import os
import subprocess

arch = ARGUMENTS.get('RTT_VDSO_ARCH') or os.getenv('RTT_VDSO_ARCH')
user_dir = os.path.normpath(Dir('.').abspath)
vdso_root = os.path.normpath(os.path.join(user_dir, '..'))

arch_def_config = {
    'aarch64': {
        'prefix': 'aarch64-none-elf-',
        'device': '-march=armv8-a -mtune=cortex-a53',
        'linker': os.path.join(user_dir, 'arch', 'aarch64', 'vdso.lds.S'),
    },
    'arm': {
        'prefix': 'arm-none-eabi-',
        'device': '-march=armv7-a -marm',
        'linker': os.path.join(user_dir, 'arch', 'arm', 'vdso.lds.S'),
    },
    'risc-v': {
        'prefix': 'riscv64-none-elf-',
        'device': '-march=rv64imafdc -mabi=lp64',
        'linker': os.path.join(user_dir, 'arch', 'risc-v', 'vdso.lds.S'),
    },
}

if arch not in arch_def_config:
    raise RuntimeError('Unsupported vDSO arch: %s' % arch)

exec_path = os.getenv('RTT_EXEC_PATH') or '/usr/bin'
prefix = os.getenv('RTT_CC_PREFIX') or arch_def_config[arch]['prefix']
device = os.getenv('RTT_DEVICE') or arch_def_config[arch]['device']
linker_script_src = arch_def_config[arch]['linker']

cc = prefix + 'gcc'
cpp = prefix + 'cpp'
ar = prefix + 'ar'

common_dir = os.path.join(user_dir, 'common')
arch_dir = os.path.join(user_dir, 'arch', arch)
build_dir = os.path.join(user_dir, 'build', arch)
os.makedirs(build_dir, exist_ok=True)
linker_script = os.path.join(build_dir, 'vdso.lds')

cflags = ' '.join([
    device,
    '-Wall',
    '-Wextra',
    '-Wno-unused-parameter',
    '-Wno-cpp',
    '-std=gnu99',
    '-O2',
    '-fPIC',
    '-ffreestanding',
    '-fno-builtin',
    '-fvisibility=hidden',
    '-nostdlib',
    '-nostartfiles',
])

linkflags = ' '.join([
    device,
    '-nostdlib',
    '-nostartfiles',
    '-shared',
    '-Wl,--gc-sections',
    '-Wl,--build-id=none',
    '-Wl,-soname=rtt-vdso.so.1',
    '-T %s' % linker_script,
])

env = Environment(
    tools=['gcc', 'link'],
    AS=cc,
    ASFLAGS='-x assembler-with-cpp',
    CC=cc,
    CFLAGS=cflags,
    CPP=cpp,
    AR=ar,
    LINK=cc,
    LINKFLAGS=linkflags,
    CPPPATH=[user_dir, common_dir, arch_dir, vdso_root],
)
env.PrependENVPath('PATH', exec_path)

def preprocess_linker_script(target, source, env):
    cmd = [env['CC'], '-E', '-P', '-x', 'assembler-with-cpp']
    for include_dir in env['CPPPATH']:
        cmd.append('-I' + include_dir)
    cmd.extend([str(source[0]), '-o', str(target[0])])
    return subprocess.call(cmd)

preprocessed_linker = env.Command(linker_script, linker_script_src, preprocess_linker_script)

target = os.path.join(build_dir, 'libvdso.so')
source = os.path.join(common_dir, 'vdso_clock_gettime.c')
objects = [env.SharedObject(target=os.path.join(build_dir, 'vdso_clock_gettime'), source=source)]
shared_lib = env.SharedLibrary(target=target, source=objects)
env.Depends(shared_lib, preprocessed_linker)

Clean(shared_lib, build_dir)
Clean(shared_lib, '.sconsign.dblite')
env.Default(shared_lib)