__init__.py

# SPDX-License-Identifier: MIT
# SPDX-FileCopyrightText: 2021 Quansight, LLC
# SPDX-FileCopyrightText: 2021 Filipe Laíns <lains@riseup.net>


"""Meson Python build backend

Implements PEP 517 hooks.
"""

from __future__ import annotations

import collections
import contextlib
import functools
import importlib.machinery
import io
import itertools
import json
import os
import pathlib
import platform
import re
import shutil
import subprocess
import sys
import sysconfig
import tarfile
import tempfile
import textwrap
import typing
import warnings

from typing import (
    Any, Callable, ClassVar, DefaultDict, Dict, List, Optional, Sequence, Set,
    TextIO, Tuple, Type, TypeVar, Union
)


if sys.version_info < (3, 11):
    import tomli as tomllib
else:
    import tomllib


import mesonpy._compat
import mesonpy._elf
import mesonpy._introspection
import mesonpy._tags
import mesonpy._util
import mesonpy._wheelfile

from mesonpy._compat import (
    Collection, Iterable, Iterator, Literal, Mapping, ParamSpec, Path,
    cached_property, read_binary, typing_get_args
)


if typing.TYPE_CHECKING:  # pragma: no cover
    import pyproject_metadata  # noqa: F401


__version__ = '0.13.0.dev0'


_COLORS = {
    'red': '\33[31m',
    'cyan': '\33[36m',
    'yellow': '\33[93m',
    'light_blue': '\33[94m',
    'bold': '\33[1m',
    'dim': '\33[2m',
    'underline': '\33[4m',
    'reset': '\33[0m',
}
_NO_COLORS = {color: '' for color in _COLORS}
_NINJA_REQUIRED_VERSION = '1.8.2'


class _depstr:
    """Namespace that holds the requirement strings for dependencies we *might*
    need at runtime. Having them in one place makes it easier to update.
    """
    patchelf = 'patchelf >= 0.11.0'
    ninja = f'ninja >= {_NINJA_REQUIRED_VERSION}'


def _init_colors() -> Dict[str, str]:
    """Detect if we should be using colors in the output. We will enable colors
    if running in a TTY, and no environment variable overrides it. Setting the
    NO_COLOR (https://no-color.org/) environment variable force-disables colors,
    and FORCE_COLOR forces color to be used, which is useful for thing like
    Github actions.
    """
    if 'NO_COLOR' in os.environ:
        if 'FORCE_COLOR' in os.environ:
            warnings.warn('Both NO_COLOR and FORCE_COLOR environment variables are set, disabling color')
        return _NO_COLORS
    elif 'FORCE_COLOR' in os.environ or sys.stdout.isatty():
        return _COLORS
    return _NO_COLORS


_STYLES = _init_colors()  # holds the color values, should be _COLORS or _NO_COLORS


_EXTENSION_SUFFIXES = importlib.machinery.EXTENSION_SUFFIXES.copy()
_EXTENSION_SUFFIX_REGEX = re.compile(r'^\.(?:(?P<abi>[^.]+)\.)?(?:so|pyd|dll)$')
assert all(re.match(_EXTENSION_SUFFIX_REGEX, x) for x in _EXTENSION_SUFFIXES)


def _showwarning(
    message: Union[Warning, str],
    category: Type[Warning],
    filename: str,
    lineno: int,
    file: Optional[TextIO] = None,
    line: Optional[str] = None,
) -> None:  # pragma: no cover
    """Callable to override the default warning handler, to have colored output."""
    print('{yellow}WARNING{reset} {}'.format(message, **_STYLES))


def _setup_cli() -> None:
    """Setup CLI stuff (eg. handlers, hooks, etc.). Should only be called when
    actually we are in control of the CLI, not on a normal import.
    """
    warnings.showwarning = _showwarning

    try:  # pragma: no cover
        import colorama
    except ModuleNotFoundError:  # pragma: no cover
        pass
    else:  # pragma: no cover
        colorama.init()  # fix colors on windows


def _as_python_declaration(value: Any) -> str:
    if isinstance(value, str):
        return f"r'{value}'"
    elif isinstance(value, os.PathLike):
        return _as_python_declaration(os.fspath(value))
    elif isinstance(value, Iterable):
        return '[' + ', '.join(map(_as_python_declaration, value)) + ']'
    raise NotImplementedError(f'Unsupported type: {type(value)}')


class Error(RuntimeError):
    def __str__(self) -> str:
        return str(self.args[0])


class ConfigError(Error):
    """Error in the backend configuration."""


class MesonBuilderError(Error):
    """Error when building the Meson package."""


class _WheelBuilder():
    """Helper class to build wheels from projects."""

    # Maps wheel scheme names to Meson placeholder directories
    _SCHEME_MAP: ClassVar[Dict[str, Tuple[str, ...]]] = {
        'scripts': ('{bindir}',),
        'purelib': ('{py_purelib}',),
        'platlib': ('{py_platlib}', '{moduledir_shared}'),
        'headers': ('{includedir}',),
        'data': ('{datadir}',),
        # our custom location
        'mesonpy-libs': ('{libdir}', '{libdir_shared}')
    }

    def __init__(
        self,
        project: Project,
        metadata: Optional[pyproject_metadata.StandardMetadata],
        source_dir: pathlib.Path,
        install_dir: pathlib.Path,
        build_dir: pathlib.Path,
        sources: Dict[str, Dict[str, Any]],
        copy_files: Dict[str, str],
    ) -> None:
        self._project = project
        self._metadata = metadata
        self._source_dir = source_dir
        self._install_dir = install_dir
        self._build_dir = build_dir
        self._sources = sources
        self._copy_files = copy_files

        self._libs_build_dir = self._build_dir / 'mesonpy-wheel-libs'

