#!/usr/bin/env python
# -*- coding: UTF-8
'''
zerk -- GREIS configurator and packet decoder

usage: zerk [OPTIONS] [server[:port[:device]]]
'''

# This program conforms to the JAVAD document:
#    GNSS Receiver External Interface Specification
#    Revised: October 11, 2017
#
# Hereafter referred to as "the specification"
#
# This file is Copyright (c) 2018 by the GPSD project
# BSD terms apply: see the file COPYING in the distribution root for details.
#
# This code runs compatibly under Python 2 and 3.x for x >= 2.
# Preserve this property!
#
# ENVIRONMENT:
#    Options in the ZERKOPTS environment variable will be parsed before
#    the CLI options.  A handy place to put your '-f /dev/ttyXX -s SPEED'
#
# example usages:
#    Coldboot the GPS:          zerk -p COLDBOOT
#    Print current serial port: zerk -c "print,/cur/term"
#    Decode raw log file:       zerk -r -f greis-binary.log -v 2
#    Change GPS port speed:     zerk -S 230400
#    Watch entire reset cycle:  zerk -p RESET -v 2 -w 20 -W
#    poll SVs Status:     zerk -W -w 2 -v 2 -c "out,,jps/{CS,ES,GS,Is,WS,QS}"
#    dump local gpsd data       zerk -v 2 -w 5 localhost
#
# TODO: no CRC16 packets handled yet
# TODO: more packet decodes

from __future__ import absolute_import, print_function, division

import binascii      # for binascii.hexlify()
import getopt        # for getopt.getopt(), to parse CLI options
import hashlib       # for hashlib.sha1
import os            # for os.environ
import socket        # for socket.error
import stat          # for stat.S_ISBLK()
import struct        # for pack()
import sys
import time
import xml.etree.ElementTree  # to parse .jpo files

PROG_NAME = 'zerk'

try:
    import serial
except ImportError:
    serial = None  # Defer complaining until we know we need it.

try:
    import gps
    import gps.misc      # for polybyte() polystr()
except ImportError:
    # PEP8 says local imports last
    sys.stderr.write("%s: failed to import gps, check PYTHON_PATH\n" %
                     PROG_NAME)
    sys.exit(2)

gps_version = '3.19-dev'
if gps.__version__ != gps_version:
    sys.stderr.write("%s: ERROR: need gps module version %s, got %s\n" %
                     (PROG_NAME, gps_version, gps.__version__))
    sys.exit(1)


VERB_QUIET = 0   # quiet
VERB_NONE = 1    # just output requested data and some info
VERB_DECODE = 2  # decode all messages
VERB_INFO = 3    # more info
VERB_RAW = 4     # raw info
VERB_PROG = 5    # program trace

# dictionary to hold all user options
opts = {
    # command to send to GPS, -c
    'command': None,
    # command for -d disable
    'disable': None,
    # command for -e enable
    'enable': None,
    # default input -f file
    'input_file_name': None,
    # default forced wait? -W
    'input_forced_wait': False,
    # default port speed -s
    'input_speed': 115200,
    # default input wait time -w in seconds
    'input_wait': 2.0,
    # the name of an OAF file, extension .jpo
    'oaf_name': None,
    # poll command -p
    'poll': None,
    # raw log file name
    'raw_file': None,
    # open port read only -r
    'read_only': False,
    # speed to set GPS -S
    'set_speed': None,
    # target gpsd (server:port:device) to connect to
    'target': {"server": None, "port": gps.GPSD_PORT, "device": None},
    # verbosity level, -v
    'verbosity': VERB_NONE,
    # contents of environment variable ZERKOPTS
    'progopts': '',
}


class greis(object):
    """A class for working with the GREIS GPS message formats

    This class contains functions to decode messages in the Javad GREIS
    "Receiver Input Language" and "Receiver Messages" formats.
    """

    # when a statement identifier is received, it is stored here
    last_statement_identifier = None
    # expected statement identifier.
    expect_statement_identifier = False
    # ID of current message as a string
    s_id = ''

    def __init__(self):
        "Initialize class"

        self.last_statement_identifier = None
        self.expect_statement_identifier = False
        # last epoch received in [~~]
        # epoch == None means never got epoch, epoch == -1 means missing.
        self.epoch = None

    def f4_s(self, f):
        "convert an '! f4' to a string"

        if gps.isfinite(f):
            # yeah, the precision is a guess
            return "%.6f" % f
        return 'X'

    def f8_s(self, f):
        "convert an '! f8' to a string"

        if gps.isfinite(f):
            # yeah, the precision is a guess
            return "%.4f" % f
        return 'X'

    def i1_s(self, i):
        "convert an '! i1' to a string"
        return 'X' if i == 127 else str(i)

    def i2_s(self, i):
        "convert an '! i2' to a string"
        return 'X' if i == 32767 else str(i)

    def i4_s(self, i):
        "convert an '! i4' to a string"
        return 'X' if i == 2147483647 else str(i)

    def u1_s(self, u):
        "convert an '! u1' to a string"
        return 'X' if u == 255 else str(u)

    def u2_s(self, u):
        "convert an '! u2' to a string"
        return 'X' if u == 65535 else str(u)

    def u4_s(self, u):
        "convert an '! u4' to a string"
        return 'X' if u == 4294967295 else str(u)

    def isuchex(self, c):
        "Is byte an upper case hex char?"
        if 48 <= c and 57 >= c:
            # 0 to 9
            return int(c) - 48
        if 65 <= c and 70 >= c:
            # A to F
            return int(c) - 55
        return -1

    soltypes = {0: "None",
                1: "3D",
                2: "DGPS",
                3: "RTK float",
                4: "RTK fixed",
                5: "fixed"
                }

    # allowable speeds
    speeds = (460800, 230400, 153600, 115200, 57600, 38400, 19200, 9600,
              4800, 2400, 1200, 600, 300)

    def msg_c_(self, payload):
        "[c?] decode, Smoothing Corrections"

        s = ' smooth'
        for i in range(0, len(payload) - 1, 2):
            u = struct.unpack_from('<h', payload, i)
            s += " " + self.i2_s(u[0])

        return s + '\n'

    def msg__p(self, payload):
        "[?p] decode, Integer Relative Carrier Phases"

        s = ' rcp'
        for i in range(0, len(payload) - 1, 4):
            u = struct.unpack_from('<l', payload, i)
            s += " " + self.i4_s(u[0])

        return s + '\n'

    def msg__d(self, payload):
        "[?d] decode, Relative Doppler"

        s = ' srdp'
        for i in range(0, len(payload) - 1, 2):
            u = struct.unpack_from('<h', payload, i)
            s += " " + self.i2_s(u[0])

        return s + '\n'

    def msg__r(self, payload):
        "[?r] decode, Integer Relative Pseudo-ranges"

        s = ' srdp'
        for i in range(0, len(payload) - 1, 2):
            u = struct.unpack_from('<h', payload, i)
            s += " " + self.i2_s(u[0])

        return s + '\n'

    def msg__A(self, payload):
        "[?A] decode, GPS, GALILEO Almanac"
        m_len = len(payload)

        if ('[EA]' == self.s_id) and (49 > m_len):
            return " Bad Length %s" % m_len

        u = struct.unpack_from('<BhlBBBfffffffff', payload, 0)

        s = (" sv %u wna %d toa %d healthA %u healthS %u config %u\n"
             "     af1 %f af0 %f rootA %f ecc %f m0 %f\n"
             "     omega0 %f argPer %f delf %f omegaDot %f\n" % u)

        if '[EA]' == self.s_id:
            u = struct.unpack_from('<H', payload, 46)
            s += ("     iod %d" % (u[0]))
        return s

    def msg__E(self, payload):
        "[?E] decode, SNR x 4"

        s = ' cnrX4'
        for i in range(0, len(payload) - 1, 1):
            u = struct.unpack_from('<B', payload, i)
            s += " " + self.u1_s(u[0])

        return s + '\n'

    def msg_WE(self, payload):
        "[WE] decode, SBAS Ephemeris"

        u = struct.unpack_from('<BBBBLdddffffffffLHB', payload, 0)
        s = (" waasPrn %u gpsPrn %u iod %u acc %u tod %u\n"
             "     xg %f yg %f zg %f\n"
             "     vxg %f vyg %f vzg %f\n"
             "     vvxg %f vvyg %f vvzg %f\n"
             "     agf0 %f agf1 %f tow %u wn %u flags %u\n" % u)

