import glob
import os
import shutil
import subprocess
import sys
import tempfile
import warnings
from sysconfig import get_config_var, get_config_vars, get_path

from .runners import (
    CCompilerRunner,
    CppCompilerRunner,
    FortranCompilerRunner
)
from .util import (
    get_abspath, make_dirs, copy, Glob, ArbitraryDepthGlob,
    glob_at_depth, import_module_from_file, pyx_is_cplus,
    sha256_of_string, sha256_of_file, CompileError
)

if os.name == 'posix':
    objext = '.o'
elif os.name == 'nt':
    objext = '.obj'
else:
    warnings.warn("Unknown os.name: {}".format(os.name))
    objext = '.o'


def compile_sources(files, Runner=None, destdir=None, cwd=None, keep_dir_struct=False,
                    per_file_kwargs=None, **kwargs):
    """ Compile source code files to object files.

    Parameters
    ==========

    files : iterable of str
        Paths to source files, if ``cwd`` is given, the paths are taken as relative.
    Runner: CompilerRunner subclass (optional)
        Could be e.g. ``FortranCompilerRunner``. Will be inferred from filename
        extensions if missing.
    destdir: str
        Output directory, if cwd is given, the path is taken as relative.
    cwd: str
        Working directory. Specify to have compiler run in other directory.
        also used as root of relative paths.
    keep_dir_struct: bool
        Reproduce directory structure in `destdir`. default: ``False``
    per_file_kwargs: dict
        Dict mapping instances in ``files`` to keyword arguments.
    \\*\\*kwargs: dict
        Default keyword arguments to pass to ``Runner``.

    """
    _per_file_kwargs = {}

    if per_file_kwargs is not None:
        for k, v in per_file_kwargs.items():
            if isinstance(k, Glob):
                for path in glob.glob(k.pathname):
                    _per_file_kwargs[path] = v
            elif isinstance(k, ArbitraryDepthGlob):
                for path in glob_at_depth(k.filename, cwd):
                    _per_file_kwargs[path] = v
            else:
                _per_file_kwargs[k] = v

    # Set up destination directory
    destdir = destdir or '.'
    if not os.path.isdir(destdir):
        if os.path.exists(destdir):
            raise OSError("{} is not a directory".format(destdir))
        else:
            make_dirs(destdir)
    if cwd is None:
        cwd = '.'
        for f in files:
            copy(f, destdir, only_update=True, dest_is_dir=True)

    # Compile files and return list of paths to the objects
    dstpaths = []
    for f in files:
        if keep_dir_struct:
            name, ext = os.path.splitext(f)
        else:
            name, ext = os.path.splitext(os.path.basename(f))
        file_kwargs = kwargs.copy()
        file_kwargs.update(_per_file_kwargs.get(f, {}))
        dstpaths.append(src2obj(f, Runner, cwd=cwd, **file_kwargs))
    return dstpaths


def get_mixed_fort_c_linker(vendor=None, cplus=False, cwd=None):
    vendor = vendor or os.environ.get('SYMPY_COMPILER_VENDOR', 'gnu')

    if vendor.lower() == 'intel':
        if cplus:
            return (FortranCompilerRunner,
                    {'flags': ['-nofor_main', '-cxxlib']}, vendor)
        else:
            return (FortranCompilerRunner,
                    {'flags': ['-nofor_main']}, vendor)
    elif vendor.lower() == 'gnu' or 'llvm':
        if cplus:
            return (CppCompilerRunner,
                    {'lib_options': ['fortran']}, vendor)
        else:
            return (FortranCompilerRunner,
                    {}, vendor)
    else:
        raise ValueError("No vendor found.")


def link(obj_files, out_file=None, shared=False, Runner=None,
         cwd=None, cplus=False, fort=False, **kwargs):
    """ Link object files.

