"""SeriesSuggestion — a confirm-only "this post may continue this series" hint.

The matcher (FC-6.3) scores a (post, candidate series) pair from several weighted
signals and, above the configured threshold, records a pending suggestion. The
operator confirms (→ the post is added as a chapter) or dismisses it; FC never
files a post into a series on its own. status is a plain string (no Postgres
ENUM — see the check-existing-enums lesson): pending | added | dismissed.
"""

from datetime import datetime

from sqlalchemy import (
    JSON,
    DateTime,
    Float,
    ForeignKey,
    Integer,
    String,
    UniqueConstraint,
    func,
)
from sqlalchemy.orm import Mapped, mapped_column

from .base import Base


class SeriesSuggestion(Base):
    __tablename__ = "series_suggestion"
    __table_args__ = (
        UniqueConstraint(
            "post_id", "series_tag_id", name="uq_series_suggestion_post_series"
        ),
    )

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    post_id: Mapped[int] = mapped_column(
        ForeignKey("post.id", ondelete="CASCADE"), nullable=False, index=True
    )
    series_tag_id: Mapped[int] = mapped_column(
        ForeignKey("tag.id", ondelete="CASCADE"), nullable=False, index=True
    )
    score: Mapped[float] = mapped_column(Float, nullable=False)
    signals: Mapped[dict | None] = mapped_column(JSON, nullable=True)
    status: Mapped[str] = mapped_column(
        String(16), nullable=False, server_default="pending", index=True
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now()
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        nullable=False,
        server_default=func.now(),
        onupdate=func.now(),
    )