"""Add tickets.sla_breach_notified column; retire sla_notified_tickets setting

Revision ID: 006_add_sla_breach_notified
Revises: 005_add_watchers_and_time_entries
Create Date: 2026-07-02

Rationale
---------
SLA breach-notification suppression was previously tracked as a
comma-separated list of ticket IDs in a single SystemSetting row
(sla_notified_tickets). That works but doesn't scale cleanly and requires
parsing a string on every 30-minute scheduler run. This migration replaces
it with a plain boolean column on the ticket itself — the natural place for
a per-ticket flag — and backfills it from the existing SystemSetting value
so already-notified tickets don't get re-notified after the upgrade.

Apply
-----
    flask db upgrade

Rollback
--------
    flask db downgrade
    (Note: the backfilled sla_breach_notified flags are not restored back
    into a SystemSetting row on downgrade — if you roll back and then
    upgrade again, already-breached tickets will re-notify once.)
"""

from alembic import op
import sqlalchemy as sa

revision      = '006_add_sla_breach_notified'
down_revision = '005_add_watchers_and_time_entries'
branch_labels = None
depends_on    = None


def upgrade():
    op.add_column(
        'tickets',
        sa.Column('sla_breach_notified', sa.Boolean, nullable=False, server_default='0'),
    )

    # Backfill from the old comma-separated SystemSetting, if present.
    conn = op.get_bind()
    row = conn.execute(
        sa.text("SELECT value FROM system_settings WHERE `key` = 'sla_notified_tickets'")
    ).fetchone()
    if row and row[0]:
        ticket_ids = [int(x) for x in row[0].split(',') if x.strip().isdigit()]
        if ticket_ids:
            conn.execute(
                sa.text(
                    "UPDATE tickets SET sla_breach_notified = 1 WHERE id IN :ids"
                ).bindparams(sa.bindparam('ids', expanding=True)),
                {'ids': ticket_ids},
            )
    conn.execute(sa.text("DELETE FROM system_settings WHERE `key` = 'sla_notified_tickets'"))


def downgrade():
    op.drop_column('tickets', 'sla_breach_notified')