using System.Collections;
using Entity;
using SepCore.UI;
using UnityEngine;
using UnityEngine.Serialization;
using UnityEngine.UI;
using UnityGameFramework.Runtime;

namespace StarForce
{
    public class HPBarItem : MonoBehaviour
    {
        private const float AnimationSeconds = 0.3f;
        private const float KeepSeconds = 0.4f;
        private const float FadeOutSeconds = 0.3f;

        [FormerlySerializedAs("m_HPBar")] [SerializeField] private Slider _hPBar = null;

        private Canvas _parentCanvas = null;
        private RectTransform _cachedTransform = null;
        private CanvasGroup _cachedCanvasGroup = null;
        private EntityBase _owner = null;
        private int m_OwnerId = 0;

        public EntityBase Owner => _owner;

        public void Init(EntityBase owner, Canvas parentCanvas, float fromHPRatio, float toHPRatio)
        {
            if (owner == null)
            {
                Log.Error("Owner is invalid.");
                return;
            }

            _parentCanvas = parentCanvas;

            gameObject.SetActive(true);
            StopAllCoroutines();

            _cachedCanvasGroup.alpha = 1f;
            if (_owner != owner || m_OwnerId != owner.Id)
            {
                _hPBar.value = fromHPRatio;
                _owner = owner;
                m_OwnerId = owner.Id;
            }

            Refresh();

            StartCoroutine(HPBarCo(toHPRatio, AnimationSeconds, KeepSeconds, FadeOutSeconds));
        }

        public bool Refresh()
        {
            if (_cachedCanvasGroup.alpha <= 0f)
            {
                return false;
            }

            if (_owner != null && Owner.Available && Owner.Id == m_OwnerId)
            {
                Vector3 worldPosition = _owner.CachedTransform.position + Vector3.forward;
                Vector3 screenPosition = GameEntry.Scene.MainCamera.WorldToScreenPoint(worldPosition);

                Vector2 position;
                if (RectTransformUtility.ScreenPointToLocalPointInRectangle((RectTransform)_parentCanvas.transform,
                        screenPosition,
                        _parentCanvas.worldCamera, out position))
                {
                    _cachedTransform.localPosition = position;
                }
            }

            return true;
        }

        public void Reset()
        {
            StopAllCoroutines();
            _cachedCanvasGroup.alpha = 1f;
            _hPBar.value = 1f;
            _owner = null;
            gameObject.SetActive(false);
        }

        private void Awake()
        {
            _cachedTransform = GetComponent<RectTransform>();
            if (_cachedTransform == null)
            {
                Log.Error("RectTransform is invalid.");
                return;
            }

            _cachedCanvasGroup = GetComponent<CanvasGroup>();
            if (_cachedCanvasGroup == null)
            {
                Log.Error("CanvasGroup is invalid.");
                return;
            }
        }

        private IEnumerator HPBarCo(float value, float animationDuration, float keepDuration, float fadeOutDuration)
        {
            yield return _hPBar.SmoothValue(value, animationDuration);
            yield return new WaitForSeconds(keepDuration);
            yield return _cachedCanvasGroup.FadeToAlpha(0f, fadeOutDuration);
        }
    }
}