using UnityEngine;

namespace EE2Clone.Hybrid
{
    /// <summary>
    /// Draws the rubber-band selection box on screen when the player is drag-selecting.
    /// </summary>
    public class SelectionBoxUI : MonoBehaviour
    {
        [SerializeField] private Color boxColor = new(0.2f, 0.8f, 0.2f, 0.25f);
        [SerializeField] private Color borderColor = new(0.2f, 0.8f, 0.2f, 0.8f);

        private Texture2D _fillTexture;
        private Texture2D _borderTexture;

        private void Awake()
        {
            _fillTexture = new Texture2D(1, 1);
            _fillTexture.SetPixel(0, 0, Color.white);
            _fillTexture.Apply();

            _borderTexture = new Texture2D(1, 1);
            _borderTexture.SetPixel(0, 0, Color.white);
            _borderTexture.Apply();
        }

        private void OnGUI()
        {
            var sel = SelectionManager.Instance;
            if (sel == null || !sel.IsDragging) return;

            var start = sel.DragStart;
            var end = sel.DragEnd;

            // Convert to GUI coordinates (Y is flipped)
            start.y = Screen.height - start.y;
            end.y = Screen.height - end.y;

            var rect = new Rect(
                Mathf.Min(start.x, end.x),
                Mathf.Min(start.y, end.y),
                Mathf.Abs(end.x - start.x),
                Mathf.Abs(end.y - start.y)
            );

            // Draw fill
            GUI.color = boxColor;
            GUI.DrawTexture(rect, _fillTexture);

            // Draw border
            GUI.color = borderColor;
            float b = 2f;
            GUI.DrawTexture(new Rect(rect.x, rect.y, rect.width, b), _borderTexture);
            GUI.DrawTexture(new Rect(rect.x, rect.yMax - b, rect.width, b), _borderTexture);
            GUI.DrawTexture(new Rect(rect.x, rect.y, b, rect.height), _borderTexture);
            GUI.DrawTexture(new Rect(rect.xMax - b, rect.y, b, rect.height), _borderTexture);

            GUI.color = Color.white;
        }

        private void OnDestroy()
        {
            if (_fillTexture != null) Destroy(_fillTexture);
            if (_borderTexture != null) Destroy(_borderTexture);
        }
    }
}