#nullable enable
using System.Collections;
using System.Collections.Specialized;
using System.Text.Json.Serialization;

namespace Terminal.Gui;

/// <summary>
///     Holds the <see cref="ColorScheme"/>s that define the <see cref="Attribute"/>s that are used by views to render
///     themselves.
/// </summary>
public sealed class Colors : INotifyCollectionChanged, IDictionary<string, ColorScheme?>
{
    static Colors ()
    {
        ColorSchemes = new (5, StringComparer.InvariantCultureIgnoreCase);
        Reset ();
    }

    /// <summary>Gets a dictionary of defined <see cref="ColorScheme"/> objects.</summary>
    /// <remarks>
    ///     <para>
    ///         The <see cref="ColorSchemes"/> dictionary includes the following keys, by default:
    ///         <list type="table">
    ///             <listheader>
    ///                 <term>Built-in Color Scheme</term> <description>Description</description>
    ///             </listheader>
    ///             <item>
    ///                 <term>Base</term> <description>The base color scheme used for most Views.</description>
    ///             </item>
    ///             <item>
    ///                 <term>TopLevel</term>
    ///                 <description>The application Toplevel color scheme; used for the <see cref="Toplevel"/> View.</description>
    ///             </item>
    ///             <item>
    ///                 <term>Dialog</term>
    ///                 <description>
    ///                     The dialog color scheme; used for <see cref="Dialog"/>, <see cref="MessageBox"/>, and
    ///                     other views dialog-like views.
    ///                 </description>
    ///             </item>
    ///             <item>
    ///                 <term>Menu</term>
    ///                 <description>
    ///                     The menu color scheme; used for <see cref="MenuBar"/>, <see cref="ContextMenu"/>, and
    ///                     <see cref="StatusBar"/>.
    ///                 </description>
    ///             </item>
    ///             <item>
    ///                 <term>Error</term>
    ///                 <description>
    ///                     The color scheme for showing errors, such as in
    ///                     <see cref="MessageBox.ErrorQuery(string, string, string[])"/>.
    ///                 </description>
    ///             </item>
    ///         </list>
    ///     </para>
    ///     <para>Changing the values of an entry in this dictionary will affect all views that use the scheme.</para>
    ///     <para>
    ///         <see cref="ConfigurationManager"/> can be used to override the default values for these schemes and add
    ///         additional schemes. See <see cref="ConfigurationManager.Themes"/>.
    ///     </para>
    /// </remarks>
    [SerializableConfigurationProperty (Scope = typeof (ThemeScope), OmitClassName = true)]
    [JsonConverter (typeof (DictionaryJsonConverter<ColorScheme?>))]
    [UsedImplicitly]
    public static Dictionary<string, ColorScheme?> ColorSchemes { get; private set; }

    /// <inheritdoc/>
    public IEnumerator<KeyValuePair<string, ColorScheme?>> GetEnumerator () { return ColorSchemes.GetEnumerator (); }

    /// <inheritdoc/>
    IEnumerator IEnumerable.GetEnumerator () { return GetEnumerator (); }

    /// <inheritdoc/>
    public void Add (KeyValuePair<string, ColorScheme?> item)
    {
        ColorSchemes.Add (item.Key, item.Value);
        CollectionChanged?.Invoke (this, new (NotifyCollectionChangedAction.Add, item));
    }

    /// <inheritdoc/>
    public void Clear ()
    {
        ColorSchemes.Clear ();
        CollectionChanged?.Invoke (this, new (NotifyCollectionChangedAction.Reset));
    }

    /// <inheritdoc/>
    public bool Contains (KeyValuePair<string, ColorScheme?> item) { return ColorSchemes.Contains (item); }

    /// <inheritdoc/>
    public void CopyTo (KeyValuePair<string, ColorScheme?> [] array, int arrayIndex) { ((ICollection)ColorSchemes).CopyTo (array, arrayIndex); }

    /// <inheritdoc/>
    public bool Remove (KeyValuePair<string, ColorScheme?> item)
    {
        if (ColorSchemes.Remove (item.Key))
        {
            CollectionChanged?.Invoke (this, new (NotifyCollectionChangedAction.Remove, item));

            return true;
        }

        return false;
    }

    /// <inheritdoc/>
    public int Count => ColorSchemes.Count;

    /// <inheritdoc/>
    public bool IsReadOnly => false;

    /// <inheritdoc/>
    public void Add (string key, ColorScheme? value) { Add (new (key, value)); }

    /// <inheritdoc/>
    public bool ContainsKey (string key) { return ColorSchemes.ContainsKey (key); }

    /// <inheritdoc/>
    public bool Remove (string key)
    {
        if (ColorSchemes.Remove (key))
        {
            CollectionChanged?.Invoke (this, new (NotifyCollectionChangedAction.Remove, key));

            return true;
        }

        return false;
    }

    /// <inheritdoc/>
    public bool TryGetValue (string key, out ColorScheme? value) { return ColorSchemes.TryGetValue (key, out value); }

