import sqlalchemy as sa
from alembic import op
from sqlalchemy.dialects import mysql

revision = "0021_billing_statements"
down_revision = "0020_knowledge_source_text"
branch_labels = None
depends_on = None


def upgrade():
    # 账单原文按批次保留；租户和来源唯一约束防止更换请求 UUID 后重复导入。
    op.create_table(
        "billing_statements",
        sa.Column("id", mysql.BINARY(16), primary_key=True),
        sa.Column("tenant_id", mysql.BINARY(16), nullable=False),
        sa.Column("applicant_id", mysql.BINARY(16), nullable=False),
        sa.Column("source_key", mysql.BINARY(32), nullable=False),
        sa.Column("payload", sa.JSON(), nullable=False),
        sa.Column("created_at", mysql.DATETIME(fsp=6), nullable=False),
        sa.ForeignKeyConstraint(["tenant_id"], ["tenants.id"], ondelete="CASCADE"),
        sa.UniqueConstraint("tenant_id", "source_key", name="uq_billing_statement_source"),
    )
    op.create_index("ix_billing_statements_tenant_id", "billing_statements", ["tenant_id", "id"])


def downgrade():
    op.drop_table("billing_statements")