# -*- coding: utf-8 -*-
'''
Common utilities
'''
import errno
import io
import os
import socket
import struct
import threading
import time
import types
from functools import partial
from typing import Any, Callable, Literal, Optional, TypeVar, Union

basestring = (str, bytes)
file = io.BytesIO

AF_MPLS = 28
_uuid32 = 0  # (singleton) the last uuid32 value saved to avoid collisions
_uuid32_lock = threading.Lock()
USE_DEFAULT_TIMEOUT = -1

size_suffixes = {
    'b': 1,
    'k': 1024,
    'kb': 1024,
    'm': 1024 * 1024,
    'mb': 1024 * 1024,
    'g': 1024 * 1024 * 1024,
    'gb': 1024 * 1024 * 1024,
    'kbit': 1024 / 8,
    'mbit': 1024 * 1024 / 8,
    'gbit': 1024 * 1024 * 1024 / 8,
}


time_suffixes = {
    's': 1,
    'sec': 1,
    'secs': 1,
    'ms': 1000,
    'msec': 1000,
    'msecs': 1000,
    'us': 1000000,
    'usec': 1000000,
    'usecs': 1000000,
}

rate_suffixes = {
    'bit': 1,
    'Kibit': 1024,
    'kbit': 1000,
    'mibit': 1024 * 1024,
    'mbit': 1000000,
    'gibit': 1024 * 1024 * 1024,
    'gbit': 1000000000,
    'tibit': 1024 * 1024 * 1024 * 1024,
    'tbit': 1000000000000,
    'Bps': 8,
    'KiBps': 8 * 1024,
    'KBps': 8000,
    'MiBps': 8 * 1024 * 1024,
    'MBps': 8000000,
    'GiBps': 8 * 1024 * 1024 * 1024,
    'GBps': 8000000000,
    'TiBps': 8 * 1024 * 1024 * 1024 * 1024,
    'TBps': 8000000000000,
}


##
# General purpose
#
class Namespace:
    def __init__(self, parent, override=None):
        raise NotImplementedError()


def _no_change(s: str) -> str:
    return s


def _default_normalize(s: str, prefix: str) -> str:
    return s[len(prefix) :].lower()


def map_namespace(
    prefix: str,
    ns: dict[str, Any],
    normalize: Union[None, Literal[True], Callable[[str], str]] = None,
) -> tuple[dict[str, int], dict[int, str]]:
    '''
    Take the namespace prefix, list all constants and build two
    dictionaries -- straight and reverse mappings. E.g.:

    ## neighbor attributes
    NDA_UNSPEC = 0
    NDA_DST = 1
    NDA_LLADDR = 2
    NDA_CACHEINFO = 3
    NDA_PROBES = 4
    (NDA_NAMES, NDA_VALUES) = map_namespace('NDA', globals())

    Will lead to::

        NDA_NAMES = {'NDA_UNSPEC': 0,
                     ...
                     'NDA_PROBES': 4}
        NDA_VALUES = {0: 'NDA_UNSPEC',
                      ...
                      4: 'NDA_PROBES'}

    The `normalize` parameter can be:

        - None — no name transformation will be done
        - True — cut the prefix and `lower()` the rest
        - lambda x: … — apply the function to every name
    '''
    transform: Callable[[str], str]

    if normalize is None:
        transform = _no_change
    elif normalize is True:
        transform = partial(_default_normalize, prefix=prefix)
    elif isinstance(normalize, types.FunctionType):
        transform = normalize
    else:
        raise ValueError("Invalid value for `normalize` parameter")

    by_name = {transform(i): ns[i] for i in ns.keys() if i.startswith(prefix)}
    by_value = {ns[i]: transform(i) for i in ns.keys() if i.startswith(prefix)}
    return (by_name, by_value)


def getbroadcast(
    addr: str, mask: int, family: socket.AddressFamily = socket.AF_INET
) -> str:
    # 1. convert addr to int
    i = socket.inet_pton(family, addr)
    if family == socket.AF_INET:
        i_unpacked = struct.unpack('>I', i)[0]
        a = 0xFFFFFFFF
        length = 32
    elif family == socket.AF_INET6:
        i_unpacked = struct.unpack('>QQ', i)
        i_unpacked = i_unpacked[0] << 64 | i_unpacked[1]
        a = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
        length = 128
    else:
        raise NotImplementedError('family not supported')
    # 2. calculate mask
    m = (a << length - mask) & a
    # 3. calculate default broadcast
    n = (i_unpacked & m) | a >> mask
    # 4. convert it back to the normal address form
    if family == socket.AF_INET:
        n = struct.pack('>I', n)
    else:
        n = struct.pack('>QQ', n >> 64, n & (a >> 64))
    return socket.inet_ntop(family, n)