    /// <inheritdoc/>
    public ColorScheme? this [string key]
    {
        get => ColorSchemes [key];
        set
        {
            if (ColorSchemes.TryAdd (key, value))
            {
                CollectionChanged?.Invoke (this, new (NotifyCollectionChangedAction.Add, new KeyValuePair<string, ColorScheme?> (key, value)));
            }
            else
            {
                ColorScheme? oldValue = ColorSchemes [key];
                ColorSchemes [key] = value;
                CollectionChanged?.Invoke (this, new (NotifyCollectionChangedAction.Replace, value, oldValue));
            }
        }
    }

    /// <inheritdoc/>
    public ICollection<string> Keys => ColorSchemes.Keys;

    /// <inheritdoc/>
    public ICollection<ColorScheme?> Values => ColorSchemes.Values;

    /// <inheritdoc/>
    public event NotifyCollectionChangedEventHandler? CollectionChanged;

    /// <summary>Resets the <see cref="ColorSchemes"/> dictionary to the default values.</summary>
    public static Dictionary<string, ColorScheme?> Reset ()
    {
        ColorSchemes.Clear ();
        ColorSchemes.Add ("TopLevel", new ());
        ColorSchemes.Add ("Base", new ());
        ColorSchemes.Add ("Dialog", new ());
        ColorSchemes.Add ("Menu", new ());
        ColorSchemes.Add ("Error", new ());

        return ColorSchemes;
    }

    /// <summary>
    ///     Open a <see cref="Dialog"/> with two <see cref="ColorPicker"/> or <see cref="ColorPicker16"/>, based on the
    ///     <see cref="ConsoleDriver.Force16Colors"/> is false or true, respectively, for <see cref="Attribute.Foreground"/>
    ///     and <see cref="Attribute.Background"/> colors.
    /// </summary>
    /// <param name="title">The title to show in the dialog.</param>
    /// <param name="currentAttribute">The current attribute used.</param>
    /// <param name="newAttribute">The new attribute.</param>
    /// <returns><see langword="true"/> if a new color was accepted, otherwise <see langword="false"/>.</returns>
    public static bool PromptForColors (string title, Attribute? currentAttribute, out Attribute newAttribute)
    {
        var accept = false;

        var d = new Dialog
        {
            Title = title,
            Width = Application.Force16Colors ? 37 : Dim.Auto (DimAutoStyle.Auto, Dim.Percent (80), Dim.Percent (90)),
            Height = 20
        };

        var btnOk = new Button
        {
            X = Pos.Center () - 5,
            Y = Application.Force16Colors ? 6 : 4,
            Text = "Ok",
            Width = Dim.Auto (),
            IsDefault = true
        };

        btnOk.Accept += (s, e) =>
                        {
                            accept = true;
                            e.Handled = true;
                            Application.RequestStop ();
                        };

        var btnCancel = new Button
        {
            X = Pos.Center () + 5,
            Y = 4,
            Text = "Cancel",
            Width = Dim.Auto ()
        };

        btnCancel.Accept += (s, e) =>
                            {
                                e.Handled = true;
                                Application.RequestStop ();
                            };

        d.Add (btnOk);
        d.Add (btnCancel);

        d.AddButton (btnOk);
        d.AddButton (btnCancel);

        View cpForeground;

        if (Application.Force16Colors)
        {
            cpForeground = new ColorPicker16
            {
                SelectedColor = currentAttribute!.Value.Foreground.GetClosestNamedColor16 (),
                Width = Dim.Fill (),
                BorderStyle = LineStyle.Single,
                Title = "Foreground"
            };
        }
        else
        {
            cpForeground = new ColorPicker
            {
                SelectedColor = currentAttribute!.Value.Foreground,
                Width = Dim.Fill (),
                Style = new () { ShowColorName = true, ShowTextFields = true },
                BorderStyle = LineStyle.Single,
                Title = "Foreground"
            };
            ((ColorPicker)cpForeground).ApplyStyleChanges ();
        }

        View cpBackground;

        if (Application.Force16Colors)
        {
            cpBackground = new ColorPicker16
            {
                SelectedColor = currentAttribute!.Value.Background.GetClosestNamedColor16 (),
                Y = Pos.Bottom (cpForeground) + 1,
                Width = Dim.Fill (),
                BorderStyle = LineStyle.Single,
                Title = "Background"
            };
        }
        else
        {
            cpBackground = new ColorPicker
            {
                SelectedColor = currentAttribute!.Value.Background,
                Width = Dim.Fill (),
                Y = Pos.Bottom (cpForeground) + 1,
                Style = new () { ShowColorName = true, ShowTextFields = true },
                BorderStyle = LineStyle.Single,
                Title = "Background"
            };
            ((ColorPicker)cpBackground).ApplyStyleChanges ();
        }

        d.Add (cpForeground, cpBackground);

        Application.Run (d);
        d.Dispose ();
        Color newForeColor = Application.Force16Colors ? ((ColorPicker16)cpForeground).SelectedColor : ((ColorPicker)cpForeground).SelectedColor;
        Color newBackColor = Application.Force16Colors ? ((ColorPicker16)cpBackground).SelectedColor : ((ColorPicker)cpBackground).SelectedColor;
        newAttribute = new (newForeColor, newBackColor);

        return accept;
    }
}