import enum
import uuid
from datetime import datetime

from sqlalchemy import DateTime, Enum, ForeignKey, Integer, String, Text
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.database import Base


def _uuid() -> str:
    return str(uuid.uuid4())


def _now() -> datetime:
    return datetime.utcnow()


class MessageRole(str, enum.Enum):
    system = "system"
    user = "user"
    assistant = "assistant"


class Conversation(Base):
    __tablename__ = "conversations"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=_uuid)
    tenant_id: Mapped[str] = mapped_column(
        String(36), ForeignKey("tenants.id"), nullable=False, index=True
    )
    employee_id: Mapped[str] = mapped_column(
        String(36), ForeignKey("digital_employees.id"), nullable=False, index=True
    )
    user_id: Mapped[str] = mapped_column(String(200), nullable=False)
    title: Mapped[str | None] = mapped_column(String(500), nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=_now)
    updated_at: Mapped[datetime] = mapped_column(DateTime, default=_now, onupdate=_now)

    messages: Mapped[list["Message"]] = relationship(
        back_populates="conversation", cascade="all, delete-orphan", lazy="selectin"
    )


class Message(Base):
    __tablename__ = "messages"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=_uuid)
    conversation_id: Mapped[str] = mapped_column(
        String(36), ForeignKey("conversations.id"), nullable=False, index=True
    )
    role: Mapped[MessageRole] = mapped_column(Enum(MessageRole), nullable=False)
    content: Mapped[str] = mapped_column(Text, nullable=False)
    token_count: Mapped[int | None] = mapped_column(Integer, nullable=True)
    sources: Mapped[str | None] = mapped_column(Text, nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=_now)

    conversation: Mapped["Conversation"] = relationship(back_populates="messages")