import os
import re
import sys
import shlex
import time
import subprocess
from copy import copy
from distutils import ccompiler
from distutils.ccompiler import (
    compiler_class, gen_lib_options, get_default_compiler, new_compiler,
    CCompiler
)
from distutils.errors import (
    DistutilsExecError, DistutilsModuleError, DistutilsPlatformError,
    CompileError, UnknownFileError
)
from distutils.sysconfig import customize_compiler
from distutils.version import LooseVersion

from numpy.distutils import log
from numpy.distutils.exec_command import (
    filepath_from_subprocess_output, forward_bytes_to_stdout
)
from numpy.distutils.misc_util import cyg2win32, is_sequence, mingw32, \
                                      get_num_build_jobs, \
                                      _commandline_dep_string

# globals for parallel build management
try:
    import threading
except ImportError:
    import dummy_threading as threading
_job_semaphore = None
_global_lock = threading.Lock()
_processing_files = set()


def _needs_build(obj, cc_args, extra_postargs, pp_opts):
    """
    Check if an objects needs to be rebuild based on its dependencies

    Parameters
    ----------
    obj : str
        object file

    Returns
    -------
    bool
    """
    # defined in unixcompiler.py
    dep_file = obj + '.d'
    if not os.path.exists(dep_file):
        return True

    # dep_file is a makefile containing 'object: dependencies'
    # formatted like posix shell (spaces escaped, \ line continuations)
    # the last line contains the compiler commandline arguments as some
    # projects may compile an extension multiple times with different
    # arguments
    with open(dep_file, "r") as f:
        lines = f.readlines()

    cmdline =_commandline_dep_string(cc_args, extra_postargs, pp_opts)
    last_cmdline = lines[-1]
    if last_cmdline != cmdline:
        return True

    contents = ''.join(lines[:-1])
    deps = [x for x in shlex.split(contents, posix=True)
            if x != "\n" and not x.endswith(":")]

    try:
        t_obj = os.stat(obj).st_mtime

        # check if any of the dependencies is newer than the object
        # the dependencies includes the source used to create the object
        for f in deps:
            if os.stat(f).st_mtime > t_obj:
                return True
    except OSError:
        # no object counts as newer (shouldn't happen if dep_file exists)
        return True

    return False


def replace_method(klass, method_name, func):
    # Py3k does not have unbound method anymore, MethodType does not work
    m = lambda self, *args, **kw: func(self, *args, **kw)
    setattr(klass, method_name, m)


######################################################################
## Method that subclasses may redefine. But don't call this method,
## it i private to CCompiler class and may return unexpected
## results if used elsewhere. So, you have been warned..

def CCompiler_find_executables(self):
    """
    Does nothing here, but is called by the get_version method and can be
    overridden by subclasses. In particular it is redefined in the `FCompiler`
    class where more documentation can be found.

    """
    pass


replace_method(CCompiler, 'find_executables', CCompiler_find_executables)


# Using customized CCompiler.spawn.
def CCompiler_spawn(self, cmd, display=None):
    """
    Execute a command in a sub-process.

    Parameters
    ----------
    cmd : str
        The command to execute.
    display : str or sequence of str, optional
        The text to add to the log file kept by `numpy.distutils`.
        If not given, `display` is equal to `cmd`.

    Returns
    -------
    None

    Raises
    ------
    DistutilsExecError
        If the command failed, i.e. the exit status was not 0.

    """
    if display is None:
        display = cmd
        if is_sequence(display):
            display = ' '.join(list(display))
    log.info(display)
    try:
        if self.verbose:
            subprocess.check_output(cmd)
        else:
            subprocess.check_output(cmd, stderr=subprocess.STDOUT)
    except subprocess.CalledProcessError as exc:
        o = exc.output
        s = exc.returncode
    except OSError:
        # OSError doesn't have the same hooks for the exception
        # output, but exec_command() historically would use an
        # empty string for EnvironmentError (base class for
        # OSError)
        o = b''
        # status previously used by exec_command() for parent
        # of OSError
        s = 127
    else:
        # use a convenience return here so that any kind of
        # caught exception will execute the default code after the
        # try / except block, which handles various exceptions
        return None

    if is_sequence(cmd):
        cmd = ' '.join(list(cmd))

    if self.verbose:
        forward_bytes_to_stdout(o)

    if re.search(b'Too many open files', o):
        msg = '\nTry rerunning setup command until build succeeds.'
    else:
        msg = ''
    raise DistutilsExecError('Command "%s" failed with exit status %d%s' %
                            (cmd, s, msg))

replace_method(CCompiler, 'spawn', CCompiler_spawn)

def CCompiler_object_filenames(self, source_filenames, strip_dir=0, output_dir=''):
    """
    Return the name of the object files for the given source files.

    Parameters
    ----------
    source_filenames : list of str
        The list of paths to source files. Paths can be either relative or
        absolute, this is handled transparently.
    strip_dir : bool, optional
        Whether to strip the directory from the returned paths. If True,
        the file name prepended by `output_dir` is returned. Default is False.
    output_dir : str, optional
        If given, this path is prepended to the returned paths to the
        object files.

