using UnityEngine;
using System.Collections;

namespace BaseGames.Player.States
{
    /// <summary>
    /// 地面冲刺状态（架构 05_PlayerModule §2 + §12）。
    /// 施加水平位移 + 无敌帧；冲刺期间重力归零，结束后恢复；
    /// 需解锁 AbilityType.Dash 才能进入（PlayerController 负责条件检查）。
    /// </summary>
    public class DashState : PlayerStateBase
    {
        private float _timer;
        private float _cooldownTimer;
        private int   _facingDir;

        public bool CanDash => _cooldownTimer <= 0f;

        /// <summary>冲刺状态期间应视为无敌，PlayerController 据此跳过受击硬直。</summary>
        public override bool IsInvincible => true;

        public DashState(PlayerController owner) : base(owner) { }

        public override void OnStateEnter()
        {
            Debug.Assert(Cfg != null, "[DashState] MovementConfig 未配置，请在 PlayerController Inspector 中绑定 MovementConfig SO。", _owner);

            _facingDir = Owner.FacingDirection;
            _timer     = Cfg.DashDuration;

            // 无敌帧
            Stats?.BeginInvincibility(Cfg.DashDuration + 0.05f);

            // 关闭重力，施加冲刺速度
            Move?.SetGravityScale(0f);
            Move?.Dash(new Vector2(_facingDir, 0f), Cfg.DashSpeed);

            // 播放冲刺动画
            if (AnimCfg?.Dash != null) Anim?.Play(AnimCfg.Dash);
        }

        public override void OnStateUpdate()
        {
            _timer -= Time.deltaTime;
            if (_timer <= 0f)
                EndDash();
        }

        public override void OnStateExit()
        {
            // 恢复默认重力
            Move?.SetGravityScale(Cfg.DefaultGravityScale);
            _cooldownTimer = Cfg.DashCooldown;
        }

        public override void OnStateFixedUpdate()
        {
            // 冲刺期间保持冲刺速度（防止摩擦力减速）
            if (_timer > 0f)
                Move?.Dash(new Vector2(_facingDir, 0f), Cfg.DashSpeed);
        }

        private void EndDash()
        {
            if (Move != null && Move.IsGrounded)
                Owner.TransitionTo(Owner.GetState<IdleState>());
            else
                Owner.TransitionTo(Owner.GetState<FallState>());
        }

        /// <summary>每帧减少冷却（由 PlayerController.Update 调用）。</summary>
        public void TickCooldown(float dt)
        {
            if (_cooldownTimer > 0f) _cooldownTimer -= dt;
        }
    }
}