    @cached_property
    def _wheel_files(self) -> DefaultDict[str, List[Tuple[pathlib.Path, str]]]:
        return self._map_to_wheel(self._sources, self._copy_files)

    @property
    def _has_internal_libs(self) -> bool:
        return bool(self._wheel_files['mesonpy-libs'])

    @property
    def _has_extension_modules(self) -> bool:
        # Assume that all code installed in {platlib} is Python ABI dependent.
        return bool(self._wheel_files['platlib'])

    @property
    def normalized_name(self) -> str:
        return self._project.name.replace('-', '_')

    @property
    def basename(self) -> str:
        """Normalized wheel name and version (eg. meson_python-1.0.0)."""
        return '{distribution}-{version}'.format(
            distribution=self.normalized_name,
            version=self._project.version,
        )

    @property
    def tag(self) -> mesonpy._tags.Tag:
        """Wheel tags."""
        if self.is_pure:
            return mesonpy._tags.Tag('py3', 'none', 'any')
        if not self._has_extension_modules:
            # The wheel has platform dependent code (is not pure) but
            # does not contain any extension module (does not
            # distribute any file in {platlib}) thus use generic
            # implementation and ABI tags.
            return mesonpy._tags.Tag('py3', 'none', None)
        return mesonpy._tags.Tag(None, self._stable_abi, None)

    @property
    def name(self) -> str:
        """Wheel name, this includes the basename and tag."""
        return '{basename}-{tag}'.format(
            basename=self.basename,
            tag=self.tag,
        )

    @property
    def distinfo_dir(self) -> str:
        return f'{self.basename}.dist-info'

    @property
    def data_dir(self) -> str:
        return f'{self.basename}.data'

    @cached_property
    def is_pure(self) -> bool:
        """Is the wheel "pure" (architecture independent)?"""
        # XXX: I imagine some users might want to force the package to be
        # non-pure, but I think it's better that we evaluate use-cases as they
        # arise and make sure allowing the user to override this is indeed the
        # best option for the use-case.
        if self._wheel_files['platlib']:
            return False
        for _, file in self._wheel_files['scripts']:
            if self._is_native(file):
                return False
        return True

    @property
    def wheel(self) -> bytes:  # noqa: F811
        """Return WHEEL file for dist-info."""
        return textwrap.dedent('''
            Wheel-Version: 1.0
            Generator: meson
            Root-Is-Purelib: {is_purelib}
            Tag: {tag}
        ''').strip().format(
            is_purelib='true' if self.is_pure else 'false',
            tag=self.tag,
        ).encode()

    @property
    def entrypoints_txt(self) -> bytes:
        """dist-info entry_points.txt."""
        if not self._metadata:
            return b''

        data = self._metadata.entrypoints.copy()
        data.update({
            'console_scripts': self._metadata.scripts,
            'gui_scripts': self._metadata.gui_scripts,
        })

        text = ''
        for entrypoint in data:
            if data[entrypoint]:
                text += f'[{entrypoint}]\n'
                for name, target in data[entrypoint].items():
                    text += f'{name} = {target}\n'
                text += '\n'

        return text.encode()

    @cached_property
    def _stable_abi(self) -> Optional[str]:
        """Determine stabe ABI compatibility.

        Examine all files installed in {platlib} that look like
        extension modules (extension .pyd on Windows, .dll on Cygwin,
        and .so on other platforms) and, if they all share the same
        PEP 3149 filename stable ABI tag, return it.

        All files that look like extension modules are verified to
        have a file name compatibel with what is expected by the
        Python interpreter. An exception is raised otherwise.

        Other files are ignored.

        """
        soext = sorted(_EXTENSION_SUFFIXES, key=len)[0]
        abis = []

        for path, src in self._wheel_files['platlib']:
            if path.suffix == soext:
                match = re.match(r'^[^.]+(.*)$', path.name)
                assert match is not None
                suffix = match.group(1)
                if suffix not in _EXTENSION_SUFFIXES:
                    raise ValueError(
                        f'Extension module {str(path)!r} not compatible with Python interpreter. '
                        f'Filename suffix {suffix!r} not in {set(_EXTENSION_SUFFIXES)}.')
                match = _EXTENSION_SUFFIX_REGEX.match(suffix)
                assert match is not None
                abis.append(match.group('abi'))

        stable = [x for x in abis if x and re.match(r'abi\d+', x)]
        if len(stable) > 0 and len(stable) == len(abis) and all(x == stable[0] for x in stable[1:]):
            return stable[0]
        return None

    @property
    def top_level_modules(self) -> Collection[str]:
        modules = set()
        for type_ in self._wheel_files:
            for path, _ in self._wheel_files[type_]:
                top_part = path.parts[0]
                # file module
                if top_part.endswith('.py'):
                    modules.add(top_part[:-3])
                else:
                    # native module
                    for extension in _EXTENSION_SUFFIXES:
                        if top_part.endswith(extension):
                            modules.add(top_part[:-len(extension)])
                            # XXX: We assume the order in _EXTENSION_SUFFIXES
                            #      goes from more specific to last, so we go
                            #      with the first match we find.
                            break
                    else:  # nobreak
                        # skip Windows import libraries
                        if top_part.endswith('.a'):
                            continue
                        # package module
                        modules.add(top_part)
        return modules

    def _is_native(self, file: Union[str, pathlib.Path]) -> bool:
        """Check if file is a native file."""
        self._project.build()  # the project needs to be built for this :/

        with open(file, 'rb') as f:
            if platform.system() == 'Linux':
                return f.read(4) == b'\x7fELF'  # ELF
            elif platform.system() == 'Darwin':
                return f.read(4) in (
                    b'\xfe\xed\xfa\xce',  # 32-bit
                    b'\xfe\xed\xfa\xcf',  # 64-bit
                    b'\xcf\xfa\xed\xfe',  # arm64
                    b'\xca\xfe\xba\xbe',  # universal / fat (same as java class so beware!)
                )
            elif platform.system() == 'Windows':
                return f.read(2) == b'MZ'

