using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.UIElements;

namespace RPGCoreCommon.Select
{
    /// <summary>
    /// Result of using <see cref="Select"/>. Contains information what was clicked in a moment of execution.
    /// </summary>
    public class SelectUtilResult
    {
        /// <summary>
        /// Source of selection:
        /// <ul>
        /// <li><see cref="SelectType.None"/> - probably pressed void, so nothing to select</li>
        /// <li><see cref="SelectType.Scene"/> - something from scene (GameObject and/or Component)</li>
        /// <li><see cref="SelectType.UI"/> - something from UI</li>
        /// </ul>
        /// </summary>
        public SelectType hit { get; private set; }
        
        /// <summary>UI only: select position on UI</summary>
        public Vector2 uiPosition { get; private set; }
        /// <summary>UI only: All that extends <see cref="ISelectableUI"/>. Can be VisualElement itself, its userData or its dataSource.</summary>
        public List<ISelectableUI> uiSelectables { get; private set; } = new();
        /// <summary>UI only: first from <see cref="uiSelectables"/></summary>
        public ISelectableUI uiSelectable => uiSelectables.FirstOrDefault();
        
        /// <summary>Scene only: select position on scene</summary>
        public Vector3 position { get; private set; }
        /// <summary>Scene only: selected GameObject</summary>
        public GameObject gameObject { get; private set; }
        /// <summary>Scene only: selected GameObject's Component</summary>
        public Component component { get; private set; }

        internal SelectUtilResult(Vector3 position, GameObject gameObject = null, Component component = null)
        {
            hit = SelectType.Scene;
            this.position = position;
            this.gameObject = gameObject;
            this.component = component;
        }

        internal SelectUtilResult(Vector2 uiPosition, VisualElement visualElement = null)
        {
            hit = visualElement == null ? SelectType.None : SelectType.UI;
            this.uiPosition = uiPosition;
            
            while (visualElement != null)
            {
                if (visualElement is ISelectableUI iSelectableUI) uiSelectables.Add(iSelectableUI);
                else if (visualElement.dataSource is ISelectableUI dataSource) uiSelectables.Add(dataSource);
                else if (visualElement.userData is ISelectableUI userData) uiSelectables.Add(userData);
                visualElement = visualElement.parent;
            }
        }

        internal SelectUtilResult()
        {
            hit = SelectType.None;
        }
    }
}