import termios
import time
import os
import fcntl
import struct
import logging
from datetime import datetime

class SIMReader:
    """
    Class that controls SIM reader
    """
    sim_write_pause = 0.005

    def __init__(self, ttyPath):
        self.ready = False
        self.iccid = ""
        self.imsi = ""
        self.app = [ 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, ]
        try:
            self.fd = open(ttyPath, mode="r+b", buffering=0)
        except Exception as err:
            logging.error("Unable to open tty port %s: %s" % (ttyPath, err))
            return
        try:
            self.set_tty_attr()
            while True: # Try to read ATR from the sim card
                if self.init_sim():
                    break
                time.sleep(5)
            self.read_ids()
            self.ready = True
        except Exception as err:
            print("Error initializing sim card: %s %s" % (type(err), err))
            self.fd.close()
        
    def set_tty_attr(self):
        """
        Set terminal attributes
        """
        attr = termios.tcgetattr(self.fd)
        # attr = [iflag, oflag, cflag, lflag, ispeed, ospeed, cc]

        logging.debug("Before attr = %s" % attr)

        # Set iflag
        # Turn off s/w flow ctrl
        attr[0] &= ~(termios.IXON | termios.IXOFF | termios.IXANY) 
        # Disable any special handling of received bytes
        attr[0] &= ~(termios.IGNBRK|termios.BRKINT|termios.PARMRK|termios.ISTRIP|termios.INLCR|termios.IGNCR|termios.ICRNL)

        # Set oflag
        # Prevent special interpretation of output bytes (e.g. newline chars)
        attr[1] &= ~termios.OPOST
        # Prevent conversion of newline to carriage return/line feed
        attr[1] &= ~termios.ONLCR

        # Set cflag
        # parity = even
        attr[2] |=  termios.PARENB
        # Clear stop field, only one stop bit used in communication (most common)
        attr[2] &= ~termios.CSTOPB
        # Clear all bits that set the data size 
        attr[2] &= ~termios.CSIZE
        # 8 bits per byte (most common)
        attr[2] |= termios.CS8
        # Disable RTS/CTS hardware flow control (most common)
        attr[2] &= ~termios.CRTSCTS
        # Turn on READ & ignore ctrl lines (CLOCAL = 1)
        attr[2] |= termios.CREAD | termios.CLOCAL

        # Set lflag
        attr[3] &= ~termios.ICANON
        # Disable echo
        attr[3] &= ~termios.ECHO
        # Disable erasure
        attr[3] &= ~termios.ECHOE
        # Disable new-line echo
        attr[3] &= ~termios.ECHONL
        # Disable interpretation of INTR, QUIT and SUSP
        attr[3] &= ~termios.ISIG

        # Set in/out baud rate to be 9600
        attr[4] = termios.B9600
        attr[5] = termios.B9600
        
        # Wait for up to 0.1s (1 deciseconds), returning as soon as any data is received.
        attr[6][termios.VTIME] = 1
        attr[6][termios.VMIN] = 0
        logging.debug("After attr = %s" % attr)
        termios.tcsetattr(self.fd, termios.TCSANOW, attr)
        
    def init_sim(self) -> bool:
        """
        Reads ATR from SIM card
        """
        self.set_rts(True) # Set SIM card reset pin
        self.read_n(256) # Read serial port buffer if any bytes left
        time.sleep(0.5)
        self.set_rts(False) # Release reset pin
        time.sleep(0.5) # Wait for SIM card to boot
        # r = os.read(self.fd.fileno(), 256)
        # buf = struct.unpack('B' * len(r), r)
        buf = self.read_n(256)
        if len(buf)<4:
            logging.error("Unable to read ATR from simcard at %s (got len: %d) %s" % (self.fd.name, len(buf), buf))
            return False
        logging.debug("%s: got ATR = (%d): %s" % (
            self.fd.name, 
            len(buf), 
            ''.join(["%02x " % x for x in buf]),
            )
        )
        return True

