"""Phase C: MWA inventory + profit accounting

Revision ID: f6a7b8c9d0e1
Revises: e5f6a7b8c9d0
Create Date: 2026-03-27
"""
from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects.postgresql import UUID

revision = "f6a7b8c9d0e1"
down_revision = "e5f6a7b8c9d0"
branch_labels = None
depends_on = None


def upgrade() -> None:
    # ── 1. erp_sku_inventory 新增 mwa_unit_cost ──
    op.add_column(
        "erp_sku_inventory",
        sa.Column("mwa_unit_cost", sa.Numeric(12, 4), server_default="0",
                  comment="移动加权均价 (Moving Weighted Average)"),
    )

    # ── 2. erp_inventory_flows 新增 purchase_unit_price + is_special_zero_cost ──
    op.add_column(
        "erp_inventory_flows",
        sa.Column("purchase_unit_price", sa.Numeric(12, 2), server_default="0",
                  comment="入库采购单价"),
    )
    op.add_column(
        "erp_inventory_flows",
        sa.Column("is_special_zero_cost", sa.Boolean, server_default="false",
                  comment="特殊零元入库标识，不参与 MWA 计算"),
    )

    # ── 3. erp_order_item_costs 新表 ──
    op.create_table(
        "erp_order_item_costs",
        sa.Column("id", UUID(as_uuid=True), primary_key=True),
        sa.Column("order_item_id", UUID(as_uuid=True),
                  sa.ForeignKey("erp_order_items.id"), nullable=False, unique=True),
        sa.Column("purchase_unit_price", sa.Numeric(12, 4), nullable=False,
                  comment="MWA 成本快照"),
        sa.Column("profit_amount", sa.Numeric(14, 2), server_default="0",
                  comment="利润额 = (售价-成本)*数量"),
        sa.Column("profit_rate", sa.Numeric(5, 4), server_default="0",
                  comment="利润率"),
        sa.Column("created_at", sa.DateTime, server_default=sa.func.now()),
    )


def downgrade() -> None:
    op.drop_table("erp_order_item_costs")
    op.drop_column("erp_inventory_flows", "is_special_zero_cost")
    op.drop_column("erp_inventory_flows", "purchase_unit_price")
    op.drop_column("erp_sku_inventory", "mwa_unit_cost")