#!/usr/bin/env python3

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

import sqlite3
import typing
import time
import os
import logging
import argparse
import coloredlogs
import ipaddress

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

DbValue = typing.Union[None, int, float, str, bytes]


class Database():
    VERSION = 3
    PATH = "blocking.db"

    def open(self) -> None:
        mode = 'rwc' if self.write else 'ro'
        uri = f'file:{self.PATH}?mode={mode}'
        self.conn = sqlite3.connect(uri, uri=True)
        self.cursor = self.conn.cursor()
        self.execute("PRAGMA foreign_keys = ON")
        # self.conn.create_function("prepare_ip4address", 1,
        #                           Database.prepare_ip4address,
        #                           deterministic=True)
        self.conn.create_function("unpack_domain", 1,
                                  lambda s: s[:-1][::-1],
                                  deterministic=True)

    def execute(self, cmd: str, args: typing.Union[
            typing.Tuple[DbValue, ...],
            typing.Dict[str, DbValue]] = None) -> None:
        # self.log.debug(cmd)
        # self.log.debug(args)
        self.cursor.execute(cmd, args or tuple())

    def get_meta(self, key: str) -> typing.Optional[int]:
        try:
            self.execute("SELECT value FROM meta WHERE key=?", (key,))
        except sqlite3.OperationalError:
            return None
        for ver, in self.cursor:
            return ver
        return None

    def set_meta(self, key: str, val: int) -> None:
        self.execute("INSERT INTO meta VALUES (?, ?) "
                     "ON CONFLICT (key) DO "
                     "UPDATE set value=?",
                     (key, val, val))

    def close(self) -> None:
        self.enter_step('close_commit')
        self.conn.commit()
        self.enter_step('close')
        self.conn.close()
        self.profile()

    def initialize(self) -> None:
        self.close()
        self.enter_step('initialize')
        if not self.write:
            self.log.error("Cannot initialize in read-only mode.")
            raise
        os.unlink(self.PATH)
        self.open()
        self.log.info("Creating database version %d.", self.VERSION)
        with open("database_schema.sql", 'r') as db_schema:
            self.cursor.executescript(db_schema.read())
        self.set_meta('version', self.VERSION)
        self.conn.commit()

    def __init__(self, write: bool = False) -> None:
        self.log = logging.getLogger('db')
        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()
        self.write = write

        self.open()
        version = self.get_meta('version')
        if version != self.VERSION:
            if version is not None:
                self.log.warning(
                    "Outdated database version: %d found, will be rebuilt.",
                    version)
            self.initialize()

    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] += 1
        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%})")

    def prepare_hostname(self, hostname: str) -> str:
        return hostname[::-1] + '.'

    def prepare_zone(self, zone: str) -> str:
        return self.prepare_hostname(zone)

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

    @staticmethod
    def prepare_ip4address(address: str) -> int:
        total = 0
        for i, octet in enumerate(address.split('.')):
            total += int(octet) << (3-i)*8
        return total
        # return '{:02x}{:02x}{:02x}{:02x}'.format(
        #     *[int(c) for c in address.split('.')])
        # return base64.b16encode(packed).decode()
        # return '{:08b}{:08b}{:08b}{:08b}'.format(
        #     *[int(c) for c in address.split('.')])
        # carg = ctypes.c_wchar_p(address)
        # ret = ACCEL.ip4_flat(carg, self.accel_ip4_buf)
        # if ret != 0:
        #     raise ValueError
        # return self.accel_ip4_buf.value
        # packed = ipaddress.ip_address(address).packed
        # return packed

    def prepare_ip4network(self, network: str) -> typing.Tuple[int, int]:
        # def prepare_ip4network(network: str) -> str:
        net = ipaddress.ip_network(network)
        mini = self.prepare_ip4address(net.network_address.exploded)
        maxi = self.prepare_ip4address(net.broadcast_address.exploded)
        # mini = net.network_address.packed
        # maxi = net.broadcast_address.packed
        return mini, maxi
        # return Database.prepare_ip4address(net.network_address.exploded)[:net.prefixlen]

    def update_references(self) -> None:
        self.enter_step('update_refs')
        self.execute('UPDATE rules AS r SET refs='
                     '(SELECT count(*) FROM rules '
                     'WHERE source=r.id)')

    def prune(self, before: int) -> None:
        self.enter_step('prune')
        self.execute('DELETE FROM rules WHERE updated<?', (before,))

