"""Extend musehub_pack_index to cover commits and snapshots.

Renames:
  object_id → entity_id
  pack_id   → mpack_id

Adds:
  entity_type VARCHAR(16) NOT NULL  — "object", "commit", or "snapshot"
  Backfills existing rows with entity_type = 'object'.

Renames index ix_musehub_pack_index_object_id → ix_musehub_pack_index_entity_id.
"""

from __future__ import annotations

import sqlalchemy as sa
from alembic import op

revision = "0063"
down_revision = "0062"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.drop_index("ix_musehub_pack_index_object_id", table_name="musehub_pack_index")

    with op.batch_alter_table("musehub_pack_index") as batch_op:
        batch_op.alter_column("object_id", new_column_name="entity_id")
        batch_op.alter_column("pack_id", new_column_name="mpack_id")
        batch_op.add_column(
            sa.Column(
                "entity_type",
                sa.String(16),
                nullable=False,
                server_default="object",
            )
        )

    op.execute("UPDATE musehub_pack_index SET entity_type = 'object'")

    op.create_index(
        "ix_musehub_pack_index_entity_id",
        "musehub_pack_index",
        ["entity_id"],
    )


def downgrade() -> None:
    op.drop_index("ix_musehub_pack_index_entity_id", table_name="musehub_pack_index")

    with op.batch_alter_table("musehub_pack_index") as batch_op:
        batch_op.drop_column("entity_type")
        batch_op.alter_column("mpack_id", new_column_name="pack_id")
        batch_op.alter_column("entity_id", new_column_name="object_id")

    op.create_index(
        "ix_musehub_pack_index_object_id",
        "musehub_pack_index",
        ["object_id"],
    )