from __future__ import annotations

import contextlib
import functools
import os.path
import platform
import shutil
import sys
import tempfile
import urllib.request
from typing import Generator
from typing import Sequence

import toml

import pre_commit.constants as C
from pre_commit import parse_shebang
from pre_commit.envcontext import envcontext
from pre_commit.envcontext import PatchesT
from pre_commit.envcontext import Var
from pre_commit.hook import Hook
from pre_commit.languages import helpers
from pre_commit.prefix import Prefix
from pre_commit.util import clean_path_on_failure
from pre_commit.util import cmd_output_b
from pre_commit.util import make_executable
from pre_commit.util import win_exe

ENVIRONMENT_DIR = 'rustenv'
health_check = helpers.basic_health_check


@functools.lru_cache(maxsize=1)
def get_default_version() -> str:
    # If rust is already installed, we can save a bunch of setup time by
    # using the installed version.
    #
    # Just detecting the executable does not suffice, because if rustup is
    # installed but no toolchain is available, then `cargo` exists but
    # cannot be used without installing a toolchain first.
    if cmd_output_b('cargo', '--version', retcode=None)[0] == 0:
        return 'system'
    else:
        return C.DEFAULT


def _rust_toolchain(language_version: str) -> str:
    """Transform the language version into a rust toolchain version."""
    if language_version == C.DEFAULT:
        return 'stable'
    else:
        return language_version


def _envdir(prefix: Prefix, version: str) -> str:
    directory = helpers.environment_dir(ENVIRONMENT_DIR, version)
    return prefix.path(directory)


def get_env_patch(target_dir: str, version: str) -> PatchesT:
    return (
        ('CARGO_HOME', target_dir),
        ('PATH', (os.path.join(target_dir, 'bin'), os.pathsep, Var('PATH'))),
        # Only set RUSTUP_TOOLCHAIN if we don't want use the system's default
        # toolchain
        *(
            (('RUSTUP_TOOLCHAIN', _rust_toolchain(version)),)
            if version != 'system' else ()
        ),
    )


@contextlib.contextmanager
def in_env(
    prefix: Prefix,
    language_version: str,
) -> Generator[None, None, None]:
    with envcontext(
        get_env_patch(_envdir(prefix, language_version), language_version),
    ):
        yield


def _add_dependencies(
        cargo_toml_path: str,
        additional_dependencies: set[str],
) -> None:
    with open(cargo_toml_path, 'r+') as f:
        cargo_toml = toml.load(f)
        cargo_toml.setdefault('dependencies', {})
        for dep in additional_dependencies:
            name, _, spec = dep.partition(':')
            cargo_toml['dependencies'][name] = spec or '*'
        f.seek(0)
        toml.dump(cargo_toml, f)
        f.truncate()


def install_rust_with_toolchain(toolchain: str) -> None:
    with tempfile.TemporaryDirectory() as rustup_dir:
        with envcontext((('RUSTUP_HOME', rustup_dir),)):
            # acquire `rustup` if not present
            if parse_shebang.find_executable('rustup') is None:
                # We did not detect rustup and need to download it first.
                if sys.platform == 'win32':  # pragma: win32 cover
                    if platform.machine() == 'x86_64':
                        url = 'https://win.rustup.rs/x86_64'
                    else:
                        url = 'https://win.rustup.rs/i686'
                else:  # pragma: win32 no cover
                    url = 'https://sh.rustup.rs'

                resp = urllib.request.urlopen(url)

                rustup_init = os.path.join(rustup_dir, win_exe('rustup-init'))
                with open(rustup_init, 'wb') as f:
                    shutil.copyfileobj(resp, f)
                make_executable(rustup_init)

                # install rustup into `$CARGO_HOME/bin`
                cmd_output_b(
                    rustup_init, '-y', '--quiet', '--no-modify-path',
                    '--default-toolchain', 'none',
                )

            cmd_output_b(
                'rustup', 'toolchain', 'install', '--no-self-update',
                toolchain,
            )


def install_environment(
        prefix: Prefix,
        version: str,
        additional_dependencies: Sequence[str],
) -> None:
    directory = _envdir(prefix, version)

    # There are two cases where we might want to specify more dependencies:
    # as dependencies for the library being built, and as binary packages
    # to be `cargo install`'d.
    #
    # Unlike e.g. Python, if we just `cargo install` a library, it won't be
    # used for compilation. And if we add a crate providing a binary to the
    # `Cargo.toml`, the binary won't be built.
    #
    # Because of this, we allow specifying "cli" dependencies by prefixing
    # with 'cli:'.
    cli_deps = {
        dep for dep in additional_dependencies if dep.startswith('cli:')
    }
    lib_deps = set(additional_dependencies) - cli_deps

    if len(lib_deps) > 0:
        _add_dependencies(prefix.path('Cargo.toml'), lib_deps)

    with clean_path_on_failure(directory):
        packages_to_install: set[tuple[str, ...]] = {('--path', '.')}
        for cli_dep in cli_deps:
            cli_dep = cli_dep[len('cli:'):]
            package, _, crate_version = cli_dep.partition(':')
            if crate_version != '':
                packages_to_install.add((package, '--version', crate_version))
            else:
                packages_to_install.add((package,))

        with in_env(prefix, version):
            if version != 'system':
                install_rust_with_toolchain(_rust_toolchain(version))

            for args in packages_to_install:
                cmd_output_b(
                    'cargo', 'install', '--bins', '--root', directory, *args,
                    cwd=prefix.prefix_dir,
                )


def run_hook(
        hook: Hook,
        file_args: Sequence[str],
        color: bool,
) -> tuple[int, bytes]:
    with in_env(hook.prefix, hook.language_version):
        return helpers.run_xargs(hook, hook.cmd, file_args, color=color)