"""
Miscellaneous utility functions, wrappers around some subprocess procedures.
"""

import ast
import os
import subprocess

import fcntl

from core.misc import log

logger = log.get_logger(__name__)


def closeonexec(fd):
    fdflags = fcntl.fcntl(fd, fcntl.F_GETFD)
    fcntl.fcntl(fd, fcntl.F_SETFD, fdflags | fcntl.FD_CLOEXEC)


def check_executables(executables):
    for executable in executables:
        if not (os.path.isfile(executable) and os.access(executable, os.X_OK)):
            raise EnvironmentError("executable not found: %s" % executable)


def which(program):
    """
    From: http://stackoverflow.com/questions/377017/test-if-executable-exists-in-python

    :param str program: program to check for
    :return: path if it exists, none otherwise
    """

    def is_exe(fpath):
        return os.path.isfile(fpath) and os.access(fpath, os.X_OK)

    fpath, fname = os.path.split(program)
    if fpath:
        if is_exe(program):
            return program
    else:
        for path in os.environ["PATH"].split(os.pathsep):
            path = path.strip('"')
            exe_file = os.path.join(path, program)
            if is_exe(exe_file):
                return exe_file

    return None


def ensurepath(pathlist):
    searchpath = os.environ["PATH"].split(":")
    for p in set(pathlist):
        if p not in searchpath:
            os.environ["PATH"] += ":" + p


def maketuple(obj):
    if hasattr(obj, "__iter__"):
        return tuple(obj)
    else:
        return obj,


def maketuplefromstr(s, type):
    s.replace('\\', '\\\\')
    return ast.literal_eval(s)
    # return tuple(type(i) for i in s[1:-1].split(','))
    # r = ()
    # for i in s.strip("()").split(','):
    #    r += (i.strip("' "), )
    # chop empty last element from "('a',)" strings
    # if r[-1] == '':
    #    r = r[:-1]
    # return r


def mutecall(*args, **kwds):
    kwds["stdout"] = open(os.devnull, "w")
    kwds["stderr"] = subprocess.STDOUT
    return subprocess.call(*args, **kwds)


def mutecheck_call(*args, **kwds):
    kwds["stdout"] = open(os.devnull, "w")
    kwds["stderr"] = subprocess.STDOUT
    return subprocess.check_call(*args, **kwds)


def spawn(*args, **kwds):
    return subprocess.Popen(*args, **kwds).pid


def mutespawn(*args, **kwds):
    kwds["stdout"] = open(os.devnull, "w")
    kwds["stderr"] = subprocess.STDOUT
    return subprocess.Popen(*args, **kwds).pid


def detachinit():
    if os.fork():
        # parent exits
        os._exit(0)
    os.setsid()


def detach(*args, **kwds):
    kwds["preexec_fn"] = detachinit
    return subprocess.Popen(*args, **kwds).pid


def mutedetach(*args, **kwds):
    kwds["preexec_fn"] = detachinit
    kwds["stdout"] = open(os.devnull, "w")
    kwds["stderr"] = subprocess.STDOUT
    return subprocess.Popen(*args, **kwds).pid


def cmdresult(args):
    """
    Execute a command on the host and return a tuple containing the
    exit status and result string. stderr output
    is folded into the stdout result string.
    """
    cmdid = subprocess.Popen(args, stdin=open(os.devnull, 'r'),
                             stdout=subprocess.PIPE,
                             stderr=subprocess.STDOUT)
    # err will always be None
    result, err = cmdid.communicate()
    status = cmdid.wait()
    return status, result


def hexdump(s, bytes_per_word=2, words_per_line=8):
    dump = ""
    count = 0
    bytes = bytes_per_word * words_per_line
    while s:
        line = s[:bytes]
        s = s[bytes:]
        tmp = map(lambda x: ("%02x" * bytes_per_word) % x,
                  zip(*[iter(map(ord, line))] * bytes_per_word))
        if len(line) % 2:
            tmp.append("%x" % ord(line[-1]))
        dump += "0x%08x: %s\n" % (count, " ".join(tmp))
        count += len(line)
    return dump[:-1]


def filemunge(pathname, header, text):
    """
    Insert text at the end of a file, surrounded by header comments.
    """
    # prevent duplicates
    filedemunge(pathname, header)
    f = open(pathname, 'a')
    f.write("# BEGIN %s\n" % header)
    f.write(text)
    f.write("# END %s\n" % header)
    f.close()


