Gracefully disable pfUI when ClassicAPI is missing

Add API_Check.lua as the first TOC entry. When the ClassicAPI DLL is
absent or below the minimum version it sets pfUI_disabled and stands up
an inert stub so the rest of the addon no-ops instead of flooding load
errors: modules and skins register their bodies into no-ops, and the
setfenv'd api/lib files run inside an environment where CreateFrame and
any missing global resolve to a null object -- so no real frames or live
handlers are created and missing API calls just return null. pfUI.lua
bails early on pfUI_disabled.

API_Check.lua

@@ -0,0 +1,104 @@
+do
+  -- ClassicAPI dependency check.
+  -- pfUI relies pervasively on the modern C_* / SuperWoW / nameplate / focus
+  -- API surface that ClassicAPI polyfills, so presence is required.
+  local PFUI_CLASSIC_API_MIN     = 11301  -- (X*10000 + Y*100 + Z)
+  local PFUI_CLASSIC_API_LATEST  = PFUI_CLASSIC_API_MIN
+  local PFUI_CLASSIC_API_WEBSITE = "https://github.com/brues-code/ClassicAPI"
+  local PFUI_CLASSIC_API_LATEST_URL = PFUI_CLASSIC_API_WEBSITE .. "/releases/latest"
+  local function FormatVersion(packed)
+    local x = math.floor(packed / 10000)
+    local y = math.floor(math.mod(packed, 10000) / 100)
+    local z = math.mod(packed, 100)
+    return string.format("v%d.%d.%d", x, y, z)
+  end
+  if not CLASSIC_API_VERSION or CLASSIC_API_VERSION < PFUI_CLASSIC_API_MIN then
+    local minVersion = FormatVersion(PFUI_CLASSIC_API_MIN)
+    pfUI_disabled = true
+    pfUI_locale = {}
+    pfUI_profiles = {}
+    pfUI_translation = {}
+
+    -- ClassicAPI is required. Rather than let the ~140 files that follow flood
+    -- errors as they load, stand up an inert stub so everything no-ops:
+    --   * modules/skins register their body into a no-op, so it never runs;
+    --   * the setfenv'd api/lib files run inside `env`, where CreateFrame and
+    --     any missing global (C_*, SuperWoW, ...) resolve to a null object --
+    --     so no real frames or live OnUpdate/OnEvent handlers get created and
+    --     missing API calls just return null instead of erroring.
+    local null  -- forward declaration so the metamethods can return it
+    local nullmt = {
+      __index = function() return null end,
+      __newindex = function() end,
+      __call = function() return null end,
+      __concat = function() return "" end,
+      __tostring = function() return "" end,
+    }
+    for _, op in ipairs({ "__add","__sub","__mul","__div","__mod","__pow","__unm" }) do
+      nullmt[op] = function() return null end
+    end
+    for _, op in ipairs({ "__lt","__le","__eq" }) do nullmt[op] = function() return false end end
+    null = setmetatable({}, nullmt)
+
+    local realG = getfenv(0)
+    pfUI = setmetatable({}, { __index = function() return null end })
+    pfUI.env = setmetatable({}, {
+      __index = function(_, k)
+        if k == "CreateFrame" then return function() return null end end
+        local v = realG[k]
+        if v ~= nil then return v end
+        return null
+      end,
+    })
+    function pfUI:RegisterModule(_, _, _) end
+    function pfUI:RegisterSkin(_, _, _) end
+    function pfUI:GetEnvironment() return pfUI.env end
+    local detail
+    if not CLASSIC_API_VERSION then
+      detail = "The ClassicAPI DLL isn't loaded. The |cff33ffcc!!!ClassicAPI|r addon ships bundled with it -- delete your |cff33ffcc!!!ClassicAPI|r folder and install the latest release from:"
+    else
+      detail = "ClassicAPI " .. minVersion .. " or newer is required. Delete your |cff33ffcc!!!ClassicAPI|r folder and reinstall the latest release from:"
+    end
+
+    local function ShowRequiredPopup()
+      StaticPopupDialogs["PFUI_CLASSICAPI_REQUIRED"] = {
+        text = "|cff33ffccpf|cffffffffUI|r has been disabled.\n\n" .. detail,
+        button1 = OKAY,
+        hasEditBox = 1,
+        editBoxWidth = 280,
+        timeout = 0,
+        whileDead = 1,
+        hideOnEscape = 1,
+        preferredIndex = 3,
+        OnShow = function()
+          local editBox = getglobal(this:GetName().."EditBox")
+          if editBox then
+            editBox:SetText(PFUI_CLASSIC_API_LATEST_URL)
+            editBox:HighlightText()
+            editBox:SetFocus()
+          end
+        end,
+      }
+      StaticPopup_Show("PFUI_CLASSICAPI_REQUIRED")
+      DEFAULT_CHAT_FRAME:AddMessage(
+        "|cff33ffccpf|cffffffffUI|r disabled: " .. detail .. " " .. PFUI_CLASSIC_API_LATEST_URL,
+        1, 0.3, 0.3
+      )
+    end
+    local loginFrame = CreateFrame("Frame")
+    loginFrame:RegisterEvent("PLAYER_ENTERING_WORLD")
+    loginFrame:SetScript("OnEvent", function()
+      loginFrame:UnregisterEvent("PLAYER_ENTERING_WORLD")
+      ShowRequiredPopup()
+    end)
+  elseif CLASSIC_API_VERSION < PFUI_CLASSIC_API_LATEST then
+    EventUtil.ContinueOnPlayerLogin(function()
+      C_Timer.After(8, function()
+        DEFAULT_CHAT_FRAME:AddMessage(
+          "|cff33ffccpf|rUI: ClassicAPI " .. FormatVersion(PFUI_CLASSIC_API_LATEST) .. " is available — " .. PFUI_CLASSIC_API_LATEST_URL,
+          1, 0.85, 0.3
+        )
+      end)
+    end)
+  end
+end

