using System.Collections.Generic;
using SepCore.Components;
using SepCore.Definition;
using GameFramework;
using SepCore.CustomUtility;
using UnityEngine;
using UnityGameFramework.Runtime;

namespace SepCore.Entity
{
    /// <summary>
    /// 武器类。
    /// </summary>
    public abstract class WeaponBase : EntityBase
    {
        protected bool _isAttacking = false;

        [SerializeField] protected bool _isEnabled = false;

        public WeaponData WeaponData { get; protected set; }
        
        public bool IsAttacking => _isAttacking;

        protected ITargetSelector TargetSelector { get; private set; }

        protected WeaponStateMachine StateMachine { get; private set; }

        protected EntityBase _target;

        private float _sqrRange;

        public EntityBase Target => _target;

        public float SqrRange => _sqrRange;

        protected StatProperty AttackStat { get; private set; } = new();

        private StatComponent _attackStatComponent;
        private System.Action<modifier, bool> _attackStatCallback;

        private static float _rotateSpeed => GameEntry.Luban.Global.WeaponRotateSpeed;
        
        protected LayerMask _hitMask;
        protected Quaternion _cachedRotation;

        #region Lifecycle

        protected override void OnInit(object userData)
        {
            base.OnInit(userData);

            TargetSelector = new NearestTargetSelector();
        }

        protected sealed override void OnShow(object userData)
        {
            base.OnShow(userData);

            WeaponData = (WeaponData)userData;
            if (WeaponData == null)
            {
                Log.Error("WeaponData is Invalid!");
                return;
            }

            StartAttackCooldown(WeaponData.Cooldown);
            _sqrRange = WeaponData.AttackRange * WeaponData.AttackRange;
            _cachedRotation = CachedTransform.rotation;

            if (WeaponData.OwnerCamp == CampType.Player)
            {
                gameObject.layer = Constant.Layer.PlayerWeaponLayerId;
                _hitMask = Constant.Layer.EnemyLayerMask;
            }
            else if (WeaponData.OwnerCamp == CampType.Enemy)
            {
                gameObject.layer = Constant.Layer.EnemyWeaponLayerId;
                _hitMask = Constant.Layer.PlayerLayerMask;
            }

            if (!OnWeaponShow(userData)) return;

            EnsureStatesBuilt();
            TransitionTo(InitialState);
        }

        protected sealed override void OnHide(bool isShutdown, object userData)
        {
            CancelAttackCooldown();
            ReleaseAttackStatSubscription();
            OnWeaponHide(userData);
            base.OnHide(isShutdown, userData);
        }

        protected sealed override void OnAttachTo(EntityLogic parentEntity, Transform parentTransform, object userData)
        {
            base.OnAttachTo(parentEntity, parentTransform, userData);

            Name = Utility.Text.Format("Weapon of {0}", parentEntity.Name);
            CachedTransform.localPosition = Vector3.zero;

            OnWeaponAttach(parentEntity, parentTransform, userData);
        }

        protected sealed override void OnDetachFrom(EntityLogic parentEntity, object userData)
        {
            OnWeaponDetach(parentEntity, userData);
            base.OnDetachFrom(parentEntity, userData);
        }

        protected virtual bool OnWeaponShow(object userData) => true;

        protected virtual void OnWeaponHide(object userData)
        {
        }

        protected virtual void OnWeaponAttach(EntityLogic parentEntity, Transform parentTransform, object userData)
        {
            BindAttackStatFromOwner(parentEntity);
        }

        protected virtual void OnWeaponDetach(EntityLogic parentEntity, object userData)
        {
            ReleaseAttackStatSubscription();
        }

        protected override void OnUpdate(float elapseSeconds, float realElapseSeconds)
        {
            base.OnUpdate(elapseSeconds, realElapseSeconds);

            if (!_isEnabled || StateMachine == null) return;
            StateMachine.Update(elapseSeconds, realElapseSeconds);
        }

        #endregion

        public virtual ImpactData GetImpactData()
        {
            return new ImpactData(WeaponData.OwnerCamp, WeaponData.Attack, AttackStat);
        }

        public abstract void Attack();

        public virtual void Check()
        {
            _target = SelectTarget(_sqrRange);
        }

        public virtual void RotateToTarget(float elapseSeconds)
        {
            if (_target == null || !_target.Available) return;

            Vector3 directionToTarget = _target.CachedTransform.position - CachedTransform.position;
            directionToTarget.y = 0f;
            if (directionToTarget.sqrMagnitude <= Mathf.Epsilon) return;

