"""聊天会话与消息模型。"""

from datetime import datetime

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

from app.core.ids import new_message_id, new_session_id
from app.core.time import utc_now
from app.db.base import Base


class ChatSession(Base):
    __tablename__ = "chat_sessions"

    id: Mapped[str] = mapped_column(String(80), primary_key=True, default=new_session_id)
    character_id: Mapped[str] = mapped_column(String(80), ForeignKey("characters.id"), index=True)
    title: Mapped[str | None] = mapped_column(String(200))
    status: Mapped[str] = mapped_column(String(40), nullable=False, default="active", index=True)
    owner_scope: Mapped[str] = mapped_column(String(80), nullable=False, default="", index=True)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utc_now)
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), default=utc_now, onupdate=utc_now
    )


class ChatMessage(Base):
    __tablename__ = "chat_messages"

    id: Mapped[str] = mapped_column(String(80), primary_key=True, default=new_message_id)
    character_id: Mapped[str] = mapped_column(String(80), ForeignKey("characters.id"), index=True)
    session_id: Mapped[str] = mapped_column(String(80), ForeignKey("chat_sessions.id"), index=True)
    role: Mapped[str] = mapped_column(String(40), nullable=False)
    content: Mapped[str] = mapped_column(Text, nullable=False)
    modality: Mapped[str] = mapped_column(String(40), nullable=False, default="text")
    run_id: Mapped[str | None] = mapped_column(String(80), ForeignKey("runs.id"), index=True)
    metadata_json: Mapped[str] = mapped_column(Text, nullable=False, default="{}")
    sensitivity: Mapped[str] = mapped_column(String(40), nullable=False, default="low")
    versions_json: Mapped[str] = mapped_column(
        Text,
        nullable=False,
        default="[]",
        comment="版本历史 JSON 数组：[{content, created_at}]，按生成顺序排列，末尾最新",
    )
    active_version_idx: Mapped[int] = mapped_column(
        Integer,
        nullable=False,
        default=0,
        comment="当前活跃版本在 versions_json 中的索引（0-based）",
    )
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utc_now)
    deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))