        return s

    def msg_r(self, payload):
        "[r?] decode, Integer Psudeo Ranges"

        s = ' spr'
        for i in range(0, len(payload) - 1, 4):
            u = struct.unpack_from('<l', payload, i)
            s += " " + self.i4_s(u[0])

        return s + '\n'

    def msg_AZ(self, payload):
        "[AZ] decode, Satellite Azimuths"

        s = " azim"
        for i in range(0, len(payload) - 1):
            # azimuth/2, 0 to 180 degrees
            s += " " + self.u1_s(payload[i])

        return s + '\n'

    def msg_BP(self, payload):
        "[BP] decode"

        u = struct.unpack_from('<f', payload, 0)
        return " acc %.3e\n" % u[0]

    def msg_D_(self, payload):
        """[D?] decode, Doppler"""

        s = " dp"
        for i in range(0, len(payload) - 1, 4):
            # This is dopple in Hz * 1e4
            u = struct.unpack_from('<l', payload, i)
            s += " " + self.i4_s(u[0])

        return s + '\n'

    def msg_DO(self, payload):
        "[DO] decode"

        u = struct.unpack_from('<ff', payload, 0)
        return " val %.3f sval %.3f\n" % u

    def msg_DP(self, payload):
        "[DP] decode"

        u = struct.unpack_from('<fffBfB', payload, 0)
        return (" hdop %f vdop %f tdop %f edop %f\n"
                "     solType %s\n" %
                (u[0], u[1], u[2], u[4], self.soltypes[u[3]]))

    def msg_E_(self, payload):
        "[E?] decode, SNR"

        s = ' cnr'
        for i in range(0, len(payload) - 1):
            s += " " + self.u1_s(payload[i])

        return s + '\n'

    def msg_ET(self, payload):
        "[::](ET) decode, Epoch time, end of epoch"

        u = struct.unpack_from('<L', payload, 0)
        if ((self.epoch is not None and self.epoch != u[0])):
            if -1 == self.epoch:
                print("Error: [::](ET) missing [~~](RT)\n")
            else:
                print("Error: [::](ET) Wrong Epoch %u, should be %u\n" %
                      (u[0], self.epoch))
        # reset epoch
        self.epoch = -1
        return "(ET) tod %u\n" % u[0]

    def msg_EL(self, payload):
        "[EL] decode, Satellite Elevations"

        s = " elev"
        for i in range(0, len(payload) - 1):
            # looking for integer (-90 to 90), not byte
            u = struct.unpack_from('<b', payload, i)
            s += " " + self.i1_s(u[0])

        return s + '\n'

    def msg_ER(self, payload):
        "[ER] decode, Error messages"

        parts = payload.split(b'%')
        if 1 < len(parts):
            self.last_statement_identifier = parts[1]

        s_payload = "".join(map(chr, payload))
        print("[ER] %s\n" % s_payload)
        return " %s\n" % s_payload

    def msg_EU(self, payload):
        "[EU] decode, GALILEO UTC and GPS Time Parameters"

        u = struct.unpack_from('<dfLHbBHbffLHH', payload, 0)
        return (" ao %f a1 %f tot %u wnt %u dtls %d dn %u wnlsf %u\n"
                "     dtlsf %d a0g %f a1g %f t0g %u wn0g %u flags %#x\n" % u)

    def msg_FC(self, payload):
        "[FC] [F1] [F2] [F3] [f5] [Fl] decode, Signal Lock Loop Flags"

        s = " flags 0x"
        for i in range(0, len(payload) - 1):
            u = struct.unpack_from('<H', payload, i)
            s += " %2x" % (u[0])

        return s + '\n'

    def msg__E1(self, payload):
        "[?E] decode, BeiDos, GPS, GALILEO, IRNSS Ephemeris "
        m_len = len(payload)
        # [GE]
        if ('[IE]' == self.s_id) and (124 > m_len):
            return " Bad Length %s" % m_len
        if ('[CN]' == self.s_id) and (132 > m_len):
            return " Bad Length %s" % m_len
        if ('[EN]' == self.s_id) and (145 > m_len):
            return " Bad Length %s" % m_len

        u = struct.unpack_from('<BLBhlbBhfffflhddddddfffffffff', payload, 0)
        s = (" sv %u tow %u flags %u iodc %d toc %d ura %d healthS %u\n"
             "     wn %d tgd %f af2 %f af1 %f af0 %f toe %d\n"
             "     iode %d rootA %f ecc %f m0 %f omega0 %f\n"
             "     inc0 %f argPer %f deln %f omegaDot %f\n"
             "     incDot %f crc %f crs %f cuc %f\n"
             "     cus %f cic %f cis %f\n" % u)

        if '[EN]' == self.s_id:
            u = struct.unpack_from('<fffffBB', payload, 122)
            s += ("     bgdE1E5a %f bgdE1E5b %f aio %f ai1 %f ai2 %f\n"
                  "     sfi %u navType %u" % u)
            if 149 <= m_len:
                # DAf0 added in 3.7.0
                u = struct.unpack_from('<f', payload, 144)
                s += (" DAf0 %f" % u)
            s += '\n'

        if ('[IE]' == self.s_id) and (124 > m_len):
            u = struct.unpack_from('<B', payload, 122)
            s += ("     navType %u\n" % u[0])

        if ('[CN]' == self.s_id) and (132 > m_len):
            u = struct.unpack_from('<fBf', payload, 122)
            s += ("     tgd2 %f navType %u DAf0 %f\n" % u)

        # TODO: decode length 160 168

        return s

    def msg_GT(self, payload):
        "[GT] decode, GPS Time "

        u = struct.unpack_from('<LH', payload, 0)
        return " tow %u wn %d\n" % u

    def msg_ID(self, payload):
        "[ID] Ionosphere Delays"

        s = ' delay'
        for i in range(0, len(payload) - 1, 4):
            u = struct.unpack_from('<f', payload, i)
            s += " %s" % self.f4_s(u[0])

        return s + '\n'

    def msg_IO(self, payload):
        "[IO] decode, GPS Ionospheric Parameters"

        u = struct.unpack_from('<LHffffffff', payload, 0)

        return (" tot %d wn %u alpha0 %f alpha1 %f alpha2 %f\n"
                "     alpha3 %f beta0 %u beta1 %d beta2 %f\n"
                "     beta3 %f\n" % u)

    def msg_LO(self, payload):
        "[LO] decode, undocumented message"

        return " Undocumented message\n"

    def msg_MF(self, payload):
        "[MF] Messages Format"

        u = struct.unpack_from('<BBBBBBB', payload, 0)
        return (" id %c%c majorVer %c%c minorVer %c%c order %c\n" %
                (chr(u[0]), chr(u[1]), chr(u[2]), chr(u[3]),
                 chr(u[4]), chr(u[5]), chr(u[6])))

    def msg_P_(self, payload):
        "[P?] decode, Carrier Phases"

        s = " cp"
        for i in range(0, len(payload) - 1, 8):
            # carrier phases in cycles
            u = struct.unpack_from('<d', payload, i)
            s += " " + self.f8_s(u[0])

        return s + '\n'

    def msg_PM(self, payload):
        "[PM] parameters"

        # PM only seems to work after a coldboot, once
        # zerk -v 2 -w 20 -c 'out,,jps/{PM}' -W
        return " %s\n" % payload

    def msg_PV(self, payload):
        "[PV] decode, Cartesian Position and Velocity"

        u = struct.unpack_from('<dddfffffBB', payload, 0)
        return (" x %s y %s z %s sigma %s\n"
                "     vx %s vy %s vz %s\n"
                "     vsigma %s soltype %s\n" %
                (self.f8_s(u[0]), self.f8_s(u[1]), self.f8_s(u[2]),
                 self.f4_s(u[3]), self.f4_s(u[4]), self.f4_s(u[5]),
                 self.f4_s(u[6]), self.f4_s(u[7]), self.soltypes[u[8]]))

    def msg_R_(self, payload):
        """[R?] decode, Pseudo-ranges"""

        s = " pr"
        for i in range(0, len(payload) - 1, 8):
            # psuedo in seconds
            u = struct.unpack_from('<d', payload, i)
            s += " %s" % self.f8_s(u[0])

        return s + '\n'

    def msg_RD(self, payload):
        "[RD] decode, Receiver Date"

        u = struct.unpack_from('<HBBB', payload, 0)
        return " year %d month %d day %d base %d\n" % u

    def msg_RE(self, payload):
        "[RE] decode"

        parts = payload.split(b'%')
        if 1 < len(parts):
            # Got a statement identifier (ID), save it?
            # Multiline statement if payload ends with comma or left brace
            if payload[-1] not in (ord(','), ord('{')):
                # yes, this is the end
                self.last_statement_identifier = parts[1]

