#!/usr/bin/env python3
"""
simple client for que.run
"""

import argparse
import configparser
import functools
import http.client
import logging
import os
import subprocess
import sys
import time
import urllib.parse
import urllib.request as request

MAX_TIMEOUT = 99999999  # basically never timeout


def auth(args):
    "Returns the auth key for the given ns from ~/.config/que.conf"
    logging.debug("auth")
    namespace = args.target.split("/")[0]
    if namespace == "pub":
        return None
    conf_file = os.path.expanduser("~/.config/que.conf")
    if not os.path.exists(conf_file):
        sys.exit("you need a ~/.config/que.conf")
    cfg = configparser.ConfigParser()
    cfg.read(conf_file)
    return cfg[namespace]["key"]


def autodecode(bytestring):
    """Attempt to decode bytes `bs` into common codecs, preferably utf-8. If
    no decoding is available, just return the raw bytes.

    For all available codecs, see:
    <https://docs.python.org/3/library/codecs.html#standard-encodings>

    """
    logging.debug("autodecode")
    codecs = ["utf-8", "ascii"]
    for codec in codecs:
        try:
            return bytestring.decode(codec)
        except UnicodeDecodeError:
            pass
    return bytestring


def retry(exception, tries=4, delay=3, backoff=2):
    "Decorator for retrying an action."

    def decorator(func):
        @functools.wraps(func)
        def func_retry(*args, **kwargs):
            mtries, mdelay = tries, delay
            while mtries > 1:
                try:
                    return func(*args, **kwargs)
                except exception as ex:
                    logging.debug(ex)
                    logging.debug("retrying...")
                    time.sleep(mdelay)
                    mtries -= 1
                    mdelay *= backoff
            return func(*args, **kwargs)

        return func_retry

    return decorator


def send(args):
    "Send a message to the que."
    logging.debug("send")
    key = auth(args)
    data = args.infile
    req = request.Request(f"{args.host}/{args.target}")
    req.add_header("User-AgenT", "Que/Client")
    if key:
        req.add_header("Authorization", key)
    if args.serve:
        logging.debug("serve")
        while not time.sleep(1):
            request.urlopen(req, data=data, timeout=MAX_TIMEOUT)

    else:
        request.urlopen(req, data=data, timeout=MAX_TIMEOUT)


def then(args, msg):
    "Perform an action when passed `--then`."
    if args.then:
        logging.debug("then")
        subprocess.run(
            args.then.format(msg=msg, que=args.target), check=False, shell=True,
        )


@retry(http.client.IncompleteRead, tries=10, delay=5, backoff=1)
@retry(http.client.RemoteDisconnected, tries=10, delay=2, backoff=2)
def recv(args):
    "Receive a message from the que."
    logging.debug("recv on: %s", args.target)
    params = urllib.parse.urlencode({"poll": args.poll})
    req = request.Request(f"{args.host}/{args.target}?{params}")
    req.add_header("User-Agent", "Que/Client")
    key = auth(args)
    if key:
        req.add_header("Authorization", key)
    with request.urlopen(req) as _req:
        if args.poll:
            logging.debug("poll")
            while not time.sleep(1):
                logging.debug("reading")
                msg = autodecode(_req.readline())
                logging.debug("read")
                print(msg, end="")
                then(args, msg)
        else:
            msg = autodecode(_req.read())
            print(msg)
            then(args, msg)


def get_args():
    "Command line parser"
    cli = argparse.ArgumentParser(description=__doc__)
    cli.add_argument("--debug", action="store_true", help="log to stderr")
    cli.add_argument(
        "--host", default="http://que.run", help="where que-server is running"
    )
    cli.add_argument(
        "--poll", default=False, action="store_true", help="stream data from the que"
    )
    cli.add_argument(
        "--then",
        help=" ".join(
            [
                "when polling, run this shell command after each response,",
                "presumably for side effects,"
                r"replacing '{que}' with the target and '{msg}' with the body of the response",
            ]
        ),
    )
    cli.add_argument(
        "--serve",
        default=False,
        action="store_true",
        help=" ".join(
            [
                "when posting to the que, do so continuously in a loop.",
                "this can be used for serving a webpage or other file continuously",
            ]
        ),
    )
    cli.add_argument(
        "target", help="namespace and path of the que, like 'ns/path/subpath'"
    )
    cli.add_argument(
        "infile",
        nargs="?",
        type=argparse.FileType("rb"),
        help="data to put on the que. Use '-' for stdin, otherwise should be a readable file",
    )
    return cli.parse_args()


if __name__ == "__main__":
    ARGV = get_args()
    if ARGV.debug:
        logging.basicConfig(
            format="%(asctime)s %(message)s",
            level=logging.DEBUG,
            datefmt="%Y.%m.%d..%H.%M.%S",
        )
    try:
        if ARGV.infile:
            send(ARGV)
        else:
            recv(ARGV)
    except KeyboardInterrupt:
        sys.exit(0)