# Copyright (c) 2009, Giampaolo Rodola'. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Common objects shared by __init__.py and _ps*.py modules."""

# Note: this module is imported by setup.py so it should not import
# psutil or third-party modules.

from __future__ import division

import contextlib
import errno
import functools
import os
import socket
import stat
import sys
import threading
import warnings
from collections import defaultdict
from collections import namedtuple
from socket import AF_INET
from socket import SOCK_DGRAM
from socket import SOCK_STREAM
try:
    from socket import AF_INET6
except ImportError:
    AF_INET6 = None
try:
    from socket import AF_UNIX
except ImportError:
    AF_UNIX = None

if sys.version_info >= (3, 4):
    import enum
else:
    enum = None

# can't take it from _common.py as this script is imported by setup.py
PY3 = sys.version_info[0] == 3

__all__ = [
    # constants
    'FREEBSD', 'BSD', 'LINUX', 'NETBSD', 'OPENBSD', 'MACOS', 'OSX', 'POSIX',
    'SUNOS', 'WINDOWS',
    'ENCODING', 'ENCODING_ERRS', 'AF_INET6',
    # connection constants
    'CONN_CLOSE', 'CONN_CLOSE_WAIT', 'CONN_CLOSING', 'CONN_ESTABLISHED',
    'CONN_FIN_WAIT1', 'CONN_FIN_WAIT2', 'CONN_LAST_ACK', 'CONN_LISTEN',
    'CONN_NONE', 'CONN_SYN_RECV', 'CONN_SYN_SENT', 'CONN_TIME_WAIT',
    # net constants
    'NIC_DUPLEX_FULL', 'NIC_DUPLEX_HALF', 'NIC_DUPLEX_UNKNOWN',
    # process status constants
    'STATUS_DEAD', 'STATUS_DISK_SLEEP', 'STATUS_IDLE', 'STATUS_LOCKED',
    'STATUS_RUNNING', 'STATUS_SLEEPING', 'STATUS_STOPPED', 'STATUS_SUSPENDED',
    'STATUS_TRACING_STOP', 'STATUS_WAITING', 'STATUS_WAKE_KILL',
    'STATUS_WAKING', 'STATUS_ZOMBIE', 'STATUS_PARKED',
    # named tuples
    'pconn', 'pcputimes', 'pctxsw', 'pgids', 'pio', 'pionice', 'popenfile',
    'pthread', 'puids', 'sconn', 'scpustats', 'sdiskio', 'sdiskpart',
    'sdiskusage', 'snetio', 'snicaddr', 'snicstats', 'sswap', 'suser',
    # utility functions
    'conn_tmap', 'deprecated_method', 'isfile_strict', 'memoize',
    'parse_environ_block', 'path_exists_strict', 'usage_percent',
    'supports_ipv6', 'sockfam_to_enum', 'socktype_to_enum', "wrap_numbers",
    'bytes2human', 'conn_to_ntuple',
]


# ===================================================================
# --- OS constants
# ===================================================================


POSIX = os.name == "posix"
WINDOWS = os.name == "nt"
LINUX = sys.platform.startswith("linux")
MACOS = sys.platform.startswith("darwin")
OSX = MACOS  # deprecated alias
FREEBSD = sys.platform.startswith("freebsd")
OPENBSD = sys.platform.startswith("openbsd")
NETBSD = sys.platform.startswith("netbsd")
BSD = FREEBSD or OPENBSD or NETBSD
SUNOS = sys.platform.startswith(("sunos", "solaris"))
AIX = sys.platform.startswith("aix")


# ===================================================================
# --- API constants
# ===================================================================


# Process.status()
STATUS_RUNNING = "running"
STATUS_SLEEPING = "sleeping"
STATUS_DISK_SLEEP = "disk-sleep"
STATUS_STOPPED = "stopped"
STATUS_TRACING_STOP = "tracing-stop"
STATUS_ZOMBIE = "zombie"
STATUS_DEAD = "dead"
STATUS_WAKE_KILL = "wake-kill"
STATUS_WAKING = "waking"
STATUS_IDLE = "idle"  # Linux, macOS, FreeBSD
STATUS_LOCKED = "locked"  # FreeBSD
STATUS_WAITING = "waiting"  # FreeBSD
STATUS_SUSPENDED = "suspended"  # NetBSD
STATUS_PARKED = "parked"  # Linux

