using System;
using System.Drawing;
using System.IO;

namespace ImageProcessing
{
    internal class Program
    {
        // Path to the input and output image files
        // The file should be located where the .exe application is
        public static string imagePath = $@"image.jpg";
        public static string newImagePath = $@"newImage.jpg";

        public static void Main(string[] args)
        {
            // Loading the image from the file
            Bitmap image = LoadImage(imagePath);

            // Checking if the image was loaded successfully
            bool test = (image != null);
            string testResult = test ? "successfully" : "unsuccessfully";

            Console.WriteLine($"Loading image: {imagePath}...\n " +
                $"... completed with {testResult}\n");

            int choice;
            while (true && test)
            {
                Console.WriteLine(
                        "Choose an option:\n" +
                        "[1] Brighten the image\n" +
                        "[2] Darken the image\n" +
                        "[3] Swap colors\n" +
                        "[0] Exit");

                choice = int.Parse(Console.ReadLine());

                Console.Clear();
                switch (choice)
                {
                    case 1:
                        //BrightenImage(image);
                        ChangeImageBrightness(image, 50);
                        break;
                    case 2:
                        //DarkenImage(image);
                        ChangeImageBrightness(image, -50);
                        break;
                    case 3:
                        SwapColors(image);
                        break;
                    case 0:
                        Console.WriteLine("Exiting the application");
                        return;
                    default:
                        Console.WriteLine("Invalid operation");
                        break;
                }
            }

            Console.ReadKey();
        }

        // Method to brighten the image
        public static void BrightenImage(Bitmap img)
        {
            int brighteningStrength = 50;
            // Iterating through each pixel of the image
            for (int i = 0; i < img.Width; i++)
            {
                for (int j = 0; j < img.Height; j++)
                {
                    // Retrieving the pixel value
                    Color pixel = img.GetPixel(i, j);

                    // Changing the brightness of the pixel by 50 units
                    Color newPixel = Color.FromArgb(
                        ClampValue(pixel.R + brighteningStrength),
                        ClampValue(pixel.G + brighteningStrength),
                        ClampValue(pixel.B + brighteningStrength));

                    // Setting the new pixel value
                    img.SetPixel(i, j, newPixel);
                }
            }

            Console.WriteLine("...Brightened \n\n");
            // Saving the modified image
            img.Save(newImagePath);
        }

        public static void DarkenImage(Bitmap img)
        {
            int darkeningStrength = 50;
            for (int i = 0; i < img.Width; i++)
            {
                for (int j = 0; j < img.Height; j++)
                {
                    // Retrieving the pixel value
                    Color pixel = img.GetPixel(i, j);

                    // Changing the brightness of the pixel by 50 units
                    Color newPixel = Color.FromArgb(
                        ClampValue(pixel.R - darkeningStrength),
                        ClampValue(pixel.G - darkeningStrength),
                        ClampValue(pixel.B - darkeningStrength));

                    // Setting the new pixel value
                    img.SetPixel(i, j, newPixel);
                }
            }

            Console.WriteLine("...Darkened \n\n");
            // Saving the modified image
            img.Save(newImagePath);
        }

        public static void ChangeImageBrightness(Bitmap img, int modificationStrength)
        {
            for (int i = 0; i < img.Width; i++)
            {
                for (int j = 0; j < img.Height; j++)
                {
                    // Retrieving the pixel value
                    Color pixel = img.GetPixel(i, j);

                    // Changing the brightness of the pixel by the specified amount
                    Color newPixel = Color.FromArgb(
                        ClampValue(pixel.R + modificationStrength),
                        ClampValue(pixel.G + modificationStrength),
                        ClampValue(pixel.B + modificationStrength));

                    // Setting the new pixel value
                    img.SetPixel(i, j, newPixel);
                }
            }

            Console.WriteLine("...Brightness changed \n\n");
            // Saving the modified image
            img.Save(newImagePath);
        }

        public static void SwapColors(Bitmap img)
        {
            Color colorToReplace, newColor;

            // Getting colors from the user
            Console.WriteLine("Enter the value of the color to be replaced in RGB format. Provide three values from the range 0-255, separated by commas (,).");
            colorToReplace = ConvertStringToColor(Console.ReadLine());

            Console.WriteLine("Enter the value of the new color in RGB format. Provide three values from the range 0-255, separated by commas (,).");
            newColor = ConvertStringToColor(Console.ReadLine());

            // Loop to iterate over each pixel and replace the matching color
            int modifiedPixelCount = 0;
            for (int i = 0; i < img.Width; i++)
            {
                for (int j = 0; j < img.Height; j++)
                {
                    Color color = img.GetPixel(i, j);

                    if (color == colorToReplace)
                    {
                        img.SetPixel(i, j, newColor);
                        modifiedPixelCount++;
                    }
                }
            }

            Console.WriteLine($"Replaced {modifiedPixelCount} pixels.\n\n");

            // Saving the modified image
            img.Save(newImagePath);
        }

        // Method to convert user-input RGB values to a Color object
        public static Color ConvertStringToColor(string rgb)
        {
            int r, g, b;

            try
            {
                string[] rgbComponents = rgb.Split(',');
                r = int.Parse(rgbComponents[0]);
                g = int.Parse(rgbComponents[1]);
                b = int.Parse(rgbComponents[2]);
                return Color.FromArgb(r, g, b);
            }
            catch (Exception e)
            {
                Console.WriteLine("Invalid color input. Setting default color (black).");
                return Color.Black;
            }
        }

        // Method to prevent values from exceeding the 0-255 (RGB) range by clamping the variables
        public static int ClampValue(int value)
        {
            if (value < 0) return 0;
            if (value > 255) return 255;

            return value;
        }

        // Method to load the image from the given path and display a message if there's an issue
        public static Bitmap LoadImage(string filePath)
        {
            if (File.Exists(filePath) == false) return null;

            try
            {
                Bitmap bitmap = new Bitmap(filePath);
                return bitmap;
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
                return null;
            }
        }
    }
}