Add SQLite dashboard cache

app/actuators/cache_db.py

@@ -0,0 +1,98 @@
+from __future__ import annotations
+
+import json
+import sqlite3
+from datetime import datetime, timezone
+from pathlib import Path
+from threading import RLock
+
+from app.ha.models import HaEntitySummary
+
+
+class DashboardCache:
+    def __init__(self, path: str | Path) -> None:
+        self._path = Path(path).resolve()
+        self._path.parent.mkdir(parents=True, exist_ok=True)
+        self._lock = RLock()
+        self._init()
+
+    def load_entities_payload(self) -> dict[str, object]:
+        with self._lock, self._connect() as connection:
+            rows = connection.execute(
+                "select entity_id, payload from ha_entities order by entity_id"
+            ).fetchall()
+            updated_at = self._get_meta(connection, "ha_entities_updated_at")
+            groups_json = self._get_meta(connection, "discovery_groups") or "[]"
+        try:
+            groups = json.loads(groups_json)
+        except ValueError:
+            groups = []
+        return {
+            "updated_at": updated_at,
+            "discovery_groups": groups if isinstance(groups, list) else [],
+            "entities": [json.loads(row[1]) for row in rows],
+        }
+
+    def save_entities_payload(
+        self,
+        *,
+        entities: list[HaEntitySummary],
+        discovery_groups: list[dict[str, object]],
+    ) -> None:
+        now = datetime.now(timezone.utc).isoformat()
+        rows = [
+            (entity.entity_id, entity.model_dump_json())
+            for entity in entities
+        ]
+        with self._lock, self._connect() as connection:
+            connection.execute("delete from ha_entities")
+            connection.executemany(
+                "insert into ha_entities(entity_id, payload) values (?, ?)",
+                rows,
+            )
+            self._set_meta(connection, "ha_entities_updated_at", now)
+            self._set_meta(
+                connection,
+                "discovery_groups",
+                json.dumps(discovery_groups, ensure_ascii=True, sort_keys=True),
+            )
+
+    def _init(self) -> None:
+        with self._connect() as connection:
+            connection.execute(
+                """
+                create table if not exists ha_entities (
+                    entity_id text primary key,
+                    payload text not null
+                )
+                """
+            )
+            connection.execute(
+                """
+                create table if not exists cache_meta (
+                    key text primary key,
+                    value text
+                )
+                """
+            )
+
+    def _connect(self) -> sqlite3.Connection:
+        return sqlite3.connect(self._path, timeout=30)
+
+    @staticmethod
+    def _get_meta(connection: sqlite3.Connection, key: str) -> str | None:
+        row = connection.execute(
+            "select value from cache_meta where key = ?",
+            (key,),
+        ).fetchone()
+        return str(row[0]) if row is not None and row[0] is not None else None
+
+    @staticmethod
+    def _set_meta(connection: sqlite3.Connection, key: str, value: str) -> None:
+        connection.execute(
+            """
+            insert into cache_meta(key, value) values (?, ?)
+            on conflict(key) do update set value = excluded.value
+            """,
+            (key, value),
+        )