from pynzb import nzb_parser
import asyncore
import asynchat
import argparse
import socket
import ssl
import sys
import re

debug = False
VERSION = 0.1

NNTP_TERMINATOR="\r\n"

class NZBParser():
    """
    Crude NZB Parser.
    We initialize a few things for tracking stats in here, as well as making
    huge arrays of things we probably don't need.
    """
    def __init__(self):
        self.results = {
            "totalBytes": 0,
            "totalFiles": 0,
            "totalArticles": 0,
            "nzbdata": None,
        }

    def parse(self, filename):
        """
        Open the given file and parse it.
        """
        try:
            fh = open(filename)
        except:
            print(("ERROR: Could not open NZB file '{filename}'".format(
                filename=filename)))
            sys.exit(1)

        nzbxml = fh.read()
        fh.close()

        nzbdata = nzbparser.parse(nzbxml)
        for nzb in nzbdata:
            self.results["totalFiles"] += 1
            for segment in nzb.segments:
                self.results["totalArticles"] += 1
                self.results["totalBytes"] += segment.bytes
        self.results["nzbdata"] = nzbdata
        return self.results


class async_chat_ssl(asynchat.async_chat):
    """
    Class to make wrap asynchat in SSL
    """
    def connect(self, host, use_ssl=False):
        """
        If we're connecting with SSL, set the socket to blocking.
        """
        self.use_ssl = use_ssl
        if use_ssl:
            self.socket.setblocking(1)
        asynchat.async_chat.connect(self, host)

    def handle_connect(self):
        """
        Wrap the socket with SSL when we connect.
        """
        if self.use_ssl:
            self.ssl = ssl.wrap_socket(self.socket)
            self.set_socket(self.ssl)

    def push(self, data):
        """
        Small wrapper for the push method, so that we can print
        out what we're pushing in debug mode.
        """
        if debug:
            print(data)
        asynchat.async_chat.push(self, "{data}{terminator}".format(
            data=data,
            terminator=NNTP_TERMINATOR
        ))


class NZBHandler(async_chat_ssl):
    def __init__(self, config, nzbdata):
        # asynchat
        asynchat.async_chat.__init__(self)
        self.set_terminator(NNTP_TERMINATOR)
        self.data = ""
        # Config
        self.conf = config
        self.nzbdata = nzbdata["nzbdata"]
        self.remaining = nzbdata["totalArticles"]
        self.totalArticles = nzbdata["totalArticles"]
        self.missing = 0
        # Status
        self.authed = False
        self.curgrp = None
        self.working = None
        self.finished = False
        self.groupname = None

    # NNTP commands that we need to send
    def group(self, groupname):
        """
        Change to a new newsgroup
        """
        self.working = True
        self.push("GROUP {groupname}".format(groupname=groupname))
        self.changed = groupname

    def noop(self):
        """
        We use the "DATE" command to do nothing, since it's cheap.
        """
        self.working = True
        self.push("DATE")

    def stat(self, article):
        """
        STAT an article in the active newsgroup
        """
        self.working = True
        self.push("STAT <{article}>".format(article=article))

    def quit(self):
        """
        QUIT and disconnect from the server.
        """
        self.working = True
        self.push("QUIT")

    # Methods for handling NNTP responses
    # DATE response.
    def response_111(self):
        self.working = False

    # Welcome banner. We send our username.
    def response_200(self):
        if self.conf.username:
            self.push("AUTHINFO USER {username}".format(
                username=self.conf.username))

    # Disconnecting.
    def response_205(self):
        if debug:
            print("205: Disconnecting.")
        self.close()
        self.finished = True

    # Group switched successfully.
    def response_211(self):
        if debug:
            print("211: Group switched.")
        self.curgrp = self.changed
        self.working = False

    # Article exists
    def response_223(self):
        if debug:
            print("223: Article exists.")
        self.working = False

    # Authenticated successfully.
    def response_281(self):
        if debug:
            print("281: Authentication successful.")
        self.authed = True

    # Request for further authentication, send password.
    def response_381(self):
        self.push("AUTHINFO PASS {password}".format(
            password=self.conf.password))

    # Non-existant group
    def response_411(self):
        if debug:
            print("411: Group does not exist.")
        self.working = False

    # No such article number in this group
    def response_423(self):
        if debug:
            print("423: No such article in this group.")
        self.working = False
        self.missing += 1

    # No such article found
    def response_430(self):
        if debug:
            print("430: No such article found.")
        self.working = False
        self.missing += 1

    # Authentication failed. We'll quit if we hit this.
    def response_452(self):
        if debug:
            print("452: Authentication failed.")
        self.working = False
        self.quit()

    # Command not recognised. We'll quit if we hit this.
    def response_500(self):
        if debug:
            print("500: Command not recognised.")
        if debug:
            print(("Command was: '{command}'.".format(command=self.lastcommand)))
        self.working = False
        self.quit()

    # Access restriction/permission denied
    def response_502(self):
        if debug:
            print("502: Access restriction.")
        self.working = False
        self.quit()