        # For unknown platforms, check for file extensions.
        _, ext = os.path.splitext(file)
        if ext in ('.so', '.a', '.out', '.exe', '.dll', '.dylib', '.pyd'):
            return True
        return False

    def _warn_unsure_platlib(self, origin: pathlib.Path, destination: pathlib.Path) -> None:
        """Warn if we are unsure if the file should be mapped to purelib or platlib.

        This happens when we use heuristics to try to map a file purelib or
        platlib but can't differentiate between the two. In which case, we place
        the file in platlib to be safe and warn the user.

        If we can detect the file is architecture dependent and indeed does not
        belong in purelib, we will skip the warning.
        """
        # {moduledir_shared} is currently handled in heuristics due to a Meson bug,
        # but we know that files that go there are supposed to go to platlib.
        if self._is_native(origin):
            # The file is architecture dependent and does not belong in puredir,
            # so the warning is skipped.
            return
        warnings.warn(
            'Could not tell if file was meant for purelib or platlib, '
            f'so it was mapped to platlib: {origin} ({destination})',
            stacklevel=2,
        )

    def _map_from_heuristics(self, origin: pathlib.Path, destination: pathlib.Path) -> Optional[Tuple[str, pathlib.Path]]:
        """Extracts scheme and relative destination with heuristics based on the
        origin file and the Meson destination path.
        """
        warnings.warn('Using heuristics to map files to wheel, this may result in incorrect locations')
        sys_paths = mesonpy._introspection.SYSCONFIG_PATHS
        # Try to map to Debian dist-packages
        if mesonpy._introspection.DEBIAN_PYTHON:
            search_path = origin
            while search_path != search_path.parent:
                search_path = search_path.parent
                if search_path.name == 'dist-packages' and search_path.parent.parent.name == 'lib':
                    calculated_path = origin.relative_to(search_path)
                    warnings.warn(f'File matched Debian heuristic ({calculated_path}): {origin} ({destination})')
                    self._warn_unsure_platlib(origin, destination)
                    return 'platlib', calculated_path
        # Try to map to the interpreter purelib or platlib
        for scheme in ('purelib', 'platlib'):
            # try to match the install path on the system to one of the known schemes
            scheme_path = pathlib.Path(sys_paths[scheme]).absolute()
            destdir_scheme_path = self._install_dir / scheme_path.relative_to(scheme_path.anchor)
            try:
                wheel_path = pathlib.Path(origin).relative_to(destdir_scheme_path)
            except ValueError:
                continue
            if sys_paths['purelib'] == sys_paths['platlib']:
                self._warn_unsure_platlib(origin, destination)
            return 'platlib', wheel_path
        return None  # no match was found

    def _map_from_scheme_map(self, destination: str) -> Optional[Tuple[str, pathlib.Path]]:
        """Extracts scheme and relative destination from Meson paths.

            Meson destination path -> (wheel scheme, subpath inside the scheme)
        Eg. {bindir}/foo/bar       -> (scripts, foo/bar)
        """
        for scheme, placeholder in [
            (scheme, placeholder)
            for scheme, placeholders in self._SCHEME_MAP.items()
            for placeholder in placeholders
        ]:  # scheme name, scheme path (see self._SCHEME_MAP)
            if destination.startswith(placeholder):
                relative_destination = pathlib.Path(destination).relative_to(placeholder)
                return scheme, relative_destination
        return None  # no match was found

    def _map_to_wheel(
        self,
        sources: Dict[str, Dict[str, Any]],
        copy_files: Dict[str, str],
    ) -> DefaultDict[str, List[Tuple[pathlib.Path, str]]]:
        """Map files to the wheel, organized by scheme."""
        wheel_files = collections.defaultdict(list)
        for files in sources.values():  # entries in intro-install_plan.json
            for file, details in files.items():  # install path -> {destination, tag}
                # try mapping to wheel location
                meson_destination = details['destination']
                install_details = (
                    # using scheme map
                    self._map_from_scheme_map(meson_destination)
                    # using heuristics
                    or self._map_from_heuristics(
                        pathlib.Path(copy_files[file]),
                        pathlib.Path(meson_destination),
                    )
                )
                if install_details:
                    scheme, destination = install_details
                    wheel_files[scheme].append((destination, file))
                    continue
                # not found
                warnings.warn(
                    'File could not be mapped to an equivalent wheel directory: '
                    '{} ({})'.format(copy_files[file], meson_destination)
                )

        return wheel_files

    def _install_path(
        self,
        wheel_file: mesonpy._wheelfile.WheelFile,
        counter: mesonpy._util.CLICounter,
        origin: Path,
        destination: pathlib.Path,
    ) -> None:
        """"Install" file or directory into the wheel
        and do the necessary processing before doing so.

