import errno
import itertools
import math
import os
import platform
import signal
import subprocess
import sys
import threading

def to_bytes(s):
    """Return the parameter as type 'bytes', possibly encoding it.

    In Python2, the 'bytes' type is the same as 'str'. In Python3, they are
    distinct.
    """
    if isinstance(s, bytes):
        # In Python2, this branch is taken for both 'str' and 'bytes'.
        # In Python3, this branch is taken only for 'bytes'.
        return s
    # In Python2, 's' is a 'unicode' object.
    # In Python3, 's' is a 'str' object.
    # Encode to UTF-8 to get 'bytes' data.
    return s.encode('utf-8')

def to_string(b):
    """Return the parameter as type 'str', possibly encoding it.

    In Python2, the 'str' type is the same as 'bytes'. In Python3, the
    'str' type is (essentially) Python2's 'unicode' type, and 'bytes' is
    distinct.
    """
    if isinstance(b, str):
        # In Python2, this branch is taken for types 'str' and 'bytes'.
        # In Python3, this branch is taken only for 'str'.
        return b
    if isinstance(b, bytes):
        # In Python2, this branch is never taken ('bytes' is handled as 'str').
        # In Python3, this is true only for 'bytes'.
        try:
            return b.decode('utf-8')
        except UnicodeDecodeError:
            # If the value is not valid Unicode, return the default
            # repr-line encoding.
            return str(b)

    # By this point, here's what we *don't* have:
    #
    #  - In Python2:
    #    - 'str' or 'bytes' (1st branch above)
    #  - In Python3:
    #    - 'str' (1st branch above)
    #    - 'bytes' (2nd branch above)
    #
    # The last type we might expect is the Python2 'unicode' type. There is no
    # 'unicode' type in Python3 (all the Python3 cases were already handled). In
    # order to get a 'str' object, we need to encode the 'unicode' object.
    try:
        return b.encode('utf-8')
    except AttributeError:
        raise TypeError('not sure how to convert %s to %s' % (type(b), str))

def detectCPUs():
    """
    Detects the number of CPUs on a system. Cribbed from pp.
    """
    # Linux, Unix and MacOS:
    if hasattr(os, "sysconf"):
        if "SC_NPROCESSORS_ONLN" in os.sysconf_names:
            # Linux & Unix:
            ncpus = os.sysconf("SC_NPROCESSORS_ONLN")
            if isinstance(ncpus, int) and ncpus > 0:
                return ncpus
        else: # OSX:
            return int(subprocess.check_output(['sysctl', '-n', 'hw.ncpu'],
                                               stderr=subprocess.STDOUT))
    # Windows:
    if "NUMBER_OF_PROCESSORS" in os.environ:
        ncpus = int(os.environ["NUMBER_OF_PROCESSORS"])
        if ncpus > 0:
            # With more than 32 processes, process creation often fails with
            # "Too many open files".  FIXME: Check if there's a better fix.
            return min(ncpus, 32)
    return 1 # Default

def mkdir_p(path):
    """mkdir_p(path) - Make the "path" directory, if it does not exist; this
    will also make directories for any missing parent directories."""
    if not path or os.path.exists(path):
        return

    parent = os.path.dirname(path)
    if parent != path:
        mkdir_p(parent)

    try:
        os.mkdir(path)
    except OSError:
        e = sys.exc_info()[1]
        # Ignore EEXIST, which may occur during a race condition.
        if e.errno != errno.EEXIST:
            raise

def listdir_files(dirname, suffixes=None, exclude_filenames=None):
    """Yields files in a directory.

    Filenames that are not excluded by rules below are yielded one at a time, as
    basenames (i.e., without dirname).

    Files starting with '.' are always skipped.

    If 'suffixes' is not None, then only filenames ending with one of its
    members will be yielded. These can be extensions, like '.exe', or strings,
    like 'Test'. (It is a lexicographic check; so an empty sequence will yield
    nothing, but a single empty string will yield all filenames.)

    If 'exclude_filenames' is not None, then none of the file basenames in it
    will be yielded.

