using System;
using BumpCombat.Combat;
using BumpCombat.Core;
using BumpCombat.Constants;
using UnityEngine;
using UnityEngine.InputSystem;
using UnityEngine.InputSystem.LowLevel;

namespace BumpCombat.Player
{
    [RequireComponent(typeof(PlayerController), typeof(Animator))]
    [RequireComponent(typeof(PlayerStats))]
    public sealed class PlayerHealth : MonoBehaviour
    {
        private static readonly int HurtParameter = Animator.StringToHash("Hurt");

        // Nonserialized overrides retain isolated test control; normal gameplay
        // reads its values from the centralized PlayerConstants asset.
        private float invulnerabilityDuration = -1f;
        private float knockbackDuration = -1f;
        private float hurtMovementLockDuration = -1f;
        private float guardCooldownDuration = -1f;
        private float guardDuration = -1f;
        private float guardSuccessCooldownRechargePercent = -1f;

        private PlayerStats playerStats;
        private PlayerController playerController;
        private Animator animator;
        private DashController dashController;
        private float invulnerableUntil;
        private float hurtMovementLockedUntil;
        private float guardUntil;
        private float guardCooldownUntil;
        private int nextGuardActivationIdentity;
        private int activeGuardActivationIdentity;
        private bool activeGuardHasBlockedAttack;
        private RunManager subscribedRunManager;

        public event Action<float, float> OnHealthChanged;
        public event Action<Vector2, float> OnDamaged;
        /// <summary>Raised only for positive health actually lost after mitigation and lethal clamping.</summary>
        public event Action<float> OnDamageTaken;
        public event Action<int> OnGuardAttackBlocked;
        public event Action<Vector2> OnGuardImpact;
        public event Action OnDied;

        public float MaxHealth => playerStats.MaxHealth;
        public float CurrentHealth { get; private set; }
        public static float DefaultGuardCooldown =>
            GameplayConstants.Current.Player.GuardCooldownDuration;
        public static float DefaultGuardDuration =>
            GameplayConstants.Current.Player.GuardDuration;
        public static float DefaultGuardSuccessCooldownRechargePercent =>
            GameplayConstants.Current.Player.GuardSuccessCooldownRechargePercent;
        public float InvulnerabilityDuration => Mathf.Max(
            ResolveOverride(invulnerabilityDuration, GameplayConstants.Current.Player.InvulnerabilityDuration),
            ResolveOverride(hurtMovementLockDuration, GameplayConstants.Current.Player.HurtMovementLockDuration)
                + GameplayConstants.Current.Player.HurtRecoveryPadding);
        public bool IsHurtMovementLocked => Time.time < hurtMovementLockedUntil;
        public float GuardCooldownDuration => ResolveOverride(
            guardCooldownDuration,
            GameplayConstants.Current.Player.GuardCooldownDuration);
        public float GuardDuration => ResolveOverride(
            guardDuration,
            GameplayConstants.Current.Player.GuardDuration);
        public float GuardSuccessCooldownRechargePercent =>
            ResolveOverride(
                guardSuccessCooldownRechargePercent,
                GameplayConstants.Current.Player.GuardSuccessCooldownRechargePercent);
        public bool IsGuardAvailable => RunManager.Instance?.IsGuardUnlocked ?? true;
        public bool IsGuarding =>
            IsGuardAvailable
            && isActiveAndEnabled
            && CurrentHealth > 0f
            && Time.time < guardUntil;
        public int ActiveGuardActivationIdentity =>
            IsGuarding ? activeGuardActivationIdentity : 0;
        public float GuardCooldownRemaining =>
            Mathf.Max(0f, guardCooldownUntil - Time.time);
        /// <summary>Remaining cooldown as a fraction: 1 immediately after use, 0 when ready.</summary>
        public float GuardCooldownNormalized => GuardCooldownDuration > 0f
            ? Mathf.Clamp01(GuardCooldownRemaining / GuardCooldownDuration)
            : 0f;
        /// <summary>Guard readiness as a fraction: 0 during cooldown, 1 when ready.</summary>
        public float GuardReadinessNormalized => IsGuardAvailable
            ? 1f - GuardCooldownNormalized
            : 0f;
        public bool IsInvulnerable =>
            IsGuarding
                || Time.time < invulnerableUntil
                || (dashController != null && dashController.IsDashing);

        private void Awake()
        {
            playerStats = GetComponent<PlayerStats>();
            playerController = GetComponent<PlayerController>();
            animator = GetComponent<Animator>();
            dashController = GetComponent<DashController>();
            CurrentHealth = MaxHealth;
            playerStats.OnStatChanged += HandleStatChanged;
        }

        private void Start()
        {
            OnHealthChanged?.Invoke(CurrentHealth, MaxHealth);
            RefreshRunManagerSubscription();
        }

        private void OnEnable()
        {
            InputSystem.onAfterUpdate += HandleInputSystemUpdate;
        }

        private void OnDestroy()
        {
            if (playerStats != null)
            {
                playerStats.OnStatChanged -= HandleStatChanged;
            }