    def export(self, first_party_only: bool = False,
               end_chain_only: bool = False) -> typing.Iterable[str]:
        command = 'SELECT unpack_domain(val) FROM rules ' \
            'INNER JOIN hostname ON rules.id = hostname.entry'
        restrictions: typing.List[str] = list()
        if first_party_only:
            restrictions.append('rules.first_party = 1')
        if end_chain_only:
            restrictions.append('rules.refs = 0')
        if restrictions:
            command += ' WHERE ' + ' AND '.join(restrictions)
        command += ' ORDER BY unpack_domain(val) ASC'
        self.execute(command)
        for val, in self.cursor:
            yield val

    def get_domain(self, domain: str) -> typing.Iterable[int]:
        self.enter_step('get_domain_prepare')
        domain_prep = self.prepare_hostname(domain)
        self.enter_step('get_domain_select')
        self.execute(
            'SELECT null, entry FROM hostname '
            'WHERE val=:d '
            'UNION '
            'SELECT * FROM ('
            'SELECT val, entry FROM zone '
            'WHERE val<=:d '
            'ORDER BY val DESC LIMIT 1'
            ')',
            {'d': domain_prep}
        )
        for val, entry in self.cursor:
            self.enter_step('get_domain_confirm')
            if not (val is None or domain_prep.startswith(val)):
                continue
            self.enter_step('get_domain_yield')
            yield entry

    def get_ip4(self, address: str) -> typing.Iterable[int]:
        self.enter_step('get_ip4_prepare')
        try:
            address_prep = self.prepare_ip4address(address)
        except (ValueError, IndexError):
            self.log.error("Invalid ip4address: %s", address)
            return
        self.enter_step('get_ip4_select')
        self.execute(
            'SELECT entry FROM ip4address '
            # 'SELECT null, entry FROM ip4address '
            'WHERE val=:a '
            'UNION '
            # 'SELECT * FROM ('
            # 'SELECT val, entry FROM ip4network '
            # 'WHERE val<=:a '
            # 'AND instr(:a, val) > 0 '
            # 'ORDER BY val DESC'
            # ')'
            'SELECT entry FROM ip4network '
            'WHERE :a BETWEEN mini AND maxi ',
            {'a': address_prep}
        )
        for val, entry in self.cursor:
            # self.enter_step('get_ip4_confirm')
            # if not (val is None or val.startswith(address_prep)):
            #     # PERF startswith but from the end
            #     continue
            self.enter_step('get_ip4_yield')
            yield entry

    def list_asn(self) -> typing.Iterable[typing.Tuple[str, int]]:
        self.enter_step('list_asn_select')
        self.enter_step('get_domain_select')
        self.execute('SELECT val, entry FROM asn')
        for val, entry in self.cursor:
            yield f'AS{val}', entry

    def _set_generic(self,
                     table: str,
                     select_query: str,
                     insert_query: str,
                     prep: typing.Dict[str, DbValue],
                     updated: int,
                     is_first_party: bool = False,
                     source: int = None,
                     ) -> None:
        # Since this isn't the bulk of the processing,
        # here abstraction > performaces

        # Fields based on the source
        if source is None:
            first_party = int(is_first_party)
            level = 0
        else:
            self.enter_step(f'set_{table}_source')
            self.execute(
                'SELECT first_party, level FROM rules '
                'WHERE id=?',
                (source,)
            )
            first_party, level = self.cursor.fetchone()
            level += 1

        self.enter_step(f'set_{table}_select')
        self.execute(select_query, prep)

        rules_prep: typing.Dict[str, DbValue] = {
            "source": source,
            "updated": updated,
            "first_party": first_party,
            "level": level,
        }

        # If the entry already exists
        for entry, in self.cursor:  # only one
            self.enter_step(f'set_{table}_update')
            rules_prep['entry'] = entry
            self.execute(
                'UPDATE rules SET '
                'source=:source, updated=:updated, '
                'first_party=:first_party, level=:level '
                'WHERE id=:entry AND (updated<:updated OR '
                'first_party<:first_party OR level<:level)',
                rules_prep
            )
            # Only update if any of the following:
            # - the entry is outdataed
            # - the entry was not a first_party but this is
            # - this is closer to the original rule
            return

