using UnityEngine;

namespace BrewMonster
{
    /// <summary>
    /// Curved movement with lateral acceleration.
    /// Mirrors C++ CGfxCurvedMove exactly (A3DSkillGfxEvent2.cpp:217-265).
    /// 带横向加速度的曲线移动，完全镜像C++ CGfxCurvedMove。
    /// </summary>
    public class CGfxCurvedMove : CGfxMoveBase
    {
        protected bool m_bFromRight;
        protected float m_fLatSpd;
        protected float m_fTime;
        protected float m_fSpeed;
        protected Vector3 m_vAxisX;
        protected Vector3 m_vAxisZ;
        protected Vector3 m_vZSpd;

        private const float _fly_speed = 20.0f / 1000.0f; // units per ms, same as C++
        private const float _curved_acc = 20.0e-6f; // lateral acceleration, same as C++

        public CGfxCurvedMove(GfxMoveMode mode) : base(mode)
        {
            m_bFromRight = true;
        }

        /// <summary>
        /// Initialize curved movement from host to target.
        /// 初始化从施法者到目标的曲线移动。
        /// </summary>
        public override void StartMove(Vector3 vHost, Vector3 vTarget)
        {
            if (m_bArea)
            {
                CalcRange((vTarget - vHost).normalized);
                m_vPos = vHost + GetRandOff();
            }
            else
            {
                m_vPos = vHost;
            }

            m_vAxisZ = vTarget - m_vPos;
            float fDist = Normalize(ref m_vAxisZ);
            float fMax = m_dwMaxFlyTime * _fly_speed;

            if (fMax >= fDist)
            {
                m_fSpeed = _fly_speed;
            }
            else
            {
                m_fSpeed = fDist / m_dwMaxFlyTime;
            }

            m_fTime = fDist / m_fSpeed;
            m_fLatSpd = _curved_acc * 0.5f * m_fTime;

            // Calculate lateral axis
            // 计算横向轴
            if (Mathf.Abs(m_vAxisZ.y) > 0.9f)
            {
                Vector3 vY = Vector3.Cross(m_vAxisZ, Vector3.right);
                Normalize(ref vY);
                m_vAxisX = Vector3.Cross(vY, m_vAxisZ);
            }
            else
            {
                m_vAxisX = Vector3.Cross(Vector3.up, m_vAxisZ);
            }

            // Randomly choose direction (left or right)
            // 随机选择方向（左或右）
            if (Random.value > 0.5f)
            {
                m_vAxisX = -m_vAxisX;
            }

            m_vZSpd = m_fSpeed * m_vAxisZ;
            m_vMoveDir = (m_vZSpd + m_fLatSpd * m_vAxisX).normalized;
        }

        /// <summary>
        /// Tick curved movement. Returns true when target is reached.
        /// 更新曲线移动。当到达目标时返回true。
        /// </summary>
        public override bool TickMove(uint dwDeltaTime, Vector3 vHostPos, Vector3 vTargetPos)
        {
            float fDelta = dwDeltaTime;
            float fVEnd = m_fLatSpd - _curved_acc * fDelta;
            float fOff = 0.5f * (m_fLatSpd + fVEnd) * fDelta;
            m_fLatSpd = fVEnd;
            m_vPos += fDelta * m_vZSpd + fOff * m_vAxisX;
            m_vMoveDir = (m_vZSpd + m_fLatSpd * m_vAxisX).normalized;
            m_fTime -= fDelta;
            return m_fTime <= 0;
        }

        /// <summary>
        /// Override to also read fromRight flag from param value.
        /// 重写以从参数值中读取fromRight标志。
        /// </summary>
        public override void SetParam(GFX_SKILL_PARAM param)
        {
            base.SetParam(param);
            m_bFromRight = param.value.bVal; // C# union access: param.value.bVal
        }
    }
}