#  -*- coding: utf-8 -*-
# *****************************************************************************
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# Module authors:
#   Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
#
# *****************************************************************************
"""Define helpers"""

import importlib
import linecache
import socket
import sys
import threading
import traceback
from configparser import ConfigParser
from os import environ, path

CONFIG = {}
unset_value = object()


def getGeneralConfig(confdir=None):
    global CONFIG  # pylint: disable=global-statement

    if CONFIG:
        if confdir:
            raise ValueError('getGeneralConfig with argument must be called first')
    else:
        repodir = path.abspath(path.join(path.dirname(__file__), '..', '..'))
        if path.splitext(sys.executable)[1] == ".exe" and not path.basename(sys.executable).startswith('python'):
            # special MS windows environment
            CONFIG = {
                'piddir': './',
                'logdir': './log',
                'confdir': './',
            }
        elif not path.exists(path.join(repodir, '.git')):
            CONFIG = {
                'piddir': '/var/run/secop',
                'logdir': '/var/log',
                'confdir': '/etc/secop',
            }
        else:
            CONFIG = {
                'piddir': path.join(repodir, 'pid'),
                'logdir': path.join(repodir, 'log'),
                'confdir': path.join(repodir, 'cfg'),
            }
        gen_config_path = confdir or environ.get('FRAPPY_CONFIG_FILE',
                                                 path.join(CONFIG['confdir'], 'generalConfig.cfg'))
        if gen_config_path and path.exists(gen_config_path):
            parser = ConfigParser()
            parser.optionxform = str
            parser.read([gen_config_path])
            CONFIG = {}
            # only the FRAPPY section is relevant, other sections might be used by others
            for key, value in parser['FRAPPY'].items():
                if value.startswith('./'):
                    CONFIG[key] = path.abspath(path.join(repodir, value))
                else:
                    # expand ~ to username, also in path lists separated with ':'
                    CONFIG[key] = ':'.join(path.expanduser(v) for v in value.split(':'))
        else:
            for dirname in CONFIG:
                CONFIG[dirname] = environ.get('SECOP_%s' % dirname.upper(), CONFIG[dirname])
        # this is not customizable
        CONFIG['basedir'] = repodir
    return CONFIG


class lazy_property:
    """A property that calculates its value only once."""

    def __init__(self, func):
        self._func = func
        self.__name__ = func.__name__
        self.__doc__ = func.__doc__

    def __get__(self, obj, obj_class):
        if obj is None:
            return self
        obj.__dict__[self.__name__] = self._func(obj)
        return obj.__dict__[self.__name__]


class attrdict(dict):
    """a normal dict, providing access also via attributes"""

    def __getattr__(self, key):
        return self[key]

    def __setattr__(self, key, value):
        self[key] = value


def clamp(_min, value, _max):
    """return the median of 3 values,

    i.e. value if min <= value <= max, else min or max depending on which side
    value lies outside the [min..max] interval. This works even when min > max!
    """
    # return median, i.e. clamp the the value between min and max
    return sorted([_min, value, _max])[1]


def get_class(spec):
    """loads a class given by string in dotted notation (as python would do)"""
    modname, classname = spec.rsplit('.', 1)
    if modname.startswith('secop'):
        module = importlib.import_module(modname)
    else:
        # rarely needed by now....
        module = importlib.import_module('secop.' + modname)
    try:
        return getattr(module, classname)
    except AttributeError:
        raise AttributeError('no such class') from None


def mkthread(func, *args, **kwds):
    t = threading.Thread(
        name='%s:%s' % (func.__module__, func.__name__),
        target=func,
        args=args,
        kwargs=kwds)
    t.daemon = True
    t.start()
    return t


def formatExtendedFrame(frame):
    ret = []
    for key, value in frame.f_locals.items():
        try:
            valstr = repr(value)[:256]
        except Exception:
            valstr = '<cannot be displayed>'
        ret.append('        %-20s = %s\n' % (key, valstr))
    ret.append('\n')
    return ret


