"""Copy a Mach-O executable and rewrite its non-system dylib dependency closure."""
import pathlib
import shutil
import subprocess
import sys

source = pathlib.Path(sys.argv[1]).resolve()
destination = pathlib.Path(sys.argv[2]).resolve()
(destination / 'lib').mkdir(parents=True, exist_ok=True)
seen = {}
names = {}

def output(*args):
    return subprocess.check_output(args, text=True)

def bundle(original, target):
    original = original.resolve()
    if original in seen:
        return
    if target.name in names and names[target.name] != original:
        raise RuntimeError(f'Dylib basename collision: {target.name}')
    names[target.name] = original
    seen[original] = target
    shutil.copy2(original, target)
    target.chmod(0o755)
    subprocess.run(['codesign', '--remove-signature', str(target)], capture_output=True)
    lines = output('otool', '-L', str(original)).splitlines()[1:]
    # Resolve @rpath against the original image, not the destination directory.
    loads = output('otool', '-l', str(original)).splitlines()
    rpaths = [loads[i + 2].strip().split(' (offset')[0].removeprefix('path ')
              for i, line in enumerate(loads) if line.strip() == 'cmd LC_RPATH']
    for line in lines:
        dependency = line.strip().split(' (compatibility')[0]
        if dependency.startswith(('/usr/lib/', '/System/Library/')):
            continue
        candidates = [dependency]
        if dependency.startswith('@rpath/'):
            candidates = [str(pathlib.Path(r) / dependency[len('@rpath/'):]) for r in rpaths]
        resolved = None
        for candidate in candidates:
            candidate = candidate.replace('@loader_path', str(original.parent)).replace('@executable_path', str(source.parent))
            if pathlib.Path(candidate).is_file():
                resolved = pathlib.Path(candidate).resolve()
                break
        if resolved == original:  # dylib's own install name
            continue
        if resolved is None:
            raise RuntimeError(f'Cannot resolve {dependency} required by {original}')
        copied = destination / 'lib' / resolved.name
        bundle(resolved, copied)
        relative = f'@loader_path/{"lib/" if target.parent == destination else ""}{copied.name}'
        subprocess.run(['install_name_tool', '-change', dependency, relative, str(target)], check=True)
    if target.parent.name == 'lib':
        subprocess.run(['install_name_tool', '-id', '@loader_path/' + target.name, str(target)], check=True)
    subprocess.run(['codesign', '--force', '--sign', '-', str(target)], check=True)

bundle(source, destination / 'ffmpeg')
# Preserve Homebrew's corresponding source and license metadata on the builder.
formula = source.parent.parent / '.brew' / 'ffmpeg.rb'
licenses = destination / 'licenses'
licenses.mkdir(exist_ok=True)
if formula.exists():
    shutil.copy2(formula, licenses / formula.name)
for original in seen:
    prefix = original.parent.parent
    for name in ('LICENSE', 'COPYING', 'COPYING.GPLv2', 'COPYING.GPLv3', 'COPYING.LGPLv2.1', 'COPYING.LGPLv3'):
        if (prefix / name).is_file():
            shutil.copy2(prefix / name, licenses / (original.name + '-' + name))