"""comparison_record: llm_cost_yuan + llm_price_snapshot(比价 LLM 调用成本 + 当时单价快照)

回填 llm_calls 时按「当时的价」逐模型算出本次比价 LLM 总成本(元),连同所用单价快照一起冻结到
记录上;admin 比价记录详情展示实际成本(旧记录 NULL → 前端回退估算)。见 services/llm_cost.py。

Revision ID: comparison_llm_cost
Revises: ad_ecpm_trace_id
Create Date: 2026-07-13
"""
from collections.abc import Sequence

import sqlalchemy as sa
from sqlalchemy.dialects import postgresql

from alembic import op

revision: str = "comparison_llm_cost"
down_revision: str | Sequence[str] | None = "ad_ecpm_trace_id"
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None

_JSONB = sa.JSON().with_variant(postgresql.JSONB(), "postgresql")


def upgrade() -> None:
    # 均可空、无索引;SQLite 原生支持 ADD COLUMN,无需 batch_alter_table(同 comparison_debug_fields)。
    op.add_column("comparison_record", sa.Column("llm_cost_yuan", sa.Float(), nullable=True))
    op.add_column("comparison_record", sa.Column("llm_price_snapshot", _JSONB, nullable=True))


def downgrade() -> None:
    op.drop_column("comparison_record", "llm_price_snapshot")
    op.drop_column("comparison_record", "llm_cost_yuan")