local getopt = require('getopt')
local utils =  require('utils')

copyright = ''
author = "Iceman"
version = 'v1.0.0'
desc = [[
This script tries to set UID on a mifare Ultralight magic card which either
 - answers to chinese backdoor commands 
 - brickable magic tag  (must write in one session)
]]
example = [[
	 -- backdoor magic tag
	 script run ul_uid -u 11223344556677
	 
	 -- brickable magic tag
	 script run ul_uid -b -u 11223344556677
]]
usage = [[
script run ul_uid -h -b -u <uid>

Arguments:
	-h             : this help
	-u <UID>       : UID (14 hexsymbols)
	-b             : write to brickable magic tag
]]

local DEBUG = true
local bxor = bit32.bxor
--- 
-- A debug printout-function
local function dbg(args)
    if not DEBUG then return end
    if type(args) == "table" then
		local i = 1
		while args[i] do
			dbg(args[i])
			i = i+1
		end
	else
		print("###", args)
	end	
end	
--- 
-- This is only meant to be used when errors occur
local function oops(err)
	print("ERROR: ",err)
	return nil, err
end
--- 
-- Usage help
local function help()
	print(copyright)
	print(author)	
	print(version)	
	print(desc)
	print('Example usage')
	print(example)
end
--
--- Set UID on magic command enabled
function magicUID(b0, b1, b2)

	print('Using backdoor Magic tag function')

	-- write block 0
	core.console("hf 14a raw -p -a -b 7 40")
	core.console("hf 14a raw -p -a 43")
	core.console("hf 14a raw -c -a A200"..b0)

	-- write block 1
	core.console("hf 14a raw -p -a -b 7 40")
	core.console("hf 14a raw -p -a 43")
	core.console("hf 14a raw -c -a A201"..b1)

	-- write block 2	
	core.console("hf 14a raw -p -a -b 7 40")
	core.console("hf 14a raw -p -a 43")
	core.console("hf 14a raw -c -a A202"..b2)
end
--
--- Set UID on magic but brickable 
function brickableUID(b0, b1, b2)
	
	print('Using BRICKABLE Magic tag function')
	
	core.console("hf 14a raw -p -s -3")
	
	-- write block 0
	core.console("hf 14a raw -p -c A200"..b0)

	-- write block 1
	core.console("hf 14a raw -p -c A201"..b1)

	-- write block 2	
	core.console("hf 14a raw -p -c A202"..b2)
end
--- 
-- The main entry point
function main(args)

	print( string.rep('--',20) )
	print( string.rep('--',20) )	
	print()

	local uid = '04112233445566'
	local tagtype = 1
	
	-- Read the parameters
	for o, a in getopt.getopt(args, 'hu:b') do
		if o == "h" then return help() end
		if o == "u" then uid = a end
		if o == "b" then tagtype = 2 end
	end	
	
	-- uid string checks
	if uid == nil then return oops('empty uid string') end
	if #uid == 0 then return oops('empty uid string') end
	if #uid ~= 14 then return oops('uid wrong length. Should be 7 hex bytes') end

	local uidbytes = utils.ConvertHexToBytes(uid)
	
	local bcc1 = bxor(bxor(bxor(uidbytes[1], uidbytes[2]), uidbytes[3]), 0x88)
	local bcc2 = bxor(bxor(bxor(uidbytes[4], uidbytes[5]), uidbytes[6]), uidbytes[7])
	
	local block0 = string.format('%02X%02X%02X%02X', uidbytes[1], uidbytes[2], uidbytes[3], bcc1)
	local block1 = string.format('%02X%02X%02X%02X', uidbytes[4], uidbytes[5], uidbytes[6], uidbytes[7])
	local block2 = string.format('%02X%02X%02X%02X', bcc2, 0x48, 0x00, 0x00)
	
	print('new UID | '..uid)
	
	core.clearCommandBuffer()
	
	if tagtype == 2 then
		brickableUID(block0, block1, block2)
	else
		magicUID(block0, block1, block2)
	end
	
		--halt
	core.console("hf 14a raw -c -a 5000")
end

main(args)
