from __future__ import with_statement
import subprocess
import functools
from contextlib import contextmanager
from plumbum.commands.processes import run_proc
from plumbum.lib import six
from tempfile import TemporaryFile
from subprocess import PIPE, Popen


class RedirectionError(Exception):
    """Raised when an attempt is made to redirect an process' standard handle,
    which was already redirected to/from a file"""


#===================================================================================================
# Utilities
#===================================================================================================
# modified from the stdlib pipes module for windows
_safechars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@%_-+=:,./'
_funnychars = '"`$\\'
def shquote(text):
    """Quotes the given text with shell escaping (assumes as syntax similar to ``sh``)"""
    if not text:
        return "''"
    text = str(text)
    if not text:
        return "''"
    for c in text:
        if c not in _safechars:
            break
    else:
        return text
    if "'" not in text:
        return "'" + text + "'"
    res = "".join(('\\' + c if c in _funnychars else c) for c in text)
    return '"' + res + '"'

def shquote_list(seq):
    return [shquote(item) for item in seq]


#===================================================================================================
# Commands
#===================================================================================================
class BaseCommand(object):
    """Base of all command objects"""

    __slots__ = ["cwd", "env", "encoding"]

    def __str__(self):
        return " ".join(self.formulate())

    def __or__(self, other):
        """Creates a pipe with the other command"""
        return Pipeline(self, other)

    def __gt__(self, file):
        """Redirects the process' stdout to the given file"""
        return StdoutRedirection(self, file)

    def __rshift__(self, file):
        """Redirects the process' stdout to the given file (appending)"""
        return AppendingStdoutRedirection(self, file)

    def __ge__(self, file):
        """Redirects the process' stderr to the given file"""
        return StderrRedirection(self, file)

    def __lt__(self, file):
        """Redirects the given file into the process' stdin"""
        return StdinRedirection(self, file)
    def __lshift__(self, data):
        """Redirects the given data into the process' stdin"""
        return StdinDataRedirection(self, data)

    def __getitem__(self, args):
        """Creates a bound-command with the given arguments"""
        if not isinstance(args, (tuple, list)):
            args = [args, ]
        if not args:
            return self
        if isinstance(self, BoundCommand):
            return BoundCommand(self.cmd, self.args + list(args))
        else:
            return BoundCommand(self, args)

    def __call__(self, *args, **kwargs):
        """A shortcut for `run(args)`, returning only the process' stdout"""
        return self.run(args, **kwargs)[1]

    def _get_encoding(self):
        raise NotImplementedError()

    def setenv(self, **envvars):
        """Creates a BoundEnvCommand with the given environment variables"""
        if not envvars:
            return self
        return BoundEnvCommand(self, envvars)

    @property
    def machine(self):
        raise NotImplementedError()

    def formulate(self, level = 0, args = ()):
        """Formulates the command into a command-line, i.e., a list of shell-quoted strings
        that can be executed by ``Popen`` or shells.

        :param level: The nesting level of the formulation; it dictates how much shell-quoting
                      (if any) should be performed

        :param args: The arguments passed to this command (a tuple)

        :returns: A list of strings
        """
        raise NotImplementedError()

    def popen(self, args = (), **kwargs):
        """Spawns the given command, returning a ``Popen``-like object.

        .. note::

           When processes run in the **background** (either via ``popen`` or
           :class:`& BG <plumbum.commands.BG>`), their stdout/stderr pipes might fill up,
           causing them to hang. If you know a process produces output, be sure to consume it
           every once in a while, using a monitoring thread/reactor in the background.
           For more info, see `#48 <https://github.com/tomerfiliba/plumbum/issues/48>`_

        :param args: Any arguments to be passed to the process (a tuple)

        :param kwargs: Any keyword-arguments to be passed to the ``Popen`` constructor

        :returns: A ``Popen``-like object
        """
        raise NotImplementedError()

    @contextmanager
    def bgrun(self, args = (), **kwargs):
        """Runs the given command as a context manager, allowing you to create a
        `pipeline <http://en.wikipedia.org/wiki/Pipeline_(computing)>`_ (not in the UNIX sense)
        of programs, parallelizing their work. In other words, instead of running programs
        one after the other, you can start all of them at the same time and wait for them to
        finish. For a more thorough review, see
        `Lightweight Asynchronism <http://tomerfiliba.com/blog/Toying-with-Context-Managers/>`_.

        Example::

            from plumbum.cmd import mkfs

            with mkfs["-t", "ext3", "/dev/sda1"] as p1:
                with mkfs["-t", "ext3", "/dev/sdb1"] as p2:
                    pass

        .. note::

           When processes run in the **background** (either via ``popen`` or
           :class:`& BG <plumbum.commands.BG>`), their stdout/stderr pipes might fill up,
           causing them to hang. If you know a process produces output, be sure to consume it
           every once in a while, using a monitoring thread/reactor in the background.
           For more info, see `#48 <https://github.com/tomerfiliba/plumbum/issues/48>`_

        For the arguments, see :func:`run <BaseCommand.run>`.