# Process.connections() and psutil.net_connections()
CONN_ESTABLISHED = "ESTABLISHED"
CONN_SYN_SENT = "SYN_SENT"
CONN_SYN_RECV = "SYN_RECV"
CONN_FIN_WAIT1 = "FIN_WAIT1"
CONN_FIN_WAIT2 = "FIN_WAIT2"
CONN_TIME_WAIT = "TIME_WAIT"
CONN_CLOSE = "CLOSE"
CONN_CLOSE_WAIT = "CLOSE_WAIT"
CONN_LAST_ACK = "LAST_ACK"
CONN_LISTEN = "LISTEN"
CONN_CLOSING = "CLOSING"
CONN_NONE = "NONE"

# net_if_stats()
if enum is None:
    NIC_DUPLEX_FULL = 2
    NIC_DUPLEX_HALF = 1
    NIC_DUPLEX_UNKNOWN = 0
else:
    class NicDuplex(enum.IntEnum):
        NIC_DUPLEX_FULL = 2
        NIC_DUPLEX_HALF = 1
        NIC_DUPLEX_UNKNOWN = 0

    globals().update(NicDuplex.__members__)

# sensors_battery()
if enum is None:
    POWER_TIME_UNKNOWN = -1
    POWER_TIME_UNLIMITED = -2
else:
    class BatteryTime(enum.IntEnum):
        POWER_TIME_UNKNOWN = -1
        POWER_TIME_UNLIMITED = -2

    globals().update(BatteryTime.__members__)

# --- others

ENCODING = sys.getfilesystemencoding()
if not PY3:
    ENCODING_ERRS = "replace"
else:
    try:
        ENCODING_ERRS = sys.getfilesystemencodeerrors()  # py 3.6
    except AttributeError:
        ENCODING_ERRS = "surrogateescape" if POSIX else "replace"


# ===================================================================
# --- namedtuples
# ===================================================================

# --- for system functions

# psutil.swap_memory()
sswap = namedtuple('sswap', ['total', 'used', 'free', 'percent', 'sin',
                             'sout'])
# psutil.disk_usage()
sdiskusage = namedtuple('sdiskusage', ['total', 'used', 'free', 'percent'])
# psutil.disk_io_counters()
sdiskio = namedtuple('sdiskio', ['read_count', 'write_count',
                                 'read_bytes', 'write_bytes',
                                 'read_time', 'write_time'])
# psutil.disk_partitions()
sdiskpart = namedtuple('sdiskpart', ['device', 'mountpoint', 'fstype', 'opts'])
# psutil.net_io_counters()
snetio = namedtuple('snetio', ['bytes_sent', 'bytes_recv',
                               'packets_sent', 'packets_recv',
                               'errin', 'errout',
                               'dropin', 'dropout'])
# psutil.users()
suser = namedtuple('suser', ['name', 'terminal', 'host', 'started', 'pid'])
# psutil.net_connections()
sconn = namedtuple('sconn', ['fd', 'family', 'type', 'laddr', 'raddr',
                             'status', 'pid'])
# psutil.net_if_addrs()
snicaddr = namedtuple('snicaddr',
                      ['family', 'address', 'netmask', 'broadcast', 'ptp'])
# psutil.net_if_stats()
snicstats = namedtuple('snicstats', ['isup', 'duplex', 'speed', 'mtu'])
# psutil.cpu_stats()
scpustats = namedtuple(
    'scpustats', ['ctx_switches', 'interrupts', 'soft_interrupts', 'syscalls'])
# psutil.cpu_freq()
scpufreq = namedtuple('scpufreq', ['current', 'min', 'max'])
# psutil.sensors_temperatures()
shwtemp = namedtuple(
    'shwtemp', ['label', 'current', 'high', 'critical'])
# psutil.sensors_battery()
sbattery = namedtuple('sbattery', ['percent', 'secsleft', 'power_plugged'])
# psutil.sensors_fans()
sfan = namedtuple('sfan', ['label', 'current'])