    Parameters
    ==========

    obj_files: iterable of str
        Paths to object files.
    out_file: str (optional)
        Path to executable/shared library, if ``None`` it will be
        deduced from the last item in obj_files.
    shared: bool
        Generate a shared library?
    Runner: CompilerRunner subclass (optional)
        If not given the ``cplus`` and ``fort`` flags will be inspected
        (fallback is the C compiler).
    cwd: str
        Path to the root of relative paths and working directory for compiler.
    cplus: bool
        C++ objects? default: ``False``.
    fort: bool
        Fortran objects? default: ``False``.
    \\*\\*kwargs: dict
        Keyword arguments passed to ``Runner``.

    Returns
    =======

    The absolute path to the generated shared object / executable.

    """
    if out_file is None:
        out_file, ext = os.path.splitext(os.path.basename(obj_files[-1]))
        if shared:
            out_file += get_config_var('EXT_SUFFIX')

    if not Runner:
        if fort:
            Runner, extra_kwargs, vendor = \
                get_mixed_fort_c_linker(
                    vendor=kwargs.get('vendor', None),
                    cplus=cplus,
                    cwd=cwd,
                )
            for k, v in extra_kwargs.items():
                if k in kwargs:
                    kwargs[k].expand(v)
                else:
                    kwargs[k] = v
        else:
            if cplus:
                Runner = CppCompilerRunner
            else:
                Runner = CCompilerRunner

    flags = kwargs.pop('flags', [])
    if shared:
        if '-shared' not in flags:
            flags.append('-shared')
    run_linker = kwargs.pop('run_linker', True)
    if not run_linker:
        raise ValueError("run_linker was set to False (nonsensical).")

    out_file = get_abspath(out_file, cwd=cwd)
    runner = Runner(obj_files, out_file, flags, cwd=cwd, **kwargs)
    runner.run()
    return out_file


def link_py_so(obj_files, so_file=None, cwd=None, libraries=None,
               cplus=False, fort=False, **kwargs):
    """ Link Python extension module (shared object) for importing

    Parameters
    ==========

    obj_files: iterable of str
        Paths to object files to be linked.
    so_file: str
        Name (path) of shared object file to create. If not specified it will
        have the basname of the last object file in `obj_files` but with the
        extension '.so' (Unix).
    cwd: path string
        Root of relative paths and working directory of linker.
    libraries: iterable of strings
        Libraries to link against, e.g. ['m'].
    cplus: bool
        Any C++ objects? default: ``False``.
    fort: bool
        Any Fortran objects? default: ``False``.
    kwargs**: dict
        Keyword arguments passed to ``link(...)``.

    Returns
    =======

    Absolute path to the generate shared object.
    """
    libraries = libraries or []

    include_dirs = kwargs.pop('include_dirs', [])
    library_dirs = kwargs.pop('library_dirs', [])

    # from distutils/command/build_ext.py:
    if sys.platform == "win32":
        warnings.warn("Windows not yet supported.")
    elif sys.platform == 'darwin':
        # Don't use the default code below
        pass
    elif sys.platform[:3] == 'aix':
        # Don't use the default code below
        pass
    else:
        if get_config_var('Py_ENABLE_SHARED'):
            cfgDict = get_config_vars()
            kwargs['linkline'] = kwargs.get('linkline', []) + [cfgDict['PY_LDFLAGS']] # PY_LDFLAGS or just LDFLAGS?
            library_dirs += [cfgDict['LIBDIR']]
            for opt in cfgDict['BLDLIBRARY'].split():
                if opt.startswith('-l'):
                    libraries += [opt[2:]]
        else:
            pass

    flags = kwargs.pop('flags', [])
    needed_flags = ('-pthread',)
    for flag in needed_flags:
        if flag not in flags:
            flags.append(flag)

    return link(obj_files, shared=True, flags=flags, cwd=cwd,
                cplus=cplus, fort=fort, include_dirs=include_dirs,
                libraries=libraries, library_dirs=library_dirs, **kwargs)


def simple_cythonize(src, destdir=None, cwd=None, **cy_kwargs):
    """ Generates a C file from a Cython source file.

