Editing Module:Navbox Automatic Groups

local p = {}

local PREFIX = '__NAVBOX_AUTO_GROUPS__'
local NOGROUP = '[nogroup]'
local CONTROL_ARGS = {
	groups = true,
	base = true,
	list = true,
	list_type = true,
	not_format = true,
	start = true
}

-- Trim a value
local function trim(value)
	return mw.text.trim(tostring(value or ''))
end

-- Split the groups parameter
local function splitGroups(value)
	local result = {}

	for _, group in ipairs(mw.text.split(value, ';', true)) do
		group = trim(group)

		if group ~= '' then
			result[#result + 1] = group
		end
	end

	return result
end

-- Normalize a group name for override matching
local function normalizeGroupName(value)
	value = trim(value):gsub('%s+', ' ')
	return mw.ustring.lower(value)
end

-- Replace the group placeholder
local function substituteGroup(value, group)
	return tostring(value or ''):gsub('%%%%group%%%%', function()
		return group
	end)
end

-- Link a group name if the page exists
local function linkGroup(group)
	local page = mw.text.decode(group or '')
	local frame = mw.getCurrentFrame()

	if page ~= ''
		and not page:match('[#<>%[%]{}]+')
		and frame:callParserFunction('PROTECTIONEXPIRY:edit', page) ~= '' then
		return '[[' .. group .. '|' .. group .. ']]'
	end

	return group
end

-- Find list_<group> overrides
local function getListOverrides(args)
	local overrides = {}

	for key, value in pairs(args) do
		local groupName = tostring(key):match('^list_(.+)$')

		if groupName then
			overrides[normalizeGroupName(groupName)] = tostring(value)
		end
	end

	return overrides
end

-- Build DPL arguments
local function getDplArgs(args, group, exclusions)
	local dplArgs = {}
	local notFormat = tostring(args.not_format or '%%group%%')

	for key, value in pairs(args) do
		key = tostring(key)

		if not CONTROL_ARGS[key] and not key:match('^list_.+$') then
			if type(value) == 'string' then
				dplArgs[key] = substituteGroup(value, group)
			else
				dplArgs[key] = value
			end
		end
	end

	-- Add automatically generated DPL exclusions
	for i, exclusion in ipairs(exclusions) do
		dplArgs['not' .. i] = substituteGroup(notFormat, exclusion)
	end

	return dplArgs
end

-- Expand Navbox DPL
local function expandDpl(frame, args, group, exclusions)
	local dplArgs = getDplArgs(args, group, exclusions)

	return frame:expandTemplate{
		title = 'Navbox DPL',
		args = dplArgs
	}
end

-- Check whether expanded content actually contains anything
local function hasContent(value)
	return mw.text.trim(tostring(value or '')) ~= ''
end

-- Main
function p.main(frame)
	local args = {}

	-- Get arguments passed directly to the module
	for key, value in pairs(frame.args) do
		args[key] = value
	end

	-- Get arguments passed through Template:Navbox Automatic Groups
	local parent = frame:getParent()

	if parent then
		for key, value in pairs(parent.args) do
			if args[key] == nil then
				args[key] = value
			end
		end
	end

	local groupsArg = trim(args.groups)
	local base = trim(args.base)
	local defaultList = tostring(args.list or '')
	local listType = mw.ustring.lower(trim(args.list_type))
	local start = tonumber(trim(args.start)) or 1

	if groupsArg == '' then
		error('Navbox Automatic Groups: missing groups parameter.')
	end

	if start < 1 or start % 1 ~= 0 then
		error('Navbox Automatic Groups: start must be a positive integer.')
	end

	local groups = splitGroups(groupsArg)
	local overrides = getListOverrides(args)
	local exclusions = {}

	-- Build the list of named groups used for [nogroup] exclusions
	for _, group in ipairs(groups) do
		if normalizeGroupName(group) ~= normalizeGroupName(NOGROUP) then
			exclusions[#exclusions + 1] = group
		end
	end

	local rows = {}

	for _, group in ipairs(groups) do
		local isNoGroup = normalizeGroupName(group) == normalizeGroupName(NOGROUP)
		local targetGroup = isNoGroup and base or group

		if isNoGroup and base == '' then
			error('Navbox Automatic Groups: [nogroup] requires a base parameter.')
		end

		local overrideKey = normalizeGroupName(isNoGroup and 'nogroup' or group)
		local list = overrides[overrideKey]

		if list == nil then
			if listType == 'dpl' then
				list = expandDpl(
					frame,
					args,
					targetGroup,
					isNoGroup and exclusions or {}
				)
			else
				list = substituteGroup(defaultList, targetGroup)
				list = list:gsub('%%%%not%%%%', '')
			end
		else
			list = substituteGroup(list, targetGroup)
			list = list:gsub('%%%%not%%%%', '')
		end

		-- Do not create a row when the generated list is empty
		if hasContent(list) then
			local row = {
				list = list
			}

			-- Link normal group names when the corresponding page exists
			if not isNoGroup then
				row.group = linkGroup(group)
			end

			rows[#rows + 1] = row
		end
	end

	return PREFIX .. mw.text.jsonEncode({
		start = start,
		rows = rows
	})
end

return p