    If specified, the containers for 'suffixes' and 'exclude_filenames' must
    support membership checking for strs.

    Args:
        dirname: a directory path.
        suffixes: (optional) a sequence of strings (set, list, etc.).
        exclude_filenames: (optional) a sequence of strings.

    Yields:
        Filenames as returned by os.listdir (generally, str).
    """
    if exclude_filenames is None:
        exclude_filenames = set()
    if suffixes is None:
        suffixes = {''}
    for filename in os.listdir(dirname):
        if (os.path.isdir(os.path.join(dirname, filename)) or
            filename.startswith('.') or
            filename in exclude_filenames or
            not any(filename.endswith(sfx) for sfx in suffixes)):
            continue
        yield filename

def which(command, paths = None):
    """which(command, [paths]) - Look up the given command in the paths string
    (or the PATH environment variable, if unspecified)."""

    if paths is None:
        paths = os.environ.get('PATH','')

    # Check for absolute match first.
    if os.path.isfile(command):
        return command

    # Would be nice if Python had a lib function for this.
    if not paths:
        paths = os.defpath

    # Get suffixes to search.
    # On Cygwin, 'PATHEXT' may exist but it should not be used.
    if os.pathsep == ';':
        pathext = os.environ.get('PATHEXT', '').split(';')
    else:
        pathext = ['']

    # Search the paths...
    for path in paths.split(os.pathsep):
        for ext in pathext:
            p = os.path.join(path, command + ext)
            if os.path.exists(p) and not os.path.isdir(p):
                return p

    return None

def checkToolsPath(dir, tools):
    for tool in tools:
        if not os.path.exists(os.path.join(dir, tool)):
            return False
    return True

def whichTools(tools, paths):
    for path in paths.split(os.pathsep):
        if checkToolsPath(path, tools):
            return path
    return None

def printHistogram(items, title = 'Items'):
    items.sort(key = lambda item: item[1])

    maxValue = max([v for _,v in items])

    # Select first "nice" bar height that produces more than 10 bars.
    power = int(math.ceil(math.log(maxValue, 10)))
    for inc in itertools.cycle((5, 2, 2.5, 1)):
        barH = inc * 10**power
        N = int(math.ceil(maxValue / barH))
        if N > 10:
            break
        elif inc == 1:
            power -= 1

    histo = [set() for i in range(N)]
    for name,v in items:
        bin = min(int(N * v/maxValue), N-1)
        histo[bin].add(name)

    barW = 40
    hr = '-' * (barW + 34)
    print('\nSlowest %s:' % title)
    print(hr)
    for name,value in items[-20:]:
        print('%.2fs: %s' % (value, name))
    print('\n%s Times:' % title)
    print(hr)
    pDigits = int(math.ceil(math.log(maxValue, 10)))
    pfDigits = max(0, 3-pDigits)
    if pfDigits:
        pDigits += pfDigits + 1
    cDigits = int(math.ceil(math.log(len(items), 10)))
    print("[%s] :: [%s] :: [%s]" % ('Range'.center((pDigits+1)*2 + 3),
                                    'Percentage'.center(barW),
                                    'Count'.center(cDigits*2 + 1)))
    print(hr)
    for i,row in enumerate(histo):
        pct = float(len(row)) / len(items)
        w = int(barW * pct)
        print("[%*.*fs,%*.*fs) :: [%s%s] :: [%*d/%*d]" % (
            pDigits, pfDigits, i*barH, pDigits, pfDigits, (i+1)*barH,
            '*'*w, ' '*(barW-w), cDigits, len(row), cDigits, len(items)))

class ExecuteCommandTimeoutException(Exception):
    def __init__(self, msg, out, err, exitCode):
        assert isinstance(msg, str)
        assert isinstance(out, str)
        assert isinstance(err, str)
        assert isinstance(exitCode, int)
        self.msg = msg
        self.out = out
        self.err = err
        self.exitCode = exitCode

# Close extra file handles on UNIX (on Windows this cannot be done while
# also redirecting input).
kUseCloseFDs = not (platform.system() == 'Windows')
def executeCommand(command, cwd=None, env=None, input=None, timeout=0):
    """
        Execute command ``command`` (list of arguments or string)
        with
        * working directory ``cwd`` (str), use None to use the current
          working directory
        * environment ``env`` (dict), use None for none
        * Input to the command ``input`` (str), use string to pass
          no input.
        * Max execution time ``timeout`` (int) seconds. Use 0 for no timeout.

