import glob
import sh
import subprocess

from multiprocessing import cpu_count
from os import environ
from os.path import dirname, exists, join
from pathlib import Path
from shutil import copy2

from pythonforandroid.logger import info, warning, shprint
from pythonforandroid.patching import version_starts_with, is_version_lt
from pythonforandroid.recipe import Recipe, TargetPythonRecipe
from pythonforandroid.util import (
    current_directory,
    ensure_dir,
    walk_valid_filens,
    BuildInterruptingException,
)

NDK_API_LOWER_THAN_SUPPORTED_MESSAGE = (
    'Target ndk-api is {ndk_api}, '
    'but the python3 recipe supports only {min_ndk_api}+'
)


class Python3Recipe(TargetPythonRecipe):
    '''
    The python3's recipe
    ^^^^^^^^^^^^^^^^^^^^

    The python 3 recipe can be built with some extra python modules, but to do
    so, we need some libraries. By default, we ship the python3 recipe with
    some common libraries, defined in ``depends``. We also support some optional
    libraries, which are less common that the ones defined in ``depends``, so
    we added them as optional dependencies (``opt_depends``).

    Below you have a relationship between the python modules and the recipe
    libraries::

        - _ctypes: you must add the recipe for ``libffi``.
        - _sqlite3: you must add the recipe for ``sqlite3``.
        - _ssl: you must add the recipe for ``openssl``.
        - _bz2: you must add the recipe for ``libbz2`` (optional).
        - _lzma: you must add the recipe for ``liblzma`` (optional).

    .. note:: This recipe can be built only against API 21+.

    .. versionchanged:: 2019.10.06.post0
        - Refactored from deleted class ``python.GuestPythonRecipe`` into here
        - Added optional dependencies: :mod:`~pythonforandroid.recipes.libbz2`
          and :mod:`~pythonforandroid.recipes.liblzma`

    .. versionchanged:: 0.6.0
        Refactored into class
        :class:`~pythonforandroid.python.GuestPythonRecipe`
    '''

    version = '3.8.1'
    url = 'https://www.python.org/ftp/python/{version}/Python-{version}.tgz'
    name = 'python3'

    patches = [
        ('patches/pyconfig_detection.patch', is_version_lt("3.8.3")),

        # Python 3.7.1
        ('patches/py3.7.1_fix-ctypes-util-find-library.patch', version_starts_with("3.7")),
        ('patches/py3.7.1_fix-zlib-version.patch', version_starts_with("3.7")),

        # Python 3.8.1
        ('patches/py3.8.1.patch', version_starts_with("3.8"))
    ]

    if sh.which('lld') is not None:
        patches = patches + [
            ("patches/py3.7.1_fix_cortex_a8.patch", version_starts_with("3.7")),
            ("patches/py3.8.1_fix_cortex_a8.patch", version_starts_with("3.8"))
        ]

    depends = ['hostpython3', 'sqlite3', 'openssl', 'libffi']
    # those optional depends allow us to build python compression modules:
    #   - _bz2.so
    #   - _lzma.so
    opt_depends = ['libbz2', 'liblzma']
    '''The optional libraries which we would like to get our python linked'''

    configure_args = (
        '--host={android_host}',
        '--build={android_build}',
        '--enable-shared',
        '--enable-ipv6',
        'ac_cv_file__dev_ptmx=yes',
        'ac_cv_file__dev_ptc=no',
        '--without-ensurepip',
        'ac_cv_little_endian_double=yes',
        '--prefix={prefix}',
        '--exec-prefix={exec_prefix}')
    '''The configure arguments needed to build the python recipe. Those are
    used in method :meth:`build_arch` (if not overwritten like python3's
    recipe does).
    '''

    MIN_NDK_API = 21
    '''Sets the minimal ndk api number needed to use the recipe.

    .. warning:: This recipe can be built only against API 21+, so it means
        that any class which inherits from class:`GuestPythonRecipe` will have
        this limitation.
    '''

    stdlib_dir_blacklist = {
        '__pycache__',
        'test',
        'tests',
        'lib2to3',
        'ensurepip',
        'idlelib',
        'tkinter',
    }
    '''The directories that we want to omit for our python bundle'''

    stdlib_filen_blacklist = [
        '*.py',
        '*.exe',
        '*.whl',
    ]
    '''The file extensions that we want to blacklist for our python bundle'''

    site_packages_dir_blacklist = {
        '__pycache__',
        'tests'
    }
    '''The directories from site packages dir that we don't want to be included
    in our python bundle.'''

    site_packages_filen_blacklist = [
        '*.py'
    ]
    '''The file extensions from site packages dir that we don't want to be
    included in our python bundle.'''

    compiled_extension = '.pyc'
    '''the default extension for compiled python files.

