import errno
import os
import random
import selectors
import signal
import socket
import sys
from test import support
from time import sleep
import unittest
import unittest.mock
import tempfile
from time import monotonic as time
try:
    import resource
except ImportError:
    resource = None


if hasattr(socket, 'socketpair'):
    socketpair = socket.socketpair
else:
    def socketpair(family=socket.AF_INET, type=socket.SOCK_STREAM, proto=0):
        with socket.socket(family, type, proto) as l:
            l.bind((support.HOST, 0))
            l.listen()
            c = socket.socket(family, type, proto)
            try:
                c.connect(l.getsockname())
                caddr = c.getsockname()
                while True:
                    a, addr = l.accept()
                    # check that we've got the correct client
                    if addr == caddr:
                        return c, a
                    a.close()
            except OSError:
                c.close()
                raise


def find_ready_matching(ready, flag):
    match = []
    for key, events in ready:
        if events & flag:
            match.append(key.fileobj)
    return match


class BaseSelectorTestCase(unittest.TestCase):

    def make_socketpair(self):
        rd, wr = socketpair()
        self.addCleanup(rd.close)
        self.addCleanup(wr.close)
        return rd, wr

    def test_register(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        key = s.register(rd, selectors.EVENT_READ, "data")
        self.assertIsInstance(key, selectors.SelectorKey)
        self.assertEqual(key.fileobj, rd)
        self.assertEqual(key.fd, rd.fileno())
        self.assertEqual(key.events, selectors.EVENT_READ)
        self.assertEqual(key.data, "data")

        # register an unknown event
        self.assertRaises(ValueError, s.register, 0, 999999)

        # register an invalid FD
        self.assertRaises(ValueError, s.register, -10, selectors.EVENT_READ)

        # register twice
        self.assertRaises(KeyError, s.register, rd, selectors.EVENT_READ)

        # register the same FD, but with a different object
        self.assertRaises(KeyError, s.register, rd.fileno(),
                          selectors.EVENT_READ)

    def test_unregister(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        s.register(rd, selectors.EVENT_READ)
        s.unregister(rd)

        # unregister an unknown file obj
        self.assertRaises(KeyError, s.unregister, 999999)

        # unregister twice
        self.assertRaises(KeyError, s.unregister, rd)

    def test_unregister_after_fd_close(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)
        rd, wr = self.make_socketpair()
        r, w = rd.fileno(), wr.fileno()
        s.register(r, selectors.EVENT_READ)
        s.register(w, selectors.EVENT_WRITE)
        rd.close()
        wr.close()
        s.unregister(r)
        s.unregister(w)

    @unittest.skipUnless(os.name == 'posix', "requires posix")
    def test_unregister_after_fd_close_and_reuse(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)
        rd, wr = self.make_socketpair()
        r, w = rd.fileno(), wr.fileno()
        s.register(r, selectors.EVENT_READ)
        s.register(w, selectors.EVENT_WRITE)
        rd2, wr2 = self.make_socketpair()
        rd.close()
        wr.close()
        os.dup2(rd2.fileno(), r)
        os.dup2(wr2.fileno(), w)
        self.addCleanup(os.close, r)
        self.addCleanup(os.close, w)
        s.unregister(r)
        s.unregister(w)

    def test_unregister_after_socket_close(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)
        rd, wr = self.make_socketpair()
        s.register(rd, selectors.EVENT_READ)
        s.register(wr, selectors.EVENT_WRITE)
        rd.close()
        wr.close()
        s.unregister(rd)
        s.unregister(wr)

    def test_modify(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        key = s.register(rd, selectors.EVENT_READ)

        # modify events
        key2 = s.modify(rd, selectors.EVENT_WRITE)
        self.assertNotEqual(key.events, key2.events)
        self.assertEqual(key2, s.get_key(rd))

        s.unregister(rd)

        # modify data
        d1 = object()
        d2 = object()

        key = s.register(rd, selectors.EVENT_READ, d1)
        key2 = s.modify(rd, selectors.EVENT_READ, d2)
        self.assertEqual(key.events, key2.events)
        self.assertNotEqual(key.data, key2.data)
        self.assertEqual(key2, s.get_key(rd))
        self.assertEqual(key2.data, d2)

