using System;
using System.Collections.Generic;
using System.Runtime.ExceptionServices;
using System.Threading;
using System.Threading.Tasks;
using FlowScope.Audio;
using FlowScope.Config;
using FlowScope.Flow;
using FlowScope.Resources;
using FlowScope.Save;
using FlowScope.UI;
using UnityEngine;
using UnityEngine.UI;
using ContainerType = FlowScope.Container.Container;

namespace FlowScope.Samples.MainMenuP0
{
    public sealed class GameBootstrap : MonoBehaviour
    {
        private const string SaveKey = "main-menu-player";

        [SerializeField] private Canvas hudCanvas;
        [SerializeField] private MainMenuPanel mainMenuPanelPrefab;
        [SerializeField] private int defaultGold;

        private ContainerType _root;
        private GameFlow _gameFlow;
        private ISaveService _saveService;
        private UIPreloadService _preloadService;
        private SampleResourceBackend _sampleBackend;
        private PlayerData _playerData;
        private CancellationTokenSource _lifetime;
        private bool _started;
        private bool _shutdownInProgress;
        private bool _shutdown;

        public int ReleasedResourceCount => _sampleBackend?.ReleaseCount ?? 0;
        /// <summary>
        /// True after runtime cleanup has completed; shutdown sub-step failures are still reported by ShutdownAsync.
        /// </summary>
        public bool IsShutdown => _shutdown;
        public Task StartupTask { get; private set; }

        private void Awake()
        {
            _lifetime = new CancellationTokenSource();
            StartupTask = RunStartupWithLoggingAsync(_lifetime.Token);
        }

        public async Task StartupAsync(CancellationToken cancellationToken)
        {
            if (_started)
            {
                return;
            }

            _started = true;
            _shutdown = false;
            _root = new ContainerType();
            _gameFlow = new GameFlow();

            _sampleBackend = new SampleResourceBackend();
            _sampleBackend.Register(
                "FlowScope/Samples/MainMenuP0/MainMenuPanel",
                ResolveMainMenuPanelPrefab().gameObject);
            var resources = new ResourceService(_sampleBackend);
            _preloadService = new UIPreloadService(resources);
            var uiManager = new UIManager(resources, _preloadService);
            uiManager.RegisterLayer("hud", ResolveHudCanvas(), 0, PanelStrategy.Destroy);
            var screenNavigator = new UIScreenNavigator(uiManager);

            var migrations = new SaveMigrationRegistry();
            migrations.Register(new PlayerDataV1ToV2Migration());
            _saveService = new SaveService(
                new FileSaveStorage(),
                new JsonSaveSerializer(2, migrations));
            _playerData = await _saveService.LoadAsync(
                SaveKey,
                new PlayerData { Gold = new R3.ReactiveProperty<int>(defaultGold) },
                cancellationToken);

            await _preloadService.PreloadAsync<MainMenuPanel>(cancellationToken);

            var audioService = gameObject.AddComponent<AudioService>().Initialize(resources);
            _root.RegisterInstance(_root);
            _root.RegisterInstance<IConfigProvider>(
                new JsonConfigProvider(new[]
                {
                    JsonConfigProvider.Mapping<SampleMenuConfig>(
                        "main_menu.json",
                        new InMemoryConfigSource(
                            new Dictionary<string, string>
                            {
                                { "main_menu.json", "[{\"Id\":1,\"Title\":\"Main Menu P1\"}]" }
                            },
                            "MainMenuP0"),
                        new JsonConfigParser())
                }));
            _root.RegisterInstance<IResourceService>(resources);
            _root.RegisterInstance<ISaveService>(_saveService);
            _root.RegisterInstance<IAudioService>(audioService);
            _root.RegisterInstance(uiManager);
            _root.RegisterInstance<IUIPreloadService>(_preloadService);
            _root.RegisterInstance<IUIScreenNavigator>(screenNavigator);
            _root.RegisterInstance(_playerData);
            _root.RegisterTransient(_ => new MainMenuFeature(screenNavigator, _playerData));

            await _gameFlow.StartupAsync<MainMenuFeature>(_root, cancellationToken);
        }

        public async Task ShutdownAsync(CancellationToken cancellationToken)
        {
            if (_shutdown || _shutdownInProgress)
            {
                return;
            }

