"""segments：Phase1/Phase2 标志（叙事延迟管线）

Revision ID: 0006_segment_memoir_phases
Revises: 0005_cleanup_story_links
"""

from typing import Sequence, Union

import sqlalchemy as sa

from alembic import op

revision: str = "0006_segment_memoir_phases"
down_revision: Union[str, None] = "0005_cleanup_story_links"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def _column_names(table_name: str) -> set[str]:
    bind = op.get_bind()
    inspector = sa.inspect(bind)
    return {column["name"] for column in inspector.get_columns(table_name)}


def upgrade() -> None:
    columns = _column_names("segments")
    if "narrated" not in columns:
        op.add_column(
            "segments",
            sa.Column(
                "narrated",
                sa.Boolean(),
                nullable=False,
                server_default=sa.text("false"),
            ),
        )
    if "skip_narrative" not in columns:
        op.add_column(
            "segments",
            sa.Column(
                "skip_narrative",
                sa.Boolean(),
                nullable=False,
                server_default=sa.text("false"),
            ),
        )


def downgrade() -> None:
    columns = _column_names("segments")
    if "skip_narrative" in columns:
        op.drop_column("segments", "skip_narrative")
    if "narrated" in columns:
        op.drop_column("segments", "narrated")