            # Get the message body
            part1 = parts[1].split(b',')

            if 'em' == parts[1]:
                # Probably no parts[2]
                print("Enable Messages %s" % parts[2])
                return " Enable Messages %s\n" % parts[2]

            if 'id' == parts[1]:
                print("ID: %s" % parts[2])
                return " ID %s\n" % parts[2]

            if 'opts' == part1[0]:
                if 1 < len(part1):
                    s = "OAF %s: %s" % (part1[1], parts[2])
                else:
                    s = " OAF: %s" % (parts[2])
                print(s)
                return " %s\n" % s

            if 'serial' == parts[1]:
                print("SERIAL: %s" % parts[2])
                return " SERIAL %s\n" % parts[2]

            if 'vendor' == parts[1]:
                print("VENDOR: %s" % parts[2])
                return " Vendor %s\n" % parts[2]

            if 'ver' == parts[1]:
                print("VER: %s" % parts[2])
                return " Version %s\n" % parts[2]

            # unknown statement identifier
            s_payload = "".join(map(chr, payload))
            print("RE: %s\n" % s_payload)

        return " %s\n" % s_payload

    def msg_RT(self, payload):
        "[~~](RT) decode, Receiver Time, start of epoch"

        if self.epoch is not None and -1 != self.epoch:
            print("Error: [~~](RT) missing [::](ET)\n")

        u = struct.unpack_from('<L', payload, 0)
        # save start of epoch
        self.epoch = u[0]
        return "(RT) tod %u\n" % self.epoch

    def msg_S_(self, payload):
        "[CS], [ES], [GS], [Is], [WS], [NS], [QS], decode, SVs Status"

        # to poll them all: zerk -W -w 2 -v 2 -c "out,,jps/{CS,ES,GS,Is,WS,QS}"
        # TODO, check @checksum

        return "%s" % payload

    def msg_SE(self, payload):
        "[SE] decode"

        u = struct.unpack_from('<BBBBB', payload, 0)
        return " data 0x %x %x %x %x %x\n" % u

    def msg_SG(self, payload):
        "[SG] decode"

        u = struct.unpack_from('<ffffBB', payload, 0)
        return (" hpos %s vpos %s hvel %s vvel %s\n"
                "     soltype %s\n" %
                (self.f4_s(u[0]), self.f4_s(u[1]), self.f4_s(u[2]),
                 self.f4_s(u[3]), self.soltypes[u[4]]))

    def msg_SI(self, payload):
        "[SI] decode, Satellite Index, deprecated by Javad, use [SX]"

        # [SX] require 3.7 firmware, we use [SI] to support 3.6
        s = " usi"
        for i in range(0, len(payload) - 1):
            s += " %d" % payload[i]

        return s + '\n'

    def msg_SP(self, payload):
        "[SP] decode, Position Covariance Matrix"

        u = struct.unpack_from('<ffffffffffB', payload, 0)
        return (" xx % f yy % f zz % f tt % f xy % f\n"
                "     xz % f xt % f yz % f yt % f zt % f\n"
                "     solType %s\n" %
                (u[0], u[1], u[2], u[3], u[4],
                 u[5], u[6], u[7], u[8], u[9],
                 self.soltypes[u[10]]))

    def msg_SS(self, payload):
        "[SS] decode, Satellite Navigation Status"

        s = " ns"
        for i in range(0, len(payload) - 2):
            s += " %d" % payload[i]

        return (s + '\n     solType %s\n' %
                self.soltypes[payload[len(payload) - 2]])

    def msg_ST(self, payload):
        "[ST] decode, Solution Time Tag"

        u = struct.unpack_from('<LBB', payload, 0)
        return (" time %u ms, soltype %s\n" %
                (u[0], self.soltypes[u[1]]))

    def msg_SX(self, payload):
        "[SX] decode, Extended Satellite Indices"

        # [SX] require 3.7 firmware
        s = " ESI"
        for i in range(0, len(payload) - 2, 2):
            u = struct.unpack_from('<BB', payload, i)
            s += " (%u, %u)" % u

        return s + '\n'

    def msg_TC(self, payload):
        "[TC] decode, CA/L1 Continous Tracking Time"

        s = " tt"
        for i in range(0, len(payload) - 1, 2):
            u = struct.unpack_from('<H', payload, i)
            s += " %.2f" % u[0]

        return s + '\n'

    def msg_TO(self, payload):
        "[TO] decode, Reference Time to Receiver Time Offset"

        u = struct.unpack_from('<dd', payload, 0)
        return " val %.3f sval %.3f\n" % u

    def msg_UO(self, payload):
        "[UO] decode, GPS UTC Time Parameters"

        u = struct.unpack_from('<dfLHbBHb', payload, 0)
        return (" a0 %f a1 %f tot %d wnt %d dtls %d\n"
                "     dn %d wnlsf %d dtlsf %d\n" % u)

    def msg_WA(self, payload):
        "[WA] decode"

        u = struct.unpack_from('<BBBBLdddfffLH', payload, 0)
        return (" waasPrn %d gpsPrn %d if %d healthS %d tod %d\n"
                "     ECEF %.3f %.3f %.3f, %.3f %.3f %.3f\n"
                "     tow %d wn %d\n" % u)

    def msg_WU(self, payload):
        "[WU] decode, SBAS UTC Time Parameters"

        u = struct.unpack_from('<dfLHbBHbfbLHB', payload, 0)
        return (" ao %f a1 %f tot %u wnt %u dtls %d dn %u\n"
                "wnlsf %u dtlsf %d utcsi %d tow %u wn %u flags %#x\n" % u)

