// Assets/_Project/Scripts/Gameplay/ISelectable.cs
using UnityEngine;

namespace TD.Gameplay
{
    /// <summary>
    /// Categorizes the kind of selectable object so HUD can decide which command
    /// buttons (tower-build vs upgrade/sell vs none) to show without doing
    /// type-tests against every concrete component.
    /// </summary>
    public enum SelectableKind
    {
        Builder,
        Tower,
        Enemy,
        BuildSite,   // tower in queued / constructing / paused / shelved state
    }

    /// <summary>
    /// Anything the local player can click to select. Implementers expose a
    /// display name for the HUD portrait, a kind for context-aware UI, and the
    /// position + size hints the <see cref="SelectionVisualizer"/> needs to draw
    /// the selection ring.
    /// </summary>
    /// <remarks>
    /// Selection is a local UI concept — implementers don't need to be
    /// NetworkBehaviours (though Builder and TowerInstance happen to be).
    /// </remarks>
    public interface ISelectable
    {
        string DisplayName { get; }
        SelectableKind Kind { get; }

        /// <summary>Transform whose XZ position the scene-wide selection ring
        /// follows. The visualizer projects Y to the buildable plane regardless
        /// of where this transform sits, so implementers can simply return
        /// <c>this.transform</c>.</summary>
        Transform SelectionTransform { get; }

        /// <summary>Half-width of the selection ring in world units. The visualizer
        /// scales its base 1-unit-diameter ring mesh to <c>2 * SelectionRadius</c>.
        /// Computed on every selection change, so implementers may derive it from
        /// runtime state (e.g., tower footprint, collider bounds).</summary>
        float SelectionRadius { get; }
    }
}