gp2.py

import json
import sys
from urllib import request, error


class GP2Exception(Exception):
    def __init__(self, *args):
        if args:
            self.message = args[0]
        else:
            self.message = 'An unknown error occured'


def eprint(*args, **kwargs):
    print(*args, file=sys.stderr, **kwargs)


def read_inputs(program_filepath, hostgraph_filepath):
    try:
        with open(program_filepath, 'r') as f:
            program = f.read()
            try:
                with open(hostgraph_filepath, 'r') as g:
                    hostgraph = g.read()
                    return program, hostgraph
            except FileNotFoundError as e:
                raise GP2Exception('The provided hostgraph file could not be read.')
    except FileNotFoundError as e:
        raise GP2Exception('The provided program file could not be read.')


def interpret(program, hostgraph):
    url = 'https://gp2.gjcampbell.co.uk/interpret'
    data = json.dumps({'program':program,'graph':hostgraph}).encode('utf8')
    headers = {'content-type': 'application/json', 'User-Agent': 'gp2i-cli/1.0'}

    try:
        response = request.urlopen(request.Request(url, data=data, headers=headers))
    except error.HTTPError as e:
        if e.code == 400:
            raise GP2Exception(json.loads(e.read().decode('utf8'))['error'])
        elif e.code == 401:
            raise GP2Exception('Access denied by the remote server.')
        else:
            raise

    return json.loads(response.read().decode('utf8'))['graph']


def main(args):
    if len(args) != 3:
        eprint('Incorrect number of arguments. Expected two arguments <program> <hostgraph>')
        return 1
    try:
        program, graph = read_inputs(args[1], args[2])
        print(interpret(program, graph).strip())
    except GP2Exception as e:
        eprint(e.message.strip())
        return 1

    return 0


if __name__ == '__main__':
    sys.exit(main(sys.argv))