        Some files might need to be fixed up to set the RPATH to the internal
        library directory on Linux wheels for eg.
        """
        location = destination.as_posix()
        counter.update(location)

        # fix file
        if os.path.isdir(origin):
            for root, dirnames, filenames in os.walk(str(origin)):
                # Sort the directory names so that `os.walk` will walk them in a
                # defined order on the next iteration.
                dirnames.sort()
                for name in sorted(filenames):
                    path = os.path.normpath(os.path.join(root, name))
                    if os.path.isfile(path):
                        arcname = os.path.join(destination, os.path.relpath(path, origin).replace(os.path.sep, '/'))
                        wheel_file.write(path, arcname)
        else:
            if self._has_internal_libs and platform.system() == 'Linux':
                # add .mesonpy.libs to the RPATH of ELF files
                if self._is_native(os.fspath(origin)):
                    # copy ELF to our working directory to avoid Meson having to regenerate the file
                    new_origin = self._libs_build_dir / pathlib.Path(origin).relative_to(self._build_dir)
                    os.makedirs(new_origin.parent, exist_ok=True)
                    shutil.copy2(origin, new_origin)
                    origin = new_origin
                    # add our in-wheel libs folder to the RPATH
                    elf = mesonpy._elf.ELF(origin)
                    libdir_path = f'$ORIGIN/{os.path.relpath(f".{self._project.name}.mesonpy.libs", destination.parent)}'
                    if libdir_path not in elf.rpath:
                        elf.rpath = [*elf.rpath, libdir_path]

            wheel_file.write(origin, location)

    def _wheel_write_metadata(self, whl: mesonpy._wheelfile.WheelFile) -> None:
        # add metadata
        whl.writestr(f'{self.distinfo_dir}/METADATA', self._project.metadata)
        whl.writestr(f'{self.distinfo_dir}/WHEEL', self.wheel)
        if self.entrypoints_txt:
            whl.writestr(f'{self.distinfo_dir}/entry_points.txt', self.entrypoints_txt)

        # add license (see https://github.com/mesonbuild/meson-python/issues/88)
        if self._project.license_file:
            whl.write(
                self._source_dir / self._project.license_file,
                f'{self.distinfo_dir}/{os.path.basename(self._project.license_file)}',
            )

    def build(self, directory: Path) -> pathlib.Path:
        self._project.build()  # ensure project is built

        wheel_file = pathlib.Path(directory, f'{self.name}.whl')

        with mesonpy._wheelfile.WheelFile(wheel_file, 'w') as whl:
            self._wheel_write_metadata(whl)

            print('{light_blue}{bold}Copying files to wheel...{reset}'.format(**_STYLES))
            with mesonpy._util.cli_counter(
                len(list(itertools.chain.from_iterable(self._wheel_files.values()))),
            ) as counter:
                # install root scheme files
                root_scheme = 'purelib' if self.is_pure else 'platlib'
                for destination, origin in self._wheel_files[root_scheme]:
                    self._install_path(whl, counter, origin, destination)

                # install bundled libraries
                for destination, origin in self._wheel_files['mesonpy-libs']:
                    assert platform.system() == 'Linux', 'Bundling libraries in wheel is currently only supported in POSIX!'
                    destination = pathlib.Path(f'.{self._project.name}.mesonpy.libs', destination)
                    self._install_path(whl, counter, origin, destination)

                # install the other schemes
                for scheme in self._SCHEME_MAP:
                    if scheme in (root_scheme, 'mesonpy-libs'):
                        continue
                    for destination, origin in self._wheel_files[scheme]:
                        destination = pathlib.Path(self.data_dir, scheme, destination)
                        self._install_path(whl, counter, origin, destination)

        return wheel_file

    def build_editable(self, directory: Path, verbose: bool = False) -> pathlib.Path:
        self._project.build()  # ensure project is built

        wheel_file = pathlib.Path(directory, f'{self.name}.whl')

        install_path = self._source_dir / '.mesonpy' / 'editable' / 'install'
        rebuild_commands = self._project.build_commands(install_path)

        import_paths = set()
        for name, raw_path in mesonpy._introspection.SYSCONFIG_PATHS.items():
            if name not in ('purelib', 'platlib'):
                continue
            path = pathlib.Path(raw_path)
            import_paths.add(install_path / path.relative_to(path.anchor))

        install_path.mkdir(parents=True, exist_ok=True)

        with mesonpy._wheelfile.WheelFile(wheel_file, 'w') as whl:
            self._wheel_write_metadata(whl)
            whl.writestr(
                f'{self.distinfo_dir}/direct_url.json',
                self._source_dir.as_uri().encode(),
            )

            # install hook module
            hook_module_name = f'_mesonpy_hook_{self.normalized_name.replace(".", "_")}'
            hook_install_code = textwrap.dedent(f'''
                MesonpyFinder.install(
                    project_name={_as_python_declaration(self._project.name)},
                    hook_name={_as_python_declaration(hook_module_name)},
                    project_path={_as_python_declaration(self._source_dir)},
                    build_path={_as_python_declaration(self._build_dir)},
                    import_paths={_as_python_declaration(import_paths)},
                    top_level_modules={_as_python_declaration(self.top_level_modules)},
                    rebuild_commands={_as_python_declaration(rebuild_commands)},
                    verbose={verbose},
                )
            ''').strip().encode()
            whl.writestr(
                f'{hook_module_name}.py',
                read_binary('mesonpy', '_editable.py') + hook_install_code,
            )
            # install .pth file
            whl.writestr(
                f'{self.normalized_name}-editable-hook.pth',
                f'import {hook_module_name}'.encode(),
            )

            # install non-code schemes
            for scheme in self._SCHEME_MAP:
                if scheme in ('purelib', 'platlib', 'mesonpy-libs'):
                    continue
                for destination, origin in self._wheel_files[scheme]:
                    destination = pathlib.Path(self.data_dir, scheme, destination)
                    whl.write(origin, destination.as_posix())

        return wheel_file


MesonArgsKeys = Literal['dist', 'setup', 'compile', 'install']
MesonArgs = Mapping[MesonArgsKeys, List[str]]


class Project():
    """Meson project wrapper to generate Python artifacts."""

