-- For testing, show results using data from [[Module:Team appearances list/data]].

local Collection = {}
Collection.__index = Collection
do
	function Collection:add(item)
		if item ~= nil then
			self.n = self.n + 1
			self[self.n] = item
		end
	end
	function Collection:join(sep)
		return table.concat(self, sep)
	end
	function Collection:sort(comp)
		table.sort(self, comp)
	end
	function Collection.new()
		return setmetatable({n = 0}, Collection)
	end
end

local function get_page_content(page_title)
	local t = mw.title.new(page_title)
	if t then
		local content = t:getContent()
		if content then
			if content:sub(-1) ~= '\n' then
				content = content .. '\n'
			end
			return content
		end
	end
	error('Could not read wikitext from "[[' .. page_title .. ']]".', 0)
end

local function make_data(modname)
	-- Return a list of tables for each competition/team in the order used in
	-- the data module, based on a hope that the data module is consistently
	-- indented with one tab before competitions and two or more before teams,
	-- and quotes (") are used for strings (not apostrophes).
	local content = get_page_content(modname)
	local lnum = 0
	local current_games
	local items = Collection.new()
	for line in string.gmatch(content, '(.-)\n') do
		lnum = lnum + 1
		local indent, title = line:match('^(\t+)%["(.-)"%]')
		if indent then
			if indent == '\t' then
				current_games = title
			else
				items:add({
					competition = current_games,
					team = title,
					line = lnum,
				})
			end
		end
	end
	return items
end

local function main(frame)
	local title = frame.args[1]
	if title == nil or title == '' then
		return 'Error: Parameter 1 must specify name of data module'
	end
	local sandbox = title:find('sandbox', 1, true) and '/sandbox' or ''
	local lister = require('Module:Team appearances list' .. sandbox)._main
	local lines = Collection.new()
	local current_games
	for _, item in ipairs(make_data(title)) do
		if current_games ~= item.competition then
			current_games = item.competition
			lines:add('==' .. current_games .. '==')
		end
		lines:add(item.team .. ' (line ' .. item.line .. ') ' .. lister(item))
	end
	return lines:join('\n')
end

return { main = main }