"""ORM model for the standalone 大屏绘制智能体 session (按 taskId 存取).

One row per external ``task_id`` — the standalone dashboard page persists its
chat transcript + the latest structured ``report_json`` so that returning to the
same task either shows the finished dashboard directly (valid report_json) or
restores the generation process.

**Global / shared by task** — like ``roundtable_drafts`` task-bound drafts, the
store keys on ``task_id`` and does **not** scope by ``user_id`` (open read +
shared writes). ``user_id`` is recorded for audit only.

``transcript`` / ``report_json`` are large JSON blobs (chat history + report
data) stored as serialized strings in ``PortableLongText`` (MySQL ``LONGTEXT``)
to dodge MySQL's 64 KB ``TEXT`` cap — same approach as ``roundtable_drafts``.
"""

from __future__ import annotations

from datetime import UTC, datetime

from sqlalchemy import String, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column

from deerflow.persistence.base import Base
from deerflow.persistence.types import BeijingDateTime, PortableLongText


class DashboardSessionRow(Base):
    __tablename__ = "dashboard_sessions"
    # One session per task — keep it unique so upsert-by-task is unambiguous.
    __table_args__ = (UniqueConstraint("task_id", name="uq_dashboard_sessions_task_id"),)

    id: Mapped[str] = mapped_column(String(64), primary_key=True)
    # External task id (deep-link). The session is shared by task, not by user.
    task_id: Mapped[str] = mapped_column(String(128), nullable=False, index=True)
    # Audit only — who last wrote. Never used for access control.
    user_id: Mapped[str | None] = mapped_column(String(64), nullable=True)
    # Chat transcript JSON (the dashboard agent's dialogue bubbles).
    transcript: Mapped[str | None] = mapped_column(PortableLongText, nullable=True)
    # Latest structured dashboard data (report-json string). Presence of a
    # parseable value = "有效结果" → the page shows the dashboard directly.
    report_json: Mapped[str | None] = mapped_column(PortableLongText, nullable=True)
    created_at: Mapped[datetime] = mapped_column(BeijingDateTime(), nullable=False, default=lambda: datetime.now(UTC))
    updated_at: Mapped[datetime] = mapped_column(
        BeijingDateTime(),
        nullable=False,
        default=lambda: datetime.now(UTC),
        onupdate=lambda: datetime.now(UTC),
    )