using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;

namespace ThermoCamUtils
{
    public class ReColorize
    {
        #region Protected Fields

        protected double delta = 0;
        protected double maxSca = 5000;
        protected double maxVal = 5000;
        protected double minSca = -999;
        protected double minVal = -999;

        #endregion Protected Fields

        #region Public Constructors

        public ReColorize(double minValue, double maxValue, double minScale, double maxScale)
        {
            minVal = minValue;
            maxVal = maxValue;
            minSca = minScale;
            maxSca = maxScale;
            delta = minVal - minSca;
        }

        #endregion Public Constructors

        #region Protected Methods

        /// <summary>
        /// Calcola colore su scala dato rapporto valore B/N su min/max
        /// </summary>
        /// <param name="ValOrig"></param>
        /// <returns></returns>
        protected Color Rescale(ref int ValRGB)
        {
            int R = 0;
            int G = 0;
            int B = 0;
            int ValScal = 0;

            // calcolo retta interpolazione per il valore in gradi...Y = M * X + DELTA
            double M = (maxVal - minVal) / 255;
            double currTemp = M * ValRGB + delta;
            // ora calcolo valore scalare
            ValScal = (int)(255 * (currTemp - minSca) / (maxSca - minSca));

            if (ValScal < 0)
            {
                R = 0;
                G = 0;
                B = 0;
            }
            else if (ValScal <= 51)
            {
                R = 0;
                G = 0;
                B = (int)(ValScal * 5);
            }
            else if (ValScal <= 102)
            {
                R = (int)((ValScal - 51) * 5);
                G = 0;
                B = 255;
            }
            else if (ValScal <= 153)
            {
                R = 255;
                G = 0;
                B = (int)(255 - ((ValScal - 102) * 5));
            }
            else if (ValScal <= 204)
            {
                R = 255;
                G = (int)((ValScal - 153) * 5);
                B = 0;
            }
            else if (ValScal <= 255)
            {
                R = 255;
                G = 255;
                B = (int)((ValScal - 204) * 5);
            }
            else
            {
                R = 255;
                G = 255;
                B = 255;
            }

            return Color.FromArgb(R, G, B);
        }

        #endregion Protected Methods

        #region Public Methods

        public Bitmap process(Bitmap original, bool doFast)
        {
            /*---------------------------------------------
            // indicazioni x ottimizzare da qui:
            // http://csharpexamples.com/tag/parallel-bitmap-processing/
            -----------------------------------------------*/

            Bitmap imgColor = original.Clone(new Rectangle(0, 0, original.Width, original.Height), original.PixelFormat);
            int currVal = 0;

            if (doFast)
            {
                BitmapData bitmapData = imgColor.LockBits(new Rectangle(0, 0, imgColor.Width, imgColor.Height), ImageLockMode.ReadWrite, imgColor.PixelFormat);

                int bytesPerPixel = Bitmap.GetPixelFormatSize(imgColor.PixelFormat) / 8;
                int byteCount = bitmapData.Stride * imgColor.Height;
                byte[] pixels = new byte[byteCount];
                IntPtr ptrFirstPixel = bitmapData.Scan0;
                Marshal.Copy(ptrFirstPixel, pixels, 0, pixels.Length);
                int heightInPixels = bitmapData.Height;
                int widthInBytes = bitmapData.Width * bytesPerPixel;

                for (int y = 0; y < heightInPixels; y++)
                {
                    int currentLine = y * bitmapData.Stride;
                    for (int x = 0; x < widthInBytes; x = x + bytesPerPixel)
                    {
                        // prendo il rosso
                        int oldRed = pixels[currentLine + x + 0];
                        currVal = pixels[currentLine + x + 2];
                        var newCol = Rescale(ref currVal);
                        pixels[currentLine + x] = (byte)newCol.B;
                        pixels[currentLine + x + 1] = (byte)newCol.G;
                        pixels[currentLine + x + 2] = (byte)newCol.R;
                        //currVal = original.GetPixel(x, y).R;
                        //imgColor.SetPixel(x, y, Rescale(ref currVal));
                    }
                }

                // copy modified bytes back
                Marshal.Copy(pixels, 0, ptrFirstPixel, pixels.Length);
                imgColor.UnlockBits(bitmapData);
            }
            else
            {
                // recupero matrice di punti con valore RGB
                for (int x = 0; x < original.Width; x++)
                {
                    for (int y = 0; y < original.Height; y++)
                    {
                        // esecuo ricalcolo
                        currVal = original.GetPixel(x, y).R;
                        imgColor.SetPixel(x, y, Rescale(ref currVal));
                    }
                }
            }

            return imgColor;
        }

        #endregion Public Methods
    }
}