# --- for Process methods

# psutil.Process.cpu_times()
pcputimes = namedtuple('pcputimes',
                       ['user', 'system', 'children_user', 'children_system'])
# psutil.Process.open_files()
popenfile = namedtuple('popenfile', ['path', 'fd'])
# psutil.Process.threads()
pthread = namedtuple('pthread', ['id', 'user_time', 'system_time'])
# psutil.Process.uids()
puids = namedtuple('puids', ['real', 'effective', 'saved'])
# psutil.Process.gids()
pgids = namedtuple('pgids', ['real', 'effective', 'saved'])
# psutil.Process.io_counters()
pio = namedtuple('pio', ['read_count', 'write_count',
                         'read_bytes', 'write_bytes'])
# psutil.Process.ionice()
pionice = namedtuple('pionice', ['ioclass', 'value'])
# psutil.Process.ctx_switches()
pctxsw = namedtuple('pctxsw', ['voluntary', 'involuntary'])
# psutil.Process.connections()
pconn = namedtuple('pconn', ['fd', 'family', 'type', 'laddr', 'raddr',
                             'status'])

# psutil.connections() and psutil.Process.connections()
addr = namedtuple('addr', ['ip', 'port'])


# ===================================================================
# --- Process.connections() 'kind' parameter mapping
# ===================================================================


conn_tmap = {
    "all": ([AF_INET, AF_INET6, AF_UNIX], [SOCK_STREAM, SOCK_DGRAM]),
    "tcp": ([AF_INET, AF_INET6], [SOCK_STREAM]),
    "tcp4": ([AF_INET], [SOCK_STREAM]),
    "udp": ([AF_INET, AF_INET6], [SOCK_DGRAM]),
    "udp4": ([AF_INET], [SOCK_DGRAM]),
    "inet": ([AF_INET, AF_INET6], [SOCK_STREAM, SOCK_DGRAM]),
    "inet4": ([AF_INET], [SOCK_STREAM, SOCK_DGRAM]),
    "inet6": ([AF_INET6], [SOCK_STREAM, SOCK_DGRAM]),
}

if AF_INET6 is not None:
    conn_tmap.update({
        "tcp6": ([AF_INET6], [SOCK_STREAM]),
        "udp6": ([AF_INET6], [SOCK_DGRAM]),
    })

if AF_UNIX is not None:
    conn_tmap.update({
        "unix": ([AF_UNIX], [SOCK_STREAM, SOCK_DGRAM]),
    })


# ===================================================================
# --- utils
# ===================================================================


def usage_percent(used, total, round_=None):
    """Calculate percentage usage of 'used' against 'total'."""
    try:
        ret = (float(used) / total) * 100
    except ZeroDivisionError:
        return 0.0
    else:
        if round_ is not None:
            ret = round(ret, round_)
        return ret


def memoize(fun):
    """A simple memoize decorator for functions supporting (hashable)
    positional arguments.
    It also provides a cache_clear() function for clearing the cache:

    >>> @memoize
    ... def foo()
    ...     return 1
        ...
    >>> foo()
    1
    >>> foo.cache_clear()
    >>>
    """
    @functools.wraps(fun)
    def wrapper(*args, **kwargs):
        key = (args, frozenset(sorted(kwargs.items())))
        try:
            return cache[key]
        except KeyError:
            ret = cache[key] = fun(*args, **kwargs)
            return ret

    def cache_clear():
        """Clear cache."""
        cache.clear()

    cache = {}
    wrapper.cache_clear = cache_clear
    return wrapper


def memoize_when_activated(fun):
    """A memoize decorator which is disabled by default. It can be
    activated and deactivated on request.
    For efficiency reasons it can be used only against class methods
    accepting no arguments.

    >>> class Foo:
    ...     @memoize
    ...     def foo()
    ...         print(1)
    ...
    >>> f = Foo()
    >>> # deactivated (default)
    >>> foo()
    1
    >>> foo()
    1
    >>>
    >>> # activated
    >>> foo.cache_activate(self)
    >>> foo()
    1
    >>> foo()
    >>> foo()
    >>>
    """
    @functools.wraps(fun)
    def wrapper(self):
        try:
            # case 1: we previously entered oneshot() ctx
            ret = self._cache[fun]
        except AttributeError:
            # case 2: we never entered oneshot() ctx
            return fun(self)
        except KeyError:
            # case 3: we entered oneshot() ctx but there's no cache
            # for this entry yet
            ret = self._cache[fun] = fun(self)
        return ret

    def cache_activate(proc):
        """Activate cache. Expects a Process instance. Cache will be
        stored as a "_cache" instance attribute."""
        proc._cache = {}

