# SPDX-License-Identifier: Apache-2.0
# Copyright © 2022-2024 Intel Corporation

"""Interpreter for converting Cargo Toml definitions to Meson AST

There are some notable limits here. We don't even try to convert something with
a build.rs: there's so few limits on what Cargo allows a build.rs (basically
none), and no good way for us to convert them. In that case, an actual meson
port will be required.
"""

from __future__ import annotations
import dataclasses
import glob
import importlib
import itertools
import json
import os
import shutil
import collections
import typing as T

from . import builder
from . import version
from ..mesonlib import MesonException, Popen_safe, OptionKey
from .. import coredata

if T.TYPE_CHECKING:
    from types import ModuleType

    from . import manifest
    from .. import mparser
    from ..environment import Environment
    from ..coredata import KeyedOptionDictType

# tomllib is present in python 3.11, before that it is a pypi module called tomli,
# we try to import tomllib, then tomli,
# TODO: add a fallback to toml2json?
tomllib: T.Optional[ModuleType] = None
toml2json: T.Optional[str] = None
for t in ['tomllib', 'tomli']:
    try:
        tomllib = importlib.import_module(t)
        break
    except ImportError:
        pass
else:
    # TODO: it would be better to use an Executable here, which could be looked
    # up in the cross file or provided by a wrap. However, that will have to be
    # passed in externally, since we don't have (and I don't think we should),
    # have access to the `Environment` for that in this module.
    toml2json = shutil.which('toml2json')


def load_toml(filename: str) -> T.Dict[object, object]:
    if tomllib:
        with open(filename, 'rb') as f:
            raw = tomllib.load(f)
    else:
        if toml2json is None:
            raise MesonException('Could not find an implementation of tomllib, nor toml2json')

        p, out, err = Popen_safe([toml2json, filename])
        if p.returncode != 0:
            raise MesonException('toml2json failed to decode output\n', err)

        raw = json.loads(out)

    if not isinstance(raw, dict):
        raise MesonException("Cargo.toml isn't a dictionary? How did that happen?")

    return raw


def fixup_meson_varname(name: str) -> str:
    """Fixup a meson variable name

    :param name: The name to fix
    :return: the fixed name
    """
    return name.replace('-', '_')


# Pylance can figure out that these do not, in fact, overlap, but mypy can't
@T.overload
def _fixup_raw_mappings(d: manifest.BuildTarget) -> manifest.FixedBuildTarget: ...  # type: ignore

@T.overload
def _fixup_raw_mappings(d: manifest.LibTarget) -> manifest.FixedLibTarget: ...  # type: ignore

@T.overload
def _fixup_raw_mappings(d: manifest.Dependency) -> manifest.FixedDependency: ...

def _fixup_raw_mappings(d: T.Union[manifest.BuildTarget, manifest.LibTarget, manifest.Dependency]
                        ) -> T.Union[manifest.FixedBuildTarget, manifest.FixedLibTarget,
                                     manifest.FixedDependency]:
    """Fixup raw cargo mappings to ones more suitable for python to consume.

    This does the following:
    * replaces any `-` with `_`, cargo likes the former, but python dicts make
      keys with `-` in them awkward to work with
    * Convert Dependndency versions from the cargo format to something meson
      understands

    :param d: The mapping to fix
    :return: the fixed string
    """
    raw = {fixup_meson_varname(k): v for k, v in d.items()}
    if 'version' in raw:
        assert isinstance(raw['version'], str), 'for mypy'
        raw['version'] = version.convert(raw['version'])
    return T.cast('T.Union[manifest.FixedBuildTarget, manifest.FixedLibTarget, manifest.FixedDependency]', raw)


@dataclasses.dataclass
class Package:

    """Representation of a Cargo Package entry, with defaults filled in."""

