require('strict');
local p = {};

--[=[------------------------< I S O _ 6 3 9 _ 3 _ E X T R A C T >---------------------------------------------

{{#invoke:Language/data/ISO 639-3/make|ISO_639_3_extract|file-date=20170217}}

Reads a local copy of iso-639-3_Retirements_YYYYMMDD.tab where (YYYYMMDD is the release date).  Download that file
in zip form from http://www-01.sil.org/iso639-3/download.asp (use the UTF-8 zip)

useful lines in the file have the form:
	<id>\t<Ref_Name>\t<Ret_Reason>\t<Change_To>\t<Ret_Remedy>\t<Effective>
where:
	<id> is the three-character ISO 639-3 language code
	<Ref_Name> is the language 'name'
	all other parts ignored
	
	like this:
		fri	Western Frisian	C	fry		2007-02-01

]=]

function p.ISO_639_3_dep_extract (frame)
	local page = mw.title.getCurrentTitle();									-- get a page object for this page
	local content = page:getContent();											-- get unparsed content
	local lang_table = {};														-- languages go here

	local code;
	local names;

	local file_date = 'File-Date: ' .. frame.args["file-date"];									-- set the file date line from |file-date=

	for code, name in mw.ustring.gmatch (content, '%f[%a](%a%a%a)\t([^\t]+)\t[^\n]+\n') do		-- get code and 'forward' name
		if code then
			table.insert (lang_table, "[\"" .. code .. "\"] = {\"" .. name .. "\"}");			-- make new table entry
		elseif not code then
			table.insert (lang_table, "[\"error\"] = {" .. record .. "}");						-- code should never be nil, but inserting an error entry in the final output can be helpful
		end
	end
	
	table.sort (lang_table)
																				-- make pretty output
	return "<br /><pre>-- " .. file_date .. "<br />return {<br />&#9;" .. table.concat (lang_table, ',<br />&#9;') .. "<br />&#9;}<br />" .. "</pre>";
end

return p;