using System.Collections;
using Unity.VisualScripting;
using UnityEngine;
using UnityEngine.UIElements;

namespace Management
{
    /// <summary>
    /// Global access pattern for services.
    /// If you need a component or some data that needs to be used in many places, here's a good spot.
    /// </summary>
    public class Services : MonoBehaviour
    {
        // Enforce singleton pattern
        public static Services Instance { get; private set; }
        
        // BGM service for playing/changing background music.
        public BGM BGM => bgm;
        
        // SFX service to serve as single spot SFX plays from.
        public SFX SFX => sfx;
        public InputRouter InputRouter => inputRouter;

        [SerializeField] private BGM bgm;
        [SerializeField] private SFX sfx;
        [SerializeField] private InputRouter inputRouter;
        [SerializeField] private GameObject transition;
        [SerializeField] private float transitionTime;
        
        private Coroutine _transitionRoutine;
        private VisualElement _loadingScreen;
        
        public void ShowTransition(bool show)
        {
            if (_transitionRoutine != null)
                StopCoroutine(_transitionRoutine);
            _transitionRoutine = StartCoroutine(TransitionRoutine(!show));
        }

        private IEnumerator TransitionRoutine(bool reverse)
        {
            var timer = 0f;
            while (timer < transitionTime)
            {
                timer += Time.deltaTime;
                _loadingScreen.style.opacity = Mathf.Lerp(
                    reverse ? 1 : 0,
                    reverse ? 0: 1, timer / transitionTime);
                yield return null;
            }
            _transitionRoutine = null;
        }
        
        private void Awake()
        {
            // enforce singleton
            if (Instance != null && Instance != this)
            {
                Destroy(gameObject);
                return;
            }
            
            Instance = this;
            
            // survive scene reloads
            DontDestroyOnLoad(gameObject);

            _loadingScreen = transition.GetComponent<UIDocument>().rootVisualElement.Q<VisualElement>("transitionContainer");
        }
    }
}