    # table from message id to respective message decoder.
    # Note: id (%id%) is different than ID (statement identifier)
    # the id is the first two characters of a GREIS receiver Message
    # see section 3.3 of the specification
    messages = {
        '[0d]': (msg__d, 1),
        '[1d]': (msg__d, 1),
        '[1E]': (msg__E, 1),
        '[1p]': (msg__p, 1),
        '[1r]': (msg__r, 1),
        '[2d]': (msg__d, 1),
        '[2E]': (msg__E, 1),
        '[2p]': (msg__p, 1),
        '[2r]': (msg__r, 1),
        '[3d]': (msg__d, 1),
        '[3E]': (msg__E, 1),
        '[3p]': (msg__p, 1),
        '[3r]': (msg__r, 1),
        '[5d]': (msg__d, 1),
        '[5E]': (msg__E, 1),
        '[5p]': (msg__p, 1),
        '[5r]': (msg__r, 1),
        '[AZ]': (msg_AZ, 1),
        '[BP]': (msg_BP, 5),
        '[c1]': (msg_c_, 1),
        '[c2]': (msg_c_, 1),
        '[c3]': (msg_c_, 1),
        '[c5]': (msg_c_, 1),
        '[CA]': (msg__A, 47),
        '[cc]': (msg_c_, 1),
        '[CE]': (msg__E, 1),
        '[cl]': (msg_c_, 1),
        '[CN]': (msg__E1, 123),
        '[cp]': (msg__p, 1),
        '[cr]': (msg__r, 1),
        '[CS]': (msg_S_, 8),
        '[D1]': (msg_D_, 1),
        '[D2]': (msg_D_, 1),
        '[D3]': (msg_D_, 1),
        '[D5]': (msg_D_, 1),
        '[DC]': (msg_D_, 1),
        '[Dl]': (msg_D_, 1),
        '[DO]': (msg_DO, 6),
        '[DP]': (msg_DP, 18),
        '[DX]': (msg_D_, 1),
        '[E1]': (msg_E_, 1),
        '[E2]': (msg_E_, 1),
        '[E3]': (msg_E_, 1),
        '[E5]': (msg_E_, 1),
        '[EA]': (msg__A, 47),
        '[EC]': (msg_E_, 1),
        '[El]': (msg_E_, 1),
        '[EL]': (msg_EL, 1),
        '[EN]': (msg__E1, 123),
        '[ER]': (msg_ER, 1),
        '[ES]': (msg_S_, 8),
        '[EU]': (msg_EU, 40),
        '[F1]': (msg_FC, 1),
        '[F2]': (msg_FC, 1),
        '[F3]': (msg_FC, 1),
        '[F5]': (msg_FC, 1),
        '[FA]': (msg_FC, 1),
        '[FC]': (msg_FC, 1),
        '[Fl]': (msg_FC, 1),
        '[GA]': (msg__A, 47),
        '[GE]': (msg__E1, 123),
        '[GS]': (msg_S_, 8),
        '[GT]': (msg_GT, 7),
        '[IA]': (msg__A, 47),
        '[ID]': (msg_ID, 1),
        '[IE]': (msg__E1, 123),
        '[IO]': (msg_IO, 39),
        '[Is]': (msg_S_, 8),
        '[ld]': (msg__d, 1),
        '[lE]': (msg__E, 1),
        '[LO]': (msg_LO, 1),
        '[lp]': (msg__p, 1),
        '[lr]': (msg__r, 1),
        '[MF]': (msg_MF, 9),
        '[::]': (msg_ET, 4),
        '[~~]': (msg_RT, 4),
        '[NS]': (msg_S_, 8),
        '[P1]': (msg_P_, 1),
        '[P2]': (msg_P_, 1),
        '[P3]': (msg_P_, 1),
        '[P5]': (msg_P_, 1),
        '[PC]': (msg_P_, 1),
        '[Pl]': (msg_P_, 1),
        '[PM]': (msg_PM, 0),
        '[PV]': (msg_PV, 46),
        '[QA]': (msg__A, 47),
        '[QE]': (msg__E1, 123),
        '[QS]': (msg_S_, 8),
        '[r1]': (msg_r, 1),
        '[R1]': (msg_R_, 1),
        '[r2]': (msg_r, 1),
        '[R2]': (msg_R_, 1),
        '[r3]': (msg_r, 1),
        '[R3]': (msg_R_, 1),
        '[r5]': (msg_r, 1),
        '[R5]': (msg_R_, 1),
        '[rc]': (msg_r, 1),
        '[RC]': (msg_R_, 1),
        '[RD]': (msg_RD, 6),
        '[RE]': (msg_RE, 1),
        '[rl]': (msg_r, 1),
        '[Rl]': (msg_R_, 1),
        '[rx]': (msg_r, 1),
        '[SE]': (msg_SE, 6),
        '[SG]': (msg_SG, 18),
        '[SI]': (msg_SI, 1),
        '[SP]': (msg_SP, 42),
        '[SS]': (msg_SS, 1),
        '[ST]': (msg_ST, 6),
        '[SX]': (msg_SX, 1),
        '[TC]': (msg_TC, 1),
        '[TO]': (msg_TO, 6),
        '[UO]': (msg_UO, 24),
        '[WA]': (msg_WA, 51),
        '[WE]': (msg_WE, 73),
        '[WS]': (msg_S_, 8),
        '[WU]': (msg_WU, 40),
    }

    def decode_msg(self, out):
        "Decode one message and then return number of chars consumed"

        state = 'BASE'
        consumed = 0
        # raw message, sometimes used for checksum calc
        m_raw = bytearray(0)

        # decode state machine
        for this_byte in out:
            consumed += 1
            if isinstance(this_byte, str):
                # a character, probably read from a file
                c = ord(this_byte)
            else:
                # a byte, probably read from a serial port
                c = int(this_byte)

            if VERB_RAW <= opts['verbosity']:
                if (ord(' ') <= c) and (ord('~') >= c):
                    # c is printable
                    print("state: %s char %c (%#x)" % (state, chr(c), c))
                else:
                    # c is not printable
                    print("state: %s char %#x" % (state, c))

            m_raw.extend([c])

            # parse input stream per GREIS Ref Guide Section 3.3.3
            if 'BASE' == state:
                # start fresh
                # place to store 'comments'
                comment = ''
                # message id byte one
                m_id1 = 0
                # message id byte two
                m_id2 = 0
                # message length as integer
                m_len = 0
                # byte array to hold payload, including possible checksum
                m_payload = bytearray(0)
                m_raw = bytearray(0)
                m_raw.extend([c])

                if (ord('0') <= c) and (ord('~') >= c):
                    # maybe id 1, '0' to '~'
                    state = 'ID1'

                    # start the grab
                    m_id1 = c
                    continue

                if ord("%") == c:
                    # start of %ID%, Receiver Input Language
                    # per GREIS Ref Guide Section 2.2
                    state = 'RIL'

                    # start fresh
                    comment = "%"
                    continue

                if ord("$") == c:
                    # NMEA line, treat as comment
                    state = 'NMEA'

                    # start fresh
                    comment = "$"
                    continue

                if ord("#") == c:
                    # comment line
                    state = 'COMMENT'

                    # start fresh
                    comment = "#"
                    continue

                if ord('\n') == c or ord('\r') == c:
                    # stray newline or linefeed, eat it
                    return consumed

                # none of the above, stay in BASE
                continue

            if state in ('COMMENT', 'JSON', 'RIL'):
                # inside comment
                if ord('\n') == c or ord('\r') == c:
                    # Got newline or linefeed
                    # GREIS terminates messages on <CR> or <LF>
                    # Done, got a full message
                    if '{"class":"ERROR"' in comment:
                        # always print gpsd errors
                        print(comment)
                    elif VERB_DECODE <= opts['verbosity']:
                        print(comment)
                    return consumed
                else:
                    comment += chr(c)
                continue

            if 'ID1' == state:
                # maybe id 2, '0' to '~'
                if ord('"') == c:
                    # technically could be GREIS, but likely JSON
                    state = 'JSON'
                    comment += chr(m_id1) + chr(c)
                elif (ord('0') <= c) and (ord('~') >= c):
                    state = 'ID2'
                    m_id2 = c
                else:
                    state = 'BASE'
                continue

            if 'ID2' == state:
                # maybe len 1, 'A' to 'F'
                x = self.isuchex(c)
                if -1 < x:
                    state = 'LEN1'
                    m_len = x * 256
                else:
                    state = 'BASE'
                continue

            if 'LEN1' == state:
                # maybe len 2, 'A' to 'F'
                x = self.isuchex(c)
                if -1 < x:
                    state = 'LEN2'
                    m_len += x * 16
                else:
                    state = 'BASE'
                continue

            if 'LEN2' == state:
                # maybe len 3, 'A' to 'F'
                x = self.isuchex(c)
                if -1 < x:
                    state = 'PAYLOAD'
                    m_len += x
                else:
                    state = 'BASE'
                continue

            if 'NMEA' == state:
                # inside NMEA
                if ord('\n') == c or ord('\r') == c:
                    # Got newline or linefeed
                    # done, got a full message
                    # GREIS terminates messages on <CR> or <LF>
                    if VERB_DECODE <= opts['verbosity']:
                        print(comment)
                    return consumed
                else:
                    comment += chr(c)
                continue

            if 'PAYLOAD' == state:
                # getting payload
                m_payload.extend([c])
                if len(m_payload) < m_len:
                    continue

                # got entire payload
                self.s_id = "[%c%c]" % (chr(m_id1), chr(m_id2))
                if VERB_DECODE <= opts['verbosity']:
                    x_payload = binascii.hexlify(m_payload)

                # [RE], [ER] and more have no 8-bit checksum
                # assume the rest do
                if ((self.s_id not in ('[CS]', '[ER]', '[ES]', '[GS]', '[Is]',
                                       '[MF]', '[NS]', '[PM]', '[QS]', '[RE]',
                                       '[WS]') and
                     not self.checksum_OK(m_raw))):
                    print("ERROR: Bad checksum\n")
                    if VERB_DECODE <= opts['verbosity']:
                        print("DECODE: id: %s len: %d\n"
                              "DECODE: payload: %s\n" %
                              (self.s_id, m_len, x_payload))
                    # skip it.
                    return consumed

                if self.s_id in self.messages:
                    if VERB_INFO <= opts['verbosity']:
                        print("INFO: id: %s len: %d\n"
                              "INFO: payload: %s\n" %
                              (self.s_id, m_len, x_payload))

