"""How long each answer took.

Revision ID: e9f0a1b2c3d4
Revises: d8e9f0a1b2c3
"""
import sqlalchemy as sa
from alembic import op
from sqlalchemy import inspect

revision = "e9f0a1b2c3d4"
down_revision = "d8e9f0a1b2c3"
branch_labels = None
depends_on = None


def upgrade():
    # Nothing recorded this, so "time per question" could not be reported at all.
    # Null means an answer from before it was measured — distinct from zero,
    # which would claim it was instant.
    columns = {c["name"] for c in inspect(op.get_bind()).get_columns("attempt_answers")}
    if "seconds_spent" not in columns:
        op.add_column("attempt_answers", sa.Column("seconds_spent", sa.Integer, nullable=True))


def downgrade():
    op.drop_column("attempt_answers", "seconds_spent")