"""Add musehub_pack_index — maps every pushed object to its mpack in MinIO.

Issue #63 Phase 1: mpack index for O(1) mpack lookup during clone/fetch.
Primary key (object_id, mpack_id) — one object may appear in multiple mpacks.
Index on (repo_id, object_id) for per-repo lookups.
"""

from __future__ import annotations

import sqlalchemy as sa
from alembic import op

revision = "0059"
down_revision = "0058"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.create_table(
        "musehub_pack_index",
        sa.Column("object_id", sa.String(128), nullable=False),
        sa.Column("pack_id", sa.String(128), nullable=False),
        sa.Column(
            "repo_id",
            sa.String(128),
            sa.ForeignKey("musehub_repos.repo_id", ondelete="CASCADE"),
            nullable=False,
        ),
        sa.Column(
            "created_at",
            sa.DateTime(timezone=True),
            nullable=False,
            server_default=sa.text("now()"),
        ),
        sa.PrimaryKeyConstraint("object_id", "pack_id"),
    )
    op.create_index(
        "ix_musehub_pack_index_repo_object",
        "musehub_pack_index",
        ["repo_id", "object_id"],
    )


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