"""add task completed_at timestamp

Revision ID: 0018_task_completed_at
Revises: 0017_memos
"""

import sqlalchemy as sa
from alembic import op

revision = "0018_task_completed_at"
down_revision = "0017_memos"
branch_labels = None
depends_on = None


def upgrade() -> None:
    with op.batch_alter_table("tasks") as batch_op:
        batch_op.add_column(sa.Column("completed_at", sa.DateTime(timezone=True), nullable=True))
        batch_op.create_index("ix_tasks_completed_at", ["completed_at"])
    op.execute("UPDATE tasks SET completed_at = updated_at WHERE completed IS TRUE AND completed_at IS NULL")


def downgrade() -> None:
    with op.batch_alter_table("tasks") as batch_op:
        batch_op.drop_index("ix_tasks_completed_at")
        batch_op.drop_column("completed_at")