    def cache_deactivate(proc):
        """Deactivate and clear cache."""
        try:
            del proc._cache
        except AttributeError:
            pass

    wrapper.cache_activate = cache_activate
    wrapper.cache_deactivate = cache_deactivate
    return wrapper


def isfile_strict(path):
    """Same as os.path.isfile() but does not swallow EACCES / EPERM
    exceptions, see:
    http://mail.python.org/pipermail/python-dev/2012-June/120787.html
    """
    try:
        st = os.stat(path)
    except OSError as err:
        if err.errno in (errno.EPERM, errno.EACCES):
            raise
        return False
    else:
        return stat.S_ISREG(st.st_mode)


def path_exists_strict(path):
    """Same as os.path.exists() but does not swallow EACCES / EPERM
    exceptions, see:
    http://mail.python.org/pipermail/python-dev/2012-June/120787.html
    """
    try:
        os.stat(path)
    except OSError as err:
        if err.errno in (errno.EPERM, errno.EACCES):
            raise
        return False
    else:
        return True


@memoize
def supports_ipv6():
    """Return True if IPv6 is supported on this platform."""
    if not socket.has_ipv6 or AF_INET6 is None:
        return False
    try:
        sock = socket.socket(AF_INET6, socket.SOCK_STREAM)
        with contextlib.closing(sock):
            sock.bind(("::1", 0))
        return True
    except socket.error:
        return False


def parse_environ_block(data):
    """Parse a C environ block of environment variables into a dictionary."""
    # The block is usually raw data from the target process.  It might contain
    # trailing garbage and lines that do not look like assignments.
    ret = {}
    pos = 0

    # localize global variable to speed up access.
    WINDOWS_ = WINDOWS
    while True:
        next_pos = data.find("\0", pos)
        # nul byte at the beginning or double nul byte means finish
        if next_pos <= pos:
            break
        # there might not be an equals sign
        equal_pos = data.find("=", pos, next_pos)
        if equal_pos > pos:
            key = data[pos:equal_pos]
            value = data[equal_pos + 1:next_pos]
            # Windows expects environment variables to be uppercase only
            if WINDOWS_:
                key = key.upper()
            ret[key] = value
        pos = next_pos + 1

    return ret


def sockfam_to_enum(num):
    """Convert a numeric socket family value to an IntEnum member.
    If it's not a known member, return the numeric value itself.
    """
    if enum is None:
        return num
    else:  # pragma: no cover
        try:
            return socket.AddressFamily(num)
        except ValueError:
            return num


def socktype_to_enum(num):
    """Convert a numeric socket type value to an IntEnum member.
    If it's not a known member, return the numeric value itself.
    """
    if enum is None:
        return num
    else:  # pragma: no cover
        try:
            return socket.SocketKind(num)
        except ValueError:
            return num


def conn_to_ntuple(fd, fam, type_, laddr, raddr, status, status_map, pid=None):
    """Convert a raw connection tuple to a proper ntuple."""
    if fam in (socket.AF_INET, AF_INET6):
        if laddr:
            laddr = addr(*laddr)
        if raddr:
            raddr = addr(*raddr)
    if type_ == socket.SOCK_STREAM and fam in (AF_INET, AF_INET6):
        status = status_map.get(status, CONN_NONE)
    else:
        status = CONN_NONE  # ignore whatever C returned to us
    fam = sockfam_to_enum(fam)
    type_ = socktype_to_enum(type_)
    if pid is None:
        return pconn(fd, fam, type_, laddr, raddr, status)
    else:
        return sconn(fd, fam, type_, laddr, raddr, status, pid)


def deprecated_method(replacement):
    """A decorator which can be used to mark a method as deprecated
    'replcement' is the method name which will be called instead.
    """
    def outer(fun):
        msg = "%s() is deprecated and will be removed; use %s() instead" % (
            fun.__name__, replacement)
        if fun.__doc__ is None:
            fun.__doc__ = msg

