#!/usr/bin/env python3
# Copyright 2023 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
'''Builds the bindgen tool.'''

import argparse
import collections
import os
import platform
import shutil
import subprocess
import sys

from build_rust import (CARGO_HOME_DIR, CIPD_DOWNLOAD_URL, FetchBetaPackage,
                        InstallBetaPackage, RustTargetTriple,
                        RUST_CROSS_TARGET_LLVM_INSTALL_DIR,
                        RUST_HOST_LLVM_INSTALL_DIR)
from update_rust import (RUST_REVISION, RUST_TOOLCHAIN_OUT_DIR,
                         THIRD_PARTY_DIR)

# Get variables and helpers from Clang update script
sys.path.append(
    os.path.join(os.path.dirname(os.path.abspath(__file__)), '..', 'clang',
                 'scripts'))

from build import (CheckoutGitRepo, DownloadAndUnpack, LLVM_BUILD_TOOLS_DIR,
                   DownloadDebianSysroot, RunCommand)
from update import (RmTree)

# The git hash to use.
BINDGEN_GIT_VERSION = '97e29b49bebaba4d067d4f5f2270748c7d28a557'
BINDGEN_GIT_REPO = ('https://chromium.googlesource.com/external/' +
                    'github.com/rust-lang/rust-bindgen')

BINDGEN_SRC_DIR = os.path.join(THIRD_PARTY_DIR, 'rust-toolchain-intermediate',
                               'bindgen-src')
BINDGEN_HOST_BUILD_DIR = os.path.join(THIRD_PARTY_DIR,
                                      'rust-toolchain-intermediate',
                                      'bindgen-host-build')
BINDGEN_CROSS_TARGET_BUILD_DIR = os.path.join(THIRD_PARTY_DIR,
                                              'rust-toolchain-intermediate',
                                              'bindgen-target-build')

NCURSESW_CIPD_LINUX_AMD_PATH = 'infra/3pp/static_libs/ncursesw/linux-amd64'
NCURSESW_CIPD_LINUX_AMD_VERSION = '6.0.chromium.1'

RUST_BETA_SYSROOT_DIR = os.path.join(THIRD_PARTY_DIR,
                                     'rust-toolchain-intermediate',
                                     'beta-sysroot')

EXE = '.exe' if sys.platform == 'win32' else ''


def InstallRustBetaSysroot(rust_git_hash, target_triples):
    if os.path.exists(RUST_BETA_SYSROOT_DIR):
        RmTree(RUST_BETA_SYSROOT_DIR)
    InstallBetaPackage(FetchBetaPackage('cargo', rust_git_hash),
                       RUST_BETA_SYSROOT_DIR)
    InstallBetaPackage(FetchBetaPackage('rustc', rust_git_hash),
                       RUST_BETA_SYSROOT_DIR)
    for t in target_triples:
        InstallBetaPackage(
            FetchBetaPackage('rust-std', rust_git_hash, triple=t),
            RUST_BETA_SYSROOT_DIR)


def FetchNcurseswLibrary():
    assert sys.platform.startswith('linux')
    ncursesw_dir = os.path.join(LLVM_BUILD_TOOLS_DIR, 'ncursesw')
    ncursesw_url = (f'{CIPD_DOWNLOAD_URL}/{NCURSESW_CIPD_LINUX_AMD_PATH}'
                    f'/+/version:2@{NCURSESW_CIPD_LINUX_AMD_VERSION}')

    if os.path.exists(ncursesw_dir):
        RmTree(ncursesw_dir)
    DownloadAndUnpack(ncursesw_url, ncursesw_dir, is_known_zip=True)
    return ncursesw_dir


def main():
    parser = argparse.ArgumentParser(description='Build and package bindgen')
    parser.add_argument(
        '--skip-checkout',
        action='store_true',
        help='skip downloading the git repo. Useful for trying local changes')
    parser.add_argument('--build-mac-arm',
                        action='store_true',
                        help='Build arm binaries. Only valid on macOS.')
    args, rest = parser.parse_known_args()

