from sqlalchemy import create_engine, Column, String, Text, ForeignKey, DateTime
from sqlalchemy.orm import sessionmaker, declarative_base, relationship
from datetime import datetime

# Database Configuration
DATABASE_URL = "sqlite:///./chats.db"
engine = create_engine(DATABASE_URL, connect_args={"check_same_thread": False})
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()

class User(Base):
    __tablename__ = "users"
    id = Column(String, primary_key=True, unique=True, nullable=False)
    email = Column(String, unique=True, nullable=False)
    name = Column(String, nullable=False)
    chats = relationship("Chat", back_populates="user", cascade="all, delete-orphan")

class Chat(Base):
    __tablename__ = "chats"
    chat_id = Column(String, primary_key=True, unique=True, nullable=False)
    user_id = Column(String, ForeignKey("users.id", ondelete="CASCADE"), nullable=False)
    title = Column(String, nullable=False)
    timestamp = Column(DateTime, default=datetime.utcnow, nullable=False)
    messages = relationship("ChatMessage", back_populates="chat", cascade="all, delete-orphan")
    documents = relationship("Document", back_populates="chat", cascade="all, delete-orphan")
    user = relationship("User", back_populates="chats")

class ChatMessage(Base):
    __tablename__ = "chat_messages"
    id = Column(String, primary_key=True, unique=True, nullable=False)
    chat_id = Column(String, ForeignKey("chats.chat_id", ondelete="CASCADE"), nullable=False)
    type = Column(String, nullable=False)  # 'user' or 'assistant'
    content = Column(Text, nullable=False)
    timestamp = Column(DateTime, default=datetime.utcnow, nullable=False)
    referenced_docs = Column(Text, nullable=True)  # JSON string of referenced documents
    chat = relationship("Chat", back_populates="messages")

class Document(Base):
    __tablename__ = "documents"
    id = Column(String, primary_key=True, unique=True, nullable=False)
    chat_id = Column(String, ForeignKey("chats.chat_id", ondelete="CASCADE"), nullable=False)
    name = Column(String, nullable=False)
    content = Column(Text, nullable=False)
    timestamp = Column(DateTime, default=datetime.utcnow, nullable=False)
    chat = relationship("Chat", back_populates="documents")

Base.metadata.create_all(bind=engine)

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