from sqlalchemy import BigInteger, Index, Text
from sqlalchemy.orm import Mapped, mapped_column

from scribe.models import Base
from scribe.models.base import CreatedAtMixin, iso

SURFACED = "surfaced"
PULLED = "pulled"


class SystemUsageEvent(Base, CreatedAtMixin):
    """One row per time a System's rulings were SHOWN to the agent because its
    files were touched, or the System was PULLED in full.

    The third of the usage tables, after `note_usage_events` and
    `rule_usage_events`, and separate from both for the reason the rule twin
    gives: identity at restore. A System id is its own namespace, mapped
    through the restore's system map; parked in either sibling's id column it
    would come back attached to whatever note or rule took that number.

    What it answers: whether an area's rulings, delivered by path rather than
    by a ranker, are then read (`get_system`) — and so whether delivery by
    path earns its line.

    FK-free on `system_id`, `user_id` and `project_id`, like its siblings:
    telemetry outlives the row it describes.
    """

    __tablename__ = "system_usage_events"

    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
    user_id: Mapped[int | None] = mapped_column(BigInteger, nullable=True)
    system_id: Mapped[int] = mapped_column(BigInteger, nullable=False)
    # 'surfaced' | 'pulled'. Plain Text, no CHECK, like the siblings.
    event: Mapped[str] = mapped_column(Text, nullable=False)
    # Which surface produced it — a convention, not a vocabulary (see the
    # note twin). `grep -rn record_system_ src/` is the authoritative list.
    source: Mapped[str] = mapped_column(Text, nullable=False)
    # The project the READER was in, not the System's own.
    project_id: Mapped[int | None] = mapped_column(BigInteger, nullable=True)

    __table_args__ = (
        Index("ix_system_usage_system_event", "system_id", "event"),
        Index("ix_system_usage_created_at", "created_at"),
    )

    def to_dict(self) -> dict:
        return {
            "id": self.id,
            "created_at": iso(self.created_at),
            "user_id": self.user_id,
            "system_id": self.system_id,
            "event": self.event,
            "source": self.source,
            "project_id": self.project_id,
        }