            _shutdownInProgress = true;
            var exceptions = new List<Exception>();

            try
            {
                if (_saveService != null && _playerData != null)
                {
                    try
                    {
                        await _saveService.SaveAsync(SaveKey, _playerData, cancellationToken);
                    }
                    catch (Exception exception)
                    {
                        exceptions.Add(exception);
                    }
                }

                if (_gameFlow != null && _gameFlow.State != GameFlowState.Disposed)
                {
                    try
                    {
                        await _gameFlow.ShutdownAsync(cancellationToken);
                    }
                    catch (Exception exception)
                    {
                        exceptions.Add(exception);
                    }
                }

                try
                {
                    _preloadService?.ReleaseAll();
                }
                catch (Exception exception)
                {
                    exceptions.Add(exception);
                }

                _shutdown = true;
            }
            finally
            {
                _shutdownInProgress = false;
            }

            if (exceptions.Count == 1)
            {
                ExceptionDispatchInfo.Capture(exceptions[0]).Throw();
            }

            if (exceptions.Count > 1)
            {
                throw new AggregateException("MainMenuP0 shutdown completed with failures.", exceptions);
            }
        }

        private void OnApplicationQuit()
        {
            _lifetime?.Cancel();
            _ = RunShutdownWithLoggingAsync(CancellationToken.None);
        }

        private void OnDestroy()
        {
            _lifetime?.Cancel();
            _lifetime?.Dispose();
        }

        private async Task RunStartupWithLoggingAsync(CancellationToken cancellationToken)
        {
            try
            {
                await StartupAsync(cancellationToken);
            }
            catch (Exception exception)
            {
                Debug.LogException(exception);
                throw;
            }
        }

        private async Task RunShutdownWithLoggingAsync(CancellationToken cancellationToken)
        {
            try
            {
                await ShutdownAsync(cancellationToken);
            }
            catch (Exception exception)
            {
                Debug.LogException(exception);
            }
        }

        private Canvas ResolveHudCanvas()
        {
            if (hudCanvas != null)
            {
                return hudCanvas;
            }

            var canvasObject = new GameObject("FlowScope HUD Canvas");
            canvasObject.transform.SetParent(transform, false);
            hudCanvas = canvasObject.AddComponent<Canvas>();
            hudCanvas.renderMode = RenderMode.ScreenSpaceOverlay;
            return hudCanvas;
        }

        private MainMenuPanel ResolveMainMenuPanelPrefab()
        {
            if (mainMenuPanelPrefab != null)
            {
                return mainMenuPanelPrefab;
            }

            var panelObject = new GameObject("MainMenuPanel Template");
            panelObject.transform.SetParent(transform, false);
            panelObject.SetActive(false);

            var panel = panelObject.AddComponent<MainMenuPanel>();

            var goldObject = new GameObject("GoldText");
            goldObject.transform.SetParent(panelObject.transform, false);
            var goldText = goldObject.AddComponent<Text>();
            goldText.text = defaultGold.ToString();
            goldText.alignment = TextAnchor.MiddleCenter;

            var buttonObject = new GameObject("IncrementGoldButton");
            buttonObject.transform.SetParent(panelObject.transform, false);
            buttonObject.AddComponent<Image>();
            var button = buttonObject.AddComponent<Button>();

            panel.Configure(goldText, button);
            mainMenuPanelPrefab = panel;
            return mainMenuPanelPrefab;
        }

        private sealed class SampleResourceBackend : IResourceBackend
        {
            private readonly Dictionary<string, GameObject> _prefabs = new();

            public string Name => "MainMenuP0Sample";
            public int ReleaseCount { get; private set; }

            public void Register(string key, GameObject prefab)
            {
                _prefabs[key] = prefab;
            }

            public Task<T> LoadAsync<T>(
                string key,
                CancellationToken cancellationToken)
                where T : class
            {
                cancellationToken.ThrowIfCancellationRequested();
                if (typeof(T) == typeof(GameObject) &&
                    _prefabs.TryGetValue(key, out var prefab))
                {
                    return Task.FromResult(prefab as T);
                }

                throw new InvalidOperationException($"Sample resource is not registered: {key}");
            }

            public void Release<T>(string key, T asset)
                where T : class
            {
                ReleaseCount++;
            }
        }

        private sealed class SampleMenuConfig : IConfigRow
        {
            public int Id { get; set; }
            public string Title { get; set; }
        }

        private sealed class PlayerDataV1ToV2Migration : ISaveMigration
        {
            public string Key => typeof(PlayerData).FullName;
            public int FromVersion => 1;
            public int ToVersion => 2;

            public string Migrate(string json) => json;
        }
    }
}