import os

import sys

import importlib.metadata

import argparse

import traceback

import contextlib

from io import StringIO

import json

import subprocess

import re

import tempfile

import email.parser

import pathlib

from pyproject_requirements_txt import convert_requirements_txt

# Some valid Python version specifiers are not supported.

# Allow only the forms we know we can handle.

VERSION_RE = re.compile(r'[a-zA-Z0-9.-]+(\.\*)?')

class EndPass(Exception):

    """End current pass of generating requirements"""

# nb: we don't use functools.partial to be able to use pytest's capsys

# see https://github.com/pytest-dev/pytest/issues/8900

def print_err(*args, **kwargs):

    kwargs.setdefault('file', sys.stderr)

    print(*args, **kwargs)

try:

    from packaging.requirements import Requirement, InvalidRequirement

    from packaging.utils import canonicalize_name

except ImportError as e:

    print_err('Import error:', e)

    # already echoed by the %pyproject_buildrequires macro

    sys.exit(0)

# uses packaging, needs to be imported after packaging is verified to be present

from pyproject_convert import convert

@contextlib.contextmanager

def hook_call():

    captured_out = StringIO()

    with contextlib.redirect_stdout(captured_out):

        yield

    for line in captured_out.getvalue().splitlines():

        print_err('HOOK STDOUT:', line)

def guess_reason_for_invalid_requirement(requirement_str):

    if ':' in requirement_str:

        message = (

            'It might be an URL. '

            '%pyproject_buildrequires cannot handle all URL-based requirements. '

            'Add PackageName@ (see PEP 508) to the URL to at least require any version of PackageName.'

        )

        if '@' in requirement_str:

            message += ' (but note that URLs might not work well with other features)'

        return message

    if '/' in requirement_str:

        return (

            'It might be a local path. '

            '%pyproject_buildrequires cannot handle local paths as requirements. '

            'Use an URL with PackageName@ (see PEP 508) to at least require any version of PackageName.'

        )

    # No more ideas

    return None

class Requirements:

    """Requirement printer"""

    def __init__(self, get_installed_version, extras=None,

                 generate_extras=False, python3_pkgversion='3'):

        self.get_installed_version = get_installed_version

        self.extras = set()

        if extras:

            for extra in extras:

                self.add_extras(*extra.split(','))

        self.missing_requirements = False

        self.generate_extras = generate_extras

        self.python3_pkgversion = python3_pkgversion

    def add_extras(self, *extras):

        self.extras |= set(e.strip() for e in extras)

    @property

    def marker_envs(self):

        if self.extras:

            return [{'extra': e} for e in sorted(self.extras)]

        return [{'extra': ''}]

    def evaluate_all_environamnets(self, requirement):

        for marker_env in self.marker_envs:

            if requirement.marker.evaluate(environment=marker_env):

                return True

        return False

    def add(self, requirement_str, *, source=None):

        """Output a Python-style requirement string as RPM dep"""

        print_err(f'Handling {requirement_str} from {source}')

        try:

            requirement = Requirement(requirement_str)

        except InvalidRequirement:

            hint = guess_reason_for_invalid_requirement(requirement_str)

            message = f'Requirement {requirement_str!r} from {source} is invalid.'

            if hint:

                message += f' Hint: {hint}'

            raise ValueError(message)

        if requirement.url:

            print_err(

                f'WARNING: Simplifying {requirement_str!r} to {requirement.name!r}.'

            )

        name = canonicalize_name(requirement.name)

        if (requirement.marker is not None and

                not self.evaluate_all_environamnets(requirement)):

            print_err(f'Ignoring alien requirement:', requirement_str)

            return

        try:

            # TODO: check if requirements with extras are satisfied

            installed = self.get_installed_version(requirement.name)

        except importlib.metadata.PackageNotFoundError:

            print_err(f'Requirement not satisfied: {requirement_str}')

            installed = None

        if installed and installed in requirement.specifier:

            print_err(f'Requirement satisfied: {requirement_str}')

            print_err(f'   (installed: {requirement.name} {installed})')

            if requirement.extras:

                print_err(f'   (extras are currently not checked)')

        else:

            self.missing_requirements = True

        if self.generate_extras:

            extra_names = [f'{name}[{extra.lower()}]' for extra in sorted(requirement.extras)]

        else:

            extra_names = []

        for name in [name] + extra_names:

            together = []

            for specifier in sorted(

                requirement.specifier,

                key=lambda s: (s.operator, s.version),

            ):

                if not VERSION_RE.fullmatch(str(specifier.version)):

                    raise ValueError(

                        f'Unknown character in version: {specifier.version}. '

