# -*- coding: utf-8 -*-
import os
import sys
import socket
from subprocess import Popen, PIPE, STDOUT
from .exceptions import CommandError

USED_PORTS = set()


def run_cmd_wait(cmd, input=None, stdout=PIPE, stderr=PIPE,
                 merge_streams=False, env=os.environ):
    "Run a subprocess and wait for it to finish"

    if input is None:
        stdin = None
    else:
        stdin = PIPE

    if merge_streams:
        stderr = STDOUT
    else:
        stderr = PIPE

    p = Popen(cmd, stdin=stdin, stdout=stdout, stderr=stderr, env=env)
    out, err = p.communicate(input)

    # In python3 we will be able use the following instead of the previous
    # line to avoid locking if task is unexpectedly waiting for input
    # try:
    #     out, err = p.communicate(input, timeout=15)
    # except TimeoutExpired:
    #     p.kill()
    #     out, err = proc.communicate()

    if p.returncode != 0:
        raise CommandError(cmd, p.returncode, out, err)

    return p.returncode, out, err


def run_cmd_wait_nofail(*args, **kwargs):
    "Same as run_cmd_wait but silence the exception if it happens"
    try:
        return run_cmd_wait(*args, **kwargs)
    except CommandError as e:
        return e.code, e.out, e.err


def port_used(addr="localhost", port=None):
    "Return True if port is in use, False otherwise"
    if port is None:
        raise TypeError("Argument 'port' may not be None")

    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    result = s.connect_ex((addr, port))
    s.close()
    # result == 0 if connection was successful
    return result == 0


def find_unused_port(addr="localhost", start=53589, track=True):
    """Find an unused port starting at `start` port

    If track=False the returned port will not be marked as in-use and the code
    will rely entirely on the ability to connect to addr:port as detection
    mechanism. Note this may cause problems if ports are assigned but not used
    immediately
    """
    maxport = 65535
    unused = None

    for port in xrange(start, maxport):
        if not port_used(addr, port):
            if track and port in USED_PORTS:
                continue

            unused = port
            break

    if unused is None:
        raise ValueError("No available port in the range {0}-{1}".format(
            start, maxport))

    if track:
        USED_PORTS.add(unused)

    return unused


def release_port(port):
    """Forget that given port was marked as'in-use
    """
    try:
        USED_PORTS.remove(port)
    except KeyError:
        pass


try:
    from shutil import which
except ImportError:
    # NOTE: This is shutil.which backported from python-3.3.3
    def which(cmd, mode=os.F_OK | os.X_OK, path=None):
        """Given a command, mode, and a PATH string, return the path which
        conforms to the given mode on the PATH, or None if there is no such
        file.

        `mode` defaults to os.F_OK | os.X_OK. `path` defaults to the result
        of os.environ.get("PATH"), or can be overridden with a custom search
        path.

        """
        # Check that a given file can be accessed with the correct mode.
        # Additionally check that `file` is not a directory, as on Windows
        # directories pass the os.access check.
        def _access_check(fn, mode):
            return (os.path.exists(fn) and os.access(fn, mode)
                    and not os.path.isdir(fn))

        # If we're given a path with a directory part, look it up directly
        # rather than referring to PATH directories. This includes checking
        # relative to the current directory, e.g. ./script
        if os.path.dirname(cmd):
            if _access_check(cmd, mode):
                return cmd
            return None

        if path is None:
            path = os.environ.get("PATH", os.defpath)
        if not path:
            return None
        path = path.split(os.pathsep)

        if sys.platform == "win32":
            # The current directory takes precedence on Windows.
            if os.curdir not in path:
                path.insert(0, os.curdir)

            # PATHEXT is necessary to check on Windows.
            pathext = os.environ.get("PATHEXT", "").split(os.pathsep)
            # See if the given file matches any of the expected path
            # extensions. This will allow us to short circuit when given
            # "python.exe". If it does match, only test that one, otherwise we
            # have to try others.
            if any(cmd.lower().endswith(ext.lower()) for ext in pathext):
                files = [cmd]
            else:
                files = [cmd + ext for ext in pathext]
        else:
            # On other platforms you don't have things like PATHEXT to tell you
            # what file suffixes are executable, so just pass on cmd as-is.
            files = [cmd]

        seen = set()
        for dir in path:
            normdir = os.path.normcase(dir)
            if normdir not in seen:
                seen.add(normdir)
                for thefile in files:
                    name = os.path.join(dir, thefile)
                    if _access_check(name, mode):
                        return name
        return None

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