def dqn2int(mask: str, family: socket.AddressFamily = socket.AF_INET) -> int:
    '''
    IPv4 dotted quad notation to int mask conversion
    '''
    ret = 0
    binary = socket.inet_pton(family, mask)
    for offset in range(len(binary) // 4):
        ret += bin(
            struct.unpack('I', binary[offset * 4 : offset * 4 + 4])[0]
        ).count('1')
    return ret


def get_address_family(address: str) -> socket.AddressFamily:
    if address.find(':') > -1:
        return socket.AF_INET6
    else:
        return socket.AF_INET


def hexdump(payload: bytes, length: int = 0) -> str:
    '''
    Represent byte string as hex -- for debug purposes
    '''
    return ':'.join('{0:02x}'.format(c) for c in payload[:length] or payload)


def load_dump(
    f: Union[str, io.StringIO], meta: Optional[dict[str, str]] = None
) -> Union[bytes, str]:
    '''
    Load a packet dump from an open file-like object or a string.

    Supported dump formats:

    * strace hex dump (\\x00\\x00...)
    * pyroute2 hex dump (00:00:...)

    Simple markup is also supported. Any data from # or ;
    till the end of the string is a comment and ignored.
    Any data after . till EOF is ignored as well.

    With #! starts an optional code block. All the data
    in the code block will be read and returned via
    metadata dictionary.
    '''
    data = ''
    code = None
    meta_data = None
    meta_label = None
    io_obj: Union[io.StringIO, str]
    if isinstance(f, str):
        io_obj = io.StringIO()
        io_obj.write(f)
        io_obj.seek(0)
    else:
        io_obj = f

    for a in io_obj.readlines():
        if code is not None:
            code += a
            continue

        if meta_data is not None:
            meta_data += a
            continue

        offset = 0
        length = len(a)
        while offset < length:
            if a[offset] in (' ', '\t', '\n'):
                offset += 1
            elif a[offset] == '#':
                if a[offset : offset + 2] == '#!':
                    # read the code block until EOF
                    code = ''
                elif a[offset : offset + 2] == '#:':
                    # read data block until EOF
                    meta_label = a.split(':')[1].strip()
                    meta_data = ''
                break
            elif a[offset] == '.':
                return data
            elif a[offset] == '\\':
                # strace hex format
                data += chr(int(a[offset + 2 : offset + 4], 16))
                offset += 4
            else:
                # pyroute2 hex format
                data += chr(int(a[offset : offset + 2], 16))
                offset += 3

    if isinstance(meta, dict):
        if code is not None:
            meta['code'] = code
        if meta_data is not None and meta_label is not None:
            meta[meta_label] = meta_data

    return bytes(data, 'iso8859-1')


class AddrPool(object):
    '''
    Address pool
    '''

    cell = 0xFFFFFFFFFFFFFFFF

    def __init__(
        self,
        minaddr: int = 0xF,
        maxaddr: int = 0xFFFFFF,
        reverse: bool = False,
        release: bool = False,
    ):
        self.cell_size = 0  # in bits
        mx = self.cell
        self.reverse = reverse
        self.release = release
        self.ban: list[dict[str, int]] = []
        while mx:
            mx >>= 8
            self.cell_size += 1
        self.cell_size *= 8
        # calculate, how many ints we need to bitmap all addresses
        self.cells = int((maxaddr - minaddr) / self.cell_size + 1)
        # initial array
        self.addr_map = [self.cell]
        self.minaddr = minaddr
        self.maxaddr = maxaddr
        self.lock = threading.RLock()

    def alloc(self) -> int:
        with self.lock:
            # gc self.ban:
            for item in tuple(self.ban):
                if item['counter'] == 0:
                    self.free(item['addr'])
                    self.ban.remove(item)
                else:
                    item['counter'] -= 1

