Editing Module:Effective protection level

local p = {}

-- Returns the permission required to perform a given action on a given title.
-- If no title is specified, the title of the page being displayed is used.
function p._main(action, pagename)
	local title
	if type(pagename) == 'table' then
		title = pagename
	else
		title = pagename and mw.title.new(pagename) or mw.title.getCurrentTitle()
	end
	pagename = title.prefixedText
	if action == 'autoreview' then
		local level = mw.getCurrentFrame():callParserFunction('PENDINGCHANGELEVEL', pagename)
		if level == 'review' then
			return 'reviewer'
		elseif level ~= '' then
			return level
		else
			return nil -- not '*'. a page not being PC-protected is distinct from it being PC-protected with anyone able to review. also not '', as that would mean PC-protected but nobody can review
		end
	elseif action ~= 'edit' and action ~= 'move' and action ~= 'create' and action ~= 'upload' then
		error( 'First parameter must be one of edit, move, create, upload, autoreview', 2 )
	end
	if title.namespace == 8 then -- MediaWiki namespace
		return 'sysop'
	elseif title.namespace == 2 and ( mw.ustring.find( pagename, '/.*%.js$') or mw.ustring.find( pagename, '/.*%.css$') ) then -- user .js or .css page
		return 'sysop'
	else
		local level = title.protectionLevels[action] and title.protectionLevels[action][1]
		if level == 'sysop' then
			return 'sysop'
		elseif mw.getCurrentFrame():callParserFunction('CASCADINGSOURCES', pagename) ~= '' then -- used by a cascading-protected page
			return 'sysop'
		elseif level == 'templateeditor' then
			return 'templateeditor'
		elseif action == 'move' then
			local blacklistentry = mw.ext.TitleBlacklist.test('edit', pagename) -- Testing action edit is correct, since this is for the source page. The target page name gets tested with action move.
			if blacklistentry and not blacklistentry.params.autoconfirmed then
				return 'accountcreator'
			elseif title.namespace == 6 then
				return 'filemover'
			else
				return 'autoconfirmed'
			end
		else
			local blacklistentry = mw.ext.TitleBlacklist.test(action, pagename)
			if blacklistentry then
				return blacklistentry.params.autoconfirmed and 'autoconfirmed' or 'accountcreator'
			elseif level then
				return level
			elseif action == 'upload' then
				return 'autoconfirmed'
			elseif action == 'create' and title.namespace % 2 == 0 and title.namespace ~= 118 then -- You need to be registered, but not autoconfirmed, to create non-talk pages other than drafts
				return 'user'
			else
				return '*'
			end
		end
	end
end

setmetatable(p, { __index = function(t, k)
	return function(frameOrPagename)
		if type(frameOrPagename) == 'table' and frameOrPagename.args then
			return t._main(k, frame.args[1])
		else
			return t._main(k, frameOrPagename)
		end
	end
end })

return p