"""capture uptime

Revision ID: d8f4a1c6e2b7
Revises: d7a3c5e9f2b1
Create Date: 2026-10-19 03:00:00.000000

"""

from collections.abc import Sequence

from alembic import op

revision: str = "d8f4a1c6e2b7"
down_revision: str | None = "d7a3c5e9f2b1"
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None

_UPTIME = """
CREATE TABLE capture_uptime (
    account_id integer NOT NULL,
    started_at timestamptz NOT NULL,
    seen_at timestamptz NOT NULL,
    PRIMARY KEY (account_id, started_at)
)
"""

_BACKFILL = """
INSERT INTO capture_uptime (account_id, started_at, seen_at)
SELECT account_id, min(ts), max(ts)
FROM (
    SELECT account_id, ts,
           count(*) FILTER (WHERE gap > interval '30 minutes')
               OVER (PARTITION BY account_id ORDER BY ts) AS stretch
    FROM (
        SELECT account_id, ts,
               ts - lag(ts) OVER (PARTITION BY account_id ORDER BY ts) AS gap
        FROM presence
    ) gaps
) stretches
GROUP BY account_id, stretch
"""


def upgrade() -> None:
    op.execute(_UPTIME)
    op.execute(_BACKFILL)


def downgrade() -> None:
    op.execute("DROP TABLE IF EXISTS capture_uptime")