local p = {}



-- NOTE: all these functions use frame solely for its args member.

-- Modules using them may therefore call them with a fake frame table

-- containing only args.



p.getUTF8 = function (frame)

	local ch = mw.ustring.char(tonumber(frame.args1 or '0', 16) or 0)

	local bytes = {mw.ustring.byte(ch, 1, -1)}

	local format = ({

		'10' = '%d',

		dec = '%d'

	})[frame.args'base']] or '%02X'

	for i = 1, #bytes do

		bytesi = format:format(bytesi])

	end

	return table.concat(bytes, ' ')

end



p.getUTF16 = function (frame)

	local codepoint = tonumber(frame.args1 or '0', 16) or 0

	local format = ({ -- TODO reduce the number of options.

		'10' = '%d',

		dec = '%d'

	})[frame.args'base']] or '%04X'

	if codepoint <= 0xFFFF then -- NB this also returns lone surrogate characters

		return format:format(codepoint)

	elseif codepoint > 0x10FFFF then -- There are no codepoints above this

		return ''

	end

	codepoint = codepoint - 0x10000

	bit32 = require('bit32')

	return (format .. ' ' .. format):format(

		bit32.rshift(codepoint, 10) + 0xD800,

		bit32.band(codepoint, 0x3FF) + 0xDC00)

end



p.fromUTF8 = function(frame)

	local basein = frame.args'basein' == 'dec' and 10 or 16

	local format = frame.args'base' == 'dec' and '%d ' or '%02X '

	local bytes = {}

	for byte in mw.text.gsplit(frame.args1], '%s') do

		table.insert(bytes, tonumber(byte, basein))

	end

	local chars = {mw.ustring.codepoint(string.char(unpack(bytes)), 1, -1)}

	return format:rep(#chars):sub(1, -2):format(unpack(chars))

end



return p