"""迁移打包：把 vps-manager 的唯一状态打成单一可校验迁移包

在源机器（如 cc1）运行：
  .venv/bin/python scripts/make_migration_bundle.py [输出tar.gz路径]

打包内容（唯一状态；代码/venv/systemd units/tailscale serve 均可由
setup.sh 与一条 serve 命令重建，故不在包内）：
  - data/assets.db、data/metrics.db：sqlite backup API 在线一致性快照（无需停服）
  - data/master_key.escrow：MASTER_KEY 托管档（若已建立）
  - data/backups/：历史备份（含 escrow 副本）
  - .env：MASTER_KEY / API_KEY / AGENT_KEY / 通知渠道 / S3 配置
  - manifest.json + manifest.sha256：版本、commit、主机、逐文件校验和

安全说明：包内含 MASTER_KEY 与全部密文，等同最高机密。传输仅用 scp 或加密
介质，恢复完成并验证后即刻删除；切勿上传公开对象存储或聊天工具。
恢复步骤见 scripts/restore_migration_bundle.py 与 docs/migration-runbook.md。
"""

import hashlib
import json
import shutil
import socket
import sqlite3
import subprocess
import sys
import tarfile
import tempfile
from datetime import datetime, timezone
from pathlib import Path

BASE = Path(__file__).resolve().parent.parent


def sha256_file(path: Path) -> str:
    h = hashlib.sha256()
    with path.open("rb") as f:
        for chunk in iter(lambda: f.read(1 << 20), b""):
            h.update(chunk)
    return h.hexdigest()


def snap_db(src: Path, dst: Path) -> None:
    """sqlite 在线一致性快照：backup API 保证事务边界完整，源库无需停服"""
    con = sqlite3.connect(str(src))
    bkp = sqlite3.connect(str(dst))
    with bkp:
        con.backup(bkp)
    bkp.close()
    con.close()


def read_git_commit() -> str:
    try:
        out = subprocess.run(
            ["git", "rev-parse", "--short", "HEAD"], cwd=BASE,
            capture_output=True, text=True, timeout=5,
        )
        return out.stdout.strip() or "unknown"
    except Exception:
        return "unknown"


def main() -> int:
    out = Path(sys.argv[1]) if len(sys.argv) > 1 else Path(
        f"/tmp/vps-manager-bundle-{datetime.now():%Y%m%d_%H%M%S}.tar.gz"
    )
    env_src = BASE / ".env"
    if not env_src.exists():
        print("[abort] 缺少 .env（MASTER_KEY 不在包内则迁移无意义）", file=sys.stderr)
        return 2

    work = Path(tempfile.mkdtemp(prefix="vps-bundle-"))
    root = work / "bundle"
    data_dst = root / "data"
    data_dst.mkdir(parents=True)
    data_src = BASE / "data"

    copied: list[str] = []
    for db in ("assets.db", "metrics.db"):
        src = data_src / db
        if src.exists():
            snap_db(src, data_dst / db)
            copied.append(f"data/{db}")
        else:
            print(f"[skip] {db} 不存在")
    escrow = data_src / "master_key.escrow"
    if escrow.exists():
        shutil.copy2(escrow, data_dst / "master_key.escrow")
        (data_dst / "master_key.escrow").chmod(0o600)
        copied.append("data/master_key.escrow")
    else:
        print("[warn] 未建立 MASTER_KEY 托管（master_key.escrow 不存在），恢复链不完整")
    backups_src = data_src / "backups"
    if backups_src.is_dir():
        shutil.copytree(backups_src, data_dst / "backups")
        for p in sorted((data_dst / "backups").rglob("*")):
            if p.is_file():
                copied.append(str(p.relative_to(root)))
    shutil.copy2(env_src, root / ".env")
    (root / ".env").chmod(0o600)
    copied.append(".env")

    manifest = {
        "app": "vps-manager",
        "version": (BASE / "VERSION").read_text(encoding="utf-8").strip()
        if (BASE / "VERSION").exists() else "dev",
        "commit": read_git_commit(),
        "source_host": socket.gethostname(),
        "created_at": datetime.now(timezone.utc).isoformat(),
        "files": {name: {"sha256": sha256_file(root / name), "size": (root / name).stat().st_size}
                  for name in copied},
    }
    (root / "manifest.json").write_text(
        json.dumps(manifest, ensure_ascii=False, indent=2), encoding="utf-8"
    )
    (root / "manifest.sha256").write_text(
        "".join(f"{v['sha256']}  {name}\n" for name, v in manifest["files"].items()),
        encoding="utf-8",
    )

    out.parent.mkdir(parents=True, exist_ok=True)
    with tarfile.open(out, "w:gz") as tar:
        tar.add(root, arcname="bundle")
    shutil.rmtree(work, ignore_errors=True)

    print(f"[ok] 迁移包：{out}")
    print(f"     大小：{out.stat().st_size / 1024:.1f} KB")
    print(f"     包校验和：{sha256_file(out)}")
    print(f"     源主机：{manifest['source_host']} · 版本 {manifest['version']} ({manifest['commit']})")
    print(f"     内含 {len(copied)} 个状态文件（两库快照 + escrow + backups + .env）")
    print("     恢复：新机器跑 setup.sh 后停服，执行")
    print(f"       .venv/bin/python scripts/restore_migration_bundle.py {out}")
    print("     ⚠ 包等同最高机密：仅 scp/加密介质传输，验证后删除")
    return 0


if __name__ == "__main__":
    sys.exit(main())