int>(lastUpdates.Keys);
            for (int i = ids.Count - 1; i >= 0; i--)
            {
                int id = ids[i];
                if (breakTime > lastUpdates[id])
                {
                    oldTouches.Remove(id);
                    lastUpdates.Remove(id);
                }
            }
        }
    }
}