    name: str
    version: str
    description: T.Optional[str] = None
    resolver: T.Optional[str] = None
    authors: T.List[str] = dataclasses.field(default_factory=list)
    edition: manifest.EDITION = '2015'
    rust_version: T.Optional[str] = None
    documentation: T.Optional[str] = None
    readme: T.Optional[str] = None
    homepage: T.Optional[str] = None
    repository: T.Optional[str] = None
    license: T.Optional[str] = None
    license_file: T.Optional[str] = None
    keywords: T.List[str] = dataclasses.field(default_factory=list)
    categories: T.List[str] = dataclasses.field(default_factory=list)
    workspace: T.Optional[str] = None
    build: T.Optional[str] = None
    links: T.Optional[str] = None
    exclude: T.List[str] = dataclasses.field(default_factory=list)
    include: T.List[str] = dataclasses.field(default_factory=list)
    publish: bool = True
    metadata: T.Dict[str, T.Dict[str, str]] = dataclasses.field(default_factory=dict)
    default_run: T.Optional[str] = None
    autobins: bool = True
    autoexamples: bool = True
    autotests: bool = True
    autobenches: bool = True


@dataclasses.dataclass
class Dependency:

    """Representation of a Cargo Dependency Entry."""

    version: T.List[str]
    registry: T.Optional[str] = None
    git: T.Optional[str] = None
    branch: T.Optional[str] = None
    rev: T.Optional[str] = None
    path: T.Optional[str] = None
    optional: bool = False
    package: T.Optional[str] = None
    default_features: bool = True
    features: T.List[str] = dataclasses.field(default_factory=list)

    @classmethod
    def from_raw(cls, raw: manifest.DependencyV) -> Dependency:
        """Create a dependency from a raw cargo dictionary"""
        if isinstance(raw, str):
            return cls(version.convert(raw))
        return cls(**_fixup_raw_mappings(raw))


@dataclasses.dataclass
class BuildTarget:

    name: str
    crate_type: T.List[manifest.CRATE_TYPE] = dataclasses.field(default_factory=lambda: ['lib'])
    path: dataclasses.InitVar[T.Optional[str]] = None

    # https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-test-field
    # True for lib, bin, test
    test: bool = True

    # https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-doctest-field
    # True for lib
    doctest: bool = False

    # https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-bench-field
    # True for lib, bin, benchmark
    bench: bool = True

    # https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-doc-field
    # True for libraries and binaries
    doc: bool = False

    harness: bool = True
    edition: manifest.EDITION = '2015'
    required_features: T.List[str] = dataclasses.field(default_factory=list)
    plugin: bool = False


@dataclasses.dataclass
class Library(BuildTarget):

    """Representation of a Cargo Library Entry."""

    doctest: bool = True
    doc: bool = True
    path: str = os.path.join('src', 'lib.rs')
    proc_macro: bool = False
    crate_type: T.List[manifest.CRATE_TYPE] = dataclasses.field(default_factory=lambda: ['lib'])
    doc_scrape_examples: bool = True


@dataclasses.dataclass
class Binary(BuildTarget):

    """Representation of a Cargo Bin Entry."""

    doc: bool = True


@dataclasses.dataclass
class Test(BuildTarget):

    """Representation of a Cargo Test Entry."""

    bench: bool = True


@dataclasses.dataclass
class Benchmark(BuildTarget):

    """Representation of a Cargo Benchmark Entry."""

    test: bool = True


@dataclasses.dataclass
class Example(BuildTarget):

    """Representation of a Cargo Example Entry."""

    crate_type: T.List[manifest.CRATE_TYPE] = dataclasses.field(default_factory=lambda: ['bin'])


@dataclasses.dataclass
class Manifest:

    """Cargo Manifest definition.

    Most of these values map up to the Cargo Manifest, but with default values
    if not provided.

    Cargo subprojects can contain what Meson wants to treat as multiple,
    interdependent, subprojects.