        Returns a tuple (out, err, exitCode) where
        * ``out`` (str) is the standard output of running the command
        * ``err`` (str) is the standard error of running the command
        * ``exitCode`` (int) is the exitCode of running the command

        If the timeout is hit an ``ExecuteCommandTimeoutException``
        is raised.
    """
    if input is not None:
        input = to_bytes(input)
    p = subprocess.Popen(command, cwd=cwd,
                         stdin=subprocess.PIPE,
                         stdout=subprocess.PIPE,
                         stderr=subprocess.PIPE,
                         env=env, close_fds=kUseCloseFDs)
    timerObject = None
    # FIXME: Because of the way nested function scopes work in Python 2.x we
    # need to use a reference to a mutable object rather than a plain
    # bool. In Python 3 we could use the "nonlocal" keyword but we need
    # to support Python 2 as well.
    hitTimeOut = [False]
    try:
        if timeout > 0:
            def killProcess():
                # We may be invoking a shell so we need to kill the
                # process and all its children.
                hitTimeOut[0] = True
                killProcessAndChildren(p.pid)

            timerObject = threading.Timer(timeout, killProcess)
            timerObject.start()

        out,err = p.communicate(input=input)
        exitCode = p.wait()
    finally:
        if timerObject != None:
            timerObject.cancel()

    # Ensure the resulting output is always of string type.
    out = to_string(out)
    err = to_string(err)

    if hitTimeOut[0]:
        raise ExecuteCommandTimeoutException(
            msg='Reached timeout of {} seconds'.format(timeout),
            out=out,
            err=err,
            exitCode=exitCode
            )

    # Detect Ctrl-C in subprocess.
    if exitCode == -signal.SIGINT:
        raise KeyboardInterrupt

    return out, err, exitCode

def usePlatformSdkOnDarwin(config, lit_config):
    # On Darwin, support relocatable SDKs by providing Clang with a
    # default system root path.
    if 'darwin' in config.target_triple:
        try:
            cmd = subprocess.Popen(['xcrun', '--show-sdk-path', '--sdk', 'macosx'],
                                   stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            out, err = cmd.communicate()
            out = out.strip()
            res = cmd.wait()
        except OSError:
            res = -1
        if res == 0 and out:
            sdk_path = out
            lit_config.note('using SDKROOT: %r' % sdk_path)
            config.environment['SDKROOT'] = sdk_path

def findPlatformSdkVersionOnMacOS(config, lit_config):
    if 'darwin' in config.target_triple:
        try:
            cmd = subprocess.Popen(['xcrun', '--show-sdk-version', '--sdk', 'macosx'],
                                   stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            out, err = cmd.communicate()
            out = out.strip()
            res = cmd.wait()
        except OSError:
            res = -1
        if res == 0 and out:
            return out
    return None

def killProcessAndChildren(pid):
    """
    This function kills a process with ``pid`` and all its
    running children (recursively). It is currently implemented
    using the psutil module which provides a simple platform
    neutral implementation.

    TODO: Reimplement this without using psutil so we can
          remove our dependency on it.
    """
    import psutil
    try:
        psutilProc = psutil.Process(pid)
        # Handle the different psutil API versions
        try:
            # psutil >= 2.x
            children_iterator = psutilProc.children(recursive=True)
        except AttributeError:
            # psutil 1.x
            children_iterator = psutilProc.get_children(recursive=True)
        for child in children_iterator:
            try:
                child.kill()
            except psutil.NoSuchProcess:
                pass
        psutilProc.kill()
    except psutil.NoSuchProcess:
        pass