using UnityEngine;

namespace PlatypusIdeas.AirPath.Runtime.Events {
    /// <summary>
    /// Handles Update calls for the ScriptableObject-based EventBus
    /// Attach this to a GameObject in your scene (preferably a persistent manager object)
    /// </summary>
    [DefaultExecutionOrder(-1000)]
    public class EventBusUpdateHandler : MonoBehaviour {
        [Header("Configuration")]
        [SerializeField] private bool persistAcrossScenes = true;
        [SerializeField] private PathfindingEventBus eventBusAsset;
        
        [Header("Debug")]
        [SerializeField] private bool showStatistics;
        
        private static EventBusUpdateHandler _instance;
        
        private void Awake() {
            // Ensure only one instance exists
            if (_instance != null && _instance != this) {
                Destroy(gameObject);
                return;
            }
            
            _instance = this;
            
            // Make persistent if configured
            if (persistAcrossScenes) {
                DontDestroyOnLoad(gameObject);
            }
            
            // Validate and initialize the event bus
            if (eventBusAsset == null) {
                Debug.LogError("[EventBusUpdateHandler] No EventBus asset assigned! " +
                               "Please assign a PathfindingEventBus asset in the inspector.", this);
                return;
            }
            
            // Set the singleton instance
            PathfindingEventBus.SetInstance(eventBusAsset);
            
            Debug.Log($"[EventBusUpdateHandler] PathfindingEventBus initialized successfully with asset '{eventBusAsset.name}'");
        }
        
        private void Update() {
            // Process the event bus update
            if (PathfindingEventBus.HasInstance) {
                PathfindingEventBus.Instance.ProcessUpdate();
            }
        }
        
        private void OnApplicationQuit() {
            PathfindingEventBus.SetApplicationQuitting();
        }
        
        private void OnDestroy() {
            if (_instance == this) {
                _instance = null;
                
                // Only set quitting if this is the actual application quit, not just scene change
                if (!persistAcrossScenes || !Application.isPlaying) {
                    PathfindingEventBus.SetApplicationQuitting();
                }
            }
        }
        
#if UNITY_EDITOR
        
        private void OnValidate() {
            // Editor-time validation
            if (eventBusAsset == null) {
                Debug.LogWarning($"[EventBusUpdateHandler] No EventBus asset assigned on '{gameObject.name}'. " +
                                 "The EventBus will not work until you assign the asset.", this);
            }
        }
        private void OnGUI() {
            if (showStatistics && eventBusAsset) {
                var stats = eventBusAsset.GetStatistics();
                
                GUILayout.BeginArea(new Rect(10, 10, 300, 150));
                GUILayout.BeginVertical("box");
                GUILayout.Label("Event Bus Statistics", UnityEditor.EditorStyles.boldLabel);
                GUILayout.Label($"Total Subscriptions: {stats.TotalSubscriptions}");
                GUILayout.Label($"Queued Events: {stats.QueuedEvents}");
                GUILayout.Label($"Event Types: {stats.EventTypes}");
                GUILayout.Label($"Immediate Processing: {stats.IsProcessingImmediately}");
                GUILayout.EndVertical();
                GUILayout.EndArea();
            }
        }
#endif
    }
}