        @functools.wraps(fun)
        def inner(self, *args, **kwargs):
            warnings.warn(msg, category=DeprecationWarning, stacklevel=2)
            return getattr(self, replacement)(*args, **kwargs)
        return inner
    return outer


class _WrapNumbers:
    """Watches numbers so that they don't overflow and wrap
    (reset to zero).
    """

    def __init__(self):
        self.lock = threading.Lock()
        self.cache = {}
        self.reminders = {}
        self.reminder_keys = {}

    def _add_dict(self, input_dict, name):
        assert name not in self.cache
        assert name not in self.reminders
        assert name not in self.reminder_keys
        self.cache[name] = input_dict
        self.reminders[name] = defaultdict(int)
        self.reminder_keys[name] = defaultdict(set)

    def _remove_dead_reminders(self, input_dict, name):
        """In case the number of keys changed between calls (e.g. a
        disk disappears) this removes the entry from self.reminders.
        """
        old_dict = self.cache[name]
        gone_keys = set(old_dict.keys()) - set(input_dict.keys())
        for gone_key in gone_keys:
            for remkey in self.reminder_keys[name][gone_key]:
                del self.reminders[name][remkey]
            del self.reminder_keys[name][gone_key]

    def run(self, input_dict, name):
        """Cache dict and sum numbers which overflow and wrap.
        Return an updated copy of `input_dict`
        """
        if name not in self.cache:
            # This was the first call.
            self._add_dict(input_dict, name)
            return input_dict

        self._remove_dead_reminders(input_dict, name)

        old_dict = self.cache[name]
        new_dict = {}
        for key in input_dict.keys():
            input_tuple = input_dict[key]
            try:
                old_tuple = old_dict[key]
            except KeyError:
                # The input dict has a new key (e.g. a new disk or NIC)
                # which didn't exist in the previous call.
                new_dict[key] = input_tuple
                continue

            bits = []
            for i in range(len(input_tuple)):
                input_value = input_tuple[i]
                old_value = old_tuple[i]
                remkey = (key, i)
                if input_value < old_value:
                    # it wrapped!
                    self.reminders[name][remkey] += old_value
                    self.reminder_keys[name][key].add(remkey)
                bits.append(input_value + self.reminders[name][remkey])

            new_dict[key] = tuple(bits)

        self.cache[name] = input_dict
        return new_dict

    def cache_clear(self, name=None):
        """Clear the internal cache, optionally only for function 'name'."""
        with self.lock:
            if name is None:
                self.cache.clear()
                self.reminders.clear()
                self.reminder_keys.clear()
            else:
                self.cache.pop(name, None)
                self.reminders.pop(name, None)
                self.reminder_keys.pop(name, None)

    def cache_info(self):
        """Return internal cache dicts as a tuple of 3 elements."""
        with self.lock:
            return (self.cache, self.reminders, self.reminder_keys)


def wrap_numbers(input_dict, name):
    """Given an `input_dict` and a function `name`, adjust the numbers
    which "wrap" (restart from zero) across different calls by adding
    "old value" to "new value" and return an updated dict.
    """
    with _wn.lock:
        return _wn.run(input_dict, name)


_wn = _WrapNumbers()
wrap_numbers.cache_clear = _wn.cache_clear
wrap_numbers.cache_info = _wn.cache_info


def open_binary(fname, **kwargs):
    return open(fname, "rb", **kwargs)


def open_text(fname, **kwargs):
    """On Python 3 opens a file in text mode by using fs encoding and
    a proper en/decoding errors handler.
    On Python 2 this is just an alias for open(name, 'rt').
    """
    if PY3:
        # See:
        # https://github.com/giampaolo/psutil/issues/675
        # https://github.com/giampaolo/psutil/pull/733
        kwargs.setdefault('encoding', ENCODING)
        kwargs.setdefault('errors', ENCODING_ERRS)
    return open(fname, "rt", **kwargs)


def bytes2human(n, format="%(value).1f%(symbol)s"):
    """Used by various scripts. See:
    http://goo.gl/zeJZl

    >>> bytes2human(10000)
    '9.8K'
    >>> bytes2human(100001221)
    '95.4M'
    """
    symbols = ('B', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y')
    prefix = {}
    for i, s in enumerate(symbols[1:]):
        prefix[s] = 1 << (i + 1) * 10
    for symbol in reversed(symbols[1:]):
        if n >= prefix[symbol]:
            value = float(n) / prefix[symbol]
            return format % locals()
    return format % dict(symbol=symbols[0], value=n)


def get_procfs_path():
    """Return updated psutil.PROCFS_PATH constant."""
    return sys.modules['ddtrace.vendor.psutil'].PROCFS_PATH


if PY3:
    def decode(s):
        return s.decode(encoding=ENCODING, errors=ENCODING_ERRS)
else:
    def decode(s):
        return s