    .. note:: the default extension for compiled python files has been .pyo for
        python 2.x-3.4 but as of Python 3.5, the .pyo filename extension is no
        longer used and has been removed in favour of extension .pyc
    '''

    def __init__(self, *args, **kwargs):
        self._ctx = None
        super().__init__(*args, **kwargs)

    @property
    def _libpython(self):
        '''return the python's library name (with extension)'''
        py_version = self.major_minor_version_string
        if self.major_minor_version_string[0] == '3':
            py_version += 'm'
        return 'libpython{version}.so'.format(version=py_version)

    def include_root(self, arch_name):
        return join(self.get_build_dir(arch_name), 'Include')

    def link_root(self, arch_name):
        return join(self.get_build_dir(arch_name), 'android-build')

    def should_build(self, arch):
        return not Path(self.link_root(arch.arch), self._libpython).is_file()

    def prebuild_arch(self, arch):
        super().prebuild_arch(arch)
        self.ctx.python_recipe = self

    def get_recipe_env(self, arch=None, with_flags_in_cc=True):
        env = environ.copy()
        env['HOSTARCH'] = arch.command_prefix

        env['CC'] = arch.get_clang_exe(with_target=True)

        env['PATH'] = (
            '{hostpython_dir}:{old_path}').format(
                hostpython_dir=self.get_recipe(
                    'host' + self.name, self.ctx).get_path_to_python(),
                old_path=env['PATH'])

        env['CFLAGS'] = ' '.join(
            [
                '-fPIC',
                '-DANDROID',
                '-D__ANDROID_API__={}'.format(self.ctx.ndk_api),
            ]
        )

        env['LDFLAGS'] = env.get('LDFLAGS', '')
        if sh.which('lld') is not None:
            # Note: The -L. is to fix a bug in python 3.7.
            # https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=234409
            env['LDFLAGS'] += ' -L. -fuse-ld=lld'
        else:
            warning('lld not found, linking without it. '
                    'Consider installing lld if linker errors occur.')

        return env

    def set_libs_flags(self, env, arch):
        '''Takes care to properly link libraries with python depending on our
        requirements and the attribute :attr:`opt_depends`.
        '''
        def add_flags(include_flags, link_dirs, link_libs):
            env['CPPFLAGS'] = env.get('CPPFLAGS', '') + include_flags
            env['LDFLAGS'] = env.get('LDFLAGS', '') + link_dirs
            env['LIBS'] = env.get('LIBS', '') + link_libs

        if 'sqlite3' in self.ctx.recipe_build_order:
            info('Activating flags for sqlite3')
            recipe = Recipe.get_recipe('sqlite3', self.ctx)
            add_flags(' -I' + recipe.get_build_dir(arch.arch),
                      ' -L' + recipe.get_lib_dir(arch), ' -lsqlite3')

        if 'libffi' in self.ctx.recipe_build_order:
            info('Activating flags for libffi')
            recipe = Recipe.get_recipe('libffi', self.ctx)
            # In order to force the correct linkage for our libffi library, we
            # set the following variable to point where is our libffi.pc file,
            # because the python build system uses pkg-config to configure it.
            env['PKG_CONFIG_PATH'] = recipe.get_build_dir(arch.arch)
            add_flags(' -I' + ' -I'.join(recipe.get_include_dirs(arch)),
                      ' -L' + join(recipe.get_build_dir(arch.arch), '.libs'),
                      ' -lffi')

        if 'openssl' in self.ctx.recipe_build_order:
            info('Activating flags for openssl')
            recipe = Recipe.get_recipe('openssl', self.ctx)
            self.configure_args += \
                ('--with-openssl=' + recipe.get_build_dir(arch.arch),)
            add_flags(recipe.include_flags(arch),
                      recipe.link_dirs_flags(arch), recipe.link_libs_flags())

        for library_name in {'libbz2', 'liblzma'}:
            if library_name in self.ctx.recipe_build_order:
                info(f'Activating flags for {library_name}')
                recipe = Recipe.get_recipe(library_name, self.ctx)
                add_flags(recipe.get_library_includes(arch),
                          recipe.get_library_ldflags(arch),
                          recipe.get_library_libs_flag())

        # python build system contains hardcoded zlib version which prevents
        # the build of zlib module, here we search for android's zlib version
        # and sets the right flags, so python can be build with android's zlib
        info("Activating flags for android's zlib")
        zlib_lib_path = join(self.ctx.ndk_platform, 'usr', 'lib')
        zlib_includes = join(self.ctx.ndk_dir, 'sysroot', 'usr', 'include')
        zlib_h = join(zlib_includes, 'zlib.h')
        try:
            with open(zlib_h) as fileh:
                zlib_data = fileh.read()
        except IOError:
            raise BuildInterruptingException(
                "Could not determine android's zlib version, no zlib.h ({}) in"
                " the NDK dir includes".format(zlib_h)
            )
        for line in zlib_data.split('\n'):
            if line.startswith('#define ZLIB_VERSION '):
                break
        else:
            raise BuildInterruptingException(
                'Could not parse zlib.h...so we cannot find zlib version,'
                'required by python build,'
            )
        env['ZLIB_VERSION'] = line.replace('#define ZLIB_VERSION ', '')
        add_flags(' -I' + zlib_includes, ' -L' + zlib_lib_path, ' -lz')

        return env

    def build_arch(self, arch):
        if self.ctx.ndk_api < self.MIN_NDK_API:
            raise BuildInterruptingException(
                NDK_API_LOWER_THAN_SUPPORTED_MESSAGE.format(
                    ndk_api=self.ctx.ndk_api, min_ndk_api=self.MIN_NDK_API
                ),
            )

        recipe_build_dir = self.get_build_dir(arch.arch)