    Parameters
    ==========

    src: str
        Path to Cython source.
    destdir: str (optional)
        Path to output directory (default: '.').
    cwd: path string (optional)
        Root of relative paths (default: '.').
    **cy_kwargs:
        Second argument passed to cy_compile. Generates a .cpp file if ``cplus=True`` in ``cy_kwargs``,
        else a .c file.
    """
    from Cython.Compiler.Main import (
        default_options, CompilationOptions
    )
    from Cython.Compiler.Main import compile as cy_compile

    assert src.lower().endswith('.pyx') or src.lower().endswith('.py')
    cwd = cwd or '.'
    destdir = destdir or '.'

    ext = '.cpp' if cy_kwargs.get('cplus', False) else '.c'
    c_name = os.path.splitext(os.path.basename(src))[0] + ext

    dstfile = os.path.join(destdir, c_name)

    if cwd:
        ori_dir = os.getcwd()
    else:
        ori_dir = '.'
    os.chdir(cwd)
    try:
        cy_options = CompilationOptions(default_options)
        cy_options.__dict__.update(cy_kwargs)
        # Set language_level if not set by cy_kwargs
        # as not setting it is deprecated
        if 'language_level' not in cy_kwargs:
            cy_options.__dict__['language_level'] = 3
        cy_result = cy_compile([src], cy_options)
        if cy_result.num_errors > 0:
            raise ValueError("Cython compilation failed.")
        if os.path.abspath(os.path.dirname(src)) != os.path.abspath(destdir):
            if os.path.exists(dstfile):
                os.unlink(dstfile)
            shutil.move(os.path.join(os.path.dirname(src), c_name), destdir)
    finally:
        os.chdir(ori_dir)
    return dstfile


extension_mapping = {
    '.c': (CCompilerRunner, None),
    '.cpp': (CppCompilerRunner, None),
    '.cxx': (CppCompilerRunner, None),
    '.f': (FortranCompilerRunner, None),
    '.for': (FortranCompilerRunner, None),
    '.ftn': (FortranCompilerRunner, None),
    '.f90': (FortranCompilerRunner, None),  # ifort only knows about .f90
    '.f95': (FortranCompilerRunner, 'f95'),
    '.f03': (FortranCompilerRunner, 'f2003'),
    '.f08': (FortranCompilerRunner, 'f2008'),
}


def src2obj(srcpath, Runner=None, objpath=None, cwd=None, inc_py=False, **kwargs):
    """ Compiles a source code file to an object file.

    Files ending with '.pyx' assumed to be cython files and
    are dispatched to pyx2obj.

    Parameters
    ==========

    srcpath: str
        Path to source file.
    Runner: CompilerRunner subclass (optional)
        If ``None``: deduced from extension of srcpath.
    objpath : str (optional)
        Path to generated object. If ``None``: deduced from ``srcpath``.
    cwd: str (optional)
        Working directory and root of relative paths. If ``None``: current dir.
    inc_py: bool
        Add Python include path to kwarg "include_dirs". Default: False
    \\*\\*kwargs: dict
        keyword arguments passed to Runner or pyx2obj

    """
    name, ext = os.path.splitext(os.path.basename(srcpath))
    if objpath is None:
        if os.path.isabs(srcpath):
            objpath = '.'
        else:
            objpath = os.path.dirname(srcpath)
            objpath = objpath or '.'  # avoid objpath == ''

    if os.path.isdir(objpath):
        objpath = os.path.join(objpath, name + objext)

    include_dirs = kwargs.pop('include_dirs', [])
    if inc_py:
        py_inc_dir = get_path('include')
        if py_inc_dir not in include_dirs:
            include_dirs.append(py_inc_dir)

    if ext.lower() == '.pyx':
        return pyx2obj(srcpath, objpath=objpath, include_dirs=include_dirs, cwd=cwd,
                       **kwargs)

    if Runner is None:
        Runner, std = extension_mapping[ext.lower()]
        if 'std' not in kwargs:
            kwargs['std'] = std

    flags = kwargs.pop('flags', [])
    needed_flags = ('-fPIC',)
    for flag in needed_flags:
        if flag not in flags:
            flags.append(flag)

