Plan Django retention from snapshot records

src/pobsync_backend/retention.py

@@ -0,0 +1,182 @@
+from __future__ import annotations
+
+import shutil
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import Any
+
+from pobsync.errors import ConfigError
+from pobsync.lock import acquire_host_lock
+from pobsync.paths import PobsyncPaths
+from pobsync.retention import Snapshot, apply_base_protection, build_retention_plan
+from pobsync.util import sanitize_host
+
+from .models import HostConfig, SnapshotRecord
+
+
+def run_sql_retention_plan(*, host: str, kind: str, protect_bases: bool) -> dict[str, Any]:
+    host = sanitize_host(host)
+    if kind not in {"scheduled", "manual", "all"}:
+        raise ConfigError("kind must be scheduled, manual, or all")
+
+    host_config = _enabled_host_config(host)
+    retention = _retention_for_host(host_config)
+    snapshots = _snapshots_for_retention(host_config=host_config, kind=kind)
+
+    plan = build_retention_plan(
+        snapshots=snapshots,
+        retention=retention,
+        now=datetime.now(timezone.utc),
+    )
+
+    keep = set(plan.keep)
+    reasons = dict(plan.reasons)
+    if protect_bases:
+        keep, reasons = apply_base_protection(snapshots=snapshots, keep=keep, reasons=reasons)
+
+    delete = [snapshot for snapshot in snapshots if snapshot.dirname not in keep]
+
+    return {
+        "ok": True,
+        "host": host,
+        "kind": kind,
+        "protect_bases": bool(protect_bases),
+        "retention": retention,
+        "source": "sql",
+        "keep": sorted(keep),
+        "delete": [_snapshot_to_delete_item(snapshot) for snapshot in delete],
+        "reasons": reasons,
+    }
+
+
+def run_sql_retention_apply(
+    *,
+    prefix: Path,
+    host: str,
+    kind: str,
+    protect_bases: bool,
+    yes: bool,
+    max_delete: int,
+    acquire_lock: bool = True,
+) -> dict[str, Any]:
+    host = sanitize_host(host)
+    if not yes:
+        raise ConfigError("Refusing to delete snapshots without --yes")
+    if max_delete < 0:
+        raise ConfigError("--max-delete must be >= 0")
+
+    paths = PobsyncPaths(home=prefix)
+
+    def _do_apply() -> dict[str, Any]:
+        plan = run_sql_retention_plan(host=host, kind=kind, protect_bases=bool(protect_bases))
+        delete_list = plan.get("delete") or []
+        if not isinstance(delete_list, list):
+            raise ConfigError("Invalid retention plan output: delete is not a list")
+        if max_delete == 0 and len(delete_list) > 0:
+            raise ConfigError("Deletion blocked by --max-delete=0")
+        if len(delete_list) > max_delete:
+            raise ConfigError(f"Refusing to delete {len(delete_list)} snapshots (exceeds --max-delete={max_delete})")
+
+        actions: list[str] = []
+        deleted: list[dict[str, Any]] = []
+
+        for item in delete_list:
+            dirname = item.get("dirname") if isinstance(item, dict) else None
+            snap_kind = item.get("kind") if isinstance(item, dict) else None
+            snap_path = item.get("path") if isinstance(item, dict) else None
+            if not isinstance(dirname, str) or not isinstance(snap_kind, str) or not isinstance(snap_path, str):
+                continue
+            if snap_kind not in {"scheduled", "manual"}:
+                raise ConfigError(f"Refusing to delete unsupported snapshot kind: {snap_kind!r}")
+
+            path = Path(snap_path)
+            if not path.exists():
+                actions.append(f"skip missing {snap_kind}/{dirname}")
+                continue
+            if not path.is_dir():
+                raise ConfigError(f"Refusing to delete non-directory path: {snap_path}")
+
+            shutil.rmtree(path)
+            SnapshotRecord.objects.filter(host__host=host, kind=snap_kind, dirname=dirname).delete()
+            actions.append(f"deleted {snap_kind} {dirname}")
+            deleted.append({"dirname": dirname, "kind": snap_kind, "path": snap_path})
+
+        return {
+            "ok": True,
+            "host": host,
+            "kind": kind,
+            "protect_bases": bool(protect_bases),
+            "max_delete": max_delete,
+            "source": "sql",
+            "deleted": deleted,
+            "actions": actions,
+        }
+
+    if acquire_lock:
+        with acquire_host_lock(paths.locks_dir, host, command="retention-apply"):
+            return _do_apply()
+    return _do_apply()
+
+
+def _enabled_host_config(host: str) -> HostConfig:
+    try:
+        return HostConfig.objects.get(host=host, enabled=True)
+    except HostConfig.DoesNotExist as exc:
+        raise ConfigError(f"Missing enabled HostConfig {host!r}") from exc
+
+
+def _retention_for_host(host_config: HostConfig) -> dict[str, int]:
+    return {
+        "daily": host_config.retention_daily,
+        "weekly": host_config.retention_weekly,
+        "monthly": host_config.retention_monthly,
+        "yearly": host_config.retention_yearly,
+    }
+
+
+def _snapshots_for_retention(*, host_config: HostConfig, kind: str) -> list[Snapshot]:
+    kinds = ["scheduled", "manual"] if kind == "all" else [kind]
+    records = (
+        SnapshotRecord.objects.filter(host=host_config, kind__in=kinds)
+        .exclude(kind=SnapshotRecord.Kind.INCOMPLETE)
+        .select_related("base")
+        .order_by("-started_at", "dirname")
+    )
+    return [_snapshot_from_record(record) for record in records]
+
+
+def _snapshot_from_record(record: SnapshotRecord) -> Snapshot:
+    return Snapshot(
+        kind=record.kind,
+        dirname=record.dirname,
+        path=record.path,
+        dt=record.started_at or datetime.fromtimestamp(0, tz=timezone.utc),
+        status=record.status or None,
+        base=_base_meta_from_record(record),
+    )
+
+
+def _base_meta_from_record(record: SnapshotRecord) -> dict[str, str] | None:
+    if record.base is not None:
+        return {
+            "kind": record.base.kind,
+            "dirname": record.base.dirname,
+            "path": record.base.path,
+        }
+    if record.base_kind and record.base_dirname:
+        return {
+            "kind": record.base_kind,
+            "dirname": record.base_dirname,
+            "path": record.base_path,
+        }
+    return None
+
+
+def _snapshot_to_delete_item(snapshot: Snapshot) -> dict[str, Any]:
+    return {
+        "dirname": snapshot.dirname,
+        "kind": snapshot.kind,
+        "path": snapshot.path,
+        "dt": snapshot.dt.isoformat(),
+        "status": snapshot.status,
+    }