from sqlalchemy import create_engine, event
from sqlalchemy.orm import declarative_base, sessionmaker
from app.core.config import settings

# SQLite database initialize kar rahe hain
# 'check_same_thread=False' SQLite ke liye zaroori hai taake FastAPI async requests par crash na ho
# ── CONNECTION POOL FIX — pehle sirf 5+10=15 connections allow hote the,
# jo zyada users/background loops ke sath "QueuePool limit reached" error deta tha.
# Ab pool bada kar diya taake zyada users ek sath handle ho sakein. ──
is_sqlite = settings.DATABASE_URL.startswith("sqlite")

engine = create_engine(
    settings.DATABASE_URL,
    connect_args={"check_same_thread": False, "timeout": 30} if is_sqlite else {},
    pool_size=50,
    max_overflow=100,
    pool_timeout=60,
    pool_recycle=1800,
)

# ── SQLITE CONCURRENCY FIX — WAL mode (sirf SQLite use karne par chalega) ──
if is_sqlite:
    @event.listens_for(engine, "connect")
    def set_sqlite_pragma(dbapi_connection, connection_record):
        cursor = dbapi_connection.cursor()
        cursor.execute("PRAGMA journal_mode=WAL")
        cursor.execute("PRAGMA busy_timeout=30000")
        cursor.execute("PRAGMA synchronous=NORMAL")
        cursor.close()

# Har request ke liye database se raabta banaye rakhne ka session manager
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

# Is Base class ko extend kar ke hamare saare models (tables) banenge
Base = declarative_base()