    _ALLOWED_DYNAMIC_FIELDS: ClassVar[List[str]] = [
        'version',
    ]
    _metadata: Optional[pyproject_metadata.StandardMetadata]

    def __init__(  # noqa: C901
        self,
        source_dir: Path,
        working_dir: Path,
        build_dir: Optional[Path] = None,
        meson_args: Optional[MesonArgs] = None,
        editable_verbose: bool = False,
    ) -> None:
        self._source_dir = pathlib.Path(source_dir).absolute()
        self._working_dir = pathlib.Path(working_dir).absolute()
        self._build_dir = pathlib.Path(build_dir).absolute() if build_dir else (self._working_dir / 'build')
        self._editable_verbose = editable_verbose
        self._install_dir = self._working_dir / 'install'
        self._meson_native_file = self._source_dir / '.mesonpy-native-file.ini'
        self._meson_cross_file = self._source_dir / '.mesonpy-cross-file.ini'
        self._meson_args: MesonArgs = collections.defaultdict(list)
        self._env = os.environ.copy()

        # prepare environment
        ninja_path = _env_ninja_command()
        if ninja_path is not None:
            self._env.setdefault('NINJA', str(ninja_path))

        # setuptools-like ARCHFLAGS environment variable support
        if sysconfig.get_platform().startswith('macosx-'):
            archflags = self._env.get('ARCHFLAGS')
            if archflags is not None:
                arch, *other = filter(None, (x.strip() for x in archflags.split('-arch')))
                if other:
                    raise ConfigError(f'Multi-architecture builds are not supported but $ARCHFLAGS={archflags!r}')
                macver, _, nativearch = platform.mac_ver()
                if arch != nativearch:
                    x = self._env.setdefault('_PYTHON_HOST_PLATFORM', f'macosx-{macver}-{arch}')
                    if not x.endswith(arch):
                        raise ConfigError(f'$ARCHFLAGS={archflags!r} and $_PYTHON_HOST_PLATFORM={x!r} do not agree')
                    family = 'aarch64' if arch == 'arm64' else arch
                    cross_file_data = textwrap.dedent(f'''
                        [binaries]
                        c = ['cc', '-arch', {arch!r}]
                        cpp = ['c++', '-arch', {arch!r}]
                        [host_machine]
                        system = 'Darwin'
                        cpu = {arch!r}
                        cpu_family = {family!r}
                        endian = 'little'
                    ''')
                    self._meson_cross_file.write_text(cross_file_data)
                    self._meson_args['setup'].extend(('--cross-file', os.fspath(self._meson_cross_file)))

        # load config -- PEP 621 support is optional
        self._config = tomllib.loads(self._source_dir.joinpath('pyproject.toml').read_text())
        self._pep621 = 'project' in self._config
        if self.pep621:
            try:
                import pyproject_metadata  # noqa: F811
            except ModuleNotFoundError:  # pragma: no cover
                self._metadata = None
            else:
                self._metadata = pyproject_metadata.StandardMetadata.from_pyproject(self._config, self._source_dir)
        else:
            print(
                '{yellow}{bold}! Using Meson to generate the project metadata '
                '(no `project` section in pyproject.toml){reset}'.format(**_STYLES)
            )
            self._metadata = None

        if self._metadata:
            self._validate_metadata()

        # load meson args
        for key in self._get_config_key('args'):
            self._meson_args[key].extend(self._get_config_key(f'args.{key}'))
        # XXX: We should validate the user args to make sure they don't conflict with ours.

        self._check_for_unknown_config_keys({
            'args': typing_get_args(MesonArgsKeys),
        })

        # meson arguments from the command line take precedence over
        # arguments from the configuration file thus are added later
        if meson_args:
            for key, value in meson_args.items():
                self._meson_args[key].extend(value)

        # make sure the build dir exists
        self._build_dir.mkdir(exist_ok=True, parents=True)
        self._install_dir.mkdir(exist_ok=True, parents=True)

        # write the native file
        native_file_data = textwrap.dedent(f'''
            [binaries]
            python = '{sys.executable}'
        ''')
        native_file_mismatch = (
            not self._meson_native_file.exists()
            or self._meson_native_file.read_text() != native_file_data
        )
        if native_file_mismatch:
            try:
                self._meson_native_file.write_text(native_file_data)
            except OSError:
                # if there are permission errors or something else in the source
                # directory, put the native file in the working directory instead
                # (this won't survive multiple calls -- Meson will have to be reconfigured)
                self._meson_native_file = self._working_dir / '.mesonpy-native-file.ini'
                self._meson_native_file.write_text(native_file_data)

        # Don't reconfigure if build directory doesn't have meson-private/coredata.data
        # (means something went wrong)
        # See https://github.com/mesonbuild/meson-python/pull/257#discussion_r1067385517
        has_valid_build_dir = self._build_dir.joinpath('meson-private', 'coredata.dat').is_file()
        self._configure(reconfigure=has_valid_build_dir and not native_file_mismatch)

        # set version if dynamic (this fetches it from Meson)
        if self._metadata and 'version' in self._metadata.dynamic:
            self._metadata.version = self.version

    def _get_config_key(self, key: str) -> Any:
        value: Any = self._config
        for part in f'tool.meson-python.{key}'.split('.'):
            if not isinstance(value, Mapping):
                raise ConfigError(f'Configuration entry "tool.meson-python.{key}" should be a TOML table not {type(value)}')
            value = value.get(part, {})
        return value

    def _proc(self, *args: str) -> None:
        """Invoke a subprocess."""
        print('{cyan}{bold}+ {}{reset}'.format(' '.join(args), **_STYLES))
        r = subprocess.run(list(args), env=self._env, cwd=self._build_dir)
        if r.returncode != 0:
            raise SystemExit(r.returncode)

    def _meson(self, *args: str) -> None:
        """Invoke Meson."""
        return self._proc('meson', *args)

    def _configure(self, reconfigure: bool = False) -> None:
        """Configure Meson project.

