#!/usr/bin/python3
# Copyright (c) 2000-2020 Synology Inc. All rights reserved.

from os import path
import configparser
import os
import sys
import argparse

DUMMPY_SECTION="ROOT"
DEFAULT_MTU=1492
DEFAULT_MRU=1492

def parse_arguments():
    parser = argparse.ArgumentParser(description="Generate PPPoE Config.")

    parser.add_argument("-i", "--input", dest="input_file", required=True,
                        help="Input file name")

    parser.add_argument("-o", "--output", dest="output_file", required=True,
                        help="Output file name")

    parser.add_argument("-r", "--override", dest="overrides", nargs=2,
                        default=[], action="append", metavar=("key", "value"),
                        help="override value in input file.")

    return parser.parse_args()

def read_config(filename):
    with open(filename) as f:
        data = "[{0}]\n".format(DUMMPY_SECTION) + f.read()

    cp = configparser.RawConfigParser()
    cp.optionxform = str
    cp.read_string(data)
    return dict(cp.items(DUMMPY_SECTION))

def override_config(config, overrides):
    override_config = dict(overrides[i][0:2] for i in range(0, len(overrides)))
    config.update(override_config)
    return config

def write_config(config, output_file):
    with open(output_file, "w+") as f:
        # default arguments.
        f.write("noipdefault noauth default-asyncmap hide-password nodetach "
                "noaccomp nodeflate nopcomp novj novjccomp\n")

        # optional arguments
        if config.get("LINUX_PLUGIN"):
            f.write("plugin {0} nic-{1}".format(config["LINUX_PLUGIN"],
                                                config["ETH"]))
            if config.get("SERVICENAME") and config["SERVICENAME"] != '""':
                f.write(" rp_pppoe_service {0}".format(config["SERVICENAME"]))

            if config.get("ACNAME") and config["ACNAME"] != '""':
                f.write(" rp_pppoe_ac {0}".format(config["ACNAME"]))

            f.write("\n")

        if config.get("UNIT"):
            f.write("unit {0}\n".format(config["UNIT"]))

        if config.get("DNSTYPE") == "SERVER":
            f.write("usepeerdns\n")

        if config.get("MTU"):
            f.write("mtu {0}\n".format(config["MTU"]))
        else:
            f.write("mtu {0}\n".format(DEFAULT_MTU))

        if config.get("MRU"):
            f.write("mru {0}\n".format(config["MRU"]))
        else:
            f.write("mru {0}\n".format(DEFAULT_MRU))

        if config.get("LCP_INTERVAL"):
            f.write("lcp-echo-interval {0}\n".format(config["LCP_INTERVAL"]))

        if config.get("LCP_FAILURE"):
            f.write("lcp-echo-failure {0}\n".format(config["LCP_FAILURE"]))

        if config.get("USER"):
            f.write("user {0}\n".format(config["USER"]))

        if config.get("DEFAULTROUTE") != "no":
            f.write("defaultroute\n")

        if config.get("DEMAND") != "no":
            f.write("demand persist idle {0} 10.112.112.112:10.112.112.113 "
                    "ipcp-accept-remote ipcp-accept-local connect true "
                    "noipdefault ktune\n".format(config["DEMAND"]))

        # extra arguments
        if config.get("PPPD_EXTRA"):
            f.write("{0}\n".format(config["PPPD_EXTRA"].strip("'\"")))

def generate(input_file, output_file, overrides):
    config = read_config(input_file)
    config = override_config(config, overrides)
    write_config(config, output_file)

def main():
    try:
        args = parse_arguments()
        generate(args.input_file, args.output_file, args.overrides)
    except ValueError as e:
        print('Parse values failed: {0}'.format(e))
        sys.exit(1)
    except Exception as e:
        print("Operation failed: {0}".format(e))
        sys.exit(1)


if __name__ == "__main__":
    main()