database.py

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
import os
from dotenv import load_dotenv

load_dotenv()

# Por defecto usa SQLite si no hay URL de Postgres configurada
# Vercel usa "POSTGRES_URL", "POSTGRES_PRISMA_URL", etc. Intentamos leer POSTGRES_URL si DATABASE_URL falla.
DATABASE_URL = os.getenv("DATABASE_URL")
if not DATABASE_URL:
    DATABASE_URL = os.getenv("POSTGRES_URL")

if not DATABASE_URL:
    # FALLBACK DIAGNOSTIC
    print("WARNING: No DATABASE_URL or POSTGRES_URL found. Falling back to SQLite.")
    # On Vercel, root is read-only. We must use /tmp if we really want to try SQLite (data will be lost)
    if os.environ.get("VERCEL") or os.getcwd().startswith("/var/task"):
        print("ERROR: Running on Vercel with SQLite (ReadOnly FS). This will likely crash.")
    DATABASE_URL = "sqlite:///./crm.db"
else:
    print(f"INFO: Database URL found (starts with {DATABASE_URL[:10]}...)")

# Fix para SQLAlchemy que removió soporte para 'postgres://' (Vercel lo usa por defecto)
if DATABASE_URL and DATABASE_URL.startswith("postgres://"):
    DATABASE_URL = DATABASE_URL.replace("postgres://", "postgresql://", 1)

engine = create_engine(
    DATABASE_URL, connect_args={"check_same_thread": False} if "sqlite" in DATABASE_URL else {}
)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()

def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()