pfUI.lua

@@ -3,6 +3,10 @@ function SlashCmdList.RELOAD(msg, editbox)
   ReloadUI()
 end
 
+if pfUI_disabled then return end
+
+local addonName = ...
+
 SLASH_PFUI1 = '/pfui'
 function SlashCmdList.PFUI(msg, editbox)
   pfUI.gui:SetShown(not pfUI.gui:IsShown())
@@ -13,7 +17,7 @@ function SlashCmdList.GM(msg, editbox)
   ToggleHelpFrame(1)
 end
 
-pfUI = CreateFrame("Frame", nil, UIParent)
+local pfUI = CreateFrame("Frame", addonName, UIParent)
 pfUI:RegisterEvent("ADDON_LOADED")
 
 -- setup bootvar
@@ -117,35 +121,24 @@ pfUI.env = {}
 -- the flag; one that lacks it should drop the flag and get the safe fallback.
 pfUI.handlesHookScript = true
 
-if not pfUI.disabled then
-  pfUI.events = Mixin({}, CallbackRegistryMixin)
-  pfUI.events:OnLoad()
-  pfUI.events:SetUndefinedEventsAllowed(true)
-end
+pfUI.events = Mixin({}, CallbackRegistryMixin)
+pfUI.events:OnLoad()
+pfUI.events:SetUndefinedEventsAllowed(true)
 
 -- check if macro addons are loaded (disables macrotweak/macroscan)
 function pfUI:MacroAddonsLoaded()
   return IsAddOnLoaded("Supermacro") or IsAddOnLoaded("SuperCleveRoidMacros") or IsAddOnLoaded("UltimaMacros")
 end
 
--- detect current addon path
-local tocs = { "", "-master", "-tbc", "-wotlk" }
-for _, name in pairs(tocs) do
-  local current = string.format("pfUI%s", name)
-  local title = C_AddOns.GetAddOnName(current)
-  if title then
-    pfUI.name = current
-    pfUI.path = "Interface\\AddOns\\" .. current
-    break
-  end
-end
+pfUI.name = addonName
+pfUI.path = "Interface\\AddOns\\" .. addonName
 
 -- handle/convert media dir paths
 pfUI.media = setmetatable({}, { __index = function(tab,key)
   local value = tostring(key)
-  if strfind(value, "img:") then
+  if value:find("img:") then
     value = string.gsub(value, "img:", pfUI.path .. "\\img\\")
-  elseif strfind(value, "font:") then
+  elseif value:find("font:") then
     value = string.gsub(value, "font:", pfUI.path .. "\\fonts\\")
   else
     value = string.gsub(value, "Interface\\AddOns\\pfUI\\", pfUI.path .. "\\")
@@ -154,9 +147,7 @@ pfUI.media = setmetatable({}, { __index = function(tab,key)
   return value
 end})
 
--- cache client version
-local _, _, _, client = GetBuildInfo()
-pfUI.client = client or 11200
+pfUI.client = INTERFACE_VERSION
 
 -- setup pfUI namespace
 setmetatable(pfUI.env, {__index = getfenv(0)})
@@ -390,14 +381,13 @@ function pfUI:CheckNewModules()
 end
 
 local function BackwardsCompatRegister(func, arg3)
-  if arg3 and type(func) == "string" and type(arg3) == "function" and string.find(func, "vanilla") then
+  if arg3 and type(func) == "string" and type(arg3) == "function" and func:find("vanilla") then
     return arg3
   end
   return func
 end
 
 function pfUI:RegisterModule(name, func, arg3)
-  if pfUI.disabled then return end
   if pfUI.module[name] then return end
   func = BackwardsCompatRegister(func, arg3)
   pfUI.module[name] = func
@@ -408,7 +398,6 @@ function pfUI:RegisterModule(name, func, arg3)
 end
 
 function pfUI:RegisterSkin(name, func, arg3)
-  if pfUI.disabled then return end
   if pfUI.skin[name] then return end
   func = BackwardsCompatRegister(func, arg3)
   pfUI.skin[name] = func
@@ -429,7 +418,6 @@ function pfUI:LoadSkin(s)
 end
 
 pfUI:SetScript("OnEvent", function()
-  if pfUI.disabled then return end
 
   -- make sure to initialize and set our fonts
   -- each time an addon got loaded but only
@@ -443,7 +431,7 @@ pfUI:SetScript("OnEvent", function()
     -- "@project-version@" until release tooling substitutes it — mark those
     -- explicitly as "dev" instead of pretending they're a real numbered build.
     local raw = tostring(GetAddOnMetadata(pfUI.name, "Version"))
-    if strfind(raw, "@") then
+    if raw:find("@") then
       pfUI.version.major, pfUI.version.minor, pfUI.version.fix = 0, 0, 0
       pfUI.version.string = "dev"
     else

pfUI.toc

@@ -8,6 +8,8 @@
 ## SavedVariablesPerCharacter: pfUI_config, pfUI_init, pfUI_playerDB
 ## X-Website: https://github.com/brues-code/pfUI
 
+API_Check.lua
+
 pfUI.lua
 
 init\env.xml