"""
Database connection manager with connection pooling
"""
import os
from sqlalchemy import create_engine, event
from sqlalchemy.orm import sessionmaker, Session
from sqlalchemy.pool import QueuePool
from contextlib import contextmanager
from typing import Generator
from dotenv import load_dotenv
from src.utils.logger import get_logger

load_dotenv()

logger = get_logger(__name__)

DB_USER = os.getenv("DB_USER", "root")
DB_PASSWORD = os.getenv("DB_PASSWORD", "root")
DB_HOST = os.getenv("DB_HOST", "127.0.0.1")
DB_PORT = os.getenv("DB_PORT", "3306")
DB_NAME = os.getenv("DB_NAME", "medicine_service")

DATABASE_URL = f"mysql+pymysql://{DB_USER}:{DB_PASSWORD}@{DB_HOST}:{DB_PORT}/{DB_NAME}?charset=utf8mb4"

logger.info(f"Connecting to database: {DB_HOST}:{DB_PORT}/{DB_NAME}")

# Create engine
engine = create_engine(
    DATABASE_URL,
    poolclass=QueuePool,
    pool_size=20,
    max_overflow=40,
    pool_timeout=30,
    pool_recycle=1800,
    pool_pre_ping=True,
    echo=False,
    future=True
)

# Session factory
SessionLocal = sessionmaker(
    bind=engine,
    autocommit=False,
    autoflush=False,
    expire_on_commit=False
)

@contextmanager
def get_db() -> Generator[Session, None, None]:
    """Context manager for database sessions"""
    db = SessionLocal()
    try:
        yield db
        db.commit()
    except Exception as e:
        db.rollback()
        raise e
    finally:
        db.close()

def get_db_dependency():
    """FastAPI dependency"""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()