from motor.motor_asyncio import AsyncIOMotorClient, AsyncIOMotorDatabase
import redis.asyncio as aioredis
from app.config import get_settings


class Database:
    client: AsyncIOMotorClient | None = None
    db: AsyncIOMotorDatabase | None = None
    redis: aioredis.Redis | None = None


db = Database()


def get_database() -> AsyncIOMotorDatabase:
    """MongoDB 데이터베이스 인스턴스를 반환한다.
    주의: `if not db.db:` 사용 금지 (pymongo 4.9.x NotImplementedError)
    """
    if db.db is None:
        raise RuntimeError("Database not initialized")
    return db.db


def get_redis() -> aioredis.Redis:
    """Redis 클라이언트 인스턴스를 반환한다."""
    if db.redis is None:
        raise RuntimeError("Redis not initialized")
    return db.redis


async def connect_db():
    """MongoDB + Redis 연결 초기화"""
    settings = get_settings()

    # MongoDB
    db.client = AsyncIOMotorClient(settings.mongodb_url)
    db.db = db.client[settings.mongodb_database]

    # 인덱스 생성
    await create_indexes(db.db)

    # Redis
    db.redis = aioredis.from_url(
        settings.redis_url,
        encoding="utf-8",
        decode_responses=True,
    )


async def disconnect_db():
    """연결 종료"""
    if db.client is not None:
        db.client.close()
    if db.redis is not None:
        await db.redis.close()


async def create_indexes(database: AsyncIOMotorDatabase):
    """컬렉션 인덱스 생성"""
    todos = database["todos"]
    categories = database["categories"]

    # todos 텍스트 검색 인덱스
    await todos.create_index(
        [("title", "text"), ("content", "text"), ("tags", "text")],
        name="text_search_index",
        weights={"title": 10, "content": 5, "tags": 3},
    )

    # todos 복합 인덱스
    await todos.create_index(
        [("category_id", 1), ("created_at", -1)],
        name="category_created",
    )
    await todos.create_index(
        [("completed", 1), ("created_at", -1)],
        name="completed_created",
    )
    await todos.create_index(
        [("priority", 1), ("created_at", -1)],
        name="priority_created",
    )
    await todos.create_index(
        [("tags", 1)],
        name="tags",
    )
    await todos.create_index(
        [("due_date", 1)],
        name="due_date",
    )
    await todos.create_index(
        [("completed", 1), ("due_date", 1)],
        name="completed_due_date",
    )

    # categories 인덱스
    await categories.create_index("name", unique=True, name="category_name_unique")
    await categories.create_index("order", name="category_order")