    if args.build_mac_arm and sys.platform != 'darwin':
        print('--build-mac-arm only valid on macOS')
        return 1
    if args.build_mac_arm and platform.machine() == 'arm64':
        print('--build-mac-arm only valid on intel to cross-build arm')
        return 1

    ncursesw_dir = None
    if sys.platform.startswith('linux'):
        ncursesw_dir = FetchNcurseswLibrary()

    if args.build_mac_arm:
        # When cross-compiling, the binaries in RUST_TOOLCHAIN_OUT_DIR are not
        # usable on this machine, so we have to fetch them. We install them,
        # along with the host and target stdlib to a sysroot dir.
        InstallRustBetaSysroot(
            RUST_REVISION,
            [RustTargetTriple(),
             RustTargetTriple(build_mac_arm=True)])
        cargo_bin = os.path.join(RUST_BETA_SYSROOT_DIR, 'bin', f'cargo{EXE}')
        rustc_bin = os.path.join(RUST_BETA_SYSROOT_DIR, 'bin', f'rustc{EXE}')

        if not os.path.exists(cargo_bin):
            print(f'Missing cargo at {cargo_bin}. The sysroot was not setup '
                  'correctly?')
            sys.exit(1)
        if not os.path.exists(rustc_bin):
            print(f'Missing rustc at {rustc_bin}. The sysroot was not setup '
                  'correctly?')
            sys.exit(1)
    else:
        cargo_bin = os.path.join(RUST_TOOLCHAIN_OUT_DIR, 'bin', f'cargo{EXE}')
        rustc_bin = os.path.join(RUST_TOOLCHAIN_OUT_DIR, 'bin', f'rustc{EXE}')

        if not os.path.exists(cargo_bin):
            print(
                f'Missing cargo at {cargo_bin}. The build_bindgen.py '
                f'script expects to be run after build_rust.py is run as '
                f'the build_rust.py script builds cargo that is needed here.')
            sys.exit(1)
        if not os.path.exists(rustc_bin):
            print(
                f'Missing rustc at {rustc_bin}. The build_bindgen.py '
                f'script expects to be run after build_rust.py is run as '
                f'the build_rust.py script builds rustc that is needed here.')
            sys.exit(1)

    clang_bins_dir = os.path.join(RUST_HOST_LLVM_INSTALL_DIR, 'bin')
    if args.build_mac_arm:
        llvm_dir = RUST_CROSS_TARGET_LLVM_INSTALL_DIR
        build_dir = BINDGEN_CROSS_TARGET_BUILD_DIR
    else:
        llvm_dir = RUST_HOST_LLVM_INSTALL_DIR
        build_dir = BINDGEN_HOST_BUILD_DIR

    if not os.path.exists(os.path.join(llvm_dir, 'bin', f'llvm-config{EXE}')):
        print(f'Missing llvm-config in {llvm_dir}. The build_bindgen.py '
              f'script expects to be run after build_rust.py is run as '
              f'the build_rust.py script produces the LLVM libraries that '
              f'are needed here.')
        sys.exit(1)

    if not args.skip_checkout:
        CheckoutGitRepo("bindgen", BINDGEN_GIT_REPO, BINDGEN_GIT_VERSION,
                        BINDGEN_SRC_DIR)

    print(f'Building bindgen in {build_dir} ...')
    if os.path.exists(build_dir):
        RmTree(build_dir)

    env = collections.defaultdict(str, os.environ)
    # Cargo normally stores files in $HOME. Override this.
    env['CARGO_HOME'] = CARGO_HOME_DIR

    # Use a rustc we deterministically provide, not a system one.
    env['RUSTC'] = rustc_bin

    # Use the LLVM libs and clang compiler from the rustc build.
    env['LLVM_CONFIG_PATH'] = os.path.join(llvm_dir, 'bin', 'llvm-config')
    if sys.platform == 'win32':
        env['LIBCLANG_PATH'] = os.path.join(llvm_dir, 'bin')
    else:
        env['LIBCLANG_PATH'] = os.path.join(llvm_dir, 'lib')
    env['LIBCLANG_STATIC_PATH'] = os.path.join(llvm_dir, 'lib')
    env['CC'] = os.path.join(clang_bins_dir, 'clang')
    env['CXX'] = os.path.join(clang_bins_dir, 'clang++')