            UnsubscribeRunManager();
        }

        private void OnDisable()
        {
            InputSystem.onAfterUpdate -= HandleInputSystemUpdate;
            // A disabled player cannot remain visibly guarded when re-enabled.
            // Keep the cooldown so disabling cannot refresh a spent guard.
            guardUntil = 0f;
            UnsubscribeRunManager();
        }

        private void Update()
        {
            RefreshRunManagerSubscription();
        }

        private void HandleInputSystemUpdate()
        {
            InputUpdateType currentUpdateType = InputState.currentUpdateType;
            if ((currentUpdateType == InputUpdateType.Dynamic
                    || currentUpdateType == InputUpdateType.Fixed
                    || currentUpdateType == InputUpdateType.Manual)
                && Keyboard.current?.dKey.wasPressedThisFrame == true)
            {
                TryActivateGuard();
            }
        }

        public bool TryActivateGuard()
        {
            if (!isActiveAndEnabled
                || Time.timeScale <= 0f
                || CurrentHealth <= 0f
                || !IsGuardAvailable
                || !RunManager.GameplayInputEnabled
                || IsHurtMovementLocked
                || IsGuarding
                || GuardCooldownRemaining > 0f)
            {
                return false;
            }

            float now = Time.time;
            nextGuardActivationIdentity = nextGuardActivationIdentity == int.MaxValue
                ? 1
                : nextGuardActivationIdentity + 1;
            activeGuardActivationIdentity = nextGuardActivationIdentity;
            activeGuardHasBlockedAttack = false;
            guardUntil = now + GuardDuration;
            guardCooldownUntil = now + GuardCooldownDuration;
            return true;
        }

        public bool TryTakeDamage(float damage, Vector2 knockbackDirection, float knockbackDistance)
        {
            if (CurrentHealth <= 0f)
            {
                return false;
            }

            float damageTaken = Mathf.Max(
                0f,
                DamageCalculator.FinalizeDamage(
                    playerStats.CalculateIncomingDamage(damage)));
            if (damageTaken <= 0f)
            {
                return false;
            }

            if (IsGuarding)
            {
                if (!activeGuardHasBlockedAttack)
                {
                    activeGuardHasBlockedAttack = true;
                    float cooldownRecharge = GuardCooldownDuration
                        * Mathf.Clamp01(
                            GuardSuccessCooldownRechargePercent / 100f);
                    guardCooldownUntil = Mathf.Max(
                        Time.time,
                        guardCooldownUntil - cooldownRecharge);
                }

                OnGuardAttackBlocked?.Invoke(activeGuardActivationIdentity);
                OnGuardImpact?.Invoke(knockbackDirection.normalized);
                return false;
            }

            if (IsInvulnerable)
            {
                return false;
            }

            float healthBefore = CurrentHealth;

            CurrentHealth = Mathf.Max(0f, CurrentHealth - damageTaken);
            float actualDamageTaken = healthBefore - CurrentHealth;
            invulnerableUntil = Time.time + InvulnerabilityDuration;
            hurtMovementLockedUntil = Time.time + ResolveOverride(
                hurtMovementLockDuration,
                GameplayConstants.Current.Player.HurtMovementLockDuration);
            playerController.ApplyDamageKnockback(
                knockbackDirection,
                knockbackDistance,
                ResolveOverride(
                    knockbackDuration,
                    GameplayConstants.Current.Player.KnockbackDuration));
            animator.SetTrigger(HurtParameter);
            OnDamaged?.Invoke(knockbackDirection.normalized, knockbackDistance);
            OnHealthChanged?.Invoke(CurrentHealth, MaxHealth);
            if (actualDamageTaken > 0f)
            {
                OnDamageTaken?.Invoke(actualDamageTaken);
            }

            if (CurrentHealth <= 0f)
            {
                OnDied?.Invoke();
                RunManager.Instance?.EndRun();
            }

            return true;
        }

        private static float ResolveOverride(float value, float configuredValue)
        {
            return value >= 0f ? value : configuredValue;
        }

        public void Heal(float amount)
        {
            if (amount <= 0f || CurrentHealth <= 0f)
            {
                return;
            }

            CurrentHealth = Mathf.Min(MaxHealth, CurrentHealth + amount);
            OnHealthChanged?.Invoke(CurrentHealth, MaxHealth);
        }

        public void GrantInvulnerability(float duration)
        {
            if (duration <= 0f || CurrentHealth <= 0f)
            {
                return;
            }

            invulnerableUntil = Mathf.Max(
                invulnerableUntil,
                Time.time + duration);
        }

        private void HandleStatChanged(CharacterStat stat)
        {
            if (stat != CharacterStat.MaxHealth)
            {
                return;
            }

            CurrentHealth = Mathf.Min(CurrentHealth, MaxHealth);
            OnHealthChanged?.Invoke(CurrentHealth, MaxHealth);
        }

        private void HandleRunStarted()
        {
            guardUntil = 0f;
            guardCooldownUntil = 0f;
            nextGuardActivationIdentity = 0;
            activeGuardActivationIdentity = 0;
            activeGuardHasBlockedAttack = false;
        }

        private void RefreshRunManagerSubscription()
        {
            RunManager current = RunManager.Instance;
            if (subscribedRunManager == current)
            {
                return;
            }

            UnsubscribeRunManager();
            subscribedRunManager = current;
            if (subscribedRunManager != null)
            {
                subscribedRunManager.OnRunStarted += HandleRunStarted;
                subscribedRunManager.OnGuardAvailabilityChanged +=
                    HandleGuardAvailabilityChanged;
                HandleGuardAvailabilityChanged(
                    subscribedRunManager.IsGuardUnlocked);
            }
        }

        private void HandleGuardAvailabilityChanged(bool isAvailable)
        {
            if (!isAvailable)
            {
                guardUntil = 0f;
            }
        }

        private void UnsubscribeRunManager()
        {
            if (subscribedRunManager == null)
            {
                return;
            }

            subscribedRunManager.OnRunStarted -= HandleRunStarted;
            subscribedRunManager.OnGuardAvailabilityChanged -=
                HandleGuardAvailabilityChanged;
            subscribedRunManager = null;
        }
    }
}