                        + '(This might be a bug in pyproject-rpm-macros.)',

                    )

                together.append(convert(python3dist(name, python3_pkgversion=self.python3_pkgversion),

                                        specifier.operator, specifier.version))

            if len(together) == 0:

                print(python3dist(name,

                                  python3_pkgversion=self.python3_pkgversion))

            elif len(together) == 1:

                print(together[0])

            else:

                print(f"({' with '.join(together)})")

    def check(self, *, source=None):

        """End current pass if any unsatisfied dependencies were output"""

        if self.missing_requirements:

            print_err(f'Exiting dependency generation pass: {source}')

            raise EndPass(source)

    def extend(self, requirement_strs, **kwargs):

        """add() several requirements"""

        for req_str in requirement_strs:

            self.add(req_str, **kwargs)

def get_backend(requirements):

    try:

        f = open('pyproject.toml')

    except FileNotFoundError:

        pyproject_data = {}

    else:

        try:

            # lazy import toml here, not needed without pyproject.toml

            import toml

        except ImportError as e:

            print_err('Import error:', e)

            # already echoed by the %pyproject_buildrequires macro

            sys.exit(0)

        with f:

            pyproject_data = toml.load(f)

    buildsystem_data = pyproject_data.get('build-system', {})

    requirements.extend(

        buildsystem_data.get('requires', ()),

        source='build-system.requires',

    )

    backend_name = buildsystem_data.get('build-backend')

    if not backend_name:

        # https://www.python.org/dev/peps/pep-0517/:

        # If the pyproject.toml file is absent, or the build-backend key is

        # missing, the source tree is not using this specification, and tools

        # should revert to the legacy behaviour of running setup.py

        # (either directly, or by implicitly invoking the [following] backend).

        # If setup.py is also not present program will mimick pip's behavior

        # and end with an error.

        if not os.path.exists('setup.py'):

            raise FileNotFoundError('File "setup.py" not found for legacy project.')

        backend_name = 'setuptools.build_meta:__legacy__'

        # Note: For projects without pyproject.toml, this was already echoed

        # by the %pyproject_buildrequires macro, but this also handles cases

        # with pyproject.toml without a specified build backend.

        # If the default requirements change, also change them in the macro!

        requirements.add('setuptools >= 40.8', source='default build backend')

        requirements.add('wheel', source='default build backend')

    requirements.check(source='build backend')

    backend_path = buildsystem_data.get('backend-path')

    if backend_path:

        # PEP 517 example shows the path as a list, but some projects don't follow that

        if isinstance(backend_path, str):

            backend_path = [backend_path]

        sys.path = backend_path + sys.path

    module_name, _, object_name = backend_name.partition(":")

    backend_module = importlib.import_module(module_name)

    if object_name:

        return getattr(backend_module, object_name)

    return backend_module

def generate_build_requirements(backend, requirements):

    get_requires = getattr(backend, 'get_requires_for_build_wheel', None)

    if get_requires:

        with hook_call():

            new_reqs = get_requires()

        requirements.extend(new_reqs, source='get_requires_for_build_wheel')

        requirements.check(source='get_requires_for_build_wheel')

def generate_run_requirements(backend, requirements):

    hook_name = 'prepare_metadata_for_build_wheel'

    prepare_metadata = getattr(backend, hook_name, None)

    if not prepare_metadata:

        raise ValueError(

            'build backend cannot provide build metadata '

            + '(incl. runtime requirements) before build'

        )

    with hook_call():

        dir_basename = prepare_metadata('.')

    with open(dir_basename + '/METADATA') as f:

        message = email.parser.Parser().parse(f, headersonly=True)

    for key in 'Requires', 'Requires-Dist':

        requires = message.get_all(key, ())

        requirements.extend(requires, source=f'wheel metadata: {key}')

def generate_tox_requirements(toxenv, requirements):

    toxenv = ','.join(toxenv)

    requirements.add('tox-current-env >= 0.0.6', source='tox itself')

    requirements.check(source='tox itself')

    with tempfile.NamedTemporaryFile('r') as deps, \

        tempfile.NamedTemporaryFile('r') as extras, \

            tempfile.NamedTemporaryFile('r') as provision:

        r = subprocess.run(

            [sys.executable, '-m', 'tox',

             '--print-deps-to', deps.name,

             '--print-extras-to', extras.name,

             '--no-provision', provision.name,

             '-qre', toxenv],

            check=False,

            encoding='utf-8',

            stdout=subprocess.PIPE,

            stderr=subprocess.STDOUT,

        )

        if r.stdout:

            print_err(r.stdout, end='')

        provision_content = provision.read()

        if provision_content and r.returncode != 0:

            provision_requires = json.loads(provision_content)

            if 'minversion' in provision_requires:

                requirements.add(f'tox >= {provision_requires["minversion"]}',

                                 source='tox provision (minversion)')

            if 'requires' in provision_requires:

                requirements.extend(provision_requires["requires"],

                                    source='tox provision (requires)')

            requirements.check(source='tox provision')  # this terminates the script

            raise RuntimeError(

                'Dependencies requested by tox provisioning appear installed, '