        # Create a subdirectory to actually perform the build
        build_dir = join(recipe_build_dir, 'android-build')
        ensure_dir(build_dir)

        # TODO: Get these dynamically, like bpo-30386 does
        sys_prefix = '/usr/local'
        sys_exec_prefix = '/usr/local'

        env = self.get_recipe_env(arch)
        env = self.set_libs_flags(env, arch)

        android_build = sh.Command(
            join(recipe_build_dir,
                 'config.guess'))().stdout.strip().decode('utf-8')

        with current_directory(build_dir):
            if not exists('config.status'):
                shprint(
                    sh.Command(join(recipe_build_dir, 'configure')),
                    *(' '.join(self.configure_args).format(
                                    android_host=env['HOSTARCH'],
                                    android_build=android_build,
                                    prefix=sys_prefix,
                                    exec_prefix=sys_exec_prefix)).split(' '),
                    _env=env)

            shprint(
                sh.make, 'all', '-j', str(cpu_count()),
                'INSTSONAME={lib_name}'.format(lib_name=self._libpython),
                _env=env
            )

            # TODO: Look into passing the path to pyconfig.h in a
            # better way, although this is probably acceptable
            sh.cp('pyconfig.h', join(recipe_build_dir, 'Include'))

    def compile_python_files(self, dir):
        '''
        Compile the python files (recursively) for the python files inside
        a given folder.

        .. note:: python2 compiles the files into extension .pyo, but in
            python3, and as of Python 3.5, the .pyo filename extension is no
            longer used...uses .pyc (https://www.python.org/dev/peps/pep-0488)
        '''
        args = [self.ctx.hostpython]
        args += ['-OO', '-m', 'compileall', '-b', '-f', dir]
        subprocess.call(args)

    def create_python_bundle(self, dirn, arch):
        """
        Create a packaged python bundle in the target directory, by
        copying all the modules and standard library to the right
        place.
        """
        # Todo: find a better way to find the build libs folder
        modules_build_dir = join(
            self.get_build_dir(arch.arch),
            'android-build',
            'build',
            'lib.linux{}-{}-{}'.format(
                '2' if self.version[0] == '2' else '',
                arch.command_prefix.split('-')[0],
                self.major_minor_version_string
            ))

        # Compile to *.pyc/*.pyo the python modules
        self.compile_python_files(modules_build_dir)
        # Compile to *.pyc/*.pyo the standard python library
        self.compile_python_files(join(self.get_build_dir(arch.arch), 'Lib'))
        # Compile to *.pyc/*.pyo the other python packages (site-packages)
        self.compile_python_files(self.ctx.get_python_install_dir())

        # Bundle compiled python modules to a folder
        modules_dir = join(dirn, 'modules')
        c_ext = self.compiled_extension
        ensure_dir(modules_dir)
        module_filens = (glob.glob(join(modules_build_dir, '*.so')) +
                         glob.glob(join(modules_build_dir, '*' + c_ext)))
        info("Copy {} files into the bundle".format(len(module_filens)))
        for filen in module_filens:
            info(" - copy {}".format(filen))
            copy2(filen, modules_dir)

        # zip up the standard library
        stdlib_zip = join(dirn, 'stdlib.zip')
        with current_directory(join(self.get_build_dir(arch.arch), 'Lib')):
            stdlib_filens = list(walk_valid_filens(
                '.', self.stdlib_dir_blacklist, self.stdlib_filen_blacklist))
            info("Zip {} files into the bundle".format(len(stdlib_filens)))
            shprint(sh.zip, stdlib_zip, *stdlib_filens)

        # copy the site-packages into place
        ensure_dir(join(dirn, 'site-packages'))
        ensure_dir(self.ctx.get_python_install_dir())
        # TODO: Improve the API around walking and copying the files
        with current_directory(self.ctx.get_python_install_dir()):
            filens = list(walk_valid_filens(
                '.', self.site_packages_dir_blacklist,
                self.site_packages_filen_blacklist))
            info("Copy {} files into the site-packages".format(len(filens)))
            for filen in filens:
                info(" - copy {}".format(filen))
                ensure_dir(join(dirn, 'site-packages', dirname(filen)))
                copy2(filen, join(dirn, 'site-packages', filen))

        # copy the python .so files into place
        python_build_dir = join(self.get_build_dir(arch.arch),
                                'android-build')
        python_lib_name = 'libpython' + self.major_minor_version_string
        if self.major_minor_version_string[0] == '3':
            python_lib_name += 'm'
        shprint(
            sh.cp,
            join(python_build_dir, python_lib_name + '.so'),
            join(self.ctx.bootstrap.dist_dir, 'libs', arch.arch)
        )

        info('Renaming .so files to reflect cross-compile')
        self.reduce_object_file_names(join(dirn, 'site-packages'))

        return join(dirn, 'site-packages')


recipe = Python3Recipe()