    :param subdir: the subdirectory that this cargo project is in
    :param path: the path within the cargo subproject.
    """

    package: Package
    dependencies: T.Dict[str, Dependency]
    dev_dependencies: T.Dict[str, Dependency]
    build_dependencies: T.Dict[str, Dependency]
    lib: Library
    bin: T.List[Binary]
    test: T.List[Test]
    bench: T.List[Benchmark]
    example: T.List[Example]
    features: T.Dict[str, T.List[str]]
    target: T.Dict[str, T.Dict[str, Dependency]]
    subdir: str
    path: str = ''

    def __post_init__(self) -> None:
        self.features.setdefault('default', [])


def _convert_manifest(raw_manifest: manifest.Manifest, subdir: str, path: str = '') -> Manifest:
    # This cast is a bit of a hack to deal with proc-macro
    lib = _fixup_raw_mappings(raw_manifest.get('lib', {}))

    # We need to set the name field if it's not set manually,
    # including if other fields are set in the lib section
    lib.setdefault('name', raw_manifest['package']['name'])

    pkg = T.cast('manifest.FixedPackage',
                 {fixup_meson_varname(k): v for k, v in raw_manifest['package'].items()})

    return Manifest(
        Package(**pkg),
        {k: Dependency.from_raw(v) for k, v in raw_manifest.get('dependencies', {}).items()},
        {k: Dependency.from_raw(v) for k, v in raw_manifest.get('dev-dependencies', {}).items()},
        {k: Dependency.from_raw(v) for k, v in raw_manifest.get('build-dependencies', {}).items()},
        Library(**lib),
        [Binary(**_fixup_raw_mappings(b)) for b in raw_manifest.get('bin', {})],
        [Test(**_fixup_raw_mappings(b)) for b in raw_manifest.get('test', {})],
        [Benchmark(**_fixup_raw_mappings(b)) for b in raw_manifest.get('bench', {})],
        [Example(**_fixup_raw_mappings(b)) for b in raw_manifest.get('example', {})],
        raw_manifest.get('features', {}),
        {k: {k2: Dependency.from_raw(v2) for k2, v2 in v.get('dependencies', {}).items()}
         for k, v in raw_manifest.get('target', {}).items()},
        subdir,
        path,
    )


def _load_manifests(subdir: str) -> T.Dict[str, Manifest]:
    filename = os.path.join(subdir, 'Cargo.toml')
    raw = load_toml(filename)

    manifests: T.Dict[str, Manifest] = {}

    raw_manifest: T.Union[manifest.Manifest, manifest.VirtualManifest]
    if 'package' in raw:
        raw_manifest = T.cast('manifest.Manifest', raw)
        manifest_ = _convert_manifest(raw_manifest, subdir)
        manifests[manifest_.package.name] = manifest_
    else:
        raw_manifest = T.cast('manifest.VirtualManifest', raw)

    if 'workspace' in raw_manifest:
        # XXX: need to verify that python glob and cargo globbing are the
        # same and probably write  a glob implementation. Blarg

        # We need to chdir here to make the glob work correctly
        pwd = os.getcwd()
        os.chdir(subdir)
        members: T.Iterable[str]
        try:
            members = itertools.chain.from_iterable(
                glob.glob(m) for m in raw_manifest['workspace']['members'])
        finally:
            os.chdir(pwd)
        if 'exclude' in raw_manifest['workspace']:
            members = (x for x in members if x not in raw_manifest['workspace']['exclude'])

        for m in members:
            filename = os.path.join(subdir, m, 'Cargo.toml')
            raw = load_toml(filename)

            raw_manifest = T.cast('manifest.Manifest', raw)
            man = _convert_manifest(raw_manifest, subdir, m)
            manifests[man.package.name] = man

    return manifests


def _dependency_name(package_name: str) -> str:
    return package_name if package_name.endswith('-rs') else f'{package_name}-rs'


def _dependency_varname(package_name: str) -> str:
    return f'{fixup_meson_varname(package_name)}_dep'


_OPTION_NAME_PREFIX = 'feature-'


def _option_name(feature: str) -> str:
    # Add a prefix to avoid collision with Meson reserved options (e.g. "debug")
    return _OPTION_NAME_PREFIX + feature


def _options_varname(depname: str) -> str:
    return f'{fixup_meson_varname(depname)}_options'


def _extra_args_varname() -> str:
    return 'extra_args'


def _extra_deps_varname() -> str:
    return 'extra_deps'


def _create_project(cargo: Manifest, build: builder.Builder) -> T.List[mparser.BaseNode]:
    """Create a function call

