using System.Collections.Generic;
using GeometryTD.CustomEvent;
using GeometryTD.DataTable;
using GeometryTD.Definition;
using GeometryTD.Entity;
using GeometryTD.UI;
using UnityEngine;
using UnityGameFramework.Runtime;

namespace GeometryTD.CustomComponent
{
    public class CombatScheduler
    {
        private enum SchedulerState : byte
        {
            Idle = 0,
            WaitingForLoading = 1,
            RunningPhase = 2,
            WaitingForFinishReturn = 3,
            Completed = 4,
            Failed = 5
        }

        private readonly List<DRLevelPhase> _phaseBuffer = new();
        private readonly Dictionary<int, IReadOnlyList<DRLevelSpawnEntry>> _spawnEntriesByPhaseId = new();
        private readonly EnemyManager _enemyManager = new();
        private readonly PhaseLoopRuntime _phaseLoopRuntime = new();
        private readonly CombatLoadSession _loadSession = new();
        private readonly CombatEventBridge _eventBridge = new();
        private readonly CombatResourceManager _combatResourceManager = new();

        private EntityComponent _entity;
        private DRLevel _currentLevel;
        private CombatFinishFormUseCase _combatFinishFormUseCase;
        private SchedulerState _state = SchedulerState.Idle;
        private bool _initialized;
        private bool _isFinishAsVictory = true;

        public bool IsRunning => _state == SchedulerState.WaitingForLoading || _state == SchedulerState.RunningPhase;
        public bool IsCompleted => _state == SchedulerState.Completed;
        public DRLevel CurrentLevel => _currentLevel;
        public DRLevelPhase CurrentPhase => _phaseLoopRuntime.CurrentPhase;
        public MapEntity CurrentMap => _loadSession.CurrentMap;
        public int DisplayPhaseIndex => _phaseLoopRuntime.DisplayPhaseIndex;
        public int PhaseCount => _phaseLoopRuntime.PhaseCount;
        public bool CanEndCombat => _phaseLoopRuntime.CanEndCombat;
        public int DefeatedEnemyCount => _enemyManager.DefeatedEnemyCount;
        public int GainedCoin => _combatResourceManager.GainedCoin;
        public int GainedGold => _combatResourceManager.GainedGold;

        public void OnInit()
        {
            if (!_initialized)
            {
                _entity = GameEntry.Entity;
                _eventBridge.Bind(
                    OnShowEntitySuccess,
                    OnShowEntityFailure,
                    OnHideEntityComplete,
                    OnOpenUIFormSuccess,
                    OnOpenUIFormFailure,
                    OnCloseUIFormComplete);
                _enemyManager.OnInit(this);
                _loadSession.OnInit(_entity);
                EnsureCombatFinishFormUseCaseBound();
                _initialized = true;
            }

            ResetRuntime();
        }

        public bool Start(
            DRLevel level,
            IReadOnlyList<DRLevelPhase> phases,
            IReadOnlyDictionary<int, IReadOnlyList<DRLevelSpawnEntry>> spawnEntriesByPhaseId)
        {
            if (!_initialized || _entity == null)
            {
                return HandleStartFailure("CombatScheduler start failed. Runtime is not initialized.");
            }

            if (level == null || phases == null || phases.Count <= 0)
            {
                return HandleStartFailure("CombatScheduler start failed. Invalid level or phase data.");
            }

            CleanupAllCombatEntities();
            CloseCombatFinishForm();
            _enemyManager.EndPhase();
            _enemyManager.ResetCombatStats();
            ResetRuntime();
            _combatResourceManager.Reset();
            _isFinishAsVictory = true;

            _currentLevel = level;
            for (int i = 0; i < phases.Count; i++)
            {
                DRLevelPhase phase = phases[i];
                if (phase != null)
                {
                    _phaseBuffer.Add(phase);
                }
            }

            if (spawnEntriesByPhaseId != null)
            {
                foreach (var pair in spawnEntriesByPhaseId)
                {
                    _spawnEntriesByPhaseId[pair.Key] = pair.Value;
                }
            }