    # src2obj implies not running the linker...
    run_linker = kwargs.pop('run_linker', False)
    if run_linker:
        raise CompileError("src2obj called with run_linker=True")

    runner = Runner([srcpath], objpath, include_dirs=include_dirs,
                    run_linker=run_linker, cwd=cwd, flags=flags, **kwargs)
    runner.run()
    return objpath


def pyx2obj(pyxpath, objpath=None, destdir=None, cwd=None,
            include_dirs=None, cy_kwargs=None, cplus=None, **kwargs):
    """
    Convenience function

    If cwd is specified, pyxpath and dst are taken to be relative
    If only_update is set to `True` the modification time is checked
    and compilation is only run if the source is newer than the
    destination

    Parameters
    ==========

    pyxpath: str
        Path to Cython source file.
    objpath: str (optional)
        Path to object file to generate.
    destdir: str (optional)
        Directory to put generated C file. When ``None``: directory of ``objpath``.
    cwd: str (optional)
        Working directory and root of relative paths.
    include_dirs: iterable of path strings (optional)
        Passed onto src2obj and via cy_kwargs['include_path']
        to simple_cythonize.
    cy_kwargs: dict (optional)
        Keyword arguments passed onto `simple_cythonize`
    cplus: bool (optional)
        Indicate whether C++ is used. default: auto-detect using ``.util.pyx_is_cplus``.
    compile_kwargs: dict
        keyword arguments passed onto src2obj

    Returns
    =======

    Absolute path of generated object file.

    """
    assert pyxpath.endswith('.pyx')
    cwd = cwd or '.'
    objpath = objpath or '.'
    destdir = destdir or os.path.dirname(objpath)

    abs_objpath = get_abspath(objpath, cwd=cwd)

    if os.path.isdir(abs_objpath):
        pyx_fname = os.path.basename(pyxpath)
        name, ext = os.path.splitext(pyx_fname)
        objpath = os.path.join(objpath, name + objext)

    cy_kwargs = cy_kwargs or {}
    cy_kwargs['output_dir'] = cwd
    if cplus is None:
        cplus = pyx_is_cplus(pyxpath)
    cy_kwargs['cplus'] = cplus

    interm_c_file = simple_cythonize(pyxpath, destdir=destdir, cwd=cwd, **cy_kwargs)

    include_dirs = include_dirs or []
    flags = kwargs.pop('flags', [])
    needed_flags = ('-fwrapv', '-pthread', '-fPIC')
    for flag in needed_flags:
        if flag not in flags:
            flags.append(flag)

    options = kwargs.pop('options', [])

    if kwargs.pop('strict_aliasing', False):
        raise CompileError("Cython requires strict aliasing to be disabled.")

    # Let's be explicit about standard
    if cplus:
        std = kwargs.pop('std', 'c++98')
    else:
        std = kwargs.pop('std', 'c99')

    return src2obj(interm_c_file, objpath=objpath, cwd=cwd,
                   include_dirs=include_dirs, flags=flags, std=std,
                   options=options, inc_py=True, strict_aliasing=False,
                   **kwargs)


def _any_X(srcs, cls):
    for src in srcs:
        name, ext = os.path.splitext(src)
        key = ext.lower()
        if key in extension_mapping:
            if extension_mapping[key][0] == cls:
                return True
    return False


def any_fortran_src(srcs):
    return _any_X(srcs, FortranCompilerRunner)


def any_cplus_src(srcs):
    return _any_X(srcs, CppCompilerRunner)


def compile_link_import_py_ext(sources, extname=None, build_dir='.', compile_kwargs=None,
                               link_kwargs=None):
    """ Compiles sources to a shared object (Python extension) and imports it

    Sources in ``sources`` which is imported. If shared object is newer than the sources, they
    are not recompiled but instead it is imported.