                'but tox disagreed.')

        else:

            r.check_returncode()

        deplines = deps.read().splitlines()

        packages = convert_requirements_txt(deplines)

        requirements.add_extras(*extras.read().splitlines())

        requirements.extend(packages,

                            source=f'tox --print-deps-only: {toxenv}')

def python3dist(name, op=None, version=None, python3_pkgversion="3"):

    prefix = f"python{python3_pkgversion}dist"

    if op is None:

        if version is not None:

            raise AssertionError('op and version go together')

        return f'{prefix}({name})'

    else:

        return f'{prefix}({name}) {op} {version}'

def generate_requires(

    *, include_runtime=False, toxenv=None, extras=None,

    get_installed_version=importlib.metadata.version,  # for dep injection

    generate_extras=False, python3_pkgversion="3", requirement_files=None, use_build_system=True

):

    """Generate the BuildRequires for the project in the current directory

    This is the main Python entry point.

    """

    requirements = Requirements(

        get_installed_version, extras=extras or [],

        generate_extras=generate_extras,

        python3_pkgversion=python3_pkgversion

    )

    try:

        if (include_runtime or toxenv) and not use_build_system:

            raise ValueError('-N option cannot be used in combination with -r, -e, -t, -x options')

        if requirement_files:

            for req_file in requirement_files:

                requirements.extend(

                    convert_requirements_txt(req_file, pathlib.Path(req_file.name)),

                    source=f'requirements file {req_file.name}'

                )

            requirements.check(source='all requirements files')

        if use_build_system:

            backend = get_backend(requirements)

            generate_build_requirements(backend, requirements)

        if toxenv:

            include_runtime = True

            generate_tox_requirements(toxenv, requirements)

        if include_runtime:

            generate_run_requirements(backend, requirements)

    except EndPass:

        return

def main(argv):

    parser = argparse.ArgumentParser(

        description='Generate BuildRequires for a Python project.'

    )

    parser.add_argument(

        '-r', '--runtime', action='store_true',

        help='Generate run-time requirements',

    )

    parser.add_argument(

        '-e', '--toxenv', metavar='TOXENVS', action='append',

        help=('specify tox environments (comma separated and/or repeated)'

              '(implies --tox)'),

    )

    parser.add_argument(

        '-t', '--tox', action='store_true',

        help=('generate test tequirements from tox environment '

              '(implies --runtime)'),

    )

    parser.add_argument(

        '-x', '--extras', metavar='EXTRAS', action='append',

        help='comma separated list of "extras" for runtime requirements '

             '(e.g. -x testing,feature-x) (implies --runtime, can be repeated)',

    )

    parser.add_argument(

        '--generate-extras', action='store_true',

        help='Generate build requirements on Python Extras',

    )

    parser.add_argument(

        '-p', '--python3_pkgversion', metavar='PYTHON3_PKGVERSION',

        default="3", help=('Python version for pythonXdist()'

                           'or pythonX.Ydist() requirements'),

    )

    parser.add_argument(

        '-N', '--no-use-build-system', dest='use_build_system',

        action='store_false', help='Use -N to indicate that project does not use any build system',

    )

    parser.add_argument(

       'requirement_files', nargs='*', type=argparse.FileType('r'),

        help=('Add buildrequires from file'),

    )

    args = parser.parse_args(argv)

    if args.toxenv:

        args.tox = True

    if args.tox:

        args.runtime = True

        if not args.toxenv:

            _default = f'py{sys.version_info.major}{sys.version_info.minor}'

            args.toxenv = [os.getenv('RPM_TOXENV', _default)]

    if args.extras:

        args.runtime = True

    try:

        generate_requires(

            include_runtime=args.runtime,

            toxenv=args.toxenv,

            extras=args.extras,

            generate_extras=args.generate_extras,

            python3_pkgversion=args.python3_pkgversion,

            requirement_files=args.requirement_files,

            use_build_system=args.use_build_system,

        )

    except Exception:

        # Log the traceback explicitly (it's useful debug info)

        traceback.print_exc()

        exit(1)

if __name__ == '__main__':

    main(sys.argv[1:])