import json

async def main(request, params_kw):
    """
    查询某产品在有效供销合同下的折扣信息。
    
    参数: productid, prodtypeid(可选)
    
    折扣查找优先级:
    1. 精确匹配 productid
    2. 匹配 prodtypeid
    3. 使用合同默认折扣
    """
    user_orgid = await get_userorgid()
    dbname = get_module_dbname('supplychain')
    
    productid = params_kw.get("productid")
    prodtypeid = params_kw.get("prodtypeid")
    
    if not productid:
        return json.dumps({"status": "error", "message": "缺少productid参数"})
    
    config = getConfig(".")
    DBPools(config.databases)
    
    async with db.sqlorContext(dbname) as sor:
        # Try exact product match
        sql = """SELECT sci.id, sci.contract_id, sci.discount, sci.settlement_price,
                        sc.contract_code, sc.contract_name, sc.supplier_id,
                        s.supplier_name
                 FROM supply_contract_items sci
                 JOIN supply_contracts sc ON sci.contract_id = sc.id
                 LEFT JOIN suppliers s ON sc.supplier_id = s.id
                 WHERE sci.resellerid = ${resellerid}$
                   AND sc.status = '1'
                   AND sc.start_date <= CURDATE()
                   AND (sc.end_date IS NULL OR sc.end_date >= CURDATE())
                   AND sci.productid = ${productid}$
                 ORDER BY sc.start_date DESC"""
        recs = await sor.sqlExe(sql, {"resellerid": user_orgid, "productid": productid})
        
        if not recs and prodtypeid:
            sql = """SELECT sci.id, sci.contract_id, sci.discount, sci.settlement_price,
                            sc.contract_code, sc.contract_name, sc.supplier_id,
                            s.supplier_name
                     FROM supply_contract_items sci
                     JOIN supply_contracts sc ON sci.contract_id = sc.id
                     LEFT JOIN suppliers s ON sc.supplier_id = s.id
                     WHERE sci.resellerid = ${resellerid}$
                       AND sc.status = '1'
                       AND sc.start_date <= CURDATE()
                       AND (sc.end_date IS NULL OR sc.end_date >= CURDATE())
                       AND sci.prodtypeid = ${prodtypeid}$
                     ORDER BY sc.start_date DESC"""
            recs = await sor.sqlExe(sql, {"resellerid": user_orgid, "prodtypeid": prodtypeid})
        
        if not recs:
            # Fallback to contract default
            sql = """SELECT id as contract_id, contract_code, contract_name, 
                            supplier_id, default_discount as discount, NULL as settlement_price
                     FROM supply_contracts
                     WHERE resellerid = ${resellerid}$
                       AND status = '1'
                       AND start_date <= CURDATE()
                       AND (end_date IS NULL OR end_date >= CURDATE())
                     ORDER BY start_date DESC"""
            recs = await sor.sqlExe(sql, {"resellerid": user_orgid})
        
        result = [dict(r) for r in recs] if recs else []
        return json.dumps({"status": "ok", "data": result})