"""tickets.reported_at column — original reported date for backdated tickets

Revision ID: d5e0f2a1c3b4
Revises: c4e8f1a2d3b4
Create Date: 2026-08-03 00:00:00.000000

Backdated-ticket support (Wahab demo): one schema change.

* Add ``tickets.reported_at`` (nullable DateTime) so historical/backfilled
  tickets keep their true report date instead of inheriting today's
  ``created_at``.
* Backfill existing rows with their ``created_at`` value so no ticket shows
  an empty reported date after the upgrade. The service layer also defaults
  new tickets without a ``reported_at`` to now, so the column is effectively
  always populated from here on.
"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa


# revision identifiers, used by Alembic.
revision: str = 'd5e0f2a1c3b4'
down_revision: Union[str, Sequence[str], None] = 'c4e8f1a2d3b4'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    """Add tickets.reported_at (nullable) and backfill from created_at."""
    op.add_column(
        'tickets',
        sa.Column(
            'reported_at',
            sa.DateTime(),
            nullable=True,
            comment='Original reported date; backdated/backfilled tickets keep their true report date',
        ),
    )
    # Backfill: every existing ticket was reported when it was created.
    op.execute('UPDATE tickets SET reported_at = created_at WHERE reported_at IS NULL')


def downgrade() -> None:
    """Drop tickets.reported_at."""
    op.drop_column('tickets', 'reported_at')