铁链：铁链拴住距离，拉近到身边

 fx-ironchain

-- @file IronChain.lua
-- 铁链 —— 铁链拴住距离，拉近到身边

local IronChain = {}

local CONST = {
    PULL_TIME     = 0.4,
    PULL_CD       = 4.0,
    STOP_OFFSET   = 80,

    COLOR_CHAIN   = "#b8a030",
    COLOR_DEEP    = "#4e3e10",
    COLOR_GHOST   = "#f0e0a8",

    ZORDER_CHAIN  = 133,
    ZORDER_FX     = 135,
    AUTOINC_BASE  = 1076000,
}

local _pullT     = 0
local _pullFrom  = 0
local _pullTo    = 0
local _pullID    = 0
local _cdLeft    = 0
local _chainFx   = nil
local _scheduler = nil
local _autoInc   = 0

local function GenID(prefix)
    _autoInc = _autoInc + 1
    return string.format("%s_%d", prefix or "IRC",
        CONST.AUTOINC_BASE + _autoInc)
end

local function GetActorPos(id)
    if not id then return nil end
    local x = SL:GetValue("ACTOR_POSITION_X", id)
    local y = SL:GetValue("ACTOR_POSITION_Y", id)
    if not x or not y then return nil end
    return { x = x, y = y }
end

local function SafeRemove(node)
    if node and not GUI:Widget_IsNull(node) then
        GUI:removeFromParent(node)
    end
end

local function ShowTip(msg)
    if msg and msg ~= "" then SL:ShowSystemTips(msg) end
end

function IronChain.Cast()
    if _cdLeft > 0 or _pullT > 0 then return end
    local tid = SL:GetValue("MARK_TARGET_ID")
    local tp = GetActorPos(tid)
    local myID = SL:GetValue("USER_ID")
    local mp = GetActorPos(myID)
    if not tid or not tp or not mp then return end
    if math.abs(tp.x - mp.x) < 100 then
        ShowTip("太近了——拉不动")
        return
    end
    _cdLeft = CONST.PULL_CD
    _pullT = CONST.PULL_TIME
    _pullFrom = tp.x
    _pullTo = mp.x + (tp.x > mp.x and CONST.STOP_OFFSET
        or -CONST.STOP_OFFSET)
    _pullID = tid
    SafeRemove(_chainFx)
    _chainFx = GUI:Layout_Create(GUI:Attach_SceneF(),
        GenID("Chain"), 0, 0, 0, 0, false)
    GUI:setLocalZOrder(_chainFx, CONST.ZORDER_CHAIN)
    SL:PlayChainThrowFx(myID)
    SL:TipAbove(tid, "缠！")
    ShowTip("铁链缠上了——拉到面前")
end

-- 定时器：拉拽插值与链线演出
if not _scheduler then
    _scheduler = SL:Schedule(function(dt)
        _cdLeft = math.max(0, _cdLeft - dt)
        if _pullT > 0 then
            _pullT = _pullT - dt
            local k = 1 - math.max(0, _pullT) / CONST.PULL_TIME
            local x = _pullFrom + (_pullTo - _pullFrom) * k
            SL:SetActorPos(_pullID, x)
            if _chainFx then
                GUI:setPosition(_chainFx,
                    (mp.x + x) / 2, GR - 80)
            end
            if _pullT <= 0 then
                SafeRemove(_chainFx)
                _chainFx = nil
                ShowTip("拉到面前了——趁现在打")
            end
        end
    end, 0.02)
end

SL:ScheduleOnce(function()
    SL:BindDebugButton("铁链", function()
        IronChain.Cast()
    end)
    ShowTip("技能已加载: 铁链 (调试按钮触发)")
end, 1.0)

function IronChain.Unload()
    if _scheduler then SL:Unschedule(_scheduler) end
    SafeRemove(_chainFx)
    _chainFx = nil
    _pullT = 0
end

return IronChain