            Quaternion startRotation = CachedTransform.rotation;
            Quaternion targetRotation = Quaternion.LookRotation(directionToTarget.normalized, Vector3.up);
            CachedTransform.rotation = Quaternion.Slerp(startRotation, targetRotation, _rotateSpeed * elapseSeconds);
        }

        public virtual void RotateToOrigin(float elapseSeconds)
        {
            Quaternion startRotation = CachedTransform.rotation;
            CachedTransform.rotation = Quaternion.Slerp(startRotation, _cachedRotation, _rotateSpeed * elapseSeconds);
        }

        protected void FaceTargetImmediately()
        {
            if (_target == null || !_target.Available) return;

            Vector3 directionToTarget = _target.CachedTransform.position - CachedTransform.position;
            directionToTarget.y = 0f;
            if (directionToTarget.sqrMagnitude <= Mathf.Epsilon) return;

            CachedTransform.rotation = Quaternion.LookRotation(directionToTarget.normalized, Vector3.up);
        }

        protected abstract void BuildStates();

        protected WeaponStateType InitialState => WeaponStateType.Idle;

        protected void RegisterState(WeaponStateBase state)
        {
            if (state == null)
            {
                Log.Error("Weapon state is invalid.");
                return;
            }

            StateMachine.Register(state);
        }

        protected void EnsureStatesBuilt()
        {
            if (StateMachine != null) return;

            StateMachine = new WeaponStateMachine(this);
            BuildStates();
        }

        public void TransitionTo(WeaponStateType newState)
        {
            if (!StateMachine.TryTransition(newState))
            {
                Log.Error("Weapon state not found: {0}", newState);
            }
        }

        public void SetEnabled(bool value)
        {
            if (value == _isEnabled) return;

            _isEnabled = value;

            OnEnabledChanged(value);

            if (StateMachine == null || !StateMachine.IsBuilt) return;

            if (value)
            {
                TransitionTo(InitialState);
                return;
            }

            if (StateMachine.Contains(WeaponStateType.None))
            {
                TransitionTo(WeaponStateType.None);
            }
        }

        protected virtual void OnEnabledChanged(bool enabled)
        {
        }
        
        protected IEnumerable<EntityBase> GetCandidates()
        {
            return GameEntry.EnemyManager.Enemies;
        }

        protected EntityBase SelectTarget(float maxSqrRange)
        {
            return TargetSelector.SelectTarget(this, GetCandidates(), maxSqrRange);
        }

        public bool IsInRange(EntityBase target, float sqrRange)
        {
            if (target == null) return false;
            return AIUtility.GetSqrMagnitudeXZ(this, target) < sqrRange;
        }

        protected bool TryQueueAreaCollisionQuery(in Vector3 center, float radius, int maxTargets = 16)
        {
            return GameEntry.SimulationWorld.TryRequestAreaCollision(Id, WeaponData.OwnerId, in center, radius,
                maxTargets);
        }

        protected bool TryQueueSectorCollisionQuery(in Vector3 center, float radius, in Vector3 direction,
            float halfAngleDeg, int maxTargets = 16)
        {
            return GameEntry.SimulationWorld.TryRequestSectorCollision(Id, WeaponData.OwnerId, in center, radius,
                in direction, halfAngleDeg, maxTargets);
        }

        protected bool TryQueueRectangleCollisionQuery(in Vector3 center, float halfWidth, float halfLength,
            in Vector3 direction, int maxTargets = 16)
        {
            return GameEntry.SimulationWorld.TryRequestRectangleCollision(Id, WeaponData.OwnerId, in center,
                halfWidth, halfLength, in direction, maxTargets);
        }

        protected void BindAttackStatFromOwner(EntityLogic parentEntity)
        {
            ReleaseAttackStatSubscription();
            AttackStat = new StatProperty();

            if (parentEntity is not Player player) return;

            var statComponent = player.GetComponent<StatComponent>();
            if (statComponent == null) return;

            AttackStat = statComponent.GetStat(StatType.Attack);
            _attackStatComponent = statComponent;
            _attackStatCallback = (modifier, isApply) =>
                statComponent.UpdateStat(AttackStat, modifier, isApply);
            statComponent.Subscribe(StatType.Attack, _attackStatCallback);
        }

        protected void ReleaseAttackStatSubscription()
        {
            if (_attackStatComponent != null && _attackStatCallback != null)
            {
                _attackStatComponent.Unsubscribe(StatType.Attack, _attackStatCallback);
            }

            _attackStatComponent = null;
            _attackStatCallback = null;
            AttackStat = new StatProperty();
        }
    }
}