                    (decode, length) = self.messages[self.s_id]
                    if m_len < length:
                        print("DECODE: %s Bad Length %s\n" %
                              (self.s_id, m_len))
                    else:
                        s = self.s_id + decode(self, m_payload)
                        if VERB_DECODE <= opts['verbosity']:
                            print(s)
                else:
                    # unknown message
                    if VERB_DECODE <= opts['verbosity']:
                        print("DECODE: Unknown: id: %s len: %d\n"
                              "DECODE: payload: %s\n" %
                              (self.s_id, m_len, x_payload))
                return consumed

            # give up
            state = 'BASE'

        # fell out of loop, no more chars to look at
        return 0

    def checksum_OK(self, raw_msg):
        "Check the i8-bit checksum on a message, return True if good"

        # some packets from the GPS use CRC16, some i8-bit checksum, some none
        # only 8-bit checksum done here for now
        calc_checksum = self.checksum(raw_msg, len(raw_msg) - 1)
        rcode = raw_msg[len(raw_msg) - 1] == calc_checksum
        if VERB_RAW <= opts['verbosity']:
            print("Checksum was %#x, calculated %#x" %
                  (raw_msg[len(raw_msg) - 1], calc_checksum))
        return rcode

    def _rol(self, value):
        "rotate a byte left 2 bits"
        return ((value << 2) | (value >> 6)) & 0x0ff

    def checksum(self, msg, m_len):
        "Calculate GREIS 8-bit checksum"

        # Calculated per section A.1.1 of the specification
        # msg may be bytes (incoming messages) or str (outgoing messages)

        ck = 0
        for c in msg[0:m_len]:
            if isinstance(c, str):
                # a string, make a byte
                c = ord(c)
            ck = self._rol(ck) ^ c

        return self._rol(ck) & 0x0ff

    def make_pkt(self, m_data):
        "Build an output message, always ASCII, add checksum and terminator"

        # build core message

        # no leading spaces, checksum includes the @
        m_data = m_data.lstrip() + b'@'

        chk = self.checksum(m_data, len(m_data))

        # all commands end with CR and/or LF
        return m_data + (b'%02X' % chk) + b'\n'

    def gps_send(self, m_data):
        "Send message to GREIS GPS"

        m_all = self.make_pkt(m_data)
        if not opts['read_only']:
            io_handle.ser.write(m_all)
            if VERB_INFO <= opts['verbosity']:
                print("sent:", m_all)
                self.decode_msg(m_all)
                sys.stdout.flush()

    # Table of known options.  From table 4-2 of the specification.
    oafs = (
        b"_AJM",
        b"AUTH",
        b"_BLT",
        b"_CAN",
        b"CDIF",
        b"CMRI",
        b"CMRO",
        b"COMP",
        b"COOP",
        b"COPN",
        b"CORI",
        b"_CPH",
        b"DEVS",
        b"DIST",
        b"_DTM",
        b"_E5B",
        b"_E6_",
        b"EDEV",
        b"ETHR",
        b"EVNT",
        b"_FRI",
        b"_FRO",
        b"_FTP",
        b"_GAL",
        b"GBAI",
        b"GBAO",
        b"GCLB",
        b"_GEN",
        b"_GEO",
        b"_GLO",
        b"_GPS",
        b"_GSM",
        b"HTTP",
        b"_IMU",
        b"INFR",
        b"IRIG",
        b"IRNS",
        b"JPSI",
        b"JPSO",
        b"_L1C",
        b"_L1_",
        b"_L2C",
        b"_L2_",
        b"_L5_",
        b"LAT1",
        b"LAT2",
        b"LAT3",
        b"LAT4",
        b"LCS2",
        b"L_CS",
        b"_LIM",
        b"LON1",
        b"LON2",
        b"LON3",
        b"LON4",
        b"MAGN",
        b"_MEM",
        b"_MPR",
        b"OCTO",
        b"OMNI",
        b"_PAR",
        b"PDIF",
        b"_POS",
        b"_PPP",
        b"_PPS",
        b"PRTT",
        b"_PTP",
        b"QZSS",
        b"RAIM",
        b"_RAW",
        b"RCVT",
        b"RM3I",
        b"RM3O",
        b"RS_A",
        b"RS_B",
        b"RS_C",
        b"RS_D",
        b"RTMI",
        b"RTMO",
        b"SPEC",
        b"TCCL",
        b"_TCP",
        b"TCPO",
        b"_TLS",
        b"TRST",
        b"UDPO",
        b"_UHF",
        b"_USB",
        b"WAAS",
        b"WIFI",
        b"_WPT",
    )

    def send_able_4hz(self, able):
        "enable basic GREIS messages at 4Hz"

        self.expect_statement_identifier = 'greis'

        # the messages we want
        # [SX] requires 3.7 firmware, we use [SI] to support 3.6
        messages = b"jps/{RT,UO,GT,PV,SG,DP,SI,EL,AZ,EC,SS,ET}"

        if able:
            # Message rate must be an integer multiple of /par/raw/msint
            # Default msint is 0.100 seconds, so that must be changed first
            self.gps_send(b"%msint%set,/par/raw/msint,250")

            self.gps_send(b"%greis%em,," + messages + b":0.25")
        else:
            self.gps_send(b"%greis%dm,," + messages)

    def send_able_comp(self, able):
        "dis/enable COMPASS, aka BeiDou"
        self.expect_statement_identifier = 'cons'
        en_dis = b'y' if 1 == able else b'n'
        self.gps_send(b"%cons%set,/par/pos/sys/comp," + en_dis)

    def send_able_constellations(self, able):
        "dis/enable all constellations"
        self.expect_statement_identifier = 'cons7'
        en_dis = b'y' if 1 == able else b'n'
        self.gps_send(b"%cons1%set,/par/pos/sys/comp," + en_dis)
        self.gps_send(b"%cons2%set,/par/pos/sys/gal," + en_dis)
        # this will fail on TR-G2H, as it has no GLONASS
        self.gps_send(b"%cons3%set,/par/pos/sys/glo," + en_dis)
        self.gps_send(b"%cons4%set,/par/pos/sys/gps," + en_dis)
        self.gps_send(b"%cons5%set,/par/pos/sys/irnss," + en_dis)
        self.gps_send(b"%cons6%set,/par/pos/sys/sbas," + en_dis)
        self.gps_send(b"%cons7%set,/par/pos/sys/qzss," + en_dis)

    def send_able_defmsg(self, able):
        "dis/enable default messages at 1Hz"
        self.expect_statement_identifier = 'defmsg'
        if able:
            self.gps_send(b"%defmsg%em,,jps/RT,/msg/def:1,jps/ET")
        else:
            # leave RT and ET to break less?
            self.gps_send(b"%defmsg%dm,,/msg/def:1")

    def send_able_gal(self, able):
        "dis/enable GALILEO"
        self.expect_statement_identifier = 'cons'
        en_dis = b'y' if 1 == able else b'n'
        self.gps_send(b"%cons%set,/par/pos/sys/gal," + en_dis)

    def send_able_glo(self, able):
        "dis/enable GLONASS"
        self.expect_statement_identifier = 'cons'
        en_dis = b'y' if 1 == able else b'n'
        self.gps_send(b"%cons%set,/par/pos/sys/glo," + en_dis)

    def send_able_gps(self, able):
        "dis/enable GPS"
        self.expect_statement_identifier = 'cons'
        en_dis = b'y' if 1 == able else b'n'
        self.gps_send(b"%cons%set,/par/pos/sys/gps," + en_dis)

    def send_able_ipr(self, able):
        "dis/enable all Integer Psuedo-Range messages"
        self.expect_statement_identifier = 'em'
        if able:
            self.gps_send(b"%em%em,,jps/{rx,rc,r1,r2,r3,r5,rl}:0.25")
        else:
            self.gps_send(b"%em%dm,,jps/{rx,rc,r1,r2,r3,r5,rl}")

    def send_able_irnss(self, able):
        "dis/enable IRNSS"
        self.expect_statement_identifier = 'cons'
        en_dis = b'y' if 1 == able else b'n'
        self.gps_send(b"%cons%set,/par/pos/sys/irnss," + en_dis)

    def send_able_nmea41(self, able):
        "dis/enable basic NMEA 4.1e messages at 4Hz"

        self.expect_statement_identifier = 'nmea'

        messages = b"nmea/{GBS,GGA,GSA,GST,GSV,RMC,VTG,ZDA}"

        if able:
            # set NMEA version 4.1e
            self.gps_send(b"%nmeaver%set,/par/nmea/ver,v4.1e")