    :param cargo: The Manifest to generate from
    :param build: The AST builder
    :return: a list nodes
    """
    args: T.List[mparser.BaseNode] = []
    args.extend([
        build.string(cargo.package.name),
        build.string('rust'),
    ])
    kwargs: T.Dict[str, mparser.BaseNode] = {
        'version': build.string(cargo.package.version),
        # Always assume that the generated meson is using the latest features
        # This will warn when when we generate deprecated code, which is helpful
        # for the upkeep of the module
        'meson_version': build.string(f'>= {coredata.stable_version}'),
        'default_options': build.array([build.string(f'rust_std={cargo.package.edition}')]),
    }
    if cargo.package.license:
        kwargs['license'] = build.string(cargo.package.license)
    elif cargo.package.license_file:
        kwargs['license_files'] = build.string(cargo.package.license_file)

    return [build.function('project', args, kwargs)]


def _process_feature(cargo: Manifest, feature: str) -> T.Tuple[T.Set[str], T.Dict[str, T.Set[str]], T.Set[str]]:
    # Set of features that must also be enabled if this feature is enabled.
    features: T.Set[str] = set()
    # Map dependency name to a set of features that must also be enabled on that
    # dependency if this feature is enabled.
    dep_features: T.Dict[str, T.Set[str]] = collections.defaultdict(set)
    # Set of dependencies that are required if this feature is enabled.
    required_deps: T.Set[str] = set()
    # Set of features that must be processed recursively.
    to_process: T.Set[str] = {feature}
    while to_process:
        f = to_process.pop()
        if '/' in f:
            dep, dep_f = f.split('/', 1)
            if dep[-1] == '?':
                dep = dep[:-1]
            else:
                required_deps.add(dep)
            dep_features[dep].add(dep_f)
        elif f.startswith('dep:'):
            required_deps.add(f[4:])
        elif f not in features:
            features.add(f)
            to_process.update(cargo.features.get(f, []))
            # A feature can also be a dependency
            if f in cargo.dependencies:
                required_deps.add(f)
    return features, dep_features, required_deps


def _create_features(cargo: Manifest, build: builder.Builder) -> T.List[mparser.BaseNode]:
    # https://doc.rust-lang.org/cargo/reference/features.html#the-features-section

    # Declare a dict that map enabled features to true. One for current project
    # and one per dependency.
    ast: T.List[mparser.BaseNode] = []
    ast.append(build.assign(build.dict({}), 'features'))
    for depname in cargo.dependencies:
        ast.append(build.assign(build.dict({}), _options_varname(depname)))

    # Declare a dict that map required dependencies to true
    ast.append(build.assign(build.dict({}), 'required_deps'))

    for feature in cargo.features:
        # if get_option(feature)
        #   required_deps += {'dep': true, ...}
        #   features += {'foo': true, ...}
        #   xxx_options += {'feature-foo': true, ...}
        #   ...
        # endif
        features, dep_features, required_deps = _process_feature(cargo, feature)
        lines: T.List[mparser.BaseNode] = [
            build.plusassign(
                build.dict({build.string(d): build.bool(True) for d in required_deps}),
                'required_deps'),
            build.plusassign(
                build.dict({build.string(f): build.bool(True) for f in features}),
                'features'),
        ]
        for depname, enabled_features in dep_features.items():
            lines.append(build.plusassign(
                build.dict({build.string(_option_name(f)): build.bool(True) for f in enabled_features}),
                _options_varname(depname)))

        ast.append(build.if_(build.function('get_option', [build.string(_option_name(feature))]), build.block(lines)))

    ast.append(build.function('message', [
        build.string('Enabled features:'),
        build.method('keys', build.identifier('features'))],
    ))

    return ast


def _create_dependencies(cargo: Manifest, build: builder.Builder) -> T.List[mparser.BaseNode]:
    ast: T.List[mparser.BaseNode] = []
    for name, dep in cargo.dependencies.items():
        package_name = dep.package or name

