"""
Backup der „Verfassung" (Shared-Memory-SQLite) + aller Configs.
Snapshot in einen Zeitstempel-Ordner; die letzten N bleiben erhalten.
"""

import shutil
import time
from pathlib import Path

from config import CONFIG_PATH, MEMORY_DB, MODELS_DIR

BACKUP_DIR = Path(MODELS_DIR) / "mc2-backups"
RETAIN = 7


def _safe_copy(src: Path, dst_dir: Path) -> str | None:
    try:
        if src and src.exists():
            shutil.copy2(src, dst_dir / src.name)
            return src.name
    except Exception:
        pass
    return None


def backup_now() -> dict:
    """Erstellt einen Snapshot (Memory-DB inkl. WAL/SHM + Configs). Alte Snapshots
    über RETAIN hinaus werden entfernt."""
    ts = time.strftime("%Y%m%d-%H%M%S")
    dst = BACKUP_DIR / ts
    dst.mkdir(parents=True, exist_ok=True)
    saved = []
    for src in (MEMORY_DB, Path(str(MEMORY_DB) + "-wal"), Path(str(MEMORY_DB) + "-shm"),
                CONFIG_PATH):
        if (name := _safe_copy(src, dst)):
            saved.append(name)
    # Aufräumen: nur die letzten RETAIN Snapshots behalten.
    snaps = sorted([p for p in BACKUP_DIR.iterdir() if p.is_dir()], reverse=True)
    for old in snaps[RETAIN:]:
        shutil.rmtree(old, ignore_errors=True)
    return {"ok": bool(saved), "snapshot": ts, "files": saved, "dir": str(dst)}


def list_backups() -> list[dict]:
    if not BACKUP_DIR.exists():
        return []
    out = []
    for p in sorted([d for d in BACKUP_DIR.iterdir() if d.is_dir()], reverse=True):
        files = [f.name for f in p.iterdir() if f.is_file()]
        out.append({"snapshot": p.name, "files": files})
    return out