        We will try to reconfigure the build directory if possible to avoid
        expensive rebuilds.
        """
        sys_paths = mesonpy._introspection.SYSCONFIG_PATHS
        setup_args = [
            f'--prefix={sys.base_prefix}',
            os.fspath(self._source_dir),
            os.fspath(self._build_dir),
            f'--native-file={os.fspath(self._meson_native_file)}',
            # TODO: Allow configuring these arguments
            '-Ddebug=false',
            '-Doptimization=2',

            # XXX: This should not be needed, but Meson is using the wrong paths
            #      in some scenarios, like on macOS.
            #      https://github.com/mesonbuild/meson-python/pull/87#discussion_r1047041306
            '--python.purelibdir',
            sys_paths['purelib'],
            '--python.platlibdir',
            sys_paths['platlib'],

            # user args
            *self._meson_args['setup'],
        ]
        if reconfigure:
            setup_args.insert(0, '--reconfigure')

        try:
            self._meson('setup', *setup_args)
        except subprocess.CalledProcessError:
            if reconfigure:  # if failed reconfiguring, try a normal configure
                self._configure()
            else:
                raise

    def _validate_metadata(self) -> None:
        """Check the pyproject.toml metadata and see if there are any issues."""

        assert self._metadata

        # check for unsupported dynamic fields
        unsupported_dynamic = {
            key for key in self._metadata.dynamic
            if key not in self._ALLOWED_DYNAMIC_FIELDS
        }
        if unsupported_dynamic:
            s = ', '.join(f'"{x}"' for x in unsupported_dynamic)
            raise MesonBuilderError(f'Unsupported dynamic fields: {s}')

        # check if we are running on an unsupported interpreter
        if self._metadata.requires_python:
            self._metadata.requires_python.prereleases = True
            if platform.python_version().rstrip('+') not in self._metadata.requires_python:
                raise MesonBuilderError(
                    f'Unsupported Python version {platform.python_version()}, '
                    f'expected {self._metadata.requires_python}'
                )

    def _check_for_unknown_config_keys(self, valid_args: Mapping[str, Collection[str]]) -> None:
        config = self._config.get('tool', {}).get('meson-python', {})

        for key, valid_subkeys in config.items():
            if key not in valid_args:
                raise ConfigError(f'Unknown configuration key "tool.meson-python.{key}"')

            for subkey in valid_args[key]:
                if subkey not in valid_subkeys:
                    raise ConfigError(f'Unknown configuration key "tool.meson-python.{key}.{subkey}"')

    @cached_property
    def _wheel_builder(self) -> _WheelBuilder:
        return _WheelBuilder(
            self,
            self._metadata,
            self._source_dir,
            self._install_dir,
            self._build_dir,
            self._install_plan,
            self._copy_files,
        )

    def build_commands(self, install_dir: Optional[pathlib.Path] = None) -> Sequence[Sequence[str]]:
        return (
            ('meson', 'compile', *self._meson_args['compile'],),
            (
                'meson',
                'install',
                '--only-changed',
                '--destdir',
                os.fspath(install_dir or self._install_dir),
                *self._meson_args['install'],
            ),
        )

    @functools.lru_cache(maxsize=None)
    def build(self) -> None:
        """Trigger the Meson build."""
        for cmd in self.build_commands():
            self._meson(*cmd[1:])

    @classmethod
    @contextlib.contextmanager
    def with_temp_working_dir(
        cls,
        source_dir: Path = os.path.curdir,
        build_dir: Optional[Path] = None,
        meson_args: Optional[MesonArgs] = None,
        editable_verbose: bool = False,
    ) -> Iterator[Project]:
        """Creates a project instance pointing to a temporary working directory."""
        with tempfile.TemporaryDirectory(prefix='.mesonpy-', dir=os.fspath(source_dir)) as tmpdir:
            yield cls(source_dir, tmpdir, build_dir, meson_args, editable_verbose)

    @functools.lru_cache()
    def _info(self, name: str) -> Dict[str, Any]:
        """Read info from meson-info directory."""
        file = self._build_dir.joinpath('meson-info', f'{name}.json')
        return typing.cast(
            Dict[str, str],
            json.loads(file.read_text())
        )

    @property
    def _install_plan(self) -> Dict[str, Dict[str, Dict[str, str]]]:
        """Meson install_plan metadata."""
        return self._info('intro-install_plan').copy()

    @property
    def _copy_files(self) -> Dict[str, str]:
        """Files that Meson will copy on install and the target location."""
        copy_files = {}
        for origin, destination in self._info('intro-installed').items():
            destination_path = pathlib.Path(destination).absolute()
            copy_files[origin] = os.fspath(
                self._install_dir / destination_path.relative_to(destination_path.anchor)
            )
        return copy_files

    @property
    def _lib_paths(self) -> Set[str]:
        copy_files = self._copy_files
        return {
            os.path.dirname(copy_files[file])
            for files in self._install_plan.values()
            for file, details in files.items()
            if details['destination'].startswith('{libdir_')
        }

