#!/usr/bin/env python3
# pylint: disable=C0103

"""
From a list of subdomains, output only
the ones resolving to a first-party tracker.
"""

import logging
import threading
import queue
import os
import re
import sys
import typing

import coloredlogs
import dns.exception
import dns.resolver
import progressbar

import regexes

DNS_TIMEOUT = 60.0

# TODO Try again does not work because sentinel get through first :/

class DnsResolver(threading.Thread):
    """
    Worker process for a DNS resolver.
    Will resolve DNS to match first-party subdomains.
    """

    def __init__(self,
                 in_queue: queue.Queue,
                 out_queue: queue.Queue,
                 server: str):
        super(DnsResolver, self).__init__()
        self.log = logging.getLogger(server)

        self.in_queue = in_queue
        self.out_queue = out_queue

        self.resolver = dns.resolver.Resolver()
        self.resolver.nameservers = [server]

    def is_subdomain_matching(self, subdomain: str) -> typing.Optional[bool]:
        """
        Indicates if the subdomain redirects to a first-party tracker.
        """
        # TODO Look at the whole chain rather than the last one
        # TODO Also match the ASN of the IP (caching the ASN subnetworks will do)
        try:
            query = self.resolver.query(subdomain, 'A', lifetime=DNS_TIMEOUT)
        except dns.resolver.NXDOMAIN:
            return False
        except dns.resolver.NoAnswer:
            return False
        except dns.resolver.YXDOMAIN:
            self.log.warning("Query name too long for %s", subdomain)
            return False
        except dns.resolver.NoNameservers:
            self.log.warning("All nameservers broken for %s", subdomain)
            return None
        except dns.exception.Timeout:
            self.log.warning("Timeout for %s", subdomain)
            return None
        except dns.name.EmptyLabel:
            self.log.warning("Empty label for %s", subdomain)
            return False
        canonical = query.canonical_name.to_text()
        for regex in regexes.REGEXES:
            if re.match(regex, canonical):
                return True
        return False

    def run(self) -> None:
        self.log.info("Started")
        for subdomain in iter(self.in_queue.get, None):
            matching = self.is_subdomain_matching(subdomain)

            # If issue, retry
            if matching is None:
                # matching = False
                self.in_queue.put(subdomain)
                continue

            result = (subdomain, matching)
            # self.log.debug("%s", result)
            self.out_queue.put(result)
        self.out_queue.put(None)
        self.log.info("Stopped")


def get_matching_subdomains(subdomains: typing.Iterable[str],
                            nameservers: typing.List[str] = None,
                            ) -> typing.Iterable[typing.Tuple[str, bool]]:
    subdomains_queue: queue.Queue = queue.Queue()
    results_queue: queue.Queue = queue.Queue()
    """
    Orchestrator of the different DnsResolver threads.
    """

    # Use interal resolver by default
    servers = nameservers or dns.resolver.Resolver().nameservers

    # Create workers
    for server in servers:
        DnsResolver(subdomains_queue, results_queue, server).start()

    # Send data to workers
    for subdomain in subdomains:
        subdomains_queue.put(subdomain)

    # Send sentinel to each worker
    # sentinel = None ~= EOF
    for _ in servers:
        subdomains_queue.put(None)

    # Wait for one sentinel per worker
    # In the meantime output results
    for _ in servers:
        for result in iter(results_queue.get, None):
            yield result


if __name__ == '__main__':
    coloredlogs.install(
        level='DEBUG',
        fmt='%(asctime)s %(name)s[%(process)d] %(levelname)s %(message)s'
    )

    # Progress bar
    widgets = [
        progressbar.Percentage(),
        ' ', progressbar.SimpleProgress(),
        ' ', progressbar.Bar(),
        ' ', progressbar.Timer(),
        ' ', progressbar.AdaptiveTransferSpeed(unit='req'),
        ' ', progressbar.AdaptiveETA(),
    ]
    progress = progressbar.ProgressBar(widgets=widgets)

    # Parsing arguments
    assert len(sys.argv) <= 2
    filename = None

    if len(sys.argv) == 2 and sys.argv[1] != '-':
        filename = sys.argv[1]
        progress.max_value = sum(1 for line in open(filename))
        textio = open(filename)
    else:
        textio = sys.stdin

    # Cleaning input
    iterator = iter(textio)
    iterator = map(str.strip, iterator)
    iterator = filter(None, iterator)

    # Reading nameservers
    servers: typing.List[str] = list()
    if os.path.isfile('nameservers'):
        servers = open('nameservers').readlines()
        servers = list(filter(None, map(str.strip, servers)))

    progress.start()
    for subdomain, matching in get_matching_subdomains(iterator, servers):
        progress.update(progress.value + 1)
        if matching:
            print(subdomain)
    progress.finish()