from __future__ import annotations
from datetime import datetime
from sqlalchemy import JSON, DateTime, Index, String, Text, text
from sqlalchemy.dialects.postgresql import ARRAY
from sqlalchemy.orm import Mapped, mapped_column
from .base import Base
from steward.core.ids import time_ordered_id


class TimelineEntry(Base):
    """One thing that happened to the infrastructure: an alert firing, a
    playbook run, a change to Steward's settings. Each row stands on its own,
    so it outlives the record it points to (`ref_type` / `ref_id`) once that
    record's retention removes it.

    `type` is a key of steward.timeline.catalog. Whether a type is shown, and
    which area it sorts under, are settings applied when the timeline is read;
    `area` is the area the event itself named when it was written, used unless
    Settings → Timeline gives its type one."""
    __tablename__ = "timeline_entries"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=time_ordered_id)
    at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
    # When something that lasted (a run) ended.
    until: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    type: Mapped[str] = mapped_column(String(64), nullable=False)
    area: Mapped[str] = mapped_column(String(32), nullable=False)
    # The hosts it happened on, by name, as every other record keyed by host.
    hosts: Mapped[list[str]] = mapped_column(ARRAY(String(128)), nullable=False, default=list)
    # What it happened to, when that is not a host: a container, a rule's resource.
    subject: Mapped[str | None] = mapped_column(String(255), nullable=True)
    summary: Mapped[str] = mapped_column(Text, nullable=False)
    detail: Mapped[dict | None] = mapped_column(JSON, nullable=True)
    # A username, "<user> via MCP", or "system".
    actor: Mapped[str] = mapped_column(String(64), nullable=False, default="system")
    ref_type: Mapped[str | None] = mapped_column(String(32), nullable=True)
    ref_id: Mapped[str | None] = mapped_column(String(64), nullable=True)

    __table_args__ = (
        Index("ix_timeline_entries_at", "at", "id"),
        Index("ix_timeline_entries_hosts", "hosts", postgresql_using="gin"),
        Index("ix_timeline_entries_type", "type"),
        # One entry per source record, so a backfill can run over rows the
        # live writers already covered.
        Index("uq_timeline_entries_ref", "ref_type", "ref_id", unique=True,
              postgresql_where=text("ref_id IS NOT NULL")),
    )