def formatExtendedTraceback(exc_info=None):
    if exc_info is None:
        etype, value, tb = sys.exc_info()
    else:
        etype, value, tb = exc_info
    ret = ['Traceback (most recent call last):\n']
    while tb is not None:
        frame = tb.tb_frame
        filename = frame.f_code.co_filename
        item = '  File "%s", line %d, in %s\n' % (filename, tb.tb_lineno,
                                                  frame.f_code.co_name)
        linecache.checkcache(filename)
        line = linecache.getline(filename, tb.tb_lineno, frame.f_globals)
        if line:
            item = item + '    %s\n' % line.strip()
        ret.append(item)
        if filename not in ('<script>', '<string>'):
            ret += formatExtendedFrame(tb.tb_frame)
        tb = tb.tb_next
    ret += traceback.format_exception_only(etype, value)
    return ''.join(ret).rstrip('\n')


def formatExtendedStack(level=1):
    f = sys._getframe(level)
    ret = ['Stack trace (most recent call last):\n\n']
    while f is not None:
        lineno = f.f_lineno
        co = f.f_code
        filename = co.co_filename
        name = co.co_name
        item = '  File "%s", line %d, in %s\n' % (filename, lineno, name)
        linecache.checkcache(filename)
        line = linecache.getline(filename, lineno, f.f_globals)
        if line:
            item = item + '    %s\n' % line.strip()
        ret.insert(1, item)
        if filename != '<script>':
            ret[2:2] = formatExtendedFrame(f)
        f = f.f_back
    return ''.join(ret).rstrip('\n')


def formatException(cut=0, exc_info=None, verbose=False):
    """Format an exception with traceback, but leave out the first `cut`
    number of frames.
    """
    if verbose:
        return formatExtendedTraceback(exc_info)
    if exc_info is None:
        typ, val, tb = sys.exc_info()
    else:
        typ, val, tb = exc_info
    res = ['Traceback (most recent call last):\n']
    tbres = traceback.format_tb(tb, sys.maxsize)
    res += tbres[cut:]
    res += traceback.format_exception_only(typ, val)
    return ''.join(res)


def parseHostPort(host, defaultport):
    """Parse host[:port] string and tuples

    Specify 'host[:port]' or a (host, port) tuple for the mandatory argument.
    If the port specification is missing, the value of the defaultport is used.
    """

    if isinstance(host, (tuple, list)):
        host, port = host
    elif ':' in host:
        host, port = host.rsplit(':', 1)
        port = int(port)
    else:
        port = defaultport
    assert 0 < port < 65536
    assert ':' not in host
    return host, port


def tcpSocket(host, defaultport, timeout=None):
    """Helper for opening a TCP client socket to a remote server.

    Specify 'host[:port]' or a (host, port) tuple for the mandatory argument.
    If the port specification is missing, the value of the defaultport is used.
    If timeout is set to a number, the timout of the connection is set to this
    number, else the socket stays in blocking mode.
    """
    host, port = parseHostPort(host, defaultport)

    # open socket and set options
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    if timeout:
        s.settimeout(timeout)
    # connect
    s.connect((host, int(port)))
    return s


# keep a reference to socket to avoid (interpreter) shut-down problems
def closeSocket(sock, socket=socket):  # pylint: disable=redefined-outer-name
    """Do our best to close a socket."""
    if sock is None:
        return
    try:
        sock.shutdown(socket.SHUT_RDWR)
    except socket.error:
        pass
    try:
        sock.close()
    except socket.error:
        pass


def getfqdn(name=''):
    """Get fully qualified hostname."""
    return socket.getfqdn(name)


def formatStatusBits(sword, labels, start=0):
    """Return a list of labels according to bit state in `sword` starting
    with bit `start` and the first label in `labels`.
    """
    result = []
    for i, lbl in enumerate(labels, start):
        if sword & (1 << i) and lbl:
            result.append(lbl)
    return result


class UniqueObject:
    def __init__(self, name):
        self.name = name

    def __repr__(self):
        return 'UniqueObject(%r)' % self.name