"""Namespaced key/value store handed to plugins (SPEC §11 ``plugin_kv``).

A :class:`PluginKv` is bound to one (plugin, user_id) slice of the core
``plugin_kv`` table; values are arbitrary JSON. This is the light-state store
every plugin gets — heavy plugins use their own ``plg_``-prefixed tables (§11.1).
"""

from __future__ import annotations

import uuid
from typing import Any

from sqlalchemy import delete, select
from sqlalchemy.dialects.postgresql import insert as pg_insert

from app.db import session_scope
from app.models import PluginKv


class PluginKvStore:
    """CRUD over one plugin's per-user KV slice. Instantiate via ``sdk.kv(user_id)``."""

    def __init__(self, plugin: str, user_id: uuid.UUID) -> None:
        self._plugin = plugin
        self._user_id = user_id

    async def get(self, key: str, default: Any = None) -> Any:
        async with session_scope() as session:
            row = await session.get(PluginKv, (self._plugin, self._user_id, key))
            return row.value if row is not None else default

    async def set(self, key: str, value: Any) -> None:
        """Upsert ``key`` -> ``value`` (JSON-serialisable)."""
        stmt = (
            pg_insert(PluginKv)
            .values(plugin=self._plugin, user_id=self._user_id, key=key, value=value)
            .on_conflict_do_update(
                index_elements=[PluginKv.plugin, PluginKv.user_id, PluginKv.key],
                set_={"value": value},
            )
        )
        async with session_scope() as session:
            await session.execute(stmt)

    async def delete(self, key: str) -> None:
        async with session_scope() as session:
            await session.execute(
                delete(PluginKv).where(
                    PluginKv.plugin == self._plugin,
                    PluginKv.user_id == self._user_id,
                    PluginKv.key == key,
                )
            )

    async def items(self) -> dict[str, Any]:
        """Return every key/value in this plugin+user slice."""
        async with session_scope() as session:
            rows = await session.execute(
                select(PluginKv.key, PluginKv.value).where(
                    PluginKv.plugin == self._plugin, PluginKv.user_id == self._user_id
                )
            )
            return dict(rows.all())  # type: ignore[arg-type]