using System.Data;
using System.Drawing.Drawing2D;
using System.IO;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using Microsoft.Win32;

namespace DSPS_Lab1;
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    private char[] File;
    private int Total;
    private int[] Count;
    private int[,] CountPair; // first index - current char, second index - next char
    private float[] Probability;
    private float[,] CombinedProbability;
    private float[,] ConditionalProbability;

    public MainWindow()
    {
        InitializeComponent();
        Count = new int[256];
        CountPair = new int[256, 256];
        Probability = new float[256];
        CombinedProbability = new float[256, 256];
        ConditionalProbability = new float[256, 256];
    }

    private async void OpenFile(object sender, RoutedEventArgs e)
    {
        var dlg = new OpenFileDialog
        {
            Title = "Open file",
            Filter = "All files|*.*"
        };

        bool? result = dlg.ShowDialog();
        if (result == true && !string.IsNullOrEmpty(dlg.FileName))
        {
            try
            {
                string content = await System.IO.File.ReadAllTextAsync(dlg.FileName, Encoding.UTF8);
                this.FileName.Content = System.IO.Path.GetFileName(dlg.FileName);
                SourceTextBox.Text = content;
                this.File = content.ToCharArray();
            }
            catch (IOException ex)
            {
                MessageBox.Show(this, $"Failed to read file: {ex.Message}", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
            }

            await CalculateTask1();
            await CalculateTask2();
            await CalculateTask3();
        }
    }

    private async Task CalculateTask1()
    {
        var result = await Task.Run(() =>
        {
            float H = 0;
            float check = 0;
            DataTable dt = new DataTable();
            foreach (char c in File)
            {
                if (c > 255) continue;
                Count[c]++;
                Total++;
            }
            DataRow row = dt.NewRow();
            for (int i = 0; i < Count.Length; i++)
            {
                dt.Columns.Add(i.ToString(), typeof(float));
                float p = (float)Count[i] / Total;
                Probability[i] = p;
                check += p;
                row[i] = Math.Round(p * 100) / 100;
                if (Count[i] == 0) continue;
                H += p * (float)Math.Log2(p);
            }
            dt.Rows.Add(row);
            return (dt, H);
        });

        DataGridTask1.ItemsSource = result.dt.DefaultView;
        Entropy1AmountLabel.Content = (-result.H).ToString();
        double max = (1 / 256.0) * Math.Log2(1 / 256.0) * -256;
        MaxEntropyAmountLabel.Content = max.ToString();
        Coefficient1.Content = ((max + result.H)/max).ToString();
    }

    private async Task CalculateTask2()
    {
        var result = await Task.Run(() =>
        {
            Total = 0;
            float H = 0;
            float check = 0;
            DataTable dt = new DataTable();
            for (int i = 0; i < File.Length - 1; i++)
            {
                if (File[i + 1] > 255 || File[i] > 255) continue;
                CountPair[File[i], File[i + 1]]++;
                Total++;
            }
            dt.Columns.Add("Char", typeof(string));
            for (int i = 0; i < CountPair.GetLength(0); i++)
                dt.Columns.Add(i.ToString(), typeof(float));
            for (int i = 0; i < CountPair.GetLength(0); i++)
            {
                DataRow row = dt.NewRow();
                row[0] = i.ToString();
                for (int j = 0; j < CountPair.GetLength(1); j++)
                {
                    float p = (float)CountPair[i, j] / Total;
                    CombinedProbability[i, j] = p;
                    check += p;
                    row[j+1] = Math.Round(p * 1000) / 1000;
                    if (CountPair[i, j] == 0) continue;
                    H += p * (float)Math.Log2(p);
                }
                dt.Rows.Add(row);
            }
            return (dt, H);
        });

        DataGridTask2.ItemsSource = result.dt.DefaultView;
        CombinedEntropyLabel.Content = (-result.H).ToString();
        double max = (1 / 256.0) * Math.Log2(1 / 256.0) * -256;
        MaxEntropy2AmountLabel.Content = max.ToString();
        Coefficient2.Content = ((max + result.H) / max).ToString();
    }

    private async Task CalculateTask3()
    {
        var result = await Task.Run(() =>
        {
            Total = 0;
            float[] Hm = new float[256];
            float H = 0;
            float[] check = new float[255];
            DataTable dt = new DataTable();
            for (int i = 0; i < File.Length - 1; i++)
            {
                if (File[i + 1] > 255 || File[i] > 255) continue;
                CountPair[File[i], File[i + 1]]++;
                Total++;
            }
            dt.Columns.Add("Char", typeof(string));
            for (int i = 0; i < CountPair.GetLength(0); i++)
                dt.Columns.Add(i.ToString(), typeof(float));
            for (int i = 0; i < CountPair.GetLength(0); i++)
            {
                Total = Enumerable.Range(0, CountPair.GetLength(1)).Select(col => CountPair[i, col]).Sum();
                if (Total == 0) continue;
                DataRow row = dt.NewRow();
                row[0] = i.ToString();
                for (int j = 0; j < CountPair.GetLength(1); j++)
                {
                    float p = (float)CountPair[i, j] / Total;
                    ConditionalProbability[i, j] = p;
                    check[i] += p;
                    row[j + 1] = Math.Round(p * 1000) / 1000;
                    if (CountPair[i, j] == 0) continue;
                    Hm[i] += p * (float)Math.Log2(p);
                }
                dt.Rows.Add(row);
                H += Hm[i] * Probability[i];
            }
            return (dt, H);
        });

        DataGridTask3.ItemsSource = result.dt.DefaultView;
        ConditionalEntropyLabel.Content = (-result.H).ToString();
        double max = (1 / 256.0) * Math.Log2(1 / 256.0) * -256;
        MaxEntropy3AmountLabel.Content = max.ToString();
        Coefficient3.Content = ((max + result.H) / max).ToString();
    }

    private void DataGridTask1_SelectedCellsChanged(object sender, SelectedCellsChangedEventArgs e)
    {
        if (e.AddedCells.Count > 0)
        {
            var cellInfo = e.AddedCells[0];

            if (cellInfo.Item is System.Data.DataRowView rowView)
            {
                int colIndex = cellInfo.Column.DisplayIndex - 1;

                Task1Helper.Content = ((Char)colIndex).ToString() + " " + Probability[colIndex + 1].ToString();
            }
        }
    }

    private void DataGridTask2_SelectedCellsChanged(object sender, SelectedCellsChangedEventArgs e)
    {
        if (e.AddedCells.Count > 0)
        {
            var cellInfo = e.AddedCells[0];

            if (cellInfo.Item is System.Data.DataRowView rowView)
            {
                int rowIndex = rowView.DataView.Table.Rows.IndexOf(rowView.Row);
                int colIndex = cellInfo.Column.DisplayIndex - 1;

                Task2Helper.Content = ((Char)rowIndex).ToString() + ((Char)colIndex).ToString() + " " + CombinedProbability[rowIndex, colIndex].ToString();
            }
        }
    }
        
    private void DataGridTask3_SelectedCellsChanged(object sender, SelectedCellsChangedEventArgs e)
    {
        if (e.AddedCells.Count > 0)
        {
            var cellInfo = e.AddedCells[0];

            if (cellInfo.Item is System.Data.DataRowView rowView)
            {
                int rowIndex = rowView.DataView.Table.Rows.IndexOf(rowView.Row);
                int colIndex = cellInfo.Column.DisplayIndex - 1;

                Task3Helper.Content = ((Char)rowIndex).ToString() + ((Char)colIndex).ToString() + " " + ConditionalProbability[rowIndex, colIndex].ToString();
            }
        }
    }
}