from sqlalchemy import Column, Integer, String, Boolean, DateTime, Text
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from datetime import datetime

from exceptions import ServiceNotConfiguredError
from services.config_service import ConfigService

Base = declarative_base()


class ApiKey(Base):
    __tablename__ = "api_keys"

    id = Column(Integer, primary_key=True, index=True)
    provider = Column(String(50), unique=True, index=True, nullable=False)
    api_key_encrypted = Column(Text, nullable=False)  # Encrypted API key
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow)


class ModelConfig(Base):
    __tablename__ = "model_configs"

    id = Column(Integer, primary_key=True, index=True)
    provider = Column(String(50), nullable=False)
    model_name = Column(String(100), nullable=False)
    display_name = Column(String(100))  # Optional display name
    is_active = Column(Boolean, default=True)
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow)

    __table_args__ = {'mysql_charset': 'utf8mb4'}


# ---------------------------------------------------------------------------
# Lazy engine / session factory — only created when first requested
# ---------------------------------------------------------------------------
_engine = None
_SessionLocal = None


def _get_engine():
    from sqlalchemy import create_engine
    global _engine
    if _engine is None:
        db_url = ConfigService.get_database_url()
        if not db_url:
            raise ServiceNotConfiguredError("数据库未配置")
        _engine = create_engine(db_url)
    return _engine


def _get_session_factory():
    global _SessionLocal
    if _SessionLocal is None:
        _SessionLocal = sessionmaker(
            autocommit=False, autoflush=False, bind=_get_engine()
        )
    return _SessionLocal


def reload_db_connection():
    """Dispose current engine and reset so next call rebuilds from config."""
    global _engine, _SessionLocal
    if _engine is not None:
        _engine.dispose()
    _engine = None
    _SessionLocal = None


def get_db():
    """FastAPI dependency that yields a DB session."""
    session_factory = _get_session_factory()
    db = session_factory()
    try:
        yield db
    finally:
        db.close()