            _phaseLoopRuntime.SetPhases(_phaseBuffer);
            if (_phaseLoopRuntime.PhaseCount <= 0)
            {
                return HandleStartFailure($"CombatScheduler start failed. Level '{level.Id}' has no phase data.");
            }

            if (!_loadSession.StartLoading(level, out string loadError))
            {
                return HandleStartFailure($"CombatScheduler start failed. {loadError}");
            }

            _state = SchedulerState.WaitingForLoading;
            Log.Info("CombatScheduler started. Level={0}, PhaseCount={1}.", _currentLevel.Id,
                _phaseLoopRuntime.PhaseCount);
            return true;
        }

        public void OnUpdate(float elapseSeconds, float realElapseSeconds)
        {
            switch (_state)
            {
                case SchedulerState.WaitingForLoading:
                    if (!_loadSession.IsReady)
                    {
                        return;
                    }

                    BeginNextPhase();
                    return;
                case SchedulerState.RunningPhase:
                    UpdateCurrentPhase(elapseSeconds, realElapseSeconds);
                    return;
                default:
                    return;
            }
        }

        public void OnDestroy()
        {
            if (!_initialized)
            {
                return;
            }

            CleanupAllCombatEntities();
            CloseCombatFinishForm();
            _enemyManager.OnDestroy();
            ResetRuntime();
            _eventBridge.Unbind();
            _combatFinishFormUseCase = null;

            _entity = null;
            _initialized = false;
        }

        public bool TryEndCombatByPlayer()
        {
            if (_state != SchedulerState.RunningPhase)
            {
                return false;
            }

            if (!_phaseLoopRuntime.TryRequestEndCombat())
            {
                return false;
            }

            EnterFinishFlow("Combat ended by player.", true);
            return true;
        }

        private void UpdateCurrentPhase(float elapseSeconds, float realElapseSeconds)
        {
            DRLevelPhase currentPhase = _phaseLoopRuntime.CurrentPhase;
            if (currentPhase == null)
            {
                EnterFailureFallback("CombatScheduler update failed. Current phase is null.");
                return;
            }

            _phaseLoopRuntime.AdvancePhaseElapsed(elapseSeconds);
            _enemyManager.OnUpdate(elapseSeconds, realElapseSeconds);

            if (!_phaseLoopRuntime.ShouldEndCurrentPhase(_enemyManager.IsPhaseSpawnCompleted,
                    _enemyManager.AliveEnemyCount))
            {
                return;
            }

            CompleteCurrentPhase();
        }

        private void CompleteCurrentPhase()
        {
            _enemyManager.EndPhase();
            Log.Info(
                "CombatScheduler phase completed. Level={0}, Phase={1}, Elapsed={2:F2}s.",
                _currentLevel != null ? _currentLevel.Id : 0,
                _phaseLoopRuntime.CurrentPhase != null ? _phaseLoopRuntime.CurrentPhase.Id : 0,
                _phaseLoopRuntime.CurrentPhaseElapsed);

            BeginNextPhase();
        }

        private void BeginNextPhase()
        {
            if (!_phaseLoopRuntime.TryEnterNextPhase(out DRLevelPhase nextPhase))
            {
                EnterFinishFlow("Combat ended after loop completion.", true);
                return;
            }

            _spawnEntriesByPhaseId.TryGetValue(nextPhase.Id, out IReadOnlyList<DRLevelSpawnEntry> spawnEntries);
            _enemyManager.BeginPhase(nextPhase, spawnEntries);
            _state = SchedulerState.RunningPhase;
            GameEntry.Event.Fire(
                this,
                CombatProcessEventArgs.Create(_phaseLoopRuntime.DisplayPhaseIndex, _phaseLoopRuntime.PhaseCount));
            GameEntry.Event.Fire(
                this,
                CombatEnemyHpRateChangedEventArgs.Create(
                    ResolveEnemyHpRateMultiplier(_phaseLoopRuntime.DisplayPhaseIndex, _phaseLoopRuntime.PhaseCount)));

