#
# Store information about servers. Filter and select based on their protocol support, etc.
#
import random
import json
from .constants import DEFAULT_PORTS


class ServerInfo(dict):
    """
    Information to be stored on a server. Originally based on IRC data published to a channel.

    """

    FIELDS = ["nickname", "hostname", "ports", "version", "pruning_limit"]

    # pylint: disable=too-many-arguments
    def __init__(
        self,
        nickname_or_dict,
        hostname=None,
        ports=None,
        version=None,
        pruning_limit=None,
        ip_addr=None,
    ):
        if not hostname and not ports:
            # promote a dict, or similar
            super().__init__(nickname_or_dict)
            return

        self["nickname"] = nickname_or_dict or None
        self["hostname"] = hostname
        self["ip_addr"] = ip_addr or None

        # For 'ports', take
        # - a number (int), assumed to be TCP port, OR
        # - a list of codes, OR
        # - a string to be split apart.
        # Keep version and pruning limit separate
        #
        if isinstance(ports, int):
            ports = [f"t{int(ports)}"]
        elif isinstance(ports, str):
            ports = ports.split()

        # check we don't have junk in the ports list
        for p in ports.copy():
            if p[0] == "v":
                version = p[1:]
                ports.remove(p)
            elif p[0] == "p":
                try:
                    pruning_limit = int(p[1:])
                except ValueError:
                    # ignore junk
                    pass
                ports.remove(p)

        assert ports, "Must have at least one port/protocol"

        self["ports"] = ports
        self["version"] = version
        self["pruning_limit"] = int(pruning_limit or 0)

    @classmethod
    def from_response(cls, response_list):
        # Create a list of servers based on data from response from Stratum.
        # Give this the response to: "server.peers.subscribe"
        #
        #     [...
        #      "91.63.237.12",
        #      "electrum3.hachre.de",
        #      [ "v1.0", "p10000", "t", "s" ]
        #       ...]
        #
        rv = []

        for params in response_list:
            ip_addr, hostname, ports = params

            if ip_addr == hostname:
                ip_addr = None

            rv.append(ServerInfo(None, hostname, ports, ip_addr=ip_addr))

        return rv

    @classmethod
    def from_dict(cls, d):
        n = d.pop("nickname", None)
        h = d.pop("hostname")
        p = d.pop("ports")
        rv = cls(n, h, p)
        rv.update(d)
        return rv

    @property
    def protocols(self):
        rv = set(i[0] for i in self["ports"])
        assert "p" not in rv, "pruning limit got in there"
        assert "v" not in rv, "version got in there"
        return rv

    @property
    def pruning_limit(self):
        return self.get("pruning_limit", 100)

    @property
    def hostname(self):
        return self.get("hostname")

    def get_port(self, for_protocol):
        """
        Return (hostname, port number, ssl) pair for the protocol.
        Assuming only one port per host.
        """
        assert len(for_protocol) == 1, "expect single letter code"

        use_ssl = for_protocol == "s"

        if "port" in self:
            return self["hostname"], int(self["port"]), use_ssl

        rv = next(i for i in self["ports"] if i[0] == for_protocol)

        port = None
        if len(rv) >= 2:
            try:
                port = int(rv[1:])
            except BaseException:
                pass
        port = port or DEFAULT_PORTS[for_protocol]

        return self["hostname"], port, use_ssl

    @property
    def is_onion(self):
        return self["hostname"].lower().endswith(".onion")

    def select(self, protocol="s", is_onion=None, min_prune=0):
        # predicate function for selection based on features/properties
        return (
            (protocol in self.protocols)
            and (self.is_onion == is_onion if is_onion is not None else True)
            and (self.pruning_limit >= min_prune)
        )

    def __repr__(self):
        # pylint: disable=consider-using-f-string
        return '<ServerInfo {hostname} nick={nickname} ports="{ports}" v={version} prune={pruning_limit}>'.format(
            **self
        )

    def __str__(self):
        # used as a dict key in a few places.
        return self["hostname"].lower()

    def __hash__(self):
        # this one-line allows use as a set member, which is really handy!
        return hash(self["hostname"].lower())


class KnownServers(dict):
    """
    Store a list of known servers and their port numbers, etc.

    - can add single entries
    - can read from a CSV for seeding/bootstrap
    - can read from IRC channel to find current hosts

    We are a dictionary, with key being the hostname (in lowercase) of the server.
    """

    def from_json(self, fname):
        """
        Read contents of a CSV containing a list of servers.
        """
        with open(fname, "rt", encoding="utf-8") as fp:
            for row in json.load(fp):
                nn = ServerInfo.from_dict(row)
                self[str(nn)] = nn

    def add_single(self, hostname, ports, nickname=None, **kws):
        """
        Explicitly add a single entry.
        Hostname is a FQDN and ports is either a single int (assumed to be TCP port)
        or Electrum protocol/port number specification with spaces in between.
        """
        nickname = nickname or hostname

        self[hostname.lower()] = ServerInfo(nickname, hostname, ports, **kws)

    def add_peer_response(self, response_list):
        # Update with response from Stratum (lacks the nickname value tho):
        #
        #      "91.63.237.12",
        #      "electrum3.hachre.de",
        #      [ "v1.0", "p10000", "t", "s" ]
        #
        additions = set()
        for params in response_list:
            ip_addr, hostname, ports = params

            if ip_addr == hostname:
                ip_addr = None

            g = self.get(hostname.lower())
            nickname = g["nickname"] if g else None

            here = ServerInfo(nickname, hostname, ports, ip_addr=ip_addr)
            self[str(here)] = here

            if not g:
                additions.add(str(here))

        return additions

    def save_json(self, fname="servers.json"):
        """
        Write out to a CSV file.
        """
        rows = sorted(self.keys())
        with open(fname, "wt", encoding="utf-8") as fp:
            json.dump([self[k] for k in rows], fp, indent=1)

    def dump(self):
        return "\n".join(repr(i) for i in self.values())

    def select(self, **kws):
        """
        Find all servers with indicated protocol support. Shuffled.

        Filter by TOR support, and pruning level.
        """
        lst = [i for i in self.values() if i.select(**kws)]

        random.shuffle(lst)

        return lst