            # Message rate must be an integer multiple of /par/raw/msint
            # Default msint is 0.100 seconds, so that must be changed first
            self.gps_send(b"%msint%set,/par/raw/msint,250")

            # now we can set the messages we want
            self.gps_send(b"%nmea%em,," + messages + b":0.25")
        else:
            # disable
            self.gps_send(b"%nmea%dm,," + messages)

    def send_able_raw(self, able):
        """dis/enable Raw mode messages"""
        self.expect_statement_identifier = 'raw'

        messages = (b"jps/{RT,UO,GT,PV,SG,DP,SI,EL,AZ,EC,SS,"
                    b"PC,P1,P2,P3,P5,Pl,"
                    b"RC,R1,R2,R3,R5,Rl,"
                    b"DC,D1,D2,D3,D5,Dl,"
                    b"ET}")

        if able:
            self.gps_send(b"%raw%em,," + messages + b":1")
        else:
            self.gps_send(b"%raw%dm,," + messages)

    def send_able_sbas(self, able):
        "dis/enable SBAS"
        self.expect_statement_identifier = 'cons'
        en_dis = b'y' if 1 == able else b'n'
        self.gps_send(b"%cons%set,/par/pos/sys/sbas," + en_dis)

    def send_able_qzss(self, able):
        "dis/enable QZSS"
        self.expect_statement_identifier = 'cons'
        en_dis = b'y' if 1 == able else b'n'
        self.gps_send(b"%cons%set,/par/pos/sys/qzss," + en_dis)

    def send_able_snr(self, able):
        "dis/enable all SNR messages, except [EC]"
        self.expect_statement_identifier = 'em'
        if able:
            self.gps_send(b"%em%em,,jps/{E1,E2,E3,E5,El}:0.25")
        else:
            self.gps_send(b"%em%dm,,jps/{E1,E2,E3,E5,El}")

    able_commands = {
        # en/disable basic GREIS messages at 4HZ
        "4HZ": {"command": send_able_4hz,
                "help": "basic GREIS messages at 4Hz"},
        # en/disable all constellations
        "CONS": {"command": send_able_constellations,
                 "help": "all constellations"},
        # en/disable COMPASS, aka Beidou
        "COMPASS": {"command": send_able_comp,
                    "help": "COMPASS"},
        # en/disable default message set.
        "DEFMSG": {"command": send_able_defmsg,
                   "help": "default message set at 1Hz"},
        # en/disable GALILEO
        "GALILEO": {"command": send_able_gal,
                    "help": "GALILEO"},
        # en/disable GLONASS
        "GLONASS": {"command": send_able_glo,
                    "help": "GLONASS"},
        # en/disable GPS
        "GPS": {"command": send_able_gps,
                "help": "GPS"},
        # en/disable Integer Psuedo Range messages
        "IPR": {"command": send_able_ipr,
                "help": "all Integer Psuedo Range messages"},
        # en/disable IRNSS
        "IRNSS": {"command": send_able_irnss,
                  "help": "IRNSS"},
        # en/disable NMEA 4.1e
        "NMEA": {"command": send_able_nmea41,
                 "help": "basic messages NMEA 4.1 at 4Hz"},
        # en/disable Psuedo Range, Carrier Phase and Doppler messages
        "RAW": {"command": send_able_raw,
                "help": "Raw mode messages"},
        # en/disable SBAS
        "SBAS": {"command": send_able_sbas,
                 "help": "SBAS"},
        # en/disable all SNRs
        "SNR": {"command": send_able_snr,
                "help": "all SNR messages, except [EC]"},
        # en/disable QZSS
        "QZSS": {"command": send_able_qzss,
                 "help": "QZSS"},
    }

    def send_coldboot(self):
        "Delete NVRAM (almanac, ephemeris, location) and restart"
        self.expect_statement_identifier = 'coldboot'
        self.gps_send(b"%coldboot%init,/dev/nvm/a")

    def send_constellations(self):
        "poll all constellations"
        self.expect_statement_identifier = 'cons'
        self.gps_send(b"%cons%print,/par/pos/sys:on")

    def send_get_id(self):
        "get receiver id"
        self.expect_statement_identifier = 'id'
        self.gps_send(b"%id%print,/par/rcv/id")

    def send_get_oaf(self):
        "poll OAF (GPS opts)"

        self.expect_statement_identifier = 'opts,_WPT'
        if VERB_RAW <= opts['verbosity']:
            # get list of all opts
            self.gps_send(b"%opts,list%list,/par/opts")

        # request opts one at a time from canned list
        for s in self.oafs:
            self.gps_send(b"%%opts,%s%%print,/par/opts/%s" % (s, s))

    def send_get_serial(self):
        "get receiver serial number"
        self.expect_statement_identifier = 'serial'
        self.gps_send(b"%serial%print,/par/rcv/sn")

    def send_reset(self):
        "reset (reboot) the GPS"
        self.expect_statement_identifier = 'reset'
        self.gps_send(b"%reset%set,/par/reset,y")

    def send_set_dm(self):
        "disable all messages"
        self.expect_statement_identifier = 'dm'
        self.gps_send(b"%dm%dm")

    def send_set_ipr(self):
        "poll Integer Psuedo-Range messages"
        self.expect_statement_identifier = 'out'
        self.gps_send(b"%out%out,,jps/{rx,rc,r1,r2,r3,r5,rl}")

    def send_get_snr(self):
        "poll all SNR messages"
        # nothing we can wait on, depending on GPS model/configuration
        # we may never see some of E2, E3, E5 or El
        self.gps_send(b"%out%out,,jps/{EC,E1,E2,E3,E5,El}")

    def send_set_speed(self, set_speed):
        "change GPS speed"
        self.expect_statement_identifier = 'setspeed'
        self.gps_send(b"%%setspeed%%set,/par/cur/term/rate,%d" %
                      set_speed)

    def send_get_vendor(self):
        "get receiver vendor"
        self.expect_statement_identifier = 'vendor'
        self.gps_send(b"%vendor%print,/par/rcv/vendor")

    def send_get_ver(self):
        "get receiver version, per section 4.4.3 of the specification"
        self.expect_statement_identifier = 'ver'
        self.gps_send(b"%ver%print,/par/rcv/ver")

    # list of canned commands that can be sent to the receiver
    commands = {
        "COLDBOOT": {"command": send_coldboot,
                     "help": "cold boot the GPS"},
        "CONS": {"command": send_constellations,
                 "help": "poll enabled constellations"},
        "DM": {"command": send_set_dm,
               "help": "disable all periodic messages"},
        "ID": {"command": send_get_id,
               "help": "poll receiver ID"},
        "IPR": {"command": send_set_ipr,
                "help": "poll all Integer Psuedo-range messages"},
        "OAF": {"command": send_get_oaf,
                "help": "poll all OAF options"},
        "RESET": {"command": send_reset,
                  "help": "reset (reboot) the GPS"},
        "SERIAL": {"command": send_get_serial,
                   "help": "poll receiver serial number"},
        "SNR": {"command": send_get_snr,
                "help": "poll all SNR messages"},
        "VENDOR": {"command": send_get_vendor,
                   "help": "poll GPS vendor"},
        "VER": {"command": send_get_ver,
                "help": "poll GPS version"},
    }


class gps_io(object):
    """All the GPS I/O in one place"

    Three types of GPS I/O
    1. read only from a file
    2. read/write through a device
    3. read only from a gpsd instance
    """

    out = b''
    ser = None
    input_is_device = False

    def __init__(self):
        "Initialize class"

        Serial = serial
        Serial_v3 = Serial and Serial.VERSION.split('.')[0] >= '3'
        # buffer to hold read data
        self.out = b''

        # open the input: device, file, or gpsd
        if opts['input_file_name'] is not None:
            # check if input file is a file or device
            try:
                mode = os.stat(opts['input_file_name']).st_mode
            except OSError:
                sys.stderr.write('%s: failed to open input file %s\n' %
                                 (PROG_NAME, opts['input_file_name']))
                sys.exit(1)

            if stat.S_ISCHR(mode):
                # character device, need not be read only
                self.input_is_device = True

            if ((opts['disable'] or opts['enable'] or opts['poll'] or
                 opts['oaf_name'])):