    # Get the next message_id from the nzbdata
    def get_message_id(self):
        message_id = None
        if len(self.nzbdata[0].segments) > 0:
            segment = self.nzbdata[0].segments.pop()
            self.groupname = self.nzbdata[0].groups[0]
            message_id = segment.message_id
        else:
            self.nzbdata.pop(0)
            self.groupname = None
            message_id = ""

    # Buffer incoming data until we get the terminator
    def collect_incoming_data(self, data):
        """
        Buffer the incoming data.
        """
        self.data += data

    def found_terminator(self):
        """
        Called when we find the terminator in the incoming data
        """
        if debug:
            print((self.data))
        nntpcode = self.data[0:3]

        # Call the appropriate method
        m = 'response_{nntpcode}'.format(nntpcode=str(nntpcode))
        if hasattr(self, m):
            getattr(self, m)()
        else:
            print(("Handler not found for response '{nntpcode}'."
                  " Quitting.".format(nntpcode=nntpcode)))
            self.quit()

        if self.finished:
            return

        if len(self.nzbdata) == 0:
            self.quit()
        # OK, here we actually do the work of switching groups and
        # checking articles.
        if self.authed and not self.working:
            message_id = None
            if len(self.nzbdata[0].segments) > 0:
                segment = self.nzbdata[0].segments.pop()
                self.groupname = self.nzbdata[0].groups[0]
                message_id = segment.message_id
            else:
                self.nzbdata.pop(0)
                self.noop()
                self.groupname = None

            if message_id:
                msg = "Remaining: {remaining}".format(remaining=self.remaining)
                if debug:
                    print (msg)
                else:
                    print((" " * (len(msg) + 1)), end=' ')
                    print(("\r{msg}".format(msg=msg)), end=' ')
                    sys.stdout.flush()
                self.stat(message_id)
                self.remaining -= 1

        # Clear out the data ready for the next run
        self.data = ""

    def completion(self):
        presentArticles = self.totalArticles - self.missing
        return 100 * float(presentArticles) / float(self.totalArticles)

    def run(self, host, port, sslmode):
        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
        self.connect((host, port), use_ssl=sslmode)
        asyncore.loop()


def getopts():
    argparser = argparse.ArgumentParser(
        description="Check article completion on an NNTP server",
        epilog="Note: The checking may take a while to complete, "
        "depending on the number of articles."
    )
    argparser.add_argument(
        '-s', '--server',
        type=str,
        required=True,
        help="Server to connect to.",
    )
    argparser.add_argument(
        '-p', '--port',
        type=int,
        default=119,
        help="Specify the port that the server is listening on.",
    )
    argparser.add_argument(
        '-S', '--ssl',
        type=bool,
        metavar='[0,1]',
        default=False,
        help="Enable SSL mode.",
    )
    argparser.add_argument(
        '-u', '--username',
        type=str,
        help="Username to authenticate as.",
    )
    argparser.add_argument(
        '-P', '--password',
        type=str,
        help="Password to authenticate with.",
    )
    argparser.add_argument(
        '-f', '--filename',
        type=str,
        required=True,
        help="NZB file to check.",
    )
    argparser.add_argument(
        '-d', '--debug',
        type=bool,
        metavar='[0,1]',
        default=False,
        help="Enable verbose output.",
    )
    argparser.add_argument(
        '-v', '--version',
        action='version',
        version='%(prog)s v{version}'.format(version=str(VERSION)),
        help="Show version information.",
    )

    return argparser.parse_args()


def pretty_size(size, real=True):
    suffixes = {
        1000: [
            'KB', 'MB', 'GB',
            'TB', 'PB', 'EB',
            'ZB', 'YB'
        ],
        1024: [
            'KiB', 'MiB', 'GiB',
            'TiB', 'PiB', 'EiB',
            'ZiB', 'YiB'
        ],
    }

    multiple = 1024 if real else 1000

    for suffix in suffixes[multiple]:
        size /= multiple
        if size < multiple:
            return '{size:.1f} {suffix}'.format(size=size, suffix=suffix)

if __name__ == '__main__':

    conf = getopts()
    if conf.debug:
        debug = True
    nzbparser = NZBParser()
    results = nzbparser.parse(conf.filename)
    print("")
    print("NZB Parsing Results")
    print("===================")
    print("Totals")
    print(("\tFiles: {files}".format(files=results["totalFiles"])))
    print(("\tArticles: {articles}".format(articles=results["totalArticles"])))
    print(("\tArticle Size: {size}".format(
        size=pretty_size(results["totalBytes"]))))
    print("")

    print("Be patient, this might take a while :)")
    nzbhandler = NZBHandler(conf, results)
    nzbhandler.run(conf.server, conf.port, conf.ssl)

    print("\n")
    print("NZB Checking Results")
    print("====================")
    print("Totals")
    print(("\tMissing Articles: {missing}".format(missing=nzbhandler.missing)))
    print(("\tCompletion: {percent:.2f}%".format(
        percent=nzbhandler.completion())))
    print("")
    print("All done!")