Module:Check bibcode

-- This module is mostly a copy of the bibcode validation used in [[Module:Citation/CS1]]

require('Module:No globals');
local p = {}

--[[--------------------------< B I B C O D E >--------------------------------------------------------------------

Validates (sort of) and formats a bibcode id.

Format for bibcodes is specified here: http://adsabs.harvard.edu/abs_doc/help_pages/data.html#bibcodes

But, this: 2015arXiv151206696F is apparently valid so apparently, the only things that really matter are length, 19 characters
and first four digits must be a year.  This function makes these tests:
	length must be 19 characters
	characters in position
		1–4 must be digits and must represent a year in the range of 1000 – next year
		5 must be a letter
		6 must be letter, ampersand, or dot (ampersand cannot directly precede a dot; &. )
		7–8 must be letter, digit, ampersand, or dot (ampersand cannot directly precede a dot; &. )
		9–18 must be letter, digit, or dot
		19 must be a letter or dot

]]

local function bibcode (id)
--	local handler = cfg.id_handlers['BIBCODE'];
	local err_type;
	local year;

--	local text = external_link_id({link=handler.link, label=handler.label,
--		prefix=handler.prefix, id=id, separator=handler.separator, encode=handler.encode});
	
	if 19 ~= id:len() then
		err_type = 'length';
	else
		year = id:match ("^(%d%d%d%d)[%a][%a&%.][%a&%.%d][%a&%.%d][%a%d%.]+[%a%.]$")	-- 
		if not year then														-- if nil then no pattern match
			err_type = 'value';													-- so value error
		else
			local next_year = tonumber(os.date ('%Y'))+1;						-- get the current year as a number and add one for next year
			year = tonumber (year);												-- convert year portion of bibcode to a number
			if (1000 > year) or (year > next_year) then
				err_type = 'year';												-- year out of bounds
			end
			if id:find('&%.') then
				err_type = 'journal';											-- journal abbreviation must not have '&.' (if it does its missing a letter)
			end
		end
	end

--	if is_set (err_type) then													-- if there was an error detected
--		text = text .. ' ' .. set_error( 'bad_bibcode', {err_type});
--	end
--	return text;
	return err_type;
end


--[[-------------------------< E N T R Y   P O I N T S >------------------------------------------------------

call this module with:
	{{#invoke:check bibcode|check_bibcode|{{{1|}}}}}
where {{{1|}}} is the bibcode

]]
function p.check_bibcode (frame)
	local err_type = bibcode (frame.args[1]);
	if err_type then
		return '<span style="font-size:100%" class="error citation-comment">Check bibcode: ' .. err_type .. ' ([[Template:Bibcode|help]])</span>';
	end
	return '';
end

return p;