    def set_rts(self, state: bool):
        """
        Set RTS line

        Attributes:
            state (bool): state to set RTS line to
        """
        s = fcntl.ioctl(self.fd, termios.TIOCMGET, "\000\000\000\000")
        i = struct.unpack('l', s)[0]
        if state:
            i |= termios.TIOCM_RTS
        else:
            i &= ~termios.TIOCM_RTS
        s = struct.pack('l', i)
        fcntl.ioctl(self.fd, termios.TIOCMSET, s)

    def read_ids(self):
        """
        Reads IMSI and ICCID from SIM card
        """
        # unlock chv
        self.exec_sim([0x00, 0x2C, 0x00, 0x01, 0x00])
        self.exec_sim([0x00, 0x20, 0x00, 0x01, 0x00])
        self.exec_sim([0x00, 0x2C, 0x00, 0x81, 0x00])
        self.exec_sim([0x00, 0x20, 0x00, 0x81, 0x00])

        # select file MF
        resp = self.exec_sim([0x00, 0xA4, 0x00, 0x04, 0x02, 0x3F, 0x00])
        print(resp)
        if len(resp)<2 or resp[0]!=0x61 or resp[1]>240:
            raise Exception("Unable to select file MF")
        resp = self.exec_sim([0x00, 0xC0, 0x00, 0x00, resp[1]])

        # select file EF.ICCID
        resp = self.exec_sim([0x00, 0xA4, 0x08, 0x04, 0x02, 0x2F, 0xE2])
        if len(resp)<2 or resp[0]!=0x61 or resp[1]>240:
            raise Exception("Unable to select file EF.ICCID (1)")
        resp = self.exec_sim([0x00, 0xC0, 0x00, 0x00, resp[1]])
        resp = self.exec_sim([0x00, 0xB0, 0x00, 0x00, 0x0a])

        if len(resp) != 12:
            raise Exception("Unable to select file EF.ICCID (2)")
        self.iccid = ''.join(["%01X%01X" % (resp[i]&0xf, resp[i]>>4) for i in range(0,10)])
        logging.info("%s: Got ICCID: %s" % (self.fd.name, self.iccid))

        # select APP
        self.app[1]=0xa4
        self.app[2]=0x04
        self.app[3]=0x04

        resp = self.exec_sim([0x00, 0xA4, 0x08, 0x04, 0x02, 0x2F, 0x00])
        if len(resp)!=2 or resp[0]!=0x61 or resp[1]>240:
            raise Exception("Unable to select APP (1)")
        resp = self.exec_sim([0x00, 0xC0, 0x00, 0x00, resp[1]])
        rec_len = 0
        rec_n=0

        i = 2
        while i < len(resp):
            tag = resp[i]
            i += 1
            if tag == 0xff:
                break
            tag_len = resp[i]
            i += 1
            if tag != 0x82:
                i += tag_len
                continue
            rec_len = resp[i + 3]
            rec_n = resp[i + 4]
            break
		
        if rec_len==0 or rec_n==0:
            raise Exception("Unable to select APP (2)")

        for nr in range(0,rec_n):
            resp = self.exec_sim([0x00, 0xB2, nr+1, 0x04, rec_len])
            i = 2
            while i<len(resp):
                tag = resp[i]
                i += 1
                if tag==0xff:
                    break
                tag_len = resp[i]
                i += 1
                if tag != 0x4f:
                    i += tag_len
                    continue
                if tag_len<200:
                    self.app[4:] = resp[i-1:i+tag_len]
                    break
            if self.app[4] != 0:
                break
		
        if self.app[4] == 0:
            raise Exception("Unable to select APP (3)")

        resp = self.exec_sim(self.app);
        if len(resp)!=2 or resp[0]!=0x61 or resp[1]>240:
            raise Exception("Unable to select APP (4)")
        self.exec_sim([0x00, 0xC0, 0x00, 0x00, resp[1]])

