libretro/scripts/build_pypi.py

#!/usr/bin/env python3
"""Build the `retrobios` package PyPI serves: install.py as a command.

The wheel and the sdist hold install.py, byte for byte the copy the
bootstraps pin, a launcher that runs it as a script (`retrobios` and
`python -m retrobios`), the metadata, README.md and LICENSE. Nothing of the
collection. packaging/pypi/ holds the project file, the README and
`__main__.py`; this script stages them with install.py and LICENSE into a
build folder, writes `__init__.py` with the version, and runs `uv build`
there with the flit_core backend pinned in the project file.

The version is the UTC date of the last commit that changed install.py,
with the zeros PEP 440 drops left out: 2026-11-09 gives 2026.11.9. When
install.py changed several times that day, the newest gets .N, its rank in
the day: the third change gives 2026.11.9.3. The same install.py always
gives the same version, so PyPI refuses a republish of unchanged code.
SOURCE_DATE_EPOCH is that commit's time, so two builds of one commit give
the same bytes.

Usage:
    python scripts/build_pypi.py
    python scripts/build_pypi.py --output-dir tmp/pypi-dist
"""

from __future__ import annotations

import argparse
import datetime
import hashlib
import os
import shutil
import subprocess
import tempfile
from pathlib import Path

from sitebootstrap import PIN, SH_NAME

ROOT = Path(__file__).resolve().parent.parent
PACKAGE_DIR = ROOT / "packaging" / "pypi"
DEFAULT_OUTPUT = ROOT / "tmp" / "pypi-dist"
MODULE = "retrobios"

# The launcher. runpy runs install.py as __main__, so its own __main__ block
# keeps the exit codes it gives a reader that left (141) and Ctrl+C (130).
LAUNCHER = '''"""The RetroBIOS installer, install.py, run as the retrobios command."""

import runpy
from pathlib import Path

__version__ = "{version}"


def main() -> None:
    runpy.run_path(str(Path(__file__).with_name("install.py")), run_name="__main__")
'''


def package_version(stamps: list[int]) -> str:
    """The version of install.py from its commit times, newest first (UTC)."""
    if not stamps:
        raise ValueError("install.py has no commit to date the package by")
    day = datetime.datetime.fromtimestamp(stamps[0], datetime.timezone.utc).date()
    rank = sum(1 for stamp in stamps
               if datetime.datetime.fromtimestamp(stamp, datetime.timezone.utc).date() == day)
    base = f"{day.year}.{day.month}.{day.day}"
    return base if rank == 1 else f"{base}.{rank}"


def install_py_commits() -> list[int]:
    """Commit times of install.py, newest first, from git."""
    out = subprocess.run(["git", "log", "--format=%ct", "--", "install.py"], cwd=ROOT,
                         capture_output=True, text=True, check=True).stdout
    return [int(line) for line in out.split()]


def installer_bytes() -> bytes:
    """install.py, refused unless it is the one install.sh pins: the package
    then runs the installer the one-line command runs, under the same id."""
    data = (ROOT / "install.py").read_bytes()
    pins = PIN[SH_NAME].findall((ROOT / "install.sh").read_text(encoding="utf-8"))
    if pins != [hashlib.sha256(data).hexdigest()]:
        raise ValueError("install.py is not the installer install.sh pins: recompute the pin")
    return data


def stage(folder: Path, version: str) -> None:
    """The project as the backend reads it."""
    module = folder / MODULE
    module.mkdir(parents=True)
    for name in ("pyproject.toml", "README.md"):
        shutil.copyfile(PACKAGE_DIR / name, folder / name)
    shutil.copyfile(ROOT / "LICENSE", folder / "LICENSE")
    shutil.copyfile(PACKAGE_DIR / MODULE / "__main__.py", module / "__main__.py")
    (module / "__init__.py").write_text(LAUNCHER.format(version=version), encoding="utf-8")
    (module / "install.py").write_bytes(installer_bytes())


def build(output_dir: Path) -> tuple[Path, Path]:
    """The wheel and the sdist in output_dir, replacing earlier builds there."""
    stamps = install_py_commits()
    version = package_version(stamps)
    output_dir.mkdir(parents=True, exist_ok=True)
    for pattern in ("*.whl", "*.tar.gz"):
        for old in output_dir.glob(f"{MODULE}-{pattern}"):
            old.unlink()
    scratch = ROOT / "tmp"
    scratch.mkdir(exist_ok=True)
    with tempfile.TemporaryDirectory(prefix="pypi-stage-", dir=scratch) as name:
        folder = Path(name) / "retrobios"
        stage(folder, version)
        # Without a flag, uv builds the sdist, then the wheel from that sdist:
        # what a user building from the sdist gets is what is published.
        subprocess.run(
            ["uv", "build", "--quiet", "--out-dir", str(output_dir.resolve()), str(folder)],
            check=True, env={**os.environ, "SOURCE_DATE_EPOCH": str(stamps[0])})
    wheel = output_dir / f"{MODULE}-{version}-py3-none-any.whl"
    sdist = output_dir / f"{MODULE}-{version}.tar.gz"
    for path in (wheel, sdist):
        if not path.is_file():
            raise RuntimeError(f"uv build wrote no {path.name}")
    return wheel, sdist


def main() -> int:
    parser = argparse.ArgumentParser(allow_abbrev=False, description=__doc__.splitlines()[0])
    parser.add_argument("--output-dir", type=Path, default=DEFAULT_OUTPUT,
                        help="where the wheel and the sdist go (default: tmp/pypi-dist)")
    args = parser.parse_args()
    for path in build(args.output_dir):
        print(path)
    return 0


if __name__ == "__main__":
    from common import run_cli

    run_cli(main)