"""ORM models for 岗位 (positions) and their per-resource tag bindings.

A **position** (岗位) is an admin-managed aggregation layer that decides which
agents / skills / scheduled tasks / recommended questions a user is subscribed
to. Each user has at most one position (the link lives on
``users.position_id``, a 1:1 relation — see ``UserRow``).

Two tables here:

- ``positions`` — the position itself. ``is_default`` marks the fallback
  position inherited by users who have not been assigned one explicitly.
- ``position_tag_bindings`` — for each ``(position, resource_type)`` the set of
  tags whose resources are granted to the position's members. **No binding for
  a resource_type means "use the default set"** (see ``deerflow.services.
  position_sync`` for what "default" resolves to per type).
"""

from __future__ import annotations

from datetime import UTC, datetime

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

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

# Resource types a position can grant. The first three reuse the existing
# typed-tag namespace (``deerflow.persistence.tags``); ``recommended_question``
# was added alongside (see TAG_TYPES). The removed ``user_prompt`` type is no
# longer accepted — ``get_tag_bindings`` drops any stale rows of that type.
POSITION_RESOURCE_TYPES: tuple[str, ...] = (
    "agent",
    "skill",
    "scheduled_task",
    "recommended_question",
)


class PositionRow(Base):
    __tablename__ = "positions"
    __table_args__ = (UniqueConstraint("name", name="uq_positions_name"),)

    id: Mapped[str] = mapped_column(String(64), primary_key=True)
    name: Mapped[str] = mapped_column(String(191), nullable=False)
    description: Mapped[str] = mapped_column(String(1024), nullable=False, default="")
    # Exactly one position should carry ``is_default=True`` at a time (the
    # router enforces "only one default" by clearing the flag on others). Users
    # with no explicit ``users.position_id`` inherit this position's grants.
    is_default: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False, index=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))


class PositionTagBindingRow(Base):
    """One bound tag for a ``(position, resource_type)`` pair.

    The absence of *any* row for a ``(position, resource_type)`` means the
    position uses the **default set** for that resource type. One or more rows
    mean the position grants the *union* of the resources carrying those tags.
    """

    __tablename__ = "position_tag_bindings"
    __table_args__ = (
        UniqueConstraint("position_id", "resource_type", "tag_id", name="uq_position_tag_bindings"),
        Index("ix_position_tag_bindings_position_type", "position_id", "resource_type"),
    )

    id: Mapped[str] = mapped_column(String(64), primary_key=True)
    position_id: Mapped[str] = mapped_column(String(64), nullable=False, index=True)
    resource_type: Mapped[str] = mapped_column(String(32), nullable=False, index=True)
    tag_id: Mapped[str] = mapped_column(String(64), nullable=False, index=True)
    created_at: Mapped[datetime] = mapped_column(BeijingDateTime(), nullable=False, default=lambda: datetime.now(UTC))