#!/usr/bin/python
# -*- coding: utf-8 -*-

# Copyright (c) 2014 clowwindy
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# from ssloop
# https://github.com/clowwindy/ssloop


import select
from collections import defaultdict


MODE_NULL = 0x00
MODE_IN = 0x01
MODE_OUT = 0x04
MODE_ERR = 0x08
MODE_HUP = 0x10
MODE_NVAL = 0x20


class EpollLoop(object):

    def __init__(self):
        self._epoll = select.epoll()

    def poll(self, timeout):
        return self._epoll.poll(timeout)

    def add_fd(self, fd, mode):
        self._epoll.register(fd, mode)

    def remove_fd(self, fd):
        self._epoll.unregister(fd)

    def modify_fd(self, fd, mode):
        self._epoll.modify(fd, mode)


class KqueueLoop(object):

    MAX_EVENTS = 1024

    def __init__(self):
        self._kqueue = select.kqueue()
        self._fds = {}

    def _control(self, fd, mode, flags):
        events = []
        if mode & MODE_IN:
            events.append(select.kevent(fd, select.KQ_FILTER_READ, flags))
        if mode & MODE_OUT:
            events.append(select.kevent(fd, select.KQ_FILTER_WRITE, flags))
        for e in events:
            self._kqueue.control([e], 0)

    def poll(self, timeout):
        if timeout < 0:
            timeout = None  # kqueue behaviour
        events = self._kqueue.control(None, KqueueLoop.MAX_EVENTS, timeout)
        results = defaultdict(lambda: MODE_NULL)
        for e in events:
            fd = e.ident
            if e.filter == select.KQ_FILTER_READ:
                results[fd] |= MODE_IN
            elif e.filter == select.KQ_FILTER_WRITE:
                results[fd] |= MODE_OUT
        return results.iteritems()

    def add_fd(self, fd, mode):
        self._fds[fd] = mode
        self._control(fd, mode, select.KQ_EV_ADD)

    def remove_fd(self, fd):
        self._control(fd, self._fds[fd], select.KQ_EV_DELETE)
        del self._fds[fd]

    def modify_fd(self, fd, mode):
        self.remove_fd(fd)
        self.add_fd(fd, mode)


class SelectLoop(object):

    def __init__(self):
        self._r_list = set()
        self._w_list = set()
        self._x_list = set()

    def poll(self, timeout):
        r, w, x = select.select(self._r_list, self._w_list, self._x_list,
                                timeout)
        results = defaultdict(lambda: MODE_NULL)
        for p in [(r, MODE_IN), (w, MODE_OUT), (x, MODE_ERR)]:
            for fd in p[0]:
                results[fd] |= p[1]
        return results.items()

    def add_fd(self, fd, mode):
        if mode & MODE_IN:
            self._r_list.add(fd)
        if mode & MODE_OUT:
            self._w_list.add(fd)
        if mode & MODE_ERR:
            self._x_list.add(fd)

    def remove_fd(self, fd):
        if fd in self._r_list:
            self._r_list.remove(fd)
        if fd in self._w_list:
            self._w_list.remove(fd)
        if fd in self._x_list:
            self._x_list.remove(fd)

    def modify_fd(self, fd, mode):
        self.remove_fd(fd)
        self.add_fd(fd, mode)


EventLoop = None

if hasattr(select, 'epoll'):
    EventLoop = EpollLoop
elif hasattr(select, 'kqueue'):
    EventLoop = KqueueLoop
elif hasattr(select, 'select'):
    EventLoop = SelectLoop
else:
    raise Exception('can not find any available functions in select package')