    @property
    def _meson_name(self) -> str:
        """Name in meson.build."""
        name = self._info('intro-projectinfo')['descriptive_name']
        assert isinstance(name, str)
        return name

    @property
    def _meson_version(self) -> str:
        """Version in meson.build."""
        name = self._info('intro-projectinfo')['version']
        assert isinstance(name, str)
        return name

    @property
    def name(self) -> str:
        """Project name. Specified in pyproject.toml."""
        name = self._metadata.name if self._metadata else self._meson_name
        assert isinstance(name, str)
        return name.replace('-', '_')

    @property
    def version(self) -> str:
        """Project version. Either specified in pyproject.toml or meson.build."""
        if self._metadata and 'version' not in self._metadata.dynamic:
            version = str(self._metadata.version)
        else:
            version = self._meson_version
        assert isinstance(version, str)
        return version

    @cached_property
    def metadata(self) -> bytes:
        """Project metadata."""
        # the rest of the keys are only available when using PEP 621 metadata
        if not self.pep621:
            data = textwrap.dedent(f'''
                Metadata-Version: 2.1
                Name: {self.name}
                Version: {self.version}
            ''').strip()
            return data.encode()

        # re-import pyproject_metadata to raise ModuleNotFoundError if it is really missing
        import pyproject_metadata  # noqa: F401, F811
        assert self._metadata

        core_metadata = self._metadata.as_rfc822()
        # use self.version as the version may be dynamic -- fetched from Meson
        #
        # we need to overwrite this field in the RFC822 field as
        # pyproject_metadata removes 'version' from the dynamic fields when
        # giving it a value via the dataclass
        core_metadata.headers['Version'] = [self.version]
        return bytes(core_metadata)

    @property
    def license_file(self) -> Optional[pathlib.Path]:
        if self._metadata:
            license_ = self._metadata.license
            if license_ and license_.file:
                return pathlib.Path(license_.file)
        return None

    @property
    def is_pure(self) -> bool:
        """Is the wheel "pure" (architecture independent)?"""
        return bool(self._wheel_builder.is_pure)

    @property
    def pep621(self) -> bool:
        """Does the project use PEP 621 metadata?"""
        return self._pep621

    def sdist(self, directory: Path) -> pathlib.Path:
        """Generates a sdist (source distribution) in the specified directory."""
        # generate meson dist file
        self._meson('dist', '--allow-dirty', '--no-tests', '--formats', 'gztar', *self._meson_args['dist'],)

        # move meson dist file to output path
        dist_name = f'{self.name}-{self.version}'
        meson_dist_name = f'{self._meson_name}-{self._meson_version}'
        meson_dist_path = pathlib.Path(self._build_dir, 'meson-dist', f'{meson_dist_name}.tar.gz')
        sdist = pathlib.Path(directory, f'{dist_name}.tar.gz')

        with tarfile.open(meson_dist_path, 'r:gz') as meson_dist, mesonpy._util.create_targz(sdist) as (tar, mtime):
            for member in meson_dist.getmembers():
                # skip the generated meson native file
                if member.name == f'{meson_dist_name}/.mesonpy-native-file.ini':
                    continue

                # calculate the file path in the source directory
                assert member.name, member.name
                member_parts = member.name.split('/')
                if len(member_parts) <= 1:
                    continue
                path = self._source_dir.joinpath(*member_parts[1:])

                if not path.exists() and member.isfile():
                    # File doesn't exists on the source directory but exists on
                    # the Meson dist, so it is generated file, which we need to
                    # include.
                    # See https://mesonbuild.com/Reference-manual_builtin_meson.html#mesonadd_dist_script

                    # MESON_DIST_ROOT could have a different base name
                    # than the actual sdist basename, so we need to rename here
                    file = meson_dist.extractfile(member.name)
                    member.name = str(pathlib.Path(dist_name, *member_parts[1:]).as_posix())
                    tar.addfile(member, file)
                    continue

                if not path.is_file():
                    continue

                info = tarfile.TarInfo(member.name)
                file_stat = os.stat(path)
                info.size = file_stat.st_size
                info.mode = int(oct(file_stat.st_mode)[-3:], 8)

                # rewrite the path if necessary, to match the sdist distribution name
                if dist_name != meson_dist_name:
                    info.name = pathlib.Path(
                        dist_name,
                        path.relative_to(self._source_dir)
                    ).as_posix()

                with path.open('rb') as f:
                    tar.addfile(info, fileobj=f)

            # add PKG-INFO to dist file to make it a sdist
            pkginfo_info = tarfile.TarInfo(f'{dist_name}/PKG-INFO')
            if mtime:
                pkginfo_info.mtime = mtime
            pkginfo_info.size = len(self.metadata)
            tar.addfile(pkginfo_info, fileobj=io.BytesIO(self.metadata))

        return sdist

    def wheel(self, directory: Path) -> pathlib.Path:
        """Generates a wheel (binary distribution) in the specified directory."""
        file = self._wheel_builder.build(directory)
        assert isinstance(file, pathlib.Path)
        return file

    def editable(self, directory: Path) -> pathlib.Path:
        file = self._wheel_builder.build_editable(directory, self._editable_verbose)
        assert isinstance(file, pathlib.Path)
        return file


@contextlib.contextmanager
def _project(config_settings: Optional[Dict[Any, Any]]) -> Iterator[Project]:
    """Create the project given the given config settings."""
    if config_settings is None:
        config_settings = {}

