#!/usr/bin/env python3

"""
Utility functions to interact with the database.
"""

import typing
import time
import logging
import coloredlogs
import pickle
import enum

coloredlogs.install(
    level='DEBUG',
    fmt='%(asctime)s %(name)s %(levelname)s %(message)s'
)

PathType = enum.Enum('PathType', 'Rule Hostname Zone Asn Ip4 Ip6')
RulePath = typing.Union[None]
Asn = int
DomainPath = typing.List[str]
Ip4Path = typing.Tuple[int, int]  # value, prefixlen
Ip6Path = typing.List[int]
Path = typing.Union[RulePath, DomainPath, Asn, Ip4Path, Ip6Path]
TypedPath = typing.Tuple[PathType, Path]
Timestamp = int
Level = int
Match = typing.Tuple[Timestamp, TypedPath, Level]

DebugPath = (PathType.Rule, None)


class DomainTreeNode():
    def __init__(self) -> None:
        self.children: typing.Dict[str, DomainTreeNode] = dict()
        self.match_zone: typing.Optional[Match] = None
        self.match_hostname: typing.Optional[Match] = None


class IpTreeNode():
    def __init__(self) -> None:
        self.children: typing.List[typing.Optional[IpTreeNode]] = [None, None]
        self.match: typing.Optional[Match] = None


class Profiler():
    def __init__(self) -> None:
        self.log = logging.getLogger('profiler')
        self.time_last = time.perf_counter()
        self.time_step = 'init'
        self.time_dict: typing.Dict[str, float] = dict()
        self.step_dict: typing.Dict[str, int] = dict()

    def enter_step(self, name: str) -> None:
        now = time.perf_counter()
        try:
            self.time_dict[self.time_step] += now - self.time_last
            self.step_dict[self.time_step] += int(name != self.time_step)
        except KeyError:
            self.time_dict[self.time_step] = now - self.time_last
            self.step_dict[self.time_step] = 1
        self.time_step = name
        self.time_last = time.perf_counter()

    def profile(self) -> None:
        self.enter_step('profile')
        total = sum(self.time_dict.values())
        for key, secs in sorted(self.time_dict.items(), key=lambda t: t[1]):
            times = self.step_dict[key]
            self.log.debug(f"{key:<20}: {times:9d} × {secs/times:5.3e} "
                           f"= {secs:9.2f} s ({secs/total:7.2%}) ")
        self.log.debug(f"{'total':<20}:                         "
                       f"{total:9.2f} s ({1:7.2%})")


class Database(Profiler):
    VERSION = 8
    PATH = "blocking.p"

    def initialize(self) -> None:
        self.log.warning(
            "Creating database version: %d ",
            Database.VERSION)
        self.domtree = DomainTreeNode()
        self.asns: typing.Set[Asn] = set()
        self.ip4tree = IpTreeNode()

    def load(self) -> None:
        self.enter_step('load')
        try:
            with open(self.PATH, 'rb') as db_fdsec:
                version, data = pickle.load(db_fdsec)
                if version == Database.VERSION:
                    self.domtree, self.asns, self.ip4tree = data
                    return
                self.log.warning(
                    "Outdated database version found: %d, "
                    "will be rebuilt.",
                    version)
        except (TypeError, AttributeError, EOFError):
            self.log.error(
                "Corrupt database found, "
                "will be rebuilt.")
        except FileNotFoundError:
            pass
        self.initialize()

    def save(self) -> None:
        self.enter_step('save')
        with open(self.PATH, 'wb') as db_fdsec:
            data = self.domtree, self.asns, self.ip4tree
            pickle.dump((self.VERSION, data), db_fdsec)
        self.profile()

    def __init__(self) -> None:
        Profiler.__init__(self)
        self.log = logging.getLogger('db')
        self.load()

    @staticmethod
    def pack_domain(domain: str) -> DomainPath:
        return domain.split('.')[::-1]

    @staticmethod
    def unpack_domain(domain: DomainPath) -> str:
        return '.'.join(domain[::-1])

    @staticmethod
    def pack_asn(asn: str) -> int:
        asn = asn.upper()
        if asn.startswith('AS'):
            asn = asn[2:]
        return int(asn)

    @staticmethod
    def unpack_asn(asn: int) -> str:
        return f'AS{asn}'

    @staticmethod
    def pack_ip4address(address: str) -> Ip4Path:
        addr = 0
        for split in address.split('.'):
            addr = (addr << 8) + int(split)
        return (addr, 32)

    @staticmethod
    def unpack_ip4address(address: Ip4Path) -> str:
        addr, prefixlen = address
        assert prefixlen == 32
        octets: typing.List[int] = list()
        octets = [0] * 4
        for o in reversed(range(4)):
            octets[o] = addr & 0xFF
            addr >>= 8
        return '.'.join(map(str, octets))

    @staticmethod
    def pack_ip4network(network: str) -> Ip4Path:
        address, prefixlen_str = network.split('/')
        prefixlen = int(prefixlen_str)
        addr, _ = Database.pack_ip4address(address)
        return (addr, prefixlen)

