#!/usr/bin/env python3
"""Build a deterministic Bootstrap Pack bundle for sealed/offline transfer.

- Reads a JSON config listing artefacts to include (images, Helm charts, extras).
- Copies artefacts into an output directory with preserved basenames.
- Generates `bootstrap-manifest.json` and `checksums.sha256` with sha256 hashes
  and sizes for evidence/verification.
- Intended to satisfy DEVOPS-AIRGAP-56-003.

Config schema (JSON):
{
  "name": "bootstrap-pack",
  "images": ["release/containers/taskrunner.tar", "release/containers/orchestrator.tar"],
  "charts": ["deploy/helm/stella.tgz"],
  "extras": ["docs/24_OFFLINE_KIT.md"]
}

Usage:
  build_bootstrap_pack.py --config bootstrap.json --output out/bootstrap-pack
  build_bootstrap_pack.py --self-test
"""
from __future__ import annotations

import argparse
import hashlib
import json
import os
import shutil
import sys
from datetime import datetime, timezone
from pathlib import Path
from typing import Dict, List, Tuple

DEFAULT_NAME = "bootstrap-pack"


def sha256_file(path: Path) -> Tuple[str, int]:
    h = hashlib.sha256()
    size = 0
    with path.open("rb") as f:
        for chunk in iter(lambda: f.read(1024 * 1024), b""):
            h.update(chunk)
            size += len(chunk)
    return h.hexdigest(), size


def load_config(path: Path) -> Dict:
    with path.open("r", encoding="utf-8") as handle:
        cfg = json.load(handle)
    if not isinstance(cfg, dict):
        raise ValueError("config must be a JSON object")
    return cfg


def ensure_list(cfg: Dict, key: str) -> List[str]:
    value = cfg.get(key, [])
    if value is None:
        return []
    if not isinstance(value, list):
        raise ValueError(f"config.{key} must be a list")
    return [str(x) for x in value]


def copy_item(src: Path, dest_root: Path, rel_dir: str) -> Tuple[str, str, int]:
    dest_dir = dest_root / rel_dir
    dest_dir.mkdir(parents=True, exist_ok=True)
    dest_path = dest_dir / src.name
    shutil.copy2(src, dest_path)
    digest, size = sha256_file(dest_path)
    rel_path = dest_path.relative_to(dest_root).as_posix()
    return rel_path, digest, size


def build_pack(config_path: Path, output_dir: Path) -> Dict:
    cfg = load_config(config_path)
    name = cfg.get("name", DEFAULT_NAME)
    images = ensure_list(cfg, "images")
    charts = ensure_list(cfg, "charts")
    extras = ensure_list(cfg, "extras")

    output_dir.mkdir(parents=True, exist_ok=True)
    items = []

    def process_list(paths: List[str], kind: str, rel_dir: str):
        for raw in sorted(paths):
            src = Path(raw).expanduser().resolve()
            if not src.exists():
                items.append({
                    "type": kind,
                    "source": raw,
                    "status": "missing"
                })
                continue
            rel_path, digest, size = copy_item(src, output_dir, rel_dir)
            items.append({
                "type": kind,
                "source": raw,
                "path": rel_path,
                "sha256": digest,
                "size": size,
                "status": "ok",
            })

    process_list(images, "image", "images")
    process_list(charts, "chart", "charts")
    process_list(extras, "extra", "extras")

    manifest = {
        "name": name,
        "created": datetime.now(timezone.utc).isoformat(),
        "items": items,
    }

    # checksums file (only for ok items)
    checksum_lines = [f"{item['sha256']}  {item['path']}" for item in items if item.get("status") == "ok"]
    (output_dir / "checksums.sha256").write_text("\n".join(checksum_lines) + ("\n" if checksum_lines else ""), encoding="utf-8")
    (output_dir / "bootstrap-manifest.json").write_text(json.dumps(manifest, ensure_ascii=False, indent=2) + "\n", encoding="utf-8")
    return manifest


def parse_args(argv: List[str]) -> argparse.Namespace:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--config", type=Path, help="Path to bootstrap pack config JSON")
    parser.add_argument("--output", type=Path, help="Output directory for the pack")
    parser.add_argument("--self-test", action="store_true", help="Run internal self-test and exit")
    return parser.parse_args(argv)


def self_test() -> int:
    import tempfile

    with tempfile.TemporaryDirectory() as tmp:
        tmpdir = Path(tmp)
        files = []
        for name, content in [("img1.tar", b"image-one"), ("chart1.tgz", b"chart-one"), ("readme.txt", b"hello")]:
            p = tmpdir / name
            p.write_bytes(content)
            files.append(p)
        cfg = {
            "images": [str(files[0])],
            "charts": [str(files[1])],
            "extras": [str(files[2])],
        }
        cfg_path = tmpdir / "bootstrap.json"
        cfg_path.write_text(json.dumps(cfg), encoding="utf-8")
        outdir = tmpdir / "out"
        manifest = build_pack(cfg_path, outdir)
        assert all(item.get("status") == "ok" for item in manifest["items"]), manifest
        for rel in ["images/img1.tar", "charts/chart1.tgz", "extras/readme.txt", "checksums.sha256", "bootstrap-manifest.json"]:
            assert (outdir / rel).exists(), f"missing {rel}"
    print("self-test passed")
    return 0


def main(argv: List[str]) -> int:
    args = parse_args(argv)
    if args.self_test:
        return self_test()
    if not (args.config and args.output):
        print("--config and --output are required unless --self-test", file=sys.stderr)
        return 2
    manifest = build_pack(args.config, args.output)
    missing = [i for i in manifest["items"] if i.get("status") == "missing"]
    if missing:
        print("Pack built with missing items:")
        for item in missing:
            print(f" - {item['source']}")
        return 1
    print(f"Bootstrap pack written to {args.output}")
    return 0


if __name__ == "__main__":  # pragma: no cover
    sys.exit(main(sys.argv[1:]))