using UnityEngine;

namespace BrewMonster
{
    /// <summary>
    /// Accelerated movement (starts slow, accelerates).
    /// Mirrors C++ CGfxAccMove exactly (A3DSkillGfxEvent2.cpp:267-295).
    /// 加速移动（从慢速开始，逐渐加速），完全镜像C++ CGfxAccMove。
    /// </summary>
    public class CGfxAccMove : CGfxMoveBase
    {
        protected float m_fAcc;
        protected float m_fSpeed;

        public CGfxAccMove(GfxMoveMode mode) : base(mode)
        {
            m_fAcc = 1.0f; // default acceleration, same as C++
        }

        /// <summary>
        /// Initialize accelerated movement from host to target.
        /// 初始化从施法者到目标的加速移动。
        /// </summary>
        public override void StartMove(Vector3 vHost, Vector3 vTarget)
        {
            m_fSpeed = 0;

            if (m_bArea)
            {
                CalcRange((vTarget - vHost).normalized);
                m_vPos = vHost + GetRandOff();
            }
            else
            {
                m_vPos = vHost;
            }

            Vector3 vDir = vTarget - m_vPos;
            m_vMoveDir = vDir.normalized;
        }

        /// <summary>
        /// Tick accelerated movement. Returns true when target is hit.
        /// 更新加速移动。当命中目标时返回true。
        /// </summary>
        public override bool TickMove(uint dwDeltaTime, Vector3 vHostPos, Vector3 vTargetPos)
        {
            float fDelta = dwDeltaTime / 1000.0f;
            Vector3 vFlyDir = vTargetPos - m_vPos;
            float fDist = Normalize(ref vFlyDir);
            float fVEnd = m_fSpeed + m_fAcc * fDelta;
            float fFlyDist = (m_fSpeed + fVEnd) * fDelta * 0.5f;
            m_fSpeed = fVEnd;

            if (fFlyDist >= fDist)
            {
                return true; // target hit / 命中目标
            }

            m_vPos += vFlyDir * fFlyDist;
            m_vMoveDir = vFlyDir;
            return false;
        }

        /// <summary>
        /// Override to also read acceleration from param value.
        /// 重写以从参数值中读取加速度。
        /// </summary>
        public override void SetParam(GFX_SKILL_PARAM param)
        {
            base.SetParam(param);
            m_fAcc = param.value.fVal; // C# union access: param.value.fVal
        }
    }
}