#!/usr/bin/env python3
"""Archive legacy HERDR metadata before the direct CLI lane takes over."""

from __future__ import annotations

import json
import os
import shutil
from datetime import datetime, timezone
from pathlib import Path
from typing import Any


DATA_ROOT = Path("/opt/data")


def _load_json(path: Path) -> dict[str, Any]:
    try:
        value = json.loads(path.read_text(encoding="utf-8"))
    except (OSError, json.JSONDecodeError):
        return {}
    return value if isinstance(value, dict) else {}


def archive_legacy_state(data_root: Path = DATA_ROOT) -> Path:
    """Persist non-secret worker references and retire the exact HERDR binary."""
    source = data_root / "home/.config/herdr/session.json"
    archive = data_root / "cli-lanes/migration/herdr-retirement.json"
    archive.parent.mkdir(parents=True, exist_ok=True)
    previous = _load_json(archive)
    legacy = _load_json(source)
    value = {
        "schema_version": 1,
        "migrated_at": previous.get("migrated_at")
        or datetime.now(timezone.utc).isoformat(),
        "source": str(source),
        "legacy_session": legacy,
        "provider_state_preserved": [
            str(data_root / "home/.claude"),
            str(data_root / "home/.codex"),
        ],
    }
    temporary = archive.with_name(f".{archive.name}.{os.getpid()}.tmp")
    temporary.write_text(json.dumps(value, indent=2, sort_keys=True) + "\n", encoding="utf-8")
    temporary.chmod(0o600)
    os.replace(temporary, archive)

    # Provider transcripts remain in .claude and .codex. HERDR itself is
    # reproducibly reinstallable from Git history, so only its pinned binary is
    # retired after the migration record is durable.
    binary = data_root / "tools/bin/herdr"
    if binary.is_file():
        binary.unlink()
    for legacy_dir in (data_root / "home/.config/herdr", data_root / "herdr"):
        if legacy_dir.is_dir():
            shutil.rmtree(legacy_dir)
    return archive


if __name__ == "__main__":
    print(archive_legacy_state())