// MIT License - Copyright (c) 2024 wallstop
// Full license text: https://github.com/wallstop/unity-helpers/blob/main/LICENSE

namespace WallstopStudios.UnityHelpers.Utils
{
    using System;
    using System.Collections.Generic;
    using UnityEngine;
    using UnityEngine.Serialization;
    using UnityEngine.UI;

    [DisallowMultipleComponent]
    public sealed class MatchColliderToSprite : MonoBehaviour
    {
        public event Action colliderUpdated;

        public Func<Sprite> spriteOverrideProducer;

        [FormerlySerializedAs("_spriteRenderer")]
        public SpriteRenderer spriteRenderer;

        [FormerlySerializedAs("_image")]
        public Image image;

        [FormerlySerializedAs("_collider")]
        public PolygonCollider2D polygonCollider;

        internal Sprite _lastHandled;

        private void Awake()
        {
            OnValidate();
        }

        private void Update()
        {
            if (spriteOverrideProducer != null && _lastHandled == spriteOverrideProducer())
            {
                return;
            }

            if (spriteRenderer != null && _lastHandled == spriteRenderer.sprite)
            {
                return;
            }

            if (image != null && _lastHandled == image.sprite)
            {
                return;
            }

            OnValidate();
        }

        public void OnValidate()
        {
            if (polygonCollider == null && !TryGetComponent(out polygonCollider))
            {
                return;
            }

            try
            {
                Sprite sprite;
                if (spriteOverrideProducer != null)
                {
                    sprite = spriteOverrideProducer();
                }
                else if (spriteRenderer != null || TryGetComponent(out spriteRenderer))
                {
                    sprite = spriteRenderer.sprite;
                }
                else if (image != null || TryGetComponent(out image))
                {
                    sprite = image.sprite;
                }
                else
                {
                    sprite = null;
                }

                _lastHandled = sprite;
                polygonCollider.points = Array.Empty<Vector2>();
                if (_lastHandled == null)
                {
                    polygonCollider.pathCount = 0;
                    return;
                }

                int physicsShapes = _lastHandled.GetPhysicsShapeCount();
                polygonCollider.pathCount = physicsShapes;
                using PooledResource<List<Vector2>> bufferResource = Buffers<Vector2>.List.Get(
                    out List<Vector2> buffer
                );
                for (int i = 0; i < physicsShapes; ++i)
                {
                    buffer.Clear();
                    _ = _lastHandled.GetPhysicsShape(i, buffer);
                    polygonCollider.SetPath(i, buffer);
                }
            }
            finally
            {
                colliderUpdated?.Invoke();
            }
        }
    }
}