"""Materialize pinned baseline/candidate headers under a new explicit output path."""

import argparse
import hashlib
import json
from pathlib import Path
import shutil
import subprocess

HERE = Path(__file__).resolve().parent
REPO = HERE.parents[2]
DATA = HERE / "data"
PIN = "d79e3f6f0a424f5bcc3a1a6d610313e49daf97a2"


def manifest():
    result = json.loads((DATA / "source_manifest.json").read_text())
    if result["baseline_commit"] != PIN:
        raise RuntimeError("Wrong baseline pin")
    return result


def verify_candidate(root):
    for name, expected in manifest()["files"].items():
        if hashlib.sha256((root / name).read_bytes()).hexdigest() != expected:
            raise RuntimeError("Candidate header hash mismatch: " + name)


def materialize(repo, output):
    """Copy only the two exact source headers, then patch the isolated copy."""
    expected = manifest()
    headers = [
        Path(name).relative_to("baseline")
        for name in expected["files"]
        if name.startswith("baseline/")
    ]
    for relative in headers:
        wanted = expected["files"][str(Path("baseline") / relative)]
        if hashlib.sha256((repo / relative).read_bytes()).hexdigest() != wanted:
            raise RuntimeError("Production header does not match d79: " + str(relative))
    output.mkdir(parents=True, exist_ok=False)
    for mode in ("baseline", "patched"):
        for relative in headers:
            target = output / mode / relative
            target.parent.mkdir(parents=True, exist_ok=True)
            shutil.copyfile(repo / relative, target)
    patch = DATA / "smagorinsky_normalization.patch"
    subprocess.run(
        ["git", "apply", "--check", str(patch)], cwd=output / "patched", check=True
    )
    subprocess.run(["git", "apply", str(patch)], cwd=output / "patched", check=True)
    verify_candidate(output)
    (output / "source_manifest.json").write_text(json.dumps(expected, indent=2) + "\n")
    return output


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--repo", type=Path, default=REPO)
    parser.add_argument("--output-dir", type=Path, required=True)
    args = parser.parse_args()
    materialize(args.repo.resolve(), args.output_dir.resolve())
    print("Pinned baseline/candidate headers verified; production files unchanged.")