        # xxx_options += {'feature-default': true, ...}
        extra_options: T.Dict[mparser.BaseNode, mparser.BaseNode] = {
            build.string(_option_name('default')): build.bool(dep.default_features),
        }
        for f in dep.features:
            extra_options[build.string(_option_name(f))] = build.bool(True)
        ast.append(build.plusassign(build.dict(extra_options), _options_varname(name)))

        kw = {
            'version': build.array([build.string(s) for s in dep.version]),
            'default_options': build.identifier(_options_varname(name)),
        }
        if dep.optional:
            kw['required'] = build.method('get', build.identifier('required_deps'), [
                build.string(name), build.bool(False)
            ])

        # Lookup for this dependency with the features we want in default_options kwarg.
        #
        # However, this subproject could have been previously configured with a
        # different set of features. Cargo collects the set of features globally
        # but Meson can only use features enabled by the first call that triggered
        # the configuration of that subproject.
        #
        # Verify all features that we need are actually enabled for that dependency,
        # otherwise abort with an error message. The user has to set the corresponding
        # option manually with -Dxxx-rs:feature-yyy=true, or the main project can do
        # that in its project(..., default_options: ['xxx-rs:feature-yyy=true']).
        ast.extend([
            # xxx_dep = dependency('xxx', version : ..., default_options : xxx_options)
            build.assign(
                build.function(
                    'dependency',
                    [build.string(_dependency_name(package_name))],
                    kw,
                ),
                _dependency_varname(package_name),
            ),
            # if xxx_dep.found()
            build.if_(build.method('found', build.identifier(_dependency_varname(package_name))), build.block([
                # actual_features = xxx_dep.get_variable('features', default_value : '').split(',')
                build.assign(
                    build.method(
                        'split',
                        build.method(
                            'get_variable',
                            build.identifier(_dependency_varname(package_name)),
                            [build.string('features')],
                            {'default_value': build.string('')}
                        ),
                        [build.string(',')],
                    ),
                    'actual_features'
                ),
                # needed_features = []
                # foreach f, _ : xxx_options
                #   needed_features += f.substring(8)
                # endforeach
                build.assign(build.array([]), 'needed_features'),
                build.foreach(['f', 'enabled'], build.identifier(_options_varname(name)), build.block([
                    build.if_(build.identifier('enabled'), build.block([
                        build.plusassign(
                            build.method('substring', build.identifier('f'), [build.number(len(_OPTION_NAME_PREFIX))]),
                            'needed_features'),
                    ])),
                ])),
                # foreach f : needed_features
                #   if f not in actual_features
                #     error()
                #   endif
                # endforeach
                build.foreach(['f'], build.identifier('needed_features'), build.block([
                    build.if_(build.not_in(build.identifier('f'), build.identifier('actual_features')), build.block([
                        build.function('error', [
                            build.string('Dependency'),
                            build.string(_dependency_name(package_name)),
                            build.string('previously configured with features'),
                            build.identifier('actual_features'),
                            build.string('but need'),
                            build.identifier('needed_features'),
                        ])
                    ]))
                ])),
            ])),
        ])
    return ast


def _create_meson_subdir(cargo: Manifest, build: builder.Builder) -> T.List[mparser.BaseNode]:
    # Allow Cargo subprojects to add extra Rust args in meson/meson.build file.
    # This is used to replace build.rs logic.

    # extra_args = []
    # extra_deps = []
    # fs = import('fs')
    # if fs.is_dir('meson')
    #  subdir('meson')
    # endif
    return [
        build.assign(build.array([]), _extra_args_varname()),
        build.assign(build.array([]), _extra_deps_varname()),
        build.assign(build.function('import', [build.string('fs')]), 'fs'),
        build.if_(build.method('is_dir', build.identifier('fs'), [build.string('meson')]),
                  build.block([build.function('subdir', [build.string('meson')])]))
    ]


def _create_lib(cargo: Manifest, build: builder.Builder, crate_type: manifest.CRATE_TYPE) -> T.List[mparser.BaseNode]:
    dependencies: T.List[mparser.BaseNode] = []
    dependency_map: T.Dict[mparser.BaseNode, mparser.BaseNode] = {}
    for name, dep in cargo.dependencies.items():
        package_name = dep.package or name
        dependencies.append(build.identifier(_dependency_varname(package_name)))
        if name != package_name:
            dependency_map[build.string(fixup_meson_varname(package_name))] = build.string(name)