    # expand all string values to single element tuples and convert collections to tuple
    config_settings = {
        key: tuple(value) if isinstance(value, Collection) and not isinstance(value, str) else (value,)
        for key, value in config_settings.items()
    }

    builddir_value = config_settings.get('builddir', {})
    if len(builddir_value) > 0:
        if len(builddir_value) != 1:
            raise ConfigError('Only one value for configuration entry "builddir" can be specified')
        builddir = builddir_value[0]
        if not isinstance(builddir, str):
            raise ConfigError(f'Configuration entry "builddir" should be a string not {type(builddir)}')
    else:
        builddir = None

    def _validate_string_collection(key: str) -> None:
        assert isinstance(config_settings, Mapping)
        problematic_items: Sequence[Any] = list(filter(None, (
            item if not isinstance(item, str) else None
            for item in config_settings.get(key, ())
        )))
        if problematic_items:
            s = ', '.join(f'"{item}" ({type(item)})' for item in problematic_items)
            raise ConfigError(f'Configuration entries for "{key}" must be strings but contain: {s}')

    meson_args_keys = typing_get_args(MesonArgsKeys)
    meson_args_cli_keys = tuple(f'{key}-args' for key in meson_args_keys)

    for key in config_settings:
        known_keys = ('builddir', 'editable-verbose', *meson_args_cli_keys)
        if key not in known_keys:
            import difflib
            matches = difflib.get_close_matches(key, known_keys, n=3)
            if len(matches):
                alternatives = ' or '.join(f'"{match}"' for match in matches)
                raise ConfigError(f'Unknown configuration entry "{key}". Did you mean {alternatives}?')
            else:
                raise ConfigError(f'Unknown configuration entry "{key}"')

    for key in meson_args_cli_keys:
        _validate_string_collection(key)

    with Project.with_temp_working_dir(
        build_dir=builddir,
        meson_args=typing.cast(MesonArgs, {
            key: config_settings.get(f'{key}-args', ())
            for key in meson_args_keys
        }),
        editable_verbose=bool(config_settings.get('editable-verbose'))
    ) as project:
        yield project


def _env_ninja_command(*, version: str = _NINJA_REQUIRED_VERSION) -> Optional[pathlib.Path]:
    """
    Returns the path to ninja, or None if no ninja found.
    """
    required_version = tuple(int(v) for v in version.split('.'))
    env_ninja = os.environ.get('NINJA', None)
    ninja_candidates = [env_ninja] if env_ninja else ['ninja', 'ninja-build', 'samu']
    for ninja in ninja_candidates:
        ninja_path = shutil.which(ninja)
        if ninja_path is None:
            continue

        result = subprocess.run([ninja_path, '--version'], check=False, text=True, capture_output=True)

        try:
            candidate_version = tuple(int(x) for x in result.stdout.split('.')[:3])
        except ValueError:
            continue
        if candidate_version < required_version:
            continue
        return pathlib.Path(ninja_path)

    return None


P = ParamSpec('P')
T = TypeVar('T')


def _pyproject_hook(func: Callable[P, T]) -> Callable[P, T]:
    @functools.wraps(func)
    def wrapper(*args: P.args, **kwargs: P.kwargs) -> T:
        try:
            return func(*args, **kwargs)
        except Error as exc:
            print('{red}meson-python: error:{reset} {msg}'.format(msg=str(exc), **_STYLES))
            raise SystemExit(1)
    return wrapper


@_pyproject_hook
def get_requires_for_build_sdist(
    config_settings: Optional[Dict[str, str]] = None,
) -> List[str]:
    return [_depstr.ninja] if _env_ninja_command() is None else []


@_pyproject_hook
def build_sdist(
    sdist_directory: str,
    config_settings: Optional[Dict[Any, Any]] = None,
) -> str:
    _setup_cli()

    out = pathlib.Path(sdist_directory)
    with _project(config_settings) as project:
        return project.sdist(out).name


@_pyproject_hook
def get_requires_for_build_wheel(
    config_settings: Optional[Dict[str, str]] = None,
) -> List[str]:
    dependencies = []

    if _env_ninja_command() is None:
        dependencies.append(_depstr.ninja)

    if sys.platform.startswith('linux'):
        # we may need patchelf
        if not shutil.which('patchelf'):
            # patchelf not already accessible on the system
            if _env_ninja_command() is not None:
                # we have ninja available, so we can run Meson and check if the project needs patchelf
                with _project(config_settings) as project:
                    if not project.is_pure:
                        dependencies.append(_depstr.patchelf)
            else:
                # we can't check if the project needs patchelf, so always add it
                # XXX: wait for https://github.com/mesonbuild/meson/pull/10779
                dependencies.append(_depstr.patchelf)

    return dependencies


@_pyproject_hook
def build_wheel(
    wheel_directory: str,
    config_settings: Optional[Dict[Any, Any]] = None,
    metadata_directory: Optional[str] = None,
) -> str:
    _setup_cli()

    out = pathlib.Path(wheel_directory)
    with _project(config_settings) as project:
        return project.wheel(out).name


@_pyproject_hook
def build_editable(
    wheel_directory: str,
    config_settings: Optional[Dict[Any, Any]] = None,
    metadata_directory: Optional[str] = None,
) -> str:
    _setup_cli()

    # force set a permanent builddir
    if not config_settings:
        config_settings = {}
    if 'builddir' not in config_settings:
        config_settings['builddir'] = os.path.join('.mesonpy', 'editable', 'build')

    out = pathlib.Path(wheel_directory)
    with _project(config_settings) as project:
        return project.editable(out).name


@_pyproject_hook
def get_requires_for_build_editable(
    config_settings: Optional[Dict[str, str]] = None,
) -> List[str]:
    return get_requires_for_build_wheel()