import uuid
from datetime import datetime

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

from database import Base


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


class SessionModel(Base):
    __tablename__ = "sessions"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=_uuid)
    title: Mapped[str] = mapped_column(String(200), default="新对话")
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
    updated_at: Mapped[datetime] = mapped_column(
        DateTime, default=datetime.utcnow, onupdate=datetime.utcnow
    )

    messages: Mapped[list["MessageModel"]] = relationship(
        back_populates="session", cascade="all, delete-orphan"
    )


class MessageModel(Base):
    __tablename__ = "messages"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=_uuid)
    session_id: Mapped[str] = mapped_column(
        String(36), ForeignKey("sessions.id", ondelete="CASCADE")
    )
    role: Mapped[str] = mapped_column(String(20))
    content: Mapped[str] = mapped_column(Text)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)

    session: Mapped["SessionModel"] = relationship(back_populates="messages")


class PresetModel(Base):
    __tablename__ = "presets"

    id: Mapped[str] = mapped_column(String(64), primary_key=True)
    title: Mapped[str] = mapped_column(String(200))
    prompt_template: Mapped[str] = mapped_column(Text)
    category: Mapped[str] = mapped_column(String(64), default="默认")
    model: Mapped[str | None] = mapped_column(String(64), nullable=True)
    sort_order: Mapped[int] = mapped_column(Integer, default=0)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)


class AppMetaModel(Base):
    __tablename__ = "app_meta"

    key: Mapped[str] = mapped_column(String(64), primary_key=True)
    value: Mapped[str] = mapped_column(String(256))