        # If it does not exist

        if source is not None:
            self.enter_step(f'set_{table}_incsrc')
            self.execute('UPDATE rules SET refs = refs + 1 WHERE id=?',
                         (source,))

        self.enter_step(f'set_{table}_insert')
        self.execute(
            'INSERT INTO rules '
            '(source, updated, first_party, refs, level) '
            'VALUES (:source, :updated, :first_party, 0, :level) ',
            rules_prep
        )
        self.execute('SELECT id FROM rules WHERE rowid=?',
                     (self.cursor.lastrowid,))
        for entry, in self.cursor:  # only one
            prep['entry'] = entry
            self.execute(insert_query, prep)
            return
        assert False

    def set_hostname(self, hostname: str,
                     *args: typing.Any, **kwargs: typing.Any) -> None:
        self.enter_step('set_hostname_prepare')
        prep: typing.Dict[str, DbValue] = {
            'val': self.prepare_hostname(hostname),
        }
        self._set_generic(
            'hostname',
            'SELECT entry FROM hostname WHERE val=:val',
            'INSERT INTO hostname (val, entry) '
            'VALUES (:val, :entry)',
            prep,
            *args, **kwargs
        )

    def set_asn(self, asn: str,
                *args: typing.Any, **kwargs: typing.Any) -> None:
        self.enter_step('set_asn_prepare')
        try:
            asn_prep = self.prepare_asn(asn)
        except ValueError:
            self.log.error("Invalid asn: %s", asn)
            return
        prep: typing.Dict[str, DbValue] = {
            'val': asn_prep,
        }
        self._set_generic(
            'asn',
            'SELECT entry FROM asn WHERE val=:val',
            'INSERT INTO asn (val, entry) '
            'VALUES (:val, :entry)',
            prep,
            *args, **kwargs
        )

    def set_ip4address(self, ip4address: str,
                       *args: typing.Any, **kwargs: typing.Any) -> None:
        # TODO Do not add if already in ip4network
        self.enter_step('set_ip4add_prepare')
        try:
            ip4address_prep = self.prepare_ip4address(ip4address)
        except (ValueError, IndexError):
            self.log.error("Invalid ip4address: %s", ip4address)
            return
        prep: typing.Dict[str, DbValue] = {
            'val': ip4address_prep,
        }
        self._set_generic(
            'ip4add',
            'SELECT entry FROM ip4address WHERE val=:val',
            'INSERT INTO ip4address (val, entry) '
            'VALUES (:val, :entry)',
            prep,
            *args, **kwargs
        )

    def set_zone(self, zone: str,
                 *args: typing.Any, **kwargs: typing.Any) -> None:
        self.enter_step('set_zone_prepare')
        prep: typing.Dict[str, DbValue] = {
            'val': self.prepare_zone(zone),
        }
        self._set_generic(
            'zone',
            'SELECT entry FROM zone WHERE val=:val',
            'INSERT INTO zone (val, entry) '
            'VALUES (:val, :entry)',
            prep,
            *args, **kwargs
        )

    def set_ip4network(self, ip4network: str,
                       *args: typing.Any, **kwargs: typing.Any) -> None:
        self.enter_step('set_ip4net_prepare')
        try:
            ip4network_prep = self.prepare_ip4network(ip4network)
        except (ValueError, IndexError):
            self.log.error("Invalid ip4network: %s", ip4network)
            return
        prep: typing.Dict[str, DbValue] = {
            'mini': ip4network_prep[0],
            'maxi': ip4network_prep[1],
        }
        self._set_generic(
            'ip4net',
            'SELECT entry FROM ip4network WHERE mini=:mini AND maxi=:maxi',
            'INSERT INTO ip4network (mini, maxi, entry) '
            'VALUES (:mini, :maxi, :entry)',
            prep,
            *args, **kwargs
        )


if __name__ == '__main__':

    # Parsing arguments
    parser = argparse.ArgumentParser(
        description="Database operations")
    parser.add_argument(
        '-i', '--initialize', action='store_true',
        help="Reconstruct the whole database")
    parser.add_argument(
        '-p', '--prune', action='store_true',
        help="Remove old (+6 months) entries from database")
    parser.add_argument(
        '-r', '--references', action='store_true',
        help="Update the reference count")
    args = parser.parse_args()

    DB = Database(write=True)

    if args.initialize:
        DB.initialize()
    if args.prune:
        DB.prune(before=int(time.time()) - 60*60*24*31*6)
    if args.references and not args.prune:
        DB.update_references()

    DB.close()