#!/usr/bin/env python3

import sys
import requests
import hmac
import hashlib
import pathlib
import os
import json
import sys
import time


def get_args():
    """ Get command line arguments """

    import argparse
    parser = argparse.ArgumentParser()
    parser.add_argument('command')
    parser.add_argument('-s', '--server', default="")
    parser.add_argument('-l', '--shortlink', default="")
    parser.add_argument('-v', '--value', default="")
    parser.add_argument('-c', '--config', type=pathlib.Path, default=pathlib.Path(os.path.expanduser('~/.config/susmng/config.json')))
    parser.add_argument('-H', '--http', action='store_true')
    return parser.parse_args()


def main(args):
    """ Entry point for script """

    if args.command == "init":
        print(f"creating config file and quitting")

        if args.config.exists():
            print("config file exists... doing nothing")
            return

        with open(args.config, 'w+') as fp:
            json.dump({ 'secrets': { 'sus.example.com': 'secret' } }, fp, indent=2)

        return

    with open(args.config) as fp:
        config = json.load(fp)

    server = args.server
    if server == "":
        server = list(config['secrets'].keys())[0]

    secret = config['secrets'][server]

    if args.command == "delete" and args.value != "confirm":
        print("--value not set to 'confirm'... delete operation may fail")

    # accoring to python documentation (https://docs.python.org/3/library/time.html#time.time)
    # this function does not explicitly have to use unix time, and implementation is dependent
    # platform.
    # most platforms (windows, unix) will probably give unix time though.
    #
    # the server side (main.go file) does explicitly use unix time (time.Now().UnixNano()) to get
    # this number, but hopefully there should be no issues on most platforms.
    timestamp = str(time.time_ns())

    data = {
        'Command': args.command,
        'Shortlink': args.shortlink,
        'Value': args.value,
        'Timestamp': timestamp,
        }

    headers = {
        'Signature': 'SUS-SIGNATURE-' + hmac.new(
            secret.encode("UTF-8"),
            (timestamp + ":" + args.command + ":" + args.shortlink + ":" + args.value).encode("UTF-8"),
            hashlib.sha256
            ).hexdigest()
        }

    print(f"{data=}")
    print(f"{headers=}")

    r = requests.post(f"{'http' if args.http else 'https'}://{server}", data=data, headers=headers)
    print(r, file=sys.stderr)
    print(r.content.decode().strip())
    return 0


if __name__ == '__main__':
    try:
        sys.exit(main(get_args()))
    except KeyboardInterrupt:
        sys.exit(0)