    Returns
    -------
    obj_names : list of str
        The list of paths to the object files corresponding to the source
        files in `source_filenames`.

    """
    if output_dir is None:
        output_dir = ''
    obj_names = []
    for src_name in source_filenames:
        base, ext = os.path.splitext(os.path.normpath(src_name))
        base = os.path.splitdrive(base)[1] # Chop off the drive
        base = base[os.path.isabs(base):]  # If abs, chop off leading /
        if base.startswith('..'):
            # Resolve starting relative path components, middle ones
            # (if any) have been handled by os.path.normpath above.
            i = base.rfind('..')+2
            d = base[:i]
            d = os.path.basename(os.path.abspath(d))
            base = d + base[i:]
        if ext not in self.src_extensions:
            raise UnknownFileError("unknown file type '%s' (from '%s')" % (ext, src_name))
        if strip_dir:
            base = os.path.basename(base)
        obj_name = os.path.join(output_dir, base + self.obj_extension)
        obj_names.append(obj_name)
    return obj_names

replace_method(CCompiler, 'object_filenames', CCompiler_object_filenames)

def CCompiler_compile(self, sources, output_dir=None, macros=None,
                      include_dirs=None, debug=0, extra_preargs=None,
                      extra_postargs=None, depends=None):
    """
    Compile one or more source files.

    Please refer to the Python distutils API reference for more details.

    Parameters
    ----------
    sources : list of str
        A list of filenames
    output_dir : str, optional
        Path to the output directory.
    macros : list of tuples
        A list of macro definitions.
    include_dirs : list of str, optional
        The directories to add to the default include file search path for
        this compilation only.
    debug : bool, optional
        Whether or not to output debug symbols in or alongside the object
        file(s).
    extra_preargs, extra_postargs : ?
        Extra pre- and post-arguments.
    depends : list of str, optional
        A list of file names that all targets depend on.

    Returns
    -------
    objects : list of str
        A list of object file names, one per source file `sources`.

    Raises
    ------
    CompileError
        If compilation fails.

    """
    # This method is effective only with Python >=2.3 distutils.
    # Any changes here should be applied also to fcompiler.compile
    # method to support pre Python 2.3 distutils.
    global _job_semaphore

    jobs = get_num_build_jobs()

    # setup semaphore to not exceed number of compile jobs when parallelized at
    # extension level (python >= 3.5)
    with _global_lock:
        if _job_semaphore is None:
            _job_semaphore = threading.Semaphore(jobs)

    if not sources:
        return []
    from numpy.distutils.fcompiler import (FCompiler, is_f_file,
                                           has_f90_header)
    if isinstance(self, FCompiler):
        display = []
        for fc in ['f77', 'f90', 'fix']:
            fcomp = getattr(self, 'compiler_'+fc)
            if fcomp is None:
                continue
            display.append("Fortran %s compiler: %s" % (fc, ' '.join(fcomp)))
        display = '\n'.join(display)
    else:
        ccomp = self.compiler_so
        display = "C compiler: %s\n" % (' '.join(ccomp),)
    log.info(display)
    macros, objects, extra_postargs, pp_opts, build = \
            self._setup_compile(output_dir, macros, include_dirs, sources,
                                depends, extra_postargs)
    cc_args = self._get_cc_args(pp_opts, debug, extra_preargs)
    display = "compile options: '%s'" % (' '.join(cc_args))
    if extra_postargs:
        display += "\nextra options: '%s'" % (' '.join(extra_postargs))
    log.info(display)

    def single_compile(args):
        obj, (src, ext) = args
        if not _needs_build(obj, cc_args, extra_postargs, pp_opts):
            return

        # check if we are currently already processing the same object
        # happens when using the same source in multiple extensions
        while True:
            # need explicit lock as there is no atomic check and add with GIL
            with _global_lock:
                # file not being worked on, start working
                if obj not in _processing_files:
                    _processing_files.add(obj)
                    break
            # wait for the processing to end
            time.sleep(0.1)

        try:
            # retrieve slot from our #job semaphore and build
            with _job_semaphore:
                self._compile(obj, src, ext, cc_args, extra_postargs, pp_opts)
        finally:
            # register being done processing
            with _global_lock:
                _processing_files.remove(obj)


    if isinstance(self, FCompiler):
        objects_to_build = list(build.keys())
        f77_objects, other_objects = [], []
        for obj in objects:
            if obj in objects_to_build:
                src, ext = build[obj]
                if self.compiler_type=='absoft':
                    obj = cyg2win32(obj)
                    src = cyg2win32(src)
                if is_f_file(src) and not has_f90_header(src):
                    f77_objects.append((obj, (src, ext)))
                else:
                    other_objects.append((obj, (src, ext)))

        # f77 objects can be built in parallel
        build_items = f77_objects
        # build f90 modules serial, module files are generated during
        # compilation and may be used by files later in the list so the