                # check that we can write
                if opts['read_only']:
                    sys.stderr.write('%s: read-only mode, '
                                     'can not send commands\n' % PROG_NAME)
                    sys.exit(1)
                if self.input_is_device is False:
                    sys.stderr.write('%s: input is plain file, '
                                     'can not send commands\n' % PROG_NAME)
                    sys.exit(1)

        if opts['target']['server'] is not None:
            # try to open local gpsd
            try:
                self.ser = gps.gpscommon(host=None)
                self.ser.connect(opts['target']['server'],
                                 opts['target']['port'])

                # alias self.ser.write() to self.write_gpsd()
                self.ser.write = self.write_gpsd
                # ask for raw, not rare, data
                data_out = b'?WATCH={'
                if opts['target']['device'] is not None:
                    # add in the requested device
                    data_out += (b'"device":"' + opts['target']['device'] +
                                 b'",')
                data_out += b'"enable":true,"raw":2}\r\n'
                if VERB_RAW <= opts['verbosity']:
                    print("sent: ", data_out)
                self.ser.send(data_out)
            except socket.error as err:
                sys.stderr.write('%s: failed to connect to gpsd %s\n' %
                                 (PROG_NAME, err))
                sys.exit(1)

        elif self.input_is_device:
            # configure the serial connections (the parameters refer to
            # the device you are connecting to)

            # pyserial Ver 3.0+ changes writeTimeout to write_timeout
            # Using the wrong one causes an error
            write_timeout_arg = ('write_timeout'
                                 if Serial_v3 else 'writeTimeout')
            try:
                self.ser = Serial.Serial(
                    baudrate=opts['input_speed'],
                    # 8N1 is GREIS default
                    bytesize=Serial.EIGHTBITS,
                    parity=Serial.PARITY_NONE,
                    port=opts['input_file_name'],
                    stopbits=Serial.STOPBITS_ONE,
                    # read timeout
                    timeout=0.05,
                    **{write_timeout_arg: 0.5}
                )
            except AttributeError:
                sys.stderr.write('%s: failed to import pyserial\n' % PROG_NAME)
                sys.exit(2)
            except Serial.serialutil.SerialException:
                # this exception happens on bad serial port device name
                sys.stderr.write('%s: failed to open serial port "%s"\n'
                                 '   Your computer has these serial ports:\n'
                                 % (PROG_NAME, opts['input_file_name']))

                # print out list of supported ports
                import serial.tools.list_ports as List_Ports
                ports = List_Ports.comports()
                for port in ports:
                    sys.stderr.write("    %s: %s\n" %
                                     (port.device, port.description))
                sys.exit(1)

            # flush input buffer, discarding all its contents
            # pyserial 3.0+ deprecates flushInput() in favor of
            # reset_input_buffer(), but flushInput() is still present.
            self.ser.flushInput()

        else:
            # Read from a plain file of GREIS messages
            try:
                self.ser = open(opts['input_file_name'], 'rb')
            except IOError:
                sys.stderr.write('%s: failed to open input %s\n' %
                                 (PROG_NAME, opts['input_file_name']))
                sys.exit(1)

    def read(self, read_opts):
        "Read from device, until timeout or expected message"

        # are we expecting a certain message?
        if gps_model.expect_statement_identifier:
            # assume failure, until we see expected message
            ret_code = 1
        else:
            # not expecting anything, so OK if we did not see it.
            ret_code = 0

        try:
            if read_opts['target']['server'] is not None:
                # gpsd input
                start = time.clock()
                while read_opts['input_wait'] > (time.clock() - start):
                    # First priority is to be sure the input buffer is read.
                    # This is to prevent input buffer overuns
                    if 0 < self.ser.waiting():
                        # We have serial input waiting, get it
                        # No timeout possible
                        # RTCM3 JSON can be over 4.4k long, so go big
                        new_out = self.ser.sock.recv(8192)
                        if raw is not None:
                            # save to raw file
                            raw.write(new_out)
                        self.out += new_out

                    consumed = gps_model.decode_msg(self.out)
                    self.out = self.out[consumed:]
                    if ((gps_model.expect_statement_identifier and
                         (gps_model.expect_statement_identifier ==
                          gps_model.last_statement_identifier))):
                        # Got what we were waiting for.  Done?
                        ret_code = 0
                        if not read_opts['input_forced_wait']:
                            # Done
                            break

            elif self.input_is_device:
                # input is a serial device
                start = time.clock()
                while read_opts['input_wait'] > (time.clock() - start):
                    # First priority is to be sure the input buffer is read.
                    # This is to prevent input buffer overuns
                    # pyserial 3.0+ deprecates inWaiting() in favor of
                    # in_waiting, but inWaiting() is still present.
                    if 0 < self.ser.inWaiting():
                        # We have serial input waiting, get it
                        # 1024 is comfortably large, almost always the
                        # Read timeout is what causes ser.read() to return
                        new_out = self.ser.read(1024)
                        if raw is not None:
                            # save to raw file
                            raw.write(new_out)
                        self.out += new_out

                    consumed = gps_model.decode_msg(self.out)
                    self.out = self.out[consumed:]
                    if ((gps_model.expect_statement_identifier and
                         (gps_model.expect_statement_identifier ==
                          gps_model.last_statement_identifier))):
                        # Got what we were waiting for.  Done?
                        ret_code = 0
                        if not read_opts['input_forced_wait']:
                            # Done
                            break
            else:
                # ordinary file, so all read at once
                self.out += self.ser.read()
                if raw is not None:
                    # save to raw file
                    raw.write(self.out)

                while True:
                    consumed = gps_model.decode_msg(self.out)
                    self.out = self.out[consumed:]
                    if 0 >= consumed:
                        break

        except IOError:
            # This happens on a good device name, but gpsd already running.
            # or if USB device unplugged
            sys.stderr.write('%s: failed to read %s\n'
                             '%s: Is gpsd already holding the port?\n'
                             % (PROG_NAME, PROG_NAME,
                                read_opts['input_file_name']))
            return 1

        if 0 < ret_code:
            # did not see the message we were expecting to see
            sys.stderr.write('%s: waited %0.2f seconds for, '
                             'but did not get: %%%s%%\n'
                             % (PROG_NAME, read_opts['input_wait'],
                                gps_model.expect_statement_identifier))
        return ret_code

    def write_gpsd(self, data):
        "write data to gpsd daemon"

        # HEXDATA_MAX = 512, from gps.h, The max hex digits can write.
        # Input data is binary, converting to hex doubles its size.
        # Limit binary data to length 255, so hex data length less than 510.
        if 255 < len(data):
            sys.stderr.write('%s: trying to send %d bytes, max is 255\n'
                             % (PROG_NAME, len(data)))
            return 1

        if opts['target']['device'] is not None:
            # add in the requested device
            data_out = b'?DEVICE={"path":"' + opts['target']['device'] + b'",'
        else:
            data_out = b'?DEVICE={'

        # Convert binary data to hex and build the message.
        data_out += b'"hexdata":"' + binascii.hexlify(data) + b'"}\r\n'
        if VERB_RAW <= opts['verbosity']:
            print("sent: ", data_out)
        self.ser.send(data_out)
        return 0


def usage():
    "Print usage information, and exit"

    print("usage: %s [-?hrVW] [-c C] [-d D] [-e E] [-f F] [-O O] [-p P]\n"
          "            [-R R] [-S S] [-s S] [-v V] [-w W]\n"
          "            [server[:port[:device]]]\n\n" % PROG_NAME)
    print('usage: %s [options]\n'
          '       -?            print this help\n'
          '       -c C          send command C to GPS\n'
          '       -d D          disable D\n'
          '       -e E          enable E\n'
          '       -f F          open F as file/device\n'
          '                     default: %s\n'
          '       -h            print this help\n'
          '       -O O          send OAF file to GPS\n'
          '       -p P          send preset GPS command P\n'
          '       -R R          save raw data from GPS in file R\n'
          '       -r            open file/device read only\n'
          '                     default: %s\n'
          '       -S S          configure GPS speed to S\n'
          '       -s S          set port speed to S\n'
          '                     default: %d bps\n'
          '       -V            print version\n'
          '       -v V          Set verbosity level to V, 0 to 4\n'
          '                     default: %d\n'
          '       -W            force entire wait time, no exit early\n'
          '       -w W          wait time, exit early on -p result\n'
          '                     default: %s seconds\n'
          '       [server[:port[:device]]] Connect to gpsd\n'
          '                     default port: 2947\n'
          '                     default device: None\n'
          '\n'
          'D and E can be one of:' %
          (PROG_NAME, opts['input_file_name'], opts['raw_file'],
           opts['input_speed'], opts['verbosity'], opts['input_wait'])
          )

