local EntityUIPositionModule = {}
local private = {}

local cameraPos = { x = 0, y = 0, z = 0 }
local cameraForward = { x = 0, y = 0, z = 0 }
local curEntityPos = { x = 0, y = 0, z = 0 }
local hasRenderEntity = false

-- 需要elementDic key是renderEntity, valye 是table {isActive、isShown、isEnemy、element}
function EntityUIPositionModule.OnLateUpdate(elementModule, elementDic, uiElementParams)
	-- 获取相机参数
	local mainTrans = AuxUtil.MainCameraTrans
	cameraPos.x, cameraPos.y, cameraPos.z = mainTrans:GetPosition()
	local forward = mainTrans.forward
	cameraForward.x, cameraForward.y, cameraForward.z = forward.x, forward.y, forward.z

	-- 获取玩家参数
	local curEntity = LogicUpdateManager._curEntity
	if curEntity then
		local expEntity = curEntity.ExpEntity
		if expEntity then
			local renderEntity = expEntity.RenderEntity
			if renderEntity then
				hasRenderEntity = true
				curEntityPos.x, curEntityPos.y, curEntityPos.z = renderEntity.Transform:GetPosition()
			else
				hasRenderEntity = false
			end
		else
			hasRenderEntity = false
		end
	else
		hasRenderEntity = false
	end

	-- 以上参数在循环前获取，一次循环只会获取一次，不要单独获取
	for renderEntity, elementData in pairs(elementDic) do
		if elementData.isActive then
			local active = not elementModule:GetElementHide(elementData)
			private.SetElementShow(elementData, active)
		end
		if elementData.isShown then
			private.UpdatePosition(renderEntity, elementData, uiElementParams)
		end
	end
end

function private.UpdatePosition(renderEntity, elementData, uiElementParams)
	local elementObj = elementData.element.gameObject
	local nodePosX, nodePosY, nodePosZ = renderEntity:GetUINodePosition(nil, nil, nil)

	if elementData.isStatue then
		if elementData.modelHeight == nil or elementData.modelHeight == 0 then
			elementData.modelHeight = renderEntity:GetModelHeight()
		end 
		nodePosY = nodePosY - elementData.modelHeight - 0.5
	end
	if elementData.uiOffsetY then
		nodePosY = nodePosY + elementData.uiOffsetY
	end
	local monsterDirX = nodePosX - cameraPos.x
	local monsterDirY = nodePosY - cameraPos.y
 	local monsterDirZ = nodePosZ - cameraPos.z

 	local show = private.GetVector3Dot(monsterDirX, monsterDirY, monsterDirZ) > 0
 	if hasRenderEntity then
 		local monsterToRoleX = nodePosX - curEntityPos.x
 		local monsterToRoleZ = nodePosZ - curEntityPos.z
 		show = show and private.GetMonsterToRoleSqrMagnitude(monsterToRoleX, 0, monsterToRoleZ) < private.GetMaxDistSqrModelUI(elementData, uiElementParams)
 	end
	local scale = 1
 	if show then
 		local screenPointX, screenPointY, screenPointZ = UIUtils.WorldToScreenPoint(nodePosX, nodePosY, nodePosZ, 0, 0, 0)
 		local uiPointX, uiPointY, uiPointZ = UIUtils.GetScreenToWorldPoint(screenPointX, screenPointY, screenPointZ, nil, nil, nil)
 		if uiPointZ > 0 then
 			uiPointZ = 0
 			elementData.elementTf:SetPosition(uiPointX, uiPointY, uiPointZ)
			if private.IsUseZoom(elementData, uiElementParams) then
	 			local length = uiElementParams.ModelUIMaxDistance - uiElementParams.ModelUIMinDistance
				local percent = private.GetPercentByMagnitude(monsterDirX, monsterDirZ, uiElementParams.ModelUIMinDistance, length) 
				-- 计算差值 Mathf.Lerp
				if percent > 1 then
					scale = uiElementParams.ModelUIMinScale
				elseif percent < 0 then
					scale = uiElementParams.ModelUIMaxScale
				else
					scale = uiElementParams.ModelUIMaxScale + (uiElementParams.ModelUIMinScale - uiElementParams.ModelUIMaxScale) * percent
				end
			end
 		else
			scale = 0
 		end
 	else
		scale = 0
 	end
	if elementData.lastScale ~= scale then
		elementData.elementTf:SetLocalScale(scale, scale, scale)
		elementData.lastScale = scale
	end
end

function private.IsUseZoom(elementData, uiElementParams)
	if elementData.extendData and elementData.extendData.UseZoom ~= nil then
		return elementData.extendData.UseZoom
	end
	return  uiElementParams.UseZoom
end

function private.GetMaxDistSqrModelUI(elementData, uiElementParams)
	if elementData.extendData and elementData.extendData.MaxDistSqrModelUI ~= nil then
		return elementData.extendData.MaxDistSqrModelUI
	end
	return  uiElementParams.MaxDistSqrModelUI
end

function private.SetElementShow(elementData, active)
	if active ~= elementData.isShown then
		UIUtils.SetActiveByScale(elementData.elementTf, active)
		elementData.isShown = active
		elementData.lastScale = active and 1 or 0
	end
end

-- 返回 Vector3.Dot(cameraTrans.forward, nodePos - private.cameraV3)
function private.GetVector3Dot(dirX, dirY, dirZ)
	return cameraForward.x * dirX + cameraForward.y * dirY + cameraForward.z * dirZ
end

-- 返回 sqrMagnitude
function private.GetMonsterToRoleSqrMagnitude(dirX, dirY, dirZ)
	return dirX * dirX + dirY * dirY + dirZ * dirZ
end

-- 返回 percent = (v2.magnitude - uiElementParams.ModelUIMinDistance) / length
function private.GetPercentByMagnitude(dirX, dirY, minDistance, length)
	local magnitude = math.sqrt(dirX * dirX + dirY * dirY)
	return (magnitude - minDistance) / length
end

return EntityUIPositionModule