Module:Etymology

require('strict')

local p = {}

local ERROR_MESSAGE = '{{[[Template:Etymology#Examples|etymology]]}} requires 1st or 2nd parameter in each triplet!'

local function trim(s)
	return s:match('^[ \t\n\r%z\v]*(.-)[ \t\n\r%z\v]*$')
end

local function language(code)
	local iso639 = require('Module:ISO 639 name')
	if iso639.iso_639_code_exists({code}) then
		return trim(iso639.iso_639_code_to_name({code, link = 'yes'}))
	end
	return '[[' .. code .. ' language|' .. code .. ']]'
end

local function language_tag(lang)
	local iso639 = require('Module:ISO 639 name')
	if iso639.iso_639_code_exists({lang}) then
		return lang
	end
	if iso639.iso_639_name_exists({lang}) then
		return iso639.iso_639_name_to_code({lang})
	end
end

local function triplet(frame, lang, word, meaning)
	lang = trim(lang)
	local parts = {}
	if lang ~= '' then
		table.insert(parts, '&#32;' .. language(lang))
	end
	if trim(word) ~= '' then
		local italic = "'' " .. word .. "''"
		local tag = lang ~= '' and language_tag(lang)
		if tag then
			italic = tostring(mw.html.create('span'):attr('lang', tag):wikitext(italic))
		end
		table.insert(parts, '&#32;' .. italic)
	end
	if trim(meaning) ~= '' then
		table.insert(parts, trim('&nbsp;' .. frame:expandTemplate{title = 'Gloss', args = {trim(meaning)}}))
	end
	return table.concat(parts)
end

function p.main(frame)
	local args = frame:getParent().args
	if trim((args[1] or '') .. (args[2] or '')) == '' then
		return require('Module:Error')._error{message = ERROR_MESSAGE}
	end

	local values = {}
	for _, value in ipairs(args) do
		table.insert(values, value)
	end

	local items = {}
	for i = 1, #values, 3 do
		table.insert(items, triplet(frame, values[i], values[i + 1] or '', values[i + 2] or ''))
	end
	return 'from' .. mw.text.listToText(items, ', ', '&#32;and')
end

return p