    # Windows uses lld-link for MSVC compat. Otherwise, we use lld via clang.
    if sys.platform == 'win32':
        linker = os.path.join(clang_bins_dir, 'lld-link')
    else:
        linker = os.path.join(clang_bins_dir, 'clang')
        env['LDFLAGS'] += ' -fuse-ld=lld'
        env['RUSTFLAGS'] += ' -Clink-arg=-fuse-ld=lld'
    env['LD'] = linker
    env['RUSTFLAGS'] += f' -Clinker={linker}'

    if sys.platform.startswith('linux'):
        # We use these flags to avoid linking with the system libstdc++.
        sysroot = DownloadDebianSysroot('amd64')
        sysroot_flag = f'--sysroot={sysroot}'
        env['CFLAGS'] += f' {sysroot_flag}'
        env['CXXFLAGS'] += f' {sysroot_flag}'
        env['LDFLAGS'] += f' {sysroot_flag}'
        env['RUSTFLAGS'] += f' -Clink-arg={sysroot_flag}'

    if ncursesw_dir:
        env['CFLAGS'] += f' -I{ncursesw_dir}/include'
        env['CXXFLAGS'] += f' -I{ncursesw_dir}/include'
        env['LDFLAGS'] += f' -L{ncursesw_dir}/lib'
        env['RUSTFLAGS'] += f' -Clink-arg=-L{ncursesw_dir}/lib'

    if sys.platform == 'darwin':
        # The system/xcode compiler would find system SDK correctly, but
        # the Clang we've built does not. See
        # https://github.com/llvm/llvm-project/issues/45225
        sdk_path = subprocess.check_output(['xcrun', '--show-sdk-path'],
                                           text=True).rstrip()
        env['CFLAGS'] += f' -isysroot {sdk_path}'
        env['CXXFLAGS'] += f' -isysroot {sdk_path}'
        env['LDFLAGS'] += f' -isysroot {sdk_path}'
        env['RUSTFLAGS'] += f' -Clink-arg=-isysroot -Clink-arg={sdk_path}'

    cargo_args = [
        'build',
        f'--manifest-path={BINDGEN_SRC_DIR}/Cargo.toml',
        f'--target-dir={build_dir}',
        f'--target={RustTargetTriple(build_mac_arm = args.build_mac_arm)}',
        f'--no-default-features',
        f'--features=logging',
        '--release',
        '--bin',
        'bindgen',
    ]
    RunCommand([cargo_bin] + cargo_args, setenv=True, env=env)

    install_dir = os.path.join(RUST_TOOLCHAIN_OUT_DIR)
    print(f'Installing bindgen to {install_dir} ...')

    shutil.copy(
        os.path.join(build_dir,
                     RustTargetTriple(build_mac_arm=args.build_mac_arm),
                     'release', f'bindgen{EXE}'),
        os.path.join(install_dir, 'bin'))
    if sys.platform == 'win32':
        shutil.copy(os.path.join(llvm_dir, 'bin', f'libclang.dll'),
                    os.path.join(install_dir, 'bin'))
    elif sys.platform == 'darwin':
        shutil.copy(os.path.join(llvm_dir, 'lib', f'libclang.dylib'),
                    os.path.join(install_dir, 'lib'))
    else:
        # Can't replace symlinks so remove existing ones.
        for filename in os.listdir(os.path.join(install_dir, 'lib')):
            if filename.startswith('libclang.so'):
                os.remove(os.path.join(install_dir, 'lib', filename))
        for filename in os.listdir(os.path.join(llvm_dir, 'lib')):
            if filename.startswith('libclang.so'):
                shutil.copy(os.path.join(llvm_dir, 'lib', filename),
                            os.path.join(install_dir, 'lib'),
                            follow_symlinks=False)
    return 0


if __name__ == '__main__':
    sys.exit(main())