"""Add global ledgers sharing the collaboration engine.

Revision ID: 20260903_01
Revises: 20260716_05
"""
import sqlalchemy as sa
from alembic import op

revision = "20260903_01"
down_revision = "20260716_05"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.alter_column("collaboration_files", "study_id", nullable=True)
    op.add_column("collaboration_files", sa.Column("scope", sa.String(16), nullable=False, server_default="PROJECT"))
    op.add_column("collaboration_files", sa.Column("ledger_key", sa.String(64), nullable=True))
    op.add_column("collaboration_files", sa.Column("description", sa.String(500), nullable=False, server_default=""))
    op.create_unique_constraint("uq_collaboration_file_ledger_key", "collaboration_files", ["ledger_key"])
    op.create_check_constraint(
        "ck_collaboration_file_scope", "collaboration_files",
        "(scope = 'PROJECT' AND study_id IS NOT NULL AND ledger_key IS NULL) OR "
        "(scope = 'LEDGER' AND study_id IS NULL AND folder_id IS NULL AND ledger_key IS NOT NULL "
        "AND file_type = 'cell' AND extension = 'xlsx' AND deleted_at IS NULL AND status IN ('ACTIVE', 'ARCHIVED'))",
    )


def downgrade() -> None:
    # Never discard retained ledger files, grants or history during rollback.
    if op.get_bind().scalar(sa.text("SELECT count(*) FROM collaboration_files WHERE scope = 'LEDGER'")):
        raise RuntimeError("已有全局台账，不能回滚台账迁移；请保留数据并使用前向修复")
    op.drop_constraint("ck_collaboration_file_scope", "collaboration_files", type_="check")
    op.drop_constraint("uq_collaboration_file_ledger_key", "collaboration_files", type_="unique")
    op.drop_column("collaboration_files", "description")
    op.drop_column("collaboration_files", "ledger_key")
    op.drop_column("collaboration_files", "scope")
    op.alter_column("collaboration_files", "study_id", nullable=False)