#!/usr/bin/env python3
#
# Author: Kyle Manna
#
import collections
import csv
import json
import paramiko
import sys
import time

#
# Class to interface to Trimble GM100 GPS Discipline PTP Grandmaster Clock
#
class GM100:

    def __init__(self, host):
        self._host = host
        self._user = 'trimblesuper'
        self._pass = 'trimblesuper'
        pass

    def connect(self):
        self._ssh = paramiko.SSHClient()
        self._ssh.set_missing_host_key_policy(paramiko.client.AutoAddPolicy())
        self._ssh.connect(self._host, username=self._user, password=self._pass)

        self._chan = self._ssh.invoke_shell()

    def wait_for_prompt(self):
        resp = b''
        while not resp.endswith(b'> '):
            buf = self._chan.recv(1024)
            resp += buf

        return resp

    def get_gnss(self):

        self._chan.send('view freq\n\r')
        resp = self.wait_for_prompt()

        if b'No frequency status available at this time.' in resp:
            return None

        # Discard first line (command sent) and last line (command prompt)
        resp = resp.split(b'\r\n')[1:-1]

        # Split the 'Key: Value' byte array in to a stripped string list
        resp = [i.decode().strip().split(': ',1) for i in resp]

        # Convert the list to a kv dictionary
        gnss = collections.OrderedDict([(kv[0], kv[1]) for kv in resp])

        return gnss

    def readline(self):
        resp = b''
        while not resp.endswith(b'\r\n'):
            # HACK cringe reading one byte at a time
            buf = self._chan.recv(1)
            resp += buf

        return resp

    def view_stream(self):
        self._chan.send('view stream\n\r')
        # Discard command echo'd back
        self.readline()

        keys = self.readline().decode().strip().split(',')

        while True:
            values = gm100.readline().decode().strip().split(',')
            yield collections.OrderedDict(zip(keys, values))

#
# Test application dumps the frequency data to stdout in CSV format
#
if __name__ == '__main__':

    gm100 = GM100(sys.argv[1])

    gm100.connect()
    gm100.wait_for_prompt()

    """
    sample = gm100.get_gnss()
    while not sample:
        sample = gm100.get_gnss()

    fieldnames = sample.keys()
    writer = csv.DictWriter(sys.stdout, fieldnames=fieldnames)
    writer.writeheader()

    while True:
        sample = gm100.get_gnss()
        #print(json.dumps(sample))
        writer.writerow(sample)
        time.sleep(10)
    """

    writer = None

    for i in gm100.view_stream():
        if not writer:
            writer = csv.DictWriter(sys.stdout, fieldnames=i.keys())
            writer.writeheader()

        #print(json.dumps(i))
        writer.writerow(i)