        :returns: A Popen object, augmented with a ``.run()`` method, which returns a tuple of
                  (return code, stdout, stderr)
        """
        retcode = kwargs.pop("retcode", 0)
        timeout = kwargs.pop("timeout", None)
        p = self.popen(args, **kwargs)
        was_run = [False]
        def runner():
            if was_run[0]:
                return  # already done
            was_run[0] = True
            try:
                return run_proc(p, retcode, timeout)
            finally:
                for f in [p.stdin, p.stdout, p.stderr]:
                    try:
                        f.close()
                    except Exception:
                        pass
        p.run = runner
        yield p
        runner()

    def run(self, args = (), **kwargs):
        """Runs the given command (equivalent to popen() followed by
        :func:`run_proc <plumbum.commands.run_proc>`). If the exit code of the process does
        not match the expected one, :class:`ProcessExecutionError
        <plumbum.commands.ProcessExecutionError>` is raised.

        :param args: Any arguments to be passed to the process (a tuple)

        :param retcode: The expected return code of this process (defaults to 0).
                        In order to disable exit-code validation, pass ``None``. It may also
                        be a tuple (or any iterable) of expected exit codes.

                        .. note:: this argument must be passed as a keyword argument.

        :param timeout: The maximal amount of time (in seconds) to allow the process to run.
                        ``None`` means no timeout is imposed; otherwise, if the process hasn't
                        terminated after that many seconds, the process will be forcefully
                        terminated an exception will be raised

                        .. note:: this argument must be passed as a keyword argument.

        :param kwargs: Any keyword-arguments to be passed to the ``Popen`` constructor

        :returns: A tuple of (return code, stdout, stderr)
        """
        with self.bgrun(args, **kwargs) as p:
            return p.run()


class BoundCommand(BaseCommand):
    __slots__ = ["cmd", "args"]
    def __init__(self, cmd, args):
        self.cmd = cmd
        self.args = list(args)
    def __repr__(self):
        return "BoundCommand(%r, %r)" % (self.cmd, self.args)
    def _get_encoding(self):
        return self.cmd._get_encoding()
    def formulate(self, level = 0, args = ()):
        return self.cmd.formulate(level + 1, self.args + list(args))
    @property
    def machine(self):
        return self.cmd.machine
    def popen(self, args = (), **kwargs):
        if isinstance(args, six.string_types):
            args = [args, ]
        return self.cmd.popen(self.args + list(args), **kwargs)

class BoundEnvCommand(BaseCommand):
    __slots__ = ["cmd", "envvars"]
    def __init__(self, cmd, envvars):
        self.cmd = cmd
        self.envvars = envvars
    def __repr__(self):
        return "BoundEnvCommand(%r, %r)" % (self.cmd, self.envvars)
    def _get_encoding(self):
        return self.cmd._get_encoding()
    def formulate(self, level = 0, args = ()):
        return self.cmd.formulate(level, args)
    @property
    def machine(self):
        return self.cmd.machine
    def popen(self, args = (), **kwargs):
        with self.machine.env(**self.envvars):
            return self.cmd.popen(args, **kwargs)

class Pipeline(BaseCommand):
    __slots__ = ["srccmd", "dstcmd"]
    def __init__(self, srccmd, dstcmd):
        self.srccmd = srccmd
        self.dstcmd = dstcmd
    def __repr__(self):
        return "Pipeline(%r, %r)" % (self.srccmd, self.dstcmd)
    def _get_encoding(self):
        return self.srccmd._get_encoding() or self.dstcmd._get_encoding()
    def formulate(self, level = 0, args = ()):
        return self.srccmd.formulate(level + 1) + ["|"] + self.dstcmd.formulate(level + 1, args)

    @property
    def machine(self):
        return self.srccmd.machine

    def popen(self, args = (), **kwargs):
        src_kwargs = kwargs.copy()
        src_kwargs["stdout"] = PIPE
        src_kwargs["stderr"] = PIPE

        srcproc = self.srccmd.popen(args, **src_kwargs)
        kwargs["stdin"] = srcproc.stdout
        dstproc = self.dstcmd.popen(**kwargs)
        # allow p1 to receive a SIGPIPE if p2 exits
        srcproc.stdout.close()
        srcproc.stderr.close()
        if srcproc.stdin:
            srcproc.stdin.close()
        dstproc.srcproc = srcproc
        
