using System.Text;

using Avalonia;
using Avalonia.Controls;
using Avalonia.Controls.Presenters;
using Avalonia.Interactivity;

namespace GSS2.Views;

public partial class TextKeyboardView : UserControl
{
    public static readonly StyledProperty<string?> ValueProperty = AvaloniaProperty.Register<NumericKeyboardView, string?>(nameof(Value));
    public string? Value
    {
        get => GetValue(ValueProperty);
        set => SetValue(ValueProperty, value);
    }
    public static readonly StyledProperty<bool> IsMultilineProperty = AvaloniaProperty.Register<NumericKeyboardView, bool>(nameof(IsMultiline), defaultValue: false);
    public bool IsMultiline
    {
        get => GetValue(IsMultilineProperty);
        set => SetValue(IsMultilineProperty, value);
    }
    public static readonly RoutedEvent<RoutedEventArgs> ClosedEvent = RoutedEvent.Register<NumericKeyboardView, RoutedEventArgs>(nameof(KeyboardClosed), RoutingStrategies.Bubble);
    public event EventHandler<RoutedEventArgs> KeyboardClosed
    {
        add => AddHandler(ClosedEvent, value);
        remove => RemoveHandler(ClosedEvent, value);
    }

    private readonly TextPresenter? _presenter;

    private StringBuilder _text = new();
    private bool _changingValue = false;
    private int _cursor = 0;

    private bool _isUppercase = false;
    private bool _isEnglish = false;

    public TextKeyboardView(string? value = null)
    {
        InitializeComponent();

        ValueProperty.Changed.AddClassHandler<TextKeyboardView>((sender, value) =>
        {
            if (sender != this)
                return;
            if (_changingValue)
                return;
            if (value.NewValue is not string strValue)
            {
                _changingValue = true;
                _text = new();
                _cursor = _text.Length;
                _changingValue = false;
                UpdateDisplay();
                return;
            }
            _changingValue = true;
            _text.Clear();
            _text.Insert(0, strValue);
            _cursor = _text.Length;
            _changingValue = false;
            UpdateDisplay();
        });

        IsMultilineProperty.Changed.AddClassHandler<TextKeyboardView>((sender, value) =>
        {
            if (sender != this)
                return;
            if (value.NewValue is not bool boolValue)
                return;
            EnterRussianLowercase.IsVisible = boolValue;
            EnterRussianUppercase.IsVisible = boolValue;
            EnterEnglishLowercase.IsVisible = boolValue;
            EnterEnglishUppercase.IsVisible = boolValue;
        });

        _presenter = this.FindControl<TextPresenter>("Text");

        if (!string.IsNullOrEmpty(value))
            _text.Append(value);
        _cursor = _text.Length;

        _presenter?.ShowCaret();
        UpdateDisplay();

        RussianLowercase.IsVisible = !_isUppercase && !_isEnglish;
        RussianUppercase.IsVisible = _isUppercase && !_isEnglish;
        EnglishLowercase.IsVisible = !_isUppercase && _isEnglish;
        EnglishUppercase.IsVisible = _isUppercase && _isEnglish;

        EnterRussianLowercase.IsVisible = IsMultiline;
        EnterRussianUppercase.IsVisible = IsMultiline;
        EnterEnglishLowercase.IsVisible = IsMultiline;
        EnterEnglishUppercase.IsVisible = IsMultiline;
    }

    private void KeyPressed(object? sender, RoutedEventArgs e)
    {
        if (sender is not Button btn || btn.Content is not string symbol) return;

        _text.Insert(_cursor, symbol);
        _cursor++;
        UpdateDisplay();
    }

    private void EnterKeyPressed(object? sender, RoutedEventArgs e)
    {
        _text.Insert(_cursor, "\n");
        _cursor++;
        UpdateDisplay();
    }

    private void Backspace(object? sender, RoutedEventArgs e)
    {
        if (_cursor > 0)
        {
            _cursor--;
            _text.Remove(_cursor, 1);
            UpdateDisplay();
        }
    }

    private void SwitchCase(object? sender, RoutedEventArgs e)
    {
        _isUppercase = !_isUppercase;
        RussianLowercase.IsVisible = !_isUppercase && !_isEnglish;
        RussianUppercase.IsVisible = _isUppercase && !_isEnglish;
        EnglishLowercase.IsVisible = !_isUppercase && _isEnglish;
        EnglishUppercase.IsVisible = _isUppercase && _isEnglish;
    }
    private void SwitchLagnuage(object? sender, RoutedEventArgs e)
    {
        _isEnglish = !_isEnglish;
        RussianLowercase.IsVisible = !_isUppercase && !_isEnglish;
        RussianUppercase.IsVisible = _isUppercase && !_isEnglish;
        EnglishLowercase.IsVisible = !_isUppercase && _isEnglish;
        EnglishUppercase.IsVisible = _isUppercase && _isEnglish;
    }

    private void MoveCursorLeft(object? sender, RoutedEventArgs e)
    {
        _cursor = Math.Max(0, _cursor - 1);
        UpdateDisplay();
    }

    private void MoveCursorRight(object? sender, RoutedEventArgs e)
    {
        _cursor = Math.Min(_text.Length, _cursor + 1);
        UpdateDisplay();
    }

    private void Accept(object? sender, RoutedEventArgs e)
    {
        Value = _text.ToString();
    }

    private void Cancel(object? sender, RoutedEventArgs e) => Value = null;

    private void UpdateDisplay()
    {
        if (_presenter is null)
            return;

        _presenter.Text = _text.ToString();
        _presenter.CaretIndex = _cursor;
        _presenter.InvalidateVisual();

        Value = _text.ToString();
    }
}