    @staticmethod
    def unpack_ip4network(network: Ip4Path) -> str:
        address, prefixlen = network
        addr = Database.unpack_ip4address((address, 32))
        return f'{addr}/{prefixlen}'

    def update_references(self) -> None:
        raise NotImplementedError

    def prune(self, before: int, base_only: bool = False) -> None:
        raise NotImplementedError

    def explain(self, entry: int) -> str:
        raise NotImplementedError

    def export(self,
               first_party_only: bool = False,
               end_chain_only: bool = False,
               explain: bool = False,
               _dic: DomainTreeNode = None,
               _par: DomainPath = None,
               ) -> typing.Iterable[str]:
        if first_party_only or end_chain_only or explain:
            raise NotImplementedError
        _dic = _dic or self.domtree
        _par = _par or list()
        if _dic.match_hostname:
            yield self.unpack_domain(_par)
        for part in _dic.children:
            dic = _dic.children[part]
            yield from self.export(_dic=dic,
                                   _par=_par + [part])

    def count_rules(self,
                    first_party_only: bool = False,
                    ) -> str:
        raise NotImplementedError

    def get_domain(self, domain_str: str) -> typing.Iterable[TypedPath]:
        self.enter_step('get_domain_pack')
        domain = self.pack_domain(domain_str)
        self.enter_step('get_domain_brws')
        dic = self.domtree
        depth = 0
        for part in domain:
            if dic.match_zone:
                self.enter_step('get_domain_yield')
                yield (PathType.Zone, domain[:depth])
            self.enter_step('get_domain_brws')
            if part not in dic.children:
                return
            dic = dic.children[part]
            depth += 1
        if dic.match_zone:
            self.enter_step('get_domain_yield')
            yield (PathType.Zone, domain)
        if dic.match_hostname:
            self.enter_step('get_domain_yield')
            yield (PathType.Hostname, domain)

    def get_ip4(self, ip4_str: str) -> typing.Iterable[TypedPath]:
        self.enter_step('get_ip4_pack')
        ip4, prefixlen = self.pack_ip4address(ip4_str)
        self.enter_step('get_ip4_brws')
        dic = self.ip4tree
        for i in reversed(range(prefixlen)):
            part = (ip4 >> i) & 0b1
            if dic.match:
                self.enter_step('get_ip4_yield')
                yield (PathType.Ip4, (ip4, 32-i))
            self.enter_step('get_ip4_brws')
            next_dic = dic.children[part]
            if next_dic is None:
                return
            dic = next_dic
        if dic.match:
            self.enter_step('get_ip4_yield')
            yield (PathType.Ip4, ip4)

    def list_asn(self) -> typing.Iterable[TypedPath]:
        for asn in self.asns:
            yield (PathType.Asn, asn)

    def set_hostname(self,
                     hostname_str: str,
                     updated: int,
                     is_first_party: bool = None,
                     source: TypedPath = None) -> None:
        self.enter_step('set_hostname_pack')
        if is_first_party or source:
            raise NotImplementedError
        self.enter_step('set_hostname_brws')
        hostname = self.pack_domain(hostname_str)
        dic = self.domtree
        for part in hostname:
            if dic.match_zone:
                # Refuse to add hostname whose zone is already matching
                return
            if part not in dic.children:
                dic.children[part] = DomainTreeNode()
            dic = dic.children[part]
        dic.match_hostname = (updated, DebugPath, 0)

    def set_zone(self,
                 zone_str: str,
                 updated: int,
                 is_first_party: bool = None,
                 source: TypedPath = None) -> None:
        self.enter_step('set_zone_pack')
        if is_first_party or source:
            raise NotImplementedError
        zone = self.pack_domain(zone_str)
        self.enter_step('set_zone_brws')
        dic = self.domtree
        for part in zone:
            if dic.match_zone:
                # Refuse to add zone whose parent zone is already matching
                return
            if part not in dic.children:
                dic.children[part] = DomainTreeNode()
            dic = dic.children[part]
        dic.match_zone = (updated, DebugPath, 0)

    def set_asn(self,
                asn_str: str,
                updated: int,
                is_first_party: bool = None,
                source: TypedPath = None) -> None:
        self.enter_step('set_asn_pack')
        if is_first_party or source:
            # TODO updated
            raise NotImplementedError
        asn = self.pack_asn(asn_str)
        self.enter_step('set_asn_brws')
        self.asns.add(asn)

    def set_ip4address(self,
                       ip4address_str: str,
                       updated: int,
                       is_first_party: bool = None,
                       source: TypedPath = None) -> None:
        self.enter_step('set_ip4add_pack')
        if is_first_party or source:
            raise NotImplementedError
        ip4, prefixlen = self.pack_ip4address(ip4address_str)
        self.enter_step('set_ip4add_brws')
        dic = self.ip4tree
        for i in reversed(range(prefixlen)):
            part = (ip4 >> i) & 0b1
            if dic.match:
                # Refuse to add ip4address whose network is already matching
                return
            next_dic = dic.children[part]
            if next_dic is None:
                next_dic = IpTreeNode()
                dic.children[part] = next_dic
            dic = next_dic
        dic.match = (updated, DebugPath, 0)

    def set_ip4network(self,
                       ip4network_str: str,
                       updated: int,
                       is_first_party: bool = None,
                       source: TypedPath = None) -> None:
        self.enter_step('set_ip4net_pack')
        if is_first_party or source:
            raise NotImplementedError
        self.enter_step('set_ip4net_brws')
        ip4, prefixlen = self.pack_ip4network(ip4network_str)
        dic = self.ip4tree
        for i in reversed(range(prefixlen)):
            part = (ip4 >> i) & 0b1
            if dic.match:
                # Refuse to add ip4network whose parent network
                # is already matching
                return
            next_dic = dic.children[part]
            if next_dic is None:
                next_dic = IpTreeNode()
                dic.children[part] = next_dic
            dic = next_dic
        dic.match = (updated, DebugPath, 0)