            Log.Info(
                "CombatScheduler phase started. Level={0}, Phase={1}, EndType={2}, Entries={3}.",
                _currentLevel != null ? _currentLevel.Id : 0,
                _phaseLoopRuntime.DisplayPhaseIndex,
                nextPhase.EndType,
                spawnEntries != null ? spawnEntries.Count : 0);
        }

        private void EnterFinishFlow(string reason, bool isVictory)
        {
            int defeatedEnemyCount = _enemyManager.DefeatedEnemyCount;
            BackpackInventoryData rewardInventory = _combatResourceManager.GetRewardInventorySnapshot();

            // Step 1: stop runtime and clear enemy entities only.
            _enemyManager.EndPhase();
            _state = SchedulerState.WaitingForFinishReturn;
            _isFinishAsVictory = isVictory;
            _enemyManager.CleanupTrackedEnemies();

            Log.Info(
                "CombatScheduler entered finish flow. Level={0}. Reason={1}",
                _currentLevel != null ? _currentLevel.Id : 0,
                reason);

            OpenCombatFinishForm(defeatedEnemyCount, _combatResourceManager.GainedGold, rewardInventory);
        }

        public void OnEnemyReachedBase(int baseDamage)
        {
            if (_state != SchedulerState.RunningPhase)
            {
                return;
            }

            int resolvedBaseDamage = Mathf.Max(0, baseDamage);
            if (resolvedBaseDamage <= 0)
            {
                return;
            }

            CombatNodeComponent combatNode = GameEntry.CombatNode;
            if (combatNode == null)
            {
                return;
            }

            int currentBaseHp = combatNode.ApplyBaseDamage(resolvedBaseDamage);
            if (currentBaseHp > 0)
            {
                return;
            }

            EnterFinishFlow("Combat ended because base HP reached zero.", false);
        }

        private void ResetRuntime()
        {
            _phaseBuffer.Clear();
            _spawnEntriesByPhaseId.Clear();
            _phaseLoopRuntime.Reset();
            _loadSession.Reset();
            _combatResourceManager.Reset();
            _currentLevel = null;
            _isFinishAsVictory = true;
            _state = SchedulerState.Idle;
        }

        private void CleanupAllCombatEntities()
        {
            _loadSession.Cleanup();
            _enemyManager.CleanupTrackedEnemies();
        }

        private void EnsureCombatFinishFormUseCaseBound()
        {
            _combatFinishFormUseCase ??= new CombatFinishFormUseCase(this);

            GameEntry.UIRouter.BindUIUseCase(UIFormType.CombatFinishForm, _combatFinishFormUseCase);
        }

        private void OpenCombatFinishForm(int defeatedEnemyCount, int gainedGold, BackpackInventoryData rewardInventory)
        {
            EnsureCombatFinishFormUseCaseBound();
            _combatFinishFormUseCase.SetSummary(
                defeatedEnemyCount,
                gainedGold,
                rewardInventory);
            GameEntry.UIRouter.OpenUI(UIFormType.CombatFinishForm);
        }

        public void OnEnemyDefeatedRewardResolved(int gainedCoin, int gainedGold)
        {
            _combatResourceManager.AddEnemyDefeatedReward(gainedCoin, gainedGold);

            if (_state != SchedulerState.RunningPhase)
            {
                return;
            }

            _combatResourceManager.TryRollOutGameItemDrop(
                _phaseLoopRuntime.DisplayPhaseIndex,
                ResolveCurrentThemeType());
        }

        private LevelThemeType ResolveCurrentThemeType()
        {
            if (_currentLevel != null)
            {
                return _currentLevel.LevelThemeType;
            }

            if (GameEntry.CombatNode != null)
            {
                return GameEntry.CombatNode.CurrentThemeType;
            }

            return LevelThemeType.None;
        }

        private void CloseCombatFinishForm()
        {
            GameEntry.UIRouter.CloseUI(UIFormType.CombatFinishForm);
        }

        public bool OnCombatFinishReturnRequested()
        {
            if (_state != SchedulerState.WaitingForFinishReturn)
            {
                return false;
            }

