from datetime import datetime, timezone
from sqlalchemy import String, Text, DateTime, ForeignKey, Integer
from sqlalchemy.orm import Mapped, mapped_column, relationship
from app.db.database import Base


class Session(Base):
    __tablename__ = "sessions"

    id: Mapped[str] = mapped_column(String, primary_key=True)
    title: Mapped[str] = mapped_column(String, default="New Chat")
    model: Mapped[str] = mapped_column(String, default="")
    created_at: Mapped[datetime] = mapped_column(DateTime, default=lambda: datetime.now(timezone.utc))
    updated_at: Mapped[datetime] = mapped_column(DateTime, default=lambda: datetime.now(timezone.utc), onupdate=lambda: datetime.now(timezone.utc))

    messages: Mapped[list["Message"]] = relationship(back_populates="session", cascade="all, delete-orphan", order_by="Message.created_at")
    memories: Mapped[list["Memory"]] = relationship(back_populates="session", cascade="all, delete-orphan")


class Message(Base):
    __tablename__ = "messages"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    session_id: Mapped[str] = mapped_column(ForeignKey("sessions.id", ondelete="CASCADE"))
    role: Mapped[str] = mapped_column(String)  # "user" | "assistant" | "system"
    content: Mapped[str] = mapped_column(Text)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=lambda: datetime.now(timezone.utc))

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


class Memory(Base):
    __tablename__ = "memories"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    session_id: Mapped[str] = mapped_column(ForeignKey("sessions.id", ondelete="CASCADE"))
    summary: Mapped[str] = mapped_column(Text)
    embedding_json: Mapped[str | None] = mapped_column(Text, nullable=True)  # 将来のベクトル検索用
    created_at: Mapped[datetime] = mapped_column(DateTime, default=lambda: datetime.now(timezone.utc))

    session: Mapped["Session"] = relationship(back_populates="memories")