using System.IO;
using System.Linq;
using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine;

namespace NightclubArcadia.EditorTools
{
    /// <summary>
    /// Makes the split-scene layout usable in the Editor.
    ///
    /// The game runs from Bootstrap, which loads Systems and a level additively AT
    /// RUNTIME. Unity discards runtime-loaded scenes when Play ends and restores
    /// whatever the Editor had open, which for someone who pressed Play in Bootstrap is
    /// Bootstrap alone. The Hierarchy comes back nearly empty and it looks as though the
    /// scenes were destroyed. They are not — nothing is written to disk — but it is an
    /// unpleasant way to work.
    ///
    /// Two fixes, both opt-outable:
    ///   - Open Game Scenes puts all three in the Hierarchy for authoring.
    ///   - The Editor's scene setup is captured before Play and restored after, so what
    ///     you had open is what you get back.
    ///
    /// GameBootstrap skips any scene that is already loaded, so having all three open
    /// and pressing Play does the right thing rather than loading anything twice.
    /// </summary>
    [InitializeOnLoad]
    public static class GameSceneWorkflow
    {
        const string RestorePrefKey = "NightclubArcadia.RestoreSceneSetup";
        const string RestoreMenu = "Tools/Nightclub Arcadia/Restore Scene Setup After Play";

        static SceneSetup[] setupBeforePlay;

        static GameSceneWorkflow()
        {
            EditorApplication.playModeStateChanged += OnPlayModeStateChanged;
        }

        [MenuItem("Tools/Nightclub Arcadia/Open Game Scenes")]
        public static void OpenGameScenes()
        {
            // The prompt cannot be shown in batch mode, where it returns false and would
            // make this menu a silent no-op.
            if (!Application.isBatchMode && !EditorSceneManager.SaveCurrentModifiedScenesIfUserWantsTo())
            {
                return;
            }

            foreach (var path in new[] { ScenePaths.Bootstrap, ScenePaths.Systems, ScenePaths.WorkingLevel })
            {
                if (!File.Exists(path))
                {
                    Debug.LogError($"[Scenes] Missing: {path}");
                    return;
                }
            }

            EditorSceneManager.OpenScene(ScenePaths.Bootstrap, OpenSceneMode.Single);
            EditorSceneManager.OpenScene(ScenePaths.Systems, OpenSceneMode.Additive);
            var level = EditorSceneManager.OpenScene(ScenePaths.WorkingLevel, OpenSceneMode.Additive);

            // The level owns the lighting and is where new objects should land.
            EditorSceneManager.SetActiveScene(level);
            Debug.Log("[Scenes] Bootstrap + Systems + SC101_ConferenceHall open. Level is active.");
        }

        [MenuItem(RestoreMenu)]
        static void ToggleRestore()
        {
            var on = !EditorPrefs.GetBool(RestorePrefKey, true);
            EditorPrefs.SetBool(RestorePrefKey, on);
            Debug.Log($"[Scenes] Restore scene setup after Play: {(on ? "on" : "off")}");
        }

        [MenuItem(RestoreMenu, true)]
        static bool ToggleRestoreValidate()
        {
            Menu.SetChecked(RestoreMenu, EditorPrefs.GetBool(RestorePrefKey, true));
            return true;
        }

        static void OnPlayModeStateChanged(PlayModeStateChange state)
        {
            if (!EditorPrefs.GetBool(RestorePrefKey, true))
            {
                return;
            }

            if (state == PlayModeStateChange.ExitingEditMode)
            {
                setupBeforePlay = EditorSceneManager.GetSceneManagerSetup();
                return;
            }

            if (state != PlayModeStateChange.EnteredEditMode || setupBeforePlay == null)
            {
                return;
            }

            var setup = setupBeforePlay;
            setupBeforePlay = null;

            // A scene deleted or renamed while Play was running would throw here, and
            // an exception in this callback leaves the Editor in a confusing state.
            var usable = setup.Where(s => File.Exists(s.path)).ToArray();
            if (usable.Length == 0)
            {
                return;
            }

            var current = EditorSceneManager.GetSceneManagerSetup();
            if (current.Length == usable.Length &&
                current.Select(s => s.path).SequenceEqual(usable.Select(s => s.path)))
            {
                return; // already what we wanted; do not disturb it
            }

            try
            {
                EditorSceneManager.RestoreSceneManagerSetup(usable);
            }
            catch (System.Exception e)
            {
                Debug.LogWarning($"[Scenes] Could not restore the pre-Play scene setup: {e.Message}");
            }
        }
    }
}