local callbacks = {}

function dna_gun(_,activator,caller)
    function removeCallbacks()
        for _,i in pairs(callbacks) do
            activator:RemoveCallback(i)
        end
    end
    local botClass = caller.m_iClass
    local backCall = caller:AddCallback(ON_DAMAGE_RECEIVED_PRE, function(entity,damageinfo,_)
        if damageinfo.DamageCustom == TF_DMG_CUSTOM_BACKSTAB  and damageinfo.Attacker == activator and (damageinfo.Damage * 3) >= caller.m_iHealth then
            activator:SwitchClassInPlace(botClass)
            if tonumber(botClass) == 5 then
                local medigunCaller = caller:GetPlayerItemBySlot(LOADOUT_POSITION_SECONDARY)
                local medigunActivator = activator:GetPlayerItemBySlot(LOADOUT_POSITION_SECONDARY)
                medigunActivator.m_flChargeLevel = medigunCaller.m_flChargeLevel
            end
            activator:AddCond(5, 5)
        end
    end)
    timer.Simple(15,function()
        caller:RemoveCallback(backCall)
    end)
    local switchBack = activator:AddCallback(ON_DEATH, function() activator:SwitchClassInPlace(8) end)
    table.insert(callbacks,switchBack)
end

function OnWaveInit()
    removeCallbacks()
end