using System.Numerics;

namespace AcDream.App.UI;

/// <summary>
/// Rectangular container with an optional translucent background and
/// border. Used as the base of every retail panel (attributes, chat,
/// inventory, login, etc.).
///
/// Retail has panel background art stored as 9-slice sprite assets in
/// the <c>0x06xxxxxx</c> RenderSurface range, and composed via
/// <c>LayoutDesc</c> (<c>0x21xxxxxx</c>) trees. Until our
/// <c>AcFont</c>/<c>UiSpriteBatch</c> consumes those directly, we draw a
/// simple translucent rectangle so panels are visible during development.
/// </summary>
public class UiPanel : UiElement
{
    /// <summary>Background fill color. Set <see cref="Vector4.Zero"/> to skip.</summary>
    public Vector4 BackgroundColor { get; set; } = new(0f, 0f, 0f, 0.55f);

    /// <summary>Border color. Set <see cref="Vector4.Zero"/> to skip.</summary>
    public Vector4 BorderColor     { get; set; } = new(0.15f, 0.15f, 0.2f, 0.8f);

    public float BorderThickness   { get; set; } = 1f;

    protected override void OnDraw(UiRenderContext ctx)
    {
        if (BackgroundColor.W > 0f)
            ctx.DrawRect(0, 0, Width, Height, BackgroundColor);

        if (BorderColor.W > 0f && BorderThickness > 0f)
            ctx.DrawRectOutline(0, 0, Width, Height, BorderColor, BorderThickness);
    }
}

/// <summary>
/// Static text label. Draws a single line of text using the context's
/// default font (or an override). Does not consume input.
///
/// Equivalent retail primitive: wide-string appended to a CString via
/// <c>FUN_0040b8f0</c> then drawn by the widget's draw method through
/// <c>FUN_00698330</c>.
/// </summary>
public class UiLabel : UiElement
{
    public string Text       { get; set; } = string.Empty;
    public Vector4 TextColor { get; set; } = new(1f, 1f, 1f, 1f);

    public UiLabel() { ClickThrough = true; }

    protected override void OnDraw(UiRenderContext ctx)
        => ctx.DrawString(Text, 0, 0, TextColor);
}

/// <summary>
/// Simple clickable button: panel background + centered label + click
/// callback. Retail equivalent is Keystone's button widget, driven by
/// a <c>StateDesc</c> per <c>UIStateId</c> (normal / hot / pressed /
/// disabled) from the panel layout.
/// </summary>
public class UiButton : UiPanel
{
    public string Text       { get; set; } = string.Empty;
    public Vector4 TextColor { get; set; } = new(1f, 1f, 1f, 1f);
    public event System.Action? Click;

    public UiButton()
    {
        BackgroundColor = new Vector4(0.1f, 0.1f, 0.15f, 0.8f);
        BorderColor     = new Vector4(0.45f, 0.45f, 0.55f, 1f);
    }

    public override bool OnEvent(in UiEvent e)
    {
        if (e.Type == UiEventType.Click && Enabled)
        {
            Click?.Invoke();
            return true;
        }
        return false;
    }

    protected override void OnDraw(UiRenderContext ctx)
    {
        base.OnDraw(ctx);
        if (Text.Length == 0 || ctx.DefaultFont is null) return;

        float textW = ctx.DefaultFont.MeasureWidth(Text);
        float tx = (Width  - textW) * 0.5f;
        float ty = (Height - ctx.DefaultFont.LineHeight) * 0.5f;
        ctx.DrawString(Text, tx, ty, TextColor);
    }
}