local dsTarget, engClass;

local function getMacroID(spellName)
    for i = 1, MAX_ACCOUNT_MACROS + MAX_CHARACTER_MACROS do
        if GetMacroSpell(i) == spellName then
            return i;
        end
    end
end

local function eventHandler(self, event, ...)
    if event == "COMBAT_LOG_EVENT_UNFILTERED" then
        if engClass == "DEATHKNIGHT" then
            local _, logEvent, _, _, srcName, _, _, _, destName, _, _, spellID, spellName = select(1, ...);
            if logEvent == "SPELL_AURA_APPLIED" and srcName == UnitName("player") and spellName == "Dark Simulacrum" then
                dsTarget = destName;
            elseif srcName and srcName == dsTarget and (logEvent == "SPELL_CAST_SUCCESS" or logEvent == "SPELL_MISSED" or logEvent == "SPELL_AURA_APPLIED") then
                if GetSpellPowerCost(spellID)[1].type == 0 then  -- Mana cost
                    SetMacroSpell(getMacroID("Dark Simulacrum"), spellName);
                    dsTarget = nil;
                end
            elseif logEvent == "SPELL_AURA_REMOVED" and srcName == UnitName("player") and destName == UnitName("player") and spellName == "Dark Simulacrum" then
                SetMacroSpell(getMacroID("Dark Simulacrum"), spellName);
                dsTarget = nil;
            end
        end
    elseif event == "ADDON_LOADED" and select(1, ...) == "DarkSimulacrumMacroTooltip" then
        _, engClass = UnitClass("player");
    end
end

local frame = CreateFrame("Frame");
frame:RegisterEvent("COMBAT_LOG_EVENT_UNFILTERED");
frame:RegisterEvent("ADDON_LOADED");
frame:SetScript("OnEvent", eventHandler);