    Parameters
    ==========

    sources : string
        List of paths to sources.
    extname : string
        Name of extension (default: ``None``).
        If ``None``: taken from the last file in ``sources`` without extension.
    build_dir: str
        Path to directory in which objects files etc. are generated.
    compile_kwargs: dict
        keyword arguments passed to ``compile_sources``
    link_kwargs: dict
        keyword arguments passed to ``link_py_so``

    Returns
    =======

    The imported module from of the Python extension.
    """
    if extname is None:
        extname = os.path.splitext(os.path.basename(sources[-1]))[0]

    compile_kwargs = compile_kwargs or {}
    link_kwargs = link_kwargs or {}

    try:
        mod = import_module_from_file(os.path.join(build_dir, extname), sources)
    except ImportError:
        objs = compile_sources(list(map(get_abspath, sources)), destdir=build_dir,
                               cwd=build_dir, **compile_kwargs)
        so = link_py_so(objs, cwd=build_dir, fort=any_fortran_src(sources),
                        cplus=any_cplus_src(sources), **link_kwargs)
        mod = import_module_from_file(so)
    return mod


def _write_sources_to_build_dir(sources, build_dir):
    build_dir = build_dir or tempfile.mkdtemp()
    if not os.path.isdir(build_dir):
        raise OSError("Non-existent directory: ", build_dir)

    source_files = []
    for name, src in sources:
        dest = os.path.join(build_dir, name)
        differs = True
        sha256_in_mem = sha256_of_string(src.encode('utf-8')).hexdigest()
        if os.path.exists(dest):
            if os.path.exists(dest + '.sha256'):
                with open(dest + '.sha256') as fh:
                    sha256_on_disk = fh.read()
            else:
                sha256_on_disk = sha256_of_file(dest).hexdigest()

            differs = sha256_on_disk != sha256_in_mem
        if differs:
            with open(dest, 'wt') as fh:
                fh.write(src)
            with open(dest + '.sha256', 'wt') as fh:
                fh.write(sha256_in_mem)
        source_files.append(dest)
    return source_files, build_dir


def compile_link_import_strings(sources, build_dir=None, **kwargs):
    """ Compiles, links and imports extension module from source.

    Parameters
    ==========

    sources : iterable of name/source pair tuples
    build_dir : string (default: None)
        Path. ``None`` implies use a temporary directory.
    **kwargs:
        Keyword arguments passed onto `compile_link_import_py_ext`.

    Returns
    =======

    mod : module
        The compiled and imported extension module.
    info : dict
        Containing ``build_dir`` as 'build_dir'.

    """
    source_files, build_dir = _write_sources_to_build_dir(sources, build_dir)
    mod = compile_link_import_py_ext(source_files, build_dir=build_dir, **kwargs)
    info = dict(build_dir=build_dir)
    return mod, info


def compile_run_strings(sources, build_dir=None, clean=False, compile_kwargs=None, link_kwargs=None):
    """ Compiles, links and runs a program built from sources.

    Parameters
    ==========

    sources : iterable of name/source pair tuples
    build_dir : string (default: None)
        Path. ``None`` implies use a temporary directory.
    clean : bool
        Whether to remove build_dir after use. This will only have an
        effect if ``build_dir`` is ``None`` (which creates a temporary directory).
        Passing ``clean == True`` and ``build_dir != None`` raises a ``ValueError``.
        This will also set ``build_dir`` in returned info dictionary to ``None``.
    compile_kwargs: dict
        Keyword arguments passed onto ``compile_sources``
    link_kwargs: dict
        Keyword arguments passed onto ``link``

    Returns
    =======

    (stdout, stderr): pair of strings
    info: dict
        Containing exit status as 'exit_status' and ``build_dir`` as 'build_dir'

    """
    if clean and build_dir is not None:
        raise ValueError("Automatic removal of build_dir is only available for temporary directory.")
    try:
        source_files, build_dir = _write_sources_to_build_dir(sources, build_dir)
        objs = compile_sources(list(map(get_abspath, source_files)), destdir=build_dir,
                               cwd=build_dir, **(compile_kwargs or {}))
        prog = link(objs, cwd=build_dir,
                    fort=any_fortran_src(source_files),
                    cplus=any_cplus_src(source_files), **(link_kwargs or {}))
        p = subprocess.Popen([prog], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        exit_status = p.wait()
        stdout, stderr = [txt.decode('utf-8') for txt in p.communicate()]
    finally:
        if clean and os.path.isdir(build_dir):
            shutil.rmtree(build_dir)
            build_dir = None
    info = dict(exit_status=exit_status, build_dir=build_dir)
    return (stdout, stderr), info