        # Select IMSI
        resp = self.exec_sim([0x00, 0xA4, 0x08, 0x04, 0x04, 0x7f, 0xff, 0x6F, 0x07])
        if len(resp)!=2 or resp[0]!=0x61 or resp[1]>240:
            raise Exception("Unable to select IMSI (1)")
        self.exec_sim([0x00, 0xC0, 0x00, 0x00, resp[1]])
        resp = self.exec_sim([0x00, 0xB0, 0x00, 0x00, 0x09])
        if len(resp) != 11:
            raise Exception("Unable to select IMSI (2)")
        self.imsi = "%01X" % (resp[1]>>4)
        self.imsi += ''.join(["%01X%01X" % (resp[i]&0xf, resp[i]>>4) for i in range(2,9)])
        logging.info("%s: IMSI: %s" % (self.fd.name, self.imsi))

    def exec_sim(self, src) -> list:
        """
        Executes a command from src in SIM card
        """
        logging.debug("Send SIM command: %s" % (''.join(["%02x " % x for x in src[0:5]])))
        if src[1]&0xF0 != 0xB0 and src[1]&0xF0 != 0xC0:
            logging.debug("Send SIM command additionaly: %s" % ''.join(["%02x " % x for x in src[5:5+src[4]]]))

        if self.write_n(src[0:5]) != 5:
            raise Exception("Unable to write to sim card (1)")
        
        buf = self.read_n(5)
        if len(buf) != 5:
            return Exception("Unable to read from sim card (1)")
        if src[4] == 0:
            buf = self.read_n(2)
            if len(buf) != 2:
                raise Exception("Unable to read from sim card (2). Expecting for 2 bytes but got %d. %s"  % (len(buf), (''.join(["%02x " % x for x in buf]))))
            logging.debug("got: %s" % ''.join(["%02x " % x for x in buf]))
            return buf
        else:
            buf = self.read_n(1)
            if len(buf) != 1:
                raise Exception("Unable to read from sim card (3)")
            if buf[0] != src[1]:
                raise Exception("Got %s instead of %s" % (buf[0], src[1]))

            if src[1]&0xF0 != 0xB0 and src[1]&0xF0 != 0xC0:
                sent = self.write_n(src[5:5+src[4]])
                if sent != src[4]:
                    raise Exception("Unable to write to sim card (2)")
                buf = self.read_n(src[4])
                if len(buf) != src[4]:
                    raise Exception("Unable to read from sim card (4)")
                buf = self.read_n(2)
                if len(buf) != 2:
                    raise Exception("Unable to read from sim card (5)")
                logging.debug("got: %s" % ''.join(["%02x " % x for x in buf]))
                return buf
            else:
                buf = self.read_n(src[4]+2)
                if len(buf) != src[4]+2:
                    raise Exception("Unable to read from sim card (6)")
                logging.debug("got: %s" % ''.join(["%02x " % x for x in buf]))
                return buf
        
    def write_n(self, buf) -> int:
        """
        Writes data to SIM card

        Returns:
            int: number of bytes written
        """
        logging.debug("Write %d bytes: %s" % (len(buf), ''.join(["%02x " % x for x in buf])))
        length = 0
        for b in buf:
            os.write(self.fd.fileno(), bytes([b]))
            time.sleep(SIMReader.sim_write_pause)
            length += 1
        return length

    def read_n(self, length: int):
        """
        Reads n bytes from SIM card with specified timeout
        """
        logging.debug("Read for %d bytes" % length)
        T = datetime.now()
        tmo = 0
        i = 0
        arr = []
        while i < length:
            now = datetime.now()
            if T != now:
                T = now
                tmo += 1
            n = os.read(self.fd.fileno(), 1)
            if len(n)<1:
                if tmo<2: 
                    continue
                logging.debug("Got %s" % ''.join(["%02x " % x for x in arr]))
                return arr
            arr.append(struct.unpack('B', n)[0])
            i += len(n)
        logging.debug("Got %s" % ''.join(["%02x " % x for x in arr]))
        return arr

    def close(self):
        """
        Closes the SIM reader file descriptor
        """
        self.fd.close()