import collections
import subprocess
import sys
import warnings

from . import protocols
from . import transports
from .coroutines import coroutine
from .log import logger


class BaseSubprocessTransport(transports.SubprocessTransport):

    def __init__(self, loop, protocol, args, shell,
                 stdin, stdout, stderr, bufsize,
                 extra=None, **kwargs):
        super().__init__(extra)
        self._closed = False
        self._protocol = protocol
        self._loop = loop
        self._pid = None

        self._pipes = {}
        if stdin == subprocess.PIPE:
            self._pipes[0] = None
        if stdout == subprocess.PIPE:
            self._pipes[1] = None
        if stderr == subprocess.PIPE:
            self._pipes[2] = None
        self._pending_calls = collections.deque()
        self._finished = False
        self._returncode = None
        self._start(args=args, shell=shell, stdin=stdin, stdout=stdout,
                    stderr=stderr, bufsize=bufsize, **kwargs)
        self._pid = self._proc.pid
        self._extra['subprocess'] = self._proc
        if self._loop.get_debug():
            if isinstance(args, (bytes, str)):
                program = args
            else:
                program = args[0]
            logger.debug('process %r created: pid %s',
                         program, self._pid)

    def __repr__(self):
        info = [self.__class__.__name__]
        if self._closed:
            info.append('closed')
        info.append('pid=%s' % self._pid)
        if self._returncode is not None:
            info.append('returncode=%s' % self._returncode)

        stdin = self._pipes.get(0)
        if stdin is not None:
            info.append('stdin=%s' % stdin.pipe)

        stdout = self._pipes.get(1)
        stderr = self._pipes.get(2)
        if stdout is not None and stderr is stdout:
            info.append('stdout=stderr=%s' % stdout.pipe)
        else:
            if stdout is not None:
                info.append('stdout=%s' % stdout.pipe)
            if stderr is not None:
                info.append('stderr=%s' % stderr.pipe)

        return '<%s>' % ' '.join(info)

    def _start(self, args, shell, stdin, stdout, stderr, bufsize, **kwargs):
        raise NotImplementedError

    def _make_write_subprocess_pipe_proto(self, fd):
        raise NotImplementedError

    def _make_read_subprocess_pipe_proto(self, fd):
        raise NotImplementedError

    def close(self):
        self._closed = True
        for proto in self._pipes.values():
            if proto is None:
                continue
            proto.pipe.close()
        if self._returncode is None:
            self.terminate()

    # On Python 3.3 and older, objects with a destructor part of a reference
    # cycle are never destroyed. It's not more the case on Python 3.4 thanks
    # to the PEP 442.
    if sys.version_info >= (3, 4):
        def __del__(self):
            if not self._closed:
                warnings.warn("unclosed transport %r" % self, ResourceWarning)
                self.close()

    def get_pid(self):
        return self._pid

    def get_returncode(self):
        return self._returncode

    def get_pipe_transport(self, fd):
        if fd in self._pipes:
            return self._pipes[fd].pipe
        else:
            return None

    def send_signal(self, signal):
        self._proc.send_signal(signal)

    def terminate(self):
        self._proc.terminate()

    def kill(self):
        self._proc.kill()

    def _kill_wait(self):
        """Close pipes, kill the subprocess and read its return status.

        Function called when an exception is raised during the creation
        of a subprocess.
        """
        self._closed = True
        if self._loop.get_debug():
            logger.warning('Exception during subprocess creation, '
                           'kill the subprocess %r',
                           self,
                           exc_info=True)

        proc = self._proc
        if proc.stdout:
            proc.stdout.close()
        if proc.stderr:
            proc.stderr.close()
        if proc.stdin:
            proc.stdin.close()

        try:
            proc.kill()
        except ProcessLookupError:
            pass
        self._returncode = proc.wait()

        self.close()

    @coroutine
    def _post_init(self):
        try:
            proc = self._proc
            loop = self._loop
            if proc.stdin is not None:
                _, pipe = yield from loop.connect_write_pipe(
                    lambda: WriteSubprocessPipeProto(self, 0),
                    proc.stdin)
                self._pipes[0] = pipe
            if proc.stdout is not None:
                _, pipe = yield from loop.connect_read_pipe(
                    lambda: ReadSubprocessPipeProto(self, 1),
                    proc.stdout)
                self._pipes[1] = pipe
            if proc.stderr is not None:
                _, pipe = yield from loop.connect_read_pipe(
                    lambda: ReadSubprocessPipeProto(self, 2),
                    proc.stderr)
                self._pipes[2] = pipe

            assert self._pending_calls is not None

            self._loop.call_soon(self._protocol.connection_made, self)
            for callback, data in self._pending_calls:
                self._loop.call_soon(callback, *data)
            self._pending_calls = None
        except:
            self._kill_wait()
            raise

    def _call(self, cb, *data):
        if self._pending_calls is not None:
            self._pending_calls.append((cb, data))
        else:
            self._loop.call_soon(cb, *data)

    def _pipe_connection_lost(self, fd, exc):
        self._call(self._protocol.pipe_connection_lost, fd, exc)
        self._try_finish()

    def _pipe_data_received(self, fd, data):
        self._call(self._protocol.pipe_data_received, fd, data)

    def _process_exited(self, returncode):
        assert returncode is not None, returncode
        assert self._returncode is None, self._returncode
        if self._loop.get_debug():
            logger.info('%r exited with return code %r',
                        self, returncode)
        self._returncode = returncode
        self._call(self._protocol.process_exited)
        self._try_finish()

    def _try_finish(self):
        assert not self._finished
        if self._returncode is None:
            return
        if all(p is not None and p.disconnected
               for p in self._pipes.values()):
            self._finished = True
            self._call(self._call_connection_lost, None)

    def _call_connection_lost(self, exc):
        try:
            self._protocol.connection_lost(exc)
        finally:
            self._proc = None
            self._protocol = None
            self._loop = None


class WriteSubprocessPipeProto(protocols.BaseProtocol):

    def __init__(self, proc, fd):
        self.proc = proc
        self.fd = fd
        self.pipe = None
        self.disconnected = False

    def connection_made(self, transport):
        self.pipe = transport

    def __repr__(self):
        return ('<%s fd=%s pipe=%r>'
                % (self.__class__.__name__, self.fd, self.pipe))

    def connection_lost(self, exc):
        self.disconnected = True
        self.proc._pipe_connection_lost(self.fd, exc)
        self.proc = None

    def pause_writing(self):
        self.proc._protocol.pause_writing()

    def resume_writing(self):
        self.proc._protocol.resume_writing()


class ReadSubprocessPipeProto(WriteSubprocessPipeProto,
                              protocols.Protocol):

    def data_received(self, data):
        self.proc._pipe_data_received(self.fd, data)