"""Database connection management using asyncpg."""

from collections.abc import AsyncGenerator
from contextlib import asynccontextmanager
from contextvars import ContextVar

import asyncpg
from asyncpg.pool import PoolConnectionProxy
import redis.asyncio as redis


class Database:
    """Manages asyncpg connection pool."""

    pool: asyncpg.Pool | None = None

    async def connect(self, dsn: str) -> None:
        """Create connection pool."""
        self.pool = await asyncpg.create_pool(
            dsn,
            min_size=5,
            max_size=20,
            command_timeout=60,
        )

    async def disconnect(self) -> None:
        """Close connection pool."""
        if self.pool:
            await self.pool.close()

    @asynccontextmanager
    async def connection(self) -> AsyncGenerator[asyncpg.Connection | PoolConnectionProxy, None]:
        """Acquire a connection from the pool."""
        if not self.pool:
            raise RuntimeError("Database not connected")
        async with self.pool.acquire() as conn:
            yield conn

    @asynccontextmanager
    async def transaction(self) -> AsyncGenerator[asyncpg.Connection | PoolConnectionProxy, None]:
        """Acquire a connection with an active transaction."""
        if not self.pool:
            raise RuntimeError("Database not connected")
        async with self.pool.acquire() as conn:
            async with conn.transaction():
                yield conn


class RedisClient:
    """Manages Redis connection."""

    client: redis.Redis | None = None

    async def connect(self, url: str) -> None:
        """Create Redis connection."""
        self.client = redis.from_url(url, decode_responses=True)

    async def disconnect(self) -> None:
        """Close Redis connection."""
        if self.client:
            await self.client.aclose()

    async def ping(self) -> bool:
        """Check if Redis is reachable."""
        if not self.client:
            return False
        try:
            await self.client.ping()
            return True
        except redis.RedisError:
            return False


# Global instances
db = Database()
redis_client = RedisClient()


_connection_ctx: ContextVar[asyncpg.Connection | PoolConnectionProxy | None] = ContextVar(
    "db_connection",
    default=None,
)


async def get_conn() -> AsyncGenerator[asyncpg.Connection | PoolConnectionProxy, None]:
    """Dependency that reuses the same DB connection within a request context."""

    existing_conn = _connection_ctx.get()
    if existing_conn is not None:
        yield existing_conn
        return

    if not db.pool:
        raise RuntimeError("Database not connected")

    async with db.pool.acquire() as conn:
        token = _connection_ctx.set(conn)
        try:
            yield conn
        finally:
            _connection_ctx.reset(token)