using System.Collections;
using UnityEngine;
using UnityEngine.SceneManagement;

namespace NightclubArcadia.Core
{
    /// <summary>
    /// The entry point. Loads the persistent Systems scene, then a level, additively.
    ///
    /// Splitting the game across scenes is what lets a level be edited without touching
    /// the systems wiring, and stops a corrupted level from taking the dialogue runner,
    /// the UI layer and the player with it. The cost is that serialized references
    /// cannot cross a scene boundary — Unity nulls those — so the handful of level
    /// objects that need a system resolve it at runtime instead. See SceneServices.
    /// </summary>
    public sealed class GameBootstrap : MonoBehaviour
    {
        [Tooltip("Persistent scene holding dialogue, skills, UI, the camera rig and the player.")]
        [SerializeField] string systemsScene = "Systems";

        [Tooltip("Level to open on start. Leave empty to load only the systems layer.")]
        [SerializeField] string startLevel = "SC101_ConferenceHall";

        IEnumerator Start()
        {
            yield return LoadIfNeeded(systemsScene);

            if (!string.IsNullOrEmpty(startLevel))
            {
                yield return LoadIfNeeded(startLevel);

                var level = SceneManager.GetSceneByName(startLevel);
                if (level.IsValid() && level.isLoaded)
                {
                    // The active scene decides where new objects land and which
                    // lighting settings apply, so it must be the level, not this one.
                    SceneManager.SetActiveScene(level);
                }
            }
        }

        static IEnumerator LoadIfNeeded(string sceneName)
        {
            if (string.IsNullOrEmpty(sceneName))
            {
                yield break;
            }

            var existing = SceneManager.GetSceneByName(sceneName);
            if (existing.IsValid() && existing.isLoaded)
            {
                yield break;
            }

            var op = SceneManager.LoadSceneAsync(sceneName, LoadSceneMode.Additive);
            if (op == null)
            {
                Debug.LogError($"[GameBootstrap] '{sceneName}' is not in the build settings.");
                yield break;
            }

            yield return op;
        }
    }
}