        # modify unknown file obj
        self.assertRaises(KeyError, s.modify, 999999, selectors.EVENT_READ)

        # modify use a shortcut
        d3 = object()
        s.register = unittest.mock.Mock()
        s.unregister = unittest.mock.Mock()

        s.modify(rd, selectors.EVENT_READ, d3)
        self.assertFalse(s.register.called)
        self.assertFalse(s.unregister.called)

    def test_modify_unregister(self):
        # Make sure the fd is unregister()ed in case of error on
        # modify(): http://bugs.python.org/issue30014
        if self.SELECTOR.__name__ == 'EpollSelector':
            patch = unittest.mock.patch(
                'selectors.EpollSelector._selector_cls')
        elif self.SELECTOR.__name__ == 'PollSelector':
            patch = unittest.mock.patch(
                'selectors.PollSelector._selector_cls')
        elif self.SELECTOR.__name__ == 'DevpollSelector':
            patch = unittest.mock.patch(
                'selectors.DevpollSelector._selector_cls')
        else:
            raise self.skipTest("")

        with patch as m:
            m.return_value.modify = unittest.mock.Mock(
                side_effect=ZeroDivisionError)
            s = self.SELECTOR()
            self.addCleanup(s.close)
            rd, wr = self.make_socketpair()
            s.register(rd, selectors.EVENT_READ)
            self.assertEqual(len(s._map), 1)
            with self.assertRaises(ZeroDivisionError):
                s.modify(rd, selectors.EVENT_WRITE)
            self.assertEqual(len(s._map), 0)

    def test_close(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        mapping = s.get_map()
        rd, wr = self.make_socketpair()

        s.register(rd, selectors.EVENT_READ)
        s.register(wr, selectors.EVENT_WRITE)

        s.close()
        self.assertRaises(RuntimeError, s.get_key, rd)
        self.assertRaises(RuntimeError, s.get_key, wr)
        self.assertRaises(KeyError, mapping.__getitem__, rd)
        self.assertRaises(KeyError, mapping.__getitem__, wr)

    def test_get_key(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        key = s.register(rd, selectors.EVENT_READ, "data")
        self.assertEqual(key, s.get_key(rd))

        # unknown file obj
        self.assertRaises(KeyError, s.get_key, 999999)

    def test_get_map(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        keys = s.get_map()
        self.assertFalse(keys)
        self.assertEqual(len(keys), 0)
        self.assertEqual(list(keys), [])
        key = s.register(rd, selectors.EVENT_READ, "data")
        self.assertIn(rd, keys)
        self.assertEqual(key, keys[rd])
        self.assertEqual(len(keys), 1)
        self.assertEqual(list(keys), [rd.fileno()])
        self.assertEqual(list(keys.values()), [key])

        # unknown file obj
        with self.assertRaises(KeyError):
            keys[999999]

        # Read-only mapping
        with self.assertRaises(TypeError):
            del keys[rd]

    def test_select(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        s.register(rd, selectors.EVENT_READ)
        wr_key = s.register(wr, selectors.EVENT_WRITE)

        result = s.select()
        for key, events in result:
            self.assertTrue(isinstance(key, selectors.SelectorKey))
            self.assertTrue(events)
            self.assertFalse(events & ~(selectors.EVENT_READ |
                                        selectors.EVENT_WRITE))

        self.assertEqual([(wr_key, selectors.EVENT_WRITE)], result)

    def test_context_manager(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        with s as sel:
            sel.register(rd, selectors.EVENT_READ)
            sel.register(wr, selectors.EVENT_WRITE)

        self.assertRaises(RuntimeError, s.get_key, rd)
        self.assertRaises(RuntimeError, s.get_key, wr)

    def test_fileno(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        if hasattr(s, 'fileno'):
            fd = s.fileno()
            self.assertTrue(isinstance(fd, int))
            self.assertGreaterEqual(fd, 0)

    def test_selector(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        NUM_SOCKETS = 12
        MSG = b" This is a test."
        MSG_LEN = len(MSG)
        readers = []
        writers = []
        r2w = {}
        w2r = {}

        for i in range(NUM_SOCKETS):
            rd, wr = self.make_socketpair()
            s.register(rd, selectors.EVENT_READ)
            s.register(wr, selectors.EVENT_WRITE)
            readers.append(rd)
            writers.append(wr)
            r2w[rd] = wr
            w2r[wr] = rd

        bufs = []

        while writers:
            ready = s.select()
            ready_writers = find_ready_matching(ready, selectors.EVENT_WRITE)
            if not ready_writers:
                self.fail("no sockets ready for writing")
            wr = random.choice(ready_writers)
            wr.send(MSG)

            for i in range(10):
                ready = s.select()
                ready_readers = find_ready_matching(ready,
                                                    selectors.EVENT_READ)
                if ready_readers:
                    break
                # there might be a delay between the write to the write end and
                # the read end is reported ready
                sleep(0.1)
            else:
                self.fail("no sockets ready for reading")
            self.assertEqual([w2r[wr]], ready_readers)
            rd = ready_readers[0]
            buf = rd.recv(MSG_LEN)
            self.assertEqual(len(buf), MSG_LEN)
            bufs.append(buf)
            s.unregister(r2w[rd])