            # iterate through addr_map
            base = 0
            for cell in self.addr_map:
                if cell:
                    # not allocated addr
                    bit = 0
                    while True:
                        if (1 << bit) & self.addr_map[base]:
                            self.addr_map[base] ^= 1 << bit
                            break
                        bit += 1
                    ret = base * self.cell_size + bit

                    if self.reverse:
                        ret = self.maxaddr - ret
                    else:
                        ret = ret + self.minaddr

                    if self.minaddr <= ret <= self.maxaddr:
                        if self.release:
                            self.free(ret, ban=self.release)
                        return ret
                    else:
                        self.free(ret)
                        raise KeyError('no free address available')

                base += 1
            # no free address available
            if len(self.addr_map) < self.cells:
                # create new cell to allocate address from
                self.addr_map.append(self.cell)
                return self.alloc()
            else:
                raise KeyError('no free address available')

    def locate(self, addr: int) -> tuple[int, int, bool]:
        if self.reverse:
            addr = self.maxaddr - addr
        else:
            addr -= self.minaddr
        base = addr // self.cell_size
        bit = addr % self.cell_size
        try:
            is_allocated = not self.addr_map[base] & (1 << bit)
        except IndexError:
            is_allocated = False
        return (base, bit, is_allocated)

    def free(self, addr: int, ban: int = 0):
        with self.lock:
            if ban != 0:
                self.ban.append({'addr': addr, 'counter': ban})
            else:
                base, bit, _ = self.locate(addr)
                if len(self.addr_map) <= base:
                    raise KeyError('address is not allocated')
                if self.addr_map[base] & (1 << bit):
                    raise KeyError('address is not allocated')
                self.addr_map[base] ^= 1 << bit


def fnv1(data: bytes) -> int:
    '''
    FNV1 -- 32bit hash, python3 version

    Returns: 32bit int hash

    See: http://www.isthe.com/chongo/tech/comp/fnv/index.html
    '''
    hval = 0x811C9DC5
    for i in range(len(data)):
        hval *= 0x01000193
        hval ^= data[i]
    return hval & 0xFFFFFFFF


def uuid32() -> int:
    '''
    Return 32bit UUID, based on the current time and pid.

    The uuid is guaranteed to be unique within one process.
    '''
    global _uuid32
    global _uuid32_lock

    with _uuid32_lock:
        candidate = _uuid32
        while candidate == _uuid32:
            candidate = fnv1(
                struct.pack('QQ', int(time.time() * 1000000), os.getpid())
            )
        _uuid32 = candidate
        return candidate


def uifname() -> str:
    '''
    Return a unique interface name based on a prime function
    '''
    return 'pr%x' % uuid32()


F = TypeVar("F", bound=Callable[..., Any])


def map_exception(
    match: Callable[[Exception], bool], subst: Callable[[Exception], Exception]
) -> Callable[[F], F]:
    '''
    Decorator to map exception types
    '''

    def wrapper(f: F) -> F:
        def decorated(*argv: Any, **kwarg: Any) -> Any:
            try:
                f(*argv, **kwarg)
            except Exception as e:
                if match(e):
                    raise subst(e)
                raise

        return decorated  # type: ignore

    return wrapper


def map_enoent(f: F) -> F:
    '''
    Shortcut to map OSError(2) -> OSError(95)
    '''
    return map_exception(
        lambda x: (isinstance(x, OSError) and x.errno == errno.ENOENT),
        lambda x: OSError(errno.EOPNOTSUPP, 'Operation not supported'),
    )(f)


T = TypeVar('T', bound=type)


def metaclass(mc: T) -> Callable[[T], T]:
    def wrapped(cls: T) -> T:
        nvars = {}
        skip = ['__dict__', '__weakref__']
        slots = cls.__dict__.get('__slots__')
        if not isinstance(slots, (list, tuple)):
            slots = [slots]
        for k in slots:
            skip.append(k)
        for k, v in cls.__dict__.items():
            if k not in skip:
                nvars[k] = v
        return mc(cls.__name__, cls.__bases__, nvars)

    return wrapped


def msg_done(msg) -> bytes:
    newmsg = struct.pack('IHH', 40, 2, 0)
    newmsg += msg.data[8:16]
    newmsg += struct.pack('I', 0)
    # nlmsgerr struct alignment
    newmsg += b'\0' * 20
    return newmsg


def get_time() -> float:
    '''
    Return seconds since arbitrary start point.

    It cannot go backward. It includes any time that the system is suspended.
    You should use this instead of time.time() to measure time between two
    execution points, like a timeout.
    '''
    return time.monotonic()