backend/app/models.py

"""
SQLAlchemy ORM models for users, documents, and chat messages.
"""
import uuid
from datetime import datetime, timezone
from sqlalchemy import Column, String, Integer, DateTime, ForeignKey, Text, Boolean
from sqlalchemy.orm import relationship
from app.database import Base


def generate_uuid():
    return str(uuid.uuid4())


class User(Base):
    __tablename__ = "users"

    id = Column(String, primary_key=True, default=generate_uuid)
    username = Column(String(80), unique=True, nullable=False, index=True)
    email = Column(String(120), unique=True, nullable=False, index=True)
    hashed_password = Column(String(255), nullable=False)
    is_admin = Column(Boolean, default=False)
    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))

    # Relationships
    documents = relationship("Document", back_populates="owner", cascade="all, delete-orphan")
    messages = relationship("ChatMessage", back_populates="user", cascade="all, delete-orphan")


class Document(Base):
    __tablename__ = "documents"

    id = Column(String, primary_key=True, default=generate_uuid)
    user_id = Column(String, ForeignKey("users.id"), nullable=False, index=True)
    filename = Column(String(255), nullable=False)        # Stored filename (UUID-based)
    original_name = Column(String(255), nullable=False)    # User's original filename
    file_size = Column(Integer, default=0)                 # Size in bytes
    page_count = Column(Integer, default=0)
    chunk_count = Column(Integer, default=0)
    status = Column(String(20), default="pending")         # pending | processing | ready | failed
    error_message = Column(Text, nullable=True)
    uploaded_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))

    # Relationships
    owner = relationship("User", back_populates="documents")
    messages = relationship("ChatMessage", back_populates="document", cascade="all, delete-orphan")


class ChatMessage(Base):
    __tablename__ = "chat_messages"

    id = Column(String, primary_key=True, default=generate_uuid)
    user_id = Column(String, ForeignKey("users.id"), nullable=False, index=True)
    document_id = Column(String, ForeignKey("documents.id"), nullable=True, index=True)
    role = Column(String(20), nullable=False)  # "user" | "assistant"
    content = Column(Text, nullable=False)
    sources_json = Column(Text, nullable=True)  # JSON string of source citations
    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))

    # Relationships
    user = relationship("User", back_populates="messages")
    document = relationship("Document", back_populates="messages")