    rust_args: T.List[mparser.BaseNode] = [
        build.identifier('features_args'),
        build.identifier(_extra_args_varname())
    ]

    dependencies.append(build.identifier(_extra_deps_varname()))

    posargs: T.List[mparser.BaseNode] = [
        build.string(fixup_meson_varname(cargo.package.name)),
        build.string(cargo.lib.path),
    ]

    kwargs: T.Dict[str, mparser.BaseNode] = {
        'dependencies': build.array(dependencies),
        'rust_dependency_map': build.dict(dependency_map),
        'rust_args': build.array(rust_args),
    }

    lib: mparser.BaseNode
    if cargo.lib.proc_macro or crate_type == 'proc-macro':
        lib = build.method('proc_macro', build.identifier('rust'), posargs, kwargs)
    else:
        if crate_type in {'lib', 'rlib', 'staticlib'}:
            target_type = 'static_library'
        elif crate_type in {'dylib', 'cdylib'}:
            target_type = 'shared_library'
        else:
            raise MesonException(f'Unsupported crate type {crate_type}')
        if crate_type in {'staticlib', 'cdylib'}:
            kwargs['rust_abi'] = build.string('c')
        lib = build.function(target_type, posargs, kwargs)

    # features_args = []
    # foreach f, _ : features
    #   features_args += ['--cfg', 'feature="' + f + '"']
    # endforeach
    # lib = xxx_library()
    # dep = declare_dependency()
    # meson.override_dependency()
    return [
        build.assign(build.array([]), 'features_args'),
        build.foreach(['f', '_'], build.identifier('features'), build.block([
            build.plusassign(
                build.array([
                    build.string('--cfg'),
                    build.plus(build.string('feature="'), build.plus(build.identifier('f'), build.string('"'))),
                ]),
                'features_args')
            ])
        ),
        build.assign(lib, 'lib'),
        build.assign(
            build.function(
                'declare_dependency',
                kw={
                    'link_with': build.identifier('lib'),
                    'variables': build.dict({
                        build.string('features'): build.method('join', build.string(','), [build.method('keys', build.identifier('features'))]),
                    })
                },
            ),
            'dep'
        ),
        build.method(
            'override_dependency',
            build.identifier('meson'),
            [
                build.string(_dependency_name(cargo.package.name)),
                build.identifier('dep'),
            ],
        ),
    ]


def interpret(subp_name: str, subdir: str, env: Environment) -> T.Tuple[mparser.CodeBlockNode, KeyedOptionDictType]:
    package_name = subp_name[:-3] if subp_name.endswith('-rs') else subp_name
    manifests = _load_manifests(os.path.join(env.source_dir, subdir))
    cargo = manifests.get(package_name)
    if not cargo:
        raise MesonException(f'Cargo package {package_name!r} not found in {subdir}')

    filename = os.path.join(cargo.subdir, cargo.path, 'Cargo.toml')
    build = builder.Builder(filename)

    # Generate project options
    options: T.Dict[OptionKey, coredata.UserOption] = {}
    for feature in cargo.features:
        key = OptionKey(_option_name(feature), subproject=subp_name)
        enabled = feature == 'default'
        options[key] = coredata.UserBooleanOption(f'Cargo {feature} feature', enabled)

    ast = _create_project(cargo, build)
    ast += [build.assign(build.function('import', [build.string('rust')]), 'rust')]
    ast += _create_features(cargo, build)
    ast += _create_dependencies(cargo, build)
    ast += _create_meson_subdir(cargo, build)

    # Libs are always auto-discovered and there's no other way to handle them,
    # which is unfortunate for reproducability
    if os.path.exists(os.path.join(env.source_dir, cargo.subdir, cargo.path, cargo.lib.path)):
        for crate_type in cargo.lib.crate_type:
            ast.extend(_create_lib(cargo, build, crate_type))

    return build.block(ast), options