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),
        )