            // Step 2: clear remaining map/UI resources and close finish form.
            _loadSession.Cleanup();
            CloseCombatFinishForm();
            _state = SchedulerState.Completed;
            GameEntry.CombatNode?.OnCombatEndedByScheduler(_isFinishAsVictory);
            return true;
        }

        private bool HandleStartFailure(string errorMessage)
        {
            Log.Warning("{0}", errorMessage);
            _state = SchedulerState.Failed;
            _enemyManager.EndPhase();
            CleanupAllCombatEntities();
            CloseCombatFinishForm();
            ResetRuntime();
            return false;
        }

        private void EnterFailureFallback(string errorMessage)
        {
            if (_state == SchedulerState.Failed || _state == SchedulerState.Completed)
            {
                return;
            }

            _state = SchedulerState.Failed;
            Log.Error("CombatScheduler failed. LevelId={0}, {1}", _currentLevel != null ? _currentLevel.Id : 0,
                errorMessage);
            _enemyManager.EndPhase();
            CleanupAllCombatEntities();
            CloseCombatFinishForm();
            GameEntry.CombatNode?.OnCombatEndedByScheduler(false);
        }

        private static int ResolveEnemyHpRateMultiplier(int displayPhaseIndex, int phaseCount)
        {
            if (displayPhaseIndex <= 0 || phaseCount <= 0)
            {
                return 1;
            }

            int completedLoopCount = Mathf.Max(0, (displayPhaseIndex - 1) / phaseCount);
            if (completedLoopCount >= 30)
            {
                return int.MaxValue;
            }

            return 1 << completedLoopCount;
        }

        #region Event Handlers

        private void OnShowEntitySuccess(ShowEntitySuccessEventArgs args)
        {
            var status = _loadSession.HandleShowEntitySuccess(args, out string errorMessage);
            if (status == CombatLoadSession.EventHandleStatus.Failed)
            {
                EnterFailureFallback(errorMessage);
                return;
            }

            if (status == CombatLoadSession.EventHandleStatus.Succeeded)
            {
                MapEntity map = _loadSession.CurrentMap;
                Log.Info(
                    "Map ready. LevelId={0}, PathCells={1}, FoundationCells={2}, Spawners={3}, House={4}.",
                    _currentLevel != null ? _currentLevel.Id : 0,
                    map.PathCells.Count,
                    map.FoundationCells.Count,
                    map.Spawners.Length,
                    map.House != null ? map.House.name : "None");
            }
        }

        private void OnShowEntityFailure(ShowEntityFailureEventArgs args)
        {
            var status = _loadSession.HandleShowEntityFailure(args, out string errorMessage);
            if (status == CombatLoadSession.EventHandleStatus.Failed)
            {
                EnterFailureFallback(errorMessage);
            }
        }

        private void OnHideEntityComplete(HideEntityCompleteEventArgs args)
        {
            _loadSession.HandleHideEntityComplete(args);
        }

        private void OnOpenUIFormSuccess(OpenUIFormSuccessEventArgs args)
        {
            var status = _loadSession.HandleOpenUIFormSuccess(args, out string errorMessage);
            if (status == CombatLoadSession.EventHandleStatus.Failed)
            {
                EnterFailureFallback(errorMessage);
            }
        }

        private void OnOpenUIFormFailure(OpenUIFormFailureEventArgs args)
        {
            var status = _loadSession.HandleOpenUIFormFailure(args, out string errorMessage);
            if (status == CombatLoadSession.EventHandleStatus.Failed)
            {
                EnterFailureFallback(errorMessage);
            }
        }

        private void OnCloseUIFormComplete(CloseUIFormCompleteEventArgs args)
        {
            _loadSession.HandleCloseUIFormComplete(args);
        }

        #endregion
    }
}