--[[
	This is a library to read 15693 tags. It can be used something like this

	local reader = require('read15')
	local info, err = reader.read()
	if not info then
		print(err)
		return
	end
	print(info.UID)

--]]
-- Loads the commands-library
local cmds = require('commands')
local utils = require('utils')
local TIMEOUT = 2000 -- Shouldn't take longer than 2 seconds


--- Sends a USBpacket to the device
-- @param command - the usb packet to send
-- @param ignoreresponse - if set to true, we don't read the device answer packet
-- 		which is usually recipe for fail. If not sent, the host will wait 2s for a
-- 		response of type CMD_ACK
-- @return 	packet,nil if successfull
--			nil, errormessage if unsuccessfull
local function sendToDevice(command, ignoreresponse)
	local err = core.SendCommand(command:getBytes())
	if err then
		print(err)
		return nil, err
	end
	if ignoreresponse then return nil, nil end

	local response = core.WaitForResponseTimeout(cmds.CMD_ACK, TIMEOUT)
	return response, nil
end

local function errorString15693(number)
	local errors = {}
	errors[0x01] =  "The command is not supported"
	errors[0x02] =  "The command is not recognised"
	errors[0x03] =  "The option is not supported."
	errors[0x0f] =  "Unknown error."
	errors[0x10] =  "The specified block is not available (doesn’t exist)."
	errors[0x11] =  "The specified block is already -locked and thus cannot be locked again"
	errors[0x12] =  "The specified block is locked and its content cannot be changed."
	errors[0x13] =  "The specified block was not successfully programmed."
	errors[0x14] =  "The specified block was not successfully locked."
	
	return errors[number] or "Reserved for Future Use or Custom command error." 
end


local function parse15693(data)
	local bytes = utils.ConvertAsciiToBytes(data)
	local tmp = utils.ConvertAsciiToHex(data)
	
	-- define ISO15_CRC_CHECK 0F47
	local crcStr = utils.Crc15(tmp, #tmp)

	if string.sub(crcStr, #crcStr - 3) ~= '470F' then
		print("CRC", crc )
		return nil, "CRC failed"
	end

	if bytes[1] % 2 == 1 then
		-- Above is a poor-mans bit check:
		-- recv[0] & ISO15_RES_ERROR //(0x01)
		local err = "Tag returned error %i: %s"
		err = string.format(err, bytes[1], errorString15693(bytes[1]))
		return nil, err
	end
	local uid = utils.ConvertBytesToHex( bytes, true )
	uid = uid:sub(5, #uid-4)
	return { uid = uid, }
end

-- This function does a connect and retrieves som info
-- @param dont_disconnect - if true, does not disable the field
-- @return if successfull: an table containing card info
-- @return if unsuccessfull : nil, error
local function read15693(slow, dont_readresponse)

--[[

	We start by trying this command:		 
	MANDATORY (present in ALL iso15693 tags) command (the example below is sent to a tag different from the above one):
	 
		pm3> hf 15 info u
		UID=E007C1A257394244         
		Tag Info: Texas Instrument; Tag-it HF-I Standard; 8x32bit         
		pm3>
	 
	From which we obtain less information than the above one.	
	
	"260100" means  
	0x26
	-- #define ISO15_REQ_SUBCARRIER_SINGLE	0x00	// Tag should respond using one subcarrier (ASK)
	-- #define ISO15_REQ_DATARATE_HIGH		0x02	// Tag should respond using high data rate
	-- #define ISO15_REQ_NONINVENTORY		0x00
	0x01  
		inventory
	0x00
	
	--]]

	local command, result, info, err, data

	data = utils.Crc15("260100")

	command = Command:new{cmd = cmds.CMD_ISO_15693_COMMAND, 
								arg1 = #data / 2,
								arg2 = 1,
								arg3 = 1,
								data = data}
														
	if slow then
		command.arg2 = 0
	end
	if dont_readresponse then
		command.arg3 = 0 
	end
	
	local result, err = sendToDevice(command, dont_readresponse)
	if not result then
		print(err)
		return nil, "15693 identify: no answer"
	end
	
	local count, cmd, len, arg2, arg3 = bin.unpack('LLLL', result)
	if  len > 0 then
		data = string.sub(result, count, count+len-1)
		info, err = parse15693(data)
		if err then 
			print(err)	
			return nil, err
		end
		return info
	else
		return nil, "Failed to get response"
	end
end

---
-- Waits for a ISO15693 card to be placed within the vicinity of the reader.
-- @return if successfull: an table containing card info
-- @return if unsuccessfull : nil, error
local function waitFor15693()
	print("Waiting for card... press any key to quit")
	while not core.ukbhit() do
		res, err = read15693()
		if res then return res end
		-- err means that there was no response from card
	end
	return nil, "Aborted by user"
end
local library = {
	read = read15693,
	waitFor15693 = waitFor15693,
	parse15693 = parse15693,
	sendToDevice = sendToDevice,
}

return library