def filedemunge(pathname, header):
    """
    Remove text that was inserted in a file surrounded by header comments.
    """
    f = open(pathname, 'r')
    lines = f.readlines()
    f.close()
    start = None
    end = None
    for i in range(len(lines)):
        if lines[i] == "# BEGIN %s\n" % header:
            start = i
        elif lines[i] == "# END %s\n" % header:
            end = i + 1
    if start is None or end is None:
        return
    f = open(pathname, 'w')
    lines = lines[:start] + lines[end:]
    f.write("".join(lines))
    f.close()


def expandcorepath(pathname, session=None, node=None):
    """
    Expand a file path given session information.
    """
    if session is not None:
        pathname = pathname.replace('~', "/home/%s" % session.user)
        pathname = pathname.replace('%SESSION%', str(session.sessionid))
        pathname = pathname.replace('%SESSION_DIR%', session.sessiondir)
        pathname = pathname.replace('%SESSION_USER%', session.user)
    if node is not None:
        pathname = pathname.replace('%NODE%', str(node.objid))
        pathname = pathname.replace('%NODENAME%', node.name)
    return pathname


def sysctldevname(devname):
    """
    Translate a device name to the name used with sysctl.
    """
    if devname is None:
        return None
    return devname.replace(".", "/")


def daemonize(rootdir="/", umask=0, close_fds=False, dontclose=(),
              stdin=os.devnull, stdout=os.devnull, stderr=os.devnull,
              stdoutmode=0644, stderrmode=0644, pidfilename=None,
              defaultmaxfd=1024):
    """
    Run the background process as a daemon.
    """
    if not hasattr(dontclose, "__contains__"):
        if not isinstance(dontclose, int):
            raise TypeError, "dontclose must be an integer"
        dontclose = (int(dontclose),)
    else:
        for fd in dontclose:
            if not isinstance(fd, int):
                raise TypeError, "dontclose must contain only integers"
    # redirect stdin
    if stdin:
        fd = os.open(stdin, os.O_RDONLY)
        os.dup2(fd, 0)
        os.close(fd)
    # redirect stdout
    if stdout:
        fd = os.open(stdout, os.O_WRONLY | os.O_CREAT | os.O_APPEND,
                     stdoutmode)
        os.dup2(fd, 1)
        if stdout == stderr:
            os.dup2(1, 2)
        os.close(fd)
    # redirect stderr
    if stderr and (stderr != stdout):
        fd = os.open(stderr, os.O_WRONLY | os.O_CREAT | os.O_APPEND,
                     stderrmode)
        os.dup2(fd, 2)
        os.close(fd)
    if os.fork():
        # parent exits
        os._exit(0)
    os.setsid()
    pid = os.fork()
    if pid:
        if pidfilename:
            try:
                f = open(pidfilename, "w")
                f.write("%s\n" % pid)
                f.close()
            except IOError:
                logger.exception("error writing to file: %s", pidfilename)
        # parent exits
        os._exit(0)
    if rootdir:
        os.chdir(rootdir)
    os.umask(umask)
    if close_fds:
        try:
            maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
            if maxfd == resource.RLIM_INFINITY:
                raise ValueError
        except:
            maxfd = defaultmaxfd
        for fd in xrange(3, maxfd):
            if fd in dontclose:
                continue
            try:
                os.close(fd)
            except:
                logger.exception("error closing file descriptor")


def readfileintodict(filename, d):
    """
    Read key=value pairs from a file, into a dict.
    Skip comments; strip newline characters and spacing.
    """
    with open(filename, 'r') as f:
        lines = f.readlines()
    for l in lines:
        if l[:1] == '#':
            continue
        try:
            key, value = l.split('=', 1)
            d[key] = value.strip()
        except ValueError:
            logger.exception("error reading file to dict: %s", filename)


def checkforkernelmodule(name):
    """
    Return a string if a Linux kernel module is loaded, None otherwise.
    The string is the line from /proc/modules containing the module name,
    memory size (bytes), number of loaded instances, dependencies, state,
    and kernel memory offset.
    """
    with open('/proc/modules', 'r') as f:
        for line in f:
            if line.startswith(name + ' '):
                return line.rstrip()
    return None