    # print list of enable/disable commands
    for item in sorted(gps_model.able_commands.keys()):
        print("    %-12s %s" % (item, gps_model.able_commands[item]["help"]))

    print('\nthe preset GPS command P can be one of:')

    # print list of possible canned commands
    for item in sorted(gps_model.commands.keys()):
        print("    %-12s %s" % (item, gps_model.commands[item]["help"]))
    print('\nOptions can be placed in the ZERKOPTS environment variable.\n'
          'ZERKOPTS is processed before the CLI options.')
    sys.exit(0)


# create the GREIS instance
gps_model = greis()

if 'ZERKOPTS' in os.environ:
    # grab the ZERKOPTS environment variable for options
    opts['progopts'] = os.environ['ZERKOPTS']
    options = opts['progopts'].split(' ') + sys.argv[1:]
else:
    options = sys.argv[1:]

try:
    (options, arguments) = getopt.getopt(options,
                                         "?c:d:e:f:hrp:s:w:v:O:R:S:WV")
except getopt.GetoptError as err:
    sys.stderr.write("%s: %s\n"
                     "Try '%s -h' for more information.\n" %
                     (PROG_NAME, str(err), PROG_NAME))
    sys.exit(2)

for (opt, val) in options:
    if opt == '-c':
        # command
        opts['command'] = val
    elif opt == '-d':
        # disable
        opts['disable'] = val
    elif opt == '-e':
        # enable
        opts['enable'] = val
    elif opt == '-f':
        # file input
        opts['input_file_name'] = val
    elif opt == '-h' or opt == '-?':
        # help
        usage()
    elif opt == '-p':
        # preprogrammed command
        opts['poll'] = val
    elif opt == '-r':
        # read only
        opts['read_only'] = True
    elif opt == '-s':
        # serial port speed
        opts['input_speed'] = int(val)
        if opts['input_speed'] not in gps_model.speeds:
            sys.stderr.write('%s: -s invalid speed %s\n' %
                             (PROG_NAME, opts['input_speed']))
            sys.exit(1)

    elif opt == '-w':
        # max wait time, seconds
        opts['input_wait'] = float(val)
    elif opt in '-v':
        # verbosity level
        opts['verbosity'] = int(val)
    elif opt in '-O':
        # OAF .jpo file
        opts['oaf_name'] = val
    elif opt in '-R':
        # raw log file
        opts['raw_file'] = val
    elif opt in '-S':
        # set GPS serial port speed
        opts['set_speed'] = int(val)
        if opts['set_speed'] not in gps_model.speeds:
            sys.stderr.write('%s: -S invalid speed %s\n' %
                             (PROG_NAME, opts['set_speed']))
            sys.exit(1)

    elif opt == '-W':
        # forced wait, no early exit on command completion
        opts['input_forced_wait'] = True
    elif opt == '-V':
        # version
        sys.stderr.write('zerk: Version %s\n' % gps_version)
        sys.exit(0)

if opts['input_file_name'] is None:
    # no input file given
    # default to local gpsd
    opts['target']['server'] = "localhost"
    opts['target']['port'] = gps.GPSD_PORT
    opts['target']['device'] = None
    if arguments:
        # server[:port[:device]]
        arg_parts = arguments[0].split(':')
        opts['target']['server'] = arg_parts[0]
        if 1 < len(arg_parts):
            opts['target']['port'] = arg_parts[1]
            if 2 < len(arg_parts):
                opts['target']['device'] = arg_parts[2]

elif arguments:
    sys.stderr.write('%s: Both input file and server specified\n' % PROG_NAME)
    sys.exit(1)

if VERB_PROG <= opts['verbosity']:
    # dump all options
    print('Options:')
    for option in sorted(opts):
        print("   %s: %s" % (option, opts[option]))

# done parsing arguments from environment and CLI

try:
    # raw log file requested?
    raw = None
    if opts['raw_file']:
        try:
            raw = open(opts['raw_file'], 'w')
        except IOError:
            sys.stderr.write('%s: failed to open raw file %s\n' %
                             (PROG_NAME, opts['raw_file']))
            sys.exit(1)

    # create the I/O instance
    io_handle = gps_io()

    # keep it simple, only one of -O, -c -d -e or -S
    if opts['oaf_name'] is not None:
        # parse an OAF file
        try:
            oaf_root = xml.etree.ElementTree.parse(opts['oaf_name']).getroot()
            oaf = dict()
            for tag in ('id', 'oaf', 'hash'):
                oaf[tag] = oaf_root.find(tag).text
            oaf['oaf'] = oaf['oaf'].split('\n')
            if VERB_PROG <= opts['verbosity']:
                print(oaf)
        except xml.etree.ElementTree.ParseError:
            sys.stderr.write('%s: failed to parse OAF "%s"\n'
                             % (PROG_NAME, opts['oaf_name']))
            sys.exit(1)
        except IOError:
            sys.stderr.write('%s: failed to read OAF "%s"\n'
                             % (PROG_NAME, opts['oaf_name']))
            sys.exit(1)

        # calculate hash
        oaf_s = '\n'.join(oaf['oaf'])
        hash_s = hashlib.sha1(oaf_s).hexdigest()
        if hash_s != oaf['hash']:
            sys.stderr.write('%s: OAF bad hash "%s", s/b %s\n'
                             % (PROG_NAME, hash_s, oaf['hash']))
            sys.exit(1)

        # TODO: probably should check the ID first...
        # TODO: prolly should send one command per handshake
        # blasting all commands at once, seems to not work reliably
        for command in oaf['oaf']:
            time.sleep(0.1)           # wait 0.1 seconds each
            gps_model.gps_send(command)
        # this will detect when it is all done
        gps_model.gps_send(b'%DONE%')
        gps_model.expect_statement_identifier = 'DONE'

    elif opts['command'] is not None:
        # zero length is OK to send
        if 1 < len(opts['command']) and '%' != opts['command'][0]:
            # add ID, if missing
            gps_model.expect_statement_identifier = 'CMD'
            opts['command'] = "%CMD%" + opts['command']

        # add trailing new line
        opts['command'] += "\n"

        if VERB_QUIET < opts['verbosity']:
            sys.stderr.write('%s: command %s\n' % (PROG_NAME, opts['command']))
        gps_model.gps_send(opts['command'])

    elif opts['disable'] is not None:
        if VERB_QUIET < opts['verbosity']:
            sys.stderr.write('%s: disable %s\n' % (PROG_NAME, opts['disable']))
        if opts['disable'] in gps_model.able_commands:
            command = gps_model.able_commands[opts['disable']]
            command["command"](gps_model, 0)
        else:
            sys.stderr.write('%s: disable %s not found\n' %
                             (PROG_NAME, opts['disable']))
            sys.exit(1)

    elif opts['enable'] is not None:
        if VERB_QUIET < opts['verbosity']:
            sys.stderr.write('%s: enable %s\n' % (PROG_NAME, opts['enable']))
        if opts['enable'] in gps_model.able_commands:
            command = gps_model.able_commands[opts['enable']]
            command["command"](gps_model, 1)
        else:
            sys.stderr.write('%s: enable %s not found\n' %
                             (PROG_NAME, opts['enable']))
            sys.exit(1)

    elif opts['poll'] is not None:
        if VERB_QUIET < opts['verbosity']:
            sys.stderr.write('%s: poll %s\n' % (PROG_NAME, opts['poll']))
        if opts['poll'] in gps_model.commands:
            command = gps_model.commands[opts['poll']]
            command["command"](gps_model)
        else:
            sys.stderr.write('%s: poll %s not found\n' %
                             (PROG_NAME, opts['poll']))
            sys.exit(1)

    elif opts['set_speed'] is not None:
        gps_model.send_set_speed(opts['set_speed'])

    exit_code = io_handle.read(opts)

    if ((VERB_RAW <= opts['verbosity']) and io_handle.out):
        # dump raw left overs
        print("Left over data:")
        print(io_handle.out)

    sys.stdout.flush()
    io_handle.ser.close()

except KeyboardInterrupt:
    print('')
    exit_code = 1

sys.exit(exit_code)