        # monkey-patch .wait() to wait on srcproc as well (it's expected to die when dstproc dies)
        dstproc_wait = dstproc.wait
        @functools.wraps(Popen.wait)
        def wait2(*args, **kwargs):
            rc = dstproc_wait(*args, **kwargs)
            srcproc.wait(*args, **kwargs)
            return rc
        dstproc.wait = wait2
        return dstproc

class BaseRedirection(BaseCommand):
    __slots__ = ["cmd", "file"]
    SYM = None
    KWARG = None
    MODE = None

    def __init__(self, cmd, file):
        self.cmd = cmd
        self.file = file
    def _get_encoding(self):
        return self.cmd._get_encoding()
    def __repr__(self):
        return "%s(%r, %r)" % (self.__class__.__name__, self.cmd, self.file)
    def formulate(self, level = 0, args = ()):
        return self.cmd.formulate(level + 1, args) + [self.SYM, shquote(getattr(self.file, "name", self.file))]
    @property
    def machine(self):
        return self.cmd.machine
    def popen(self, args = (), **kwargs):
        from plumbum.machines.local import LocalPath
        from plumbum.machines.remote import RemotePath

        if self.KWARG in kwargs and kwargs[self.KWARG] not in (PIPE, None):
            raise RedirectionError("%s is already redirected" % (self.KWARG,))
        if isinstance(self.file, six.string_types + (LocalPath,)):
            f = kwargs[self.KWARG] = open(str(self.file), self.MODE)
        elif isinstance(self.file, RemotePath):
            raise TypeError("Cannot redirect to/from remote paths")
        else:
            kwargs[self.KWARG] = self.file
            f = None
        try:
            return self.cmd.popen(args, **kwargs)
        finally:
            if f:
                f.close()

class StdinRedirection(BaseRedirection):
    __slots__ = []
    SYM = "<"
    KWARG = "stdin"
    MODE = "r"

class StdoutRedirection(BaseRedirection):
    __slots__ = []
    SYM = ">"
    KWARG = "stdout"
    MODE = "w"

class AppendingStdoutRedirection(BaseRedirection):
    __slots__ = []
    SYM = ">>"
    KWARG = "stdout"
    MODE = "a"

class StderrRedirection(BaseRedirection):
    __slots__ = []
    SYM = "2>"
    KWARG = "stderr"
    MODE = "w"

class ERROUT(int):
    def __repr__(self):
        return "ERROUT"
    def __str__(self):
        return "&1"
ERROUT = ERROUT(subprocess.STDOUT)

class StdinDataRedirection(BaseCommand):
    __slots__ = ["cmd", "data"]
    CHUNK_SIZE = 16000

    def __init__(self, cmd, data):
        self.cmd = cmd
        self.data = data
    def _get_encoding(self):
        return self.cmd._get_encoding()

    def formulate(self, level = 0, args = ()):
        return ["echo %s" % (shquote(self.data),), "|", self.cmd.formulate(level + 1, args)]
    @property
    def machine(self):
        return self.cmd.machine
    def popen(self, args = (), **kwargs):
        if "stdin" in kwargs and kwargs["stdin"] != PIPE:
            raise RedirectionError("stdin is already redirected")
        data = self.data
        if isinstance(data, six.unicode_type) and self._get_encoding() is not None:
            data = data.encode(self._get_encoding())
        f = TemporaryFile()
        while data:
            chunk = data[:self.CHUNK_SIZE]
            f.write(chunk)
            data = data[self.CHUNK_SIZE:]
        f.seek(0)
        # try:
        return self.cmd.popen(args, stdin = f, **kwargs)
        # finally:
        #    f.close()

class ConcreteCommand(BaseCommand):
    QUOTE_LEVEL = None
    __slots__ = ["executable", "encoding"]
    def __init__(self, executable, encoding):
        self.executable = executable
        self.encoding = encoding
        self.cwd = None
        self.env = None
    def __str__(self):
        return str(self.executable)
    def _get_encoding(self):
        return self.encoding

    @property
    def machine(self):
        return self.cmd.machine

    def formulate(self, level = 0, args = ()):
        argv = [str(self.executable)]
        for a in args:
            if not a and a != "":
                continue
            if isinstance(a, BaseCommand):
                if level >= self.QUOTE_LEVEL:
                    argv.extend(shquote_list(a.formulate(level + 1)))
                else:
                    argv.extend(a.formulate(level + 1))
            elif isinstance(a, (list, tuple)):
                argv.extend(shquote(b) if level >= self.QUOTE_LEVEL else str(b) for b in a)
            else:
                argv.append(shquote(a) if level >= self.QUOTE_LEVEL else str(a))
        # if self.encoding:
        #    argv = [a.encode(self.encoding) for a in argv if isinstance(a, six.string_types)]
        return argv