-- 应收模块运行期优化脚本（不回填历史数据）
--
-- 用于已经存在业务表的环境。脚本可重复执行：字段或索引已存在时自动跳过，
-- 不会修改历史订单的 ar_bill_status，也不会重算历史账单版本。
SET NAMES utf8mb4;
SET @db_name := DATABASE();

-- 1. 账单唯一性调整。
-- 旧版本 uk_ar_bill_customer_period 会禁止同一客户同一账期再次生成账单，
-- 与 bill_version 版本化方案冲突，必须删除。
SET @has_old_bill_unique := (
    SELECT COUNT(*)
    FROM information_schema.STATISTICS
    WHERE TABLE_SCHEMA = @db_name
      AND TABLE_NAME = 'ar_bill'
      AND INDEX_NAME = 'uk_ar_bill_customer_period'
);
SET @sql := IF(@has_old_bill_unique > 0,
    'ALTER TABLE ar_bill DROP INDEX uk_ar_bill_customer_period',
    'SELECT 1');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

-- 新唯一键要求已有数据的 bill_version 已正确区分。
-- 如果这里创建失败，请先执行 ar_bill_cutoff_status_migration.sql 回填历史版本。
SET @has_bill_version_unique := (
    SELECT COUNT(*)
    FROM information_schema.STATISTICS
    WHERE TABLE_SCHEMA = @db_name
      AND TABLE_NAME = 'ar_bill'
      AND INDEX_NAME = 'uk_ar_bill_customer_cutoff_version'
);
SET @sql := IF(@has_bill_version_unique = 0,
    'ALTER TABLE ar_bill ADD UNIQUE KEY uk_ar_bill_customer_cutoff_version (customer_id, currency, bill_period_end, bill_version)',
    'SELECT 1');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

-- 2. 计费订单应收账单占用状态。
SET @has_ar_bill_status := (
    SELECT COUNT(*)
    FROM information_schema.COLUMNS
    WHERE TABLE_SCHEMA = @db_name
      AND TABLE_NAME = 'prc_order_bill'
      AND COLUMN_NAME = 'ar_bill_status'
);
SET @sql := IF(@has_ar_bill_status = 0,
    'ALTER TABLE prc_order_bill ADD COLUMN ar_bill_status VARCHAR(20) NOT NULL DEFAULT ''UNBILLED'' COMMENT ''应收账单占用状态：UNBILLED/BILLED'' AFTER currency',
    'SELECT 1');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

-- 3. 订单预览、占用和释放使用的组合索引。
SET @has_order_status_index := (
    SELECT COUNT(*)
    FROM information_schema.STATISTICS
    WHERE TABLE_SCHEMA = @db_name
      AND TABLE_NAME = 'prc_order_bill'
      AND INDEX_NAME = 'idx_bill_ar_status'
);
SET @sql := IF(@has_order_status_index = 0,
    'ALTER TABLE prc_order_bill ADD INDEX idx_bill_ar_status (customer_id, currency, ar_bill_status, biz_date)',
    'SELECT 1');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

-- 4. 详情页批量关联费用时使用的排序索引。
SET @has_detail_fee_index := (
    SELECT COUNT(*)
    FROM information_schema.STATISTICS
    WHERE TABLE_SCHEMA = @db_name
      AND TABLE_NAME = 'ar_bill_detail_fee'
      AND INDEX_NAME = 'idx_ar_detail_fee_order'
);
SET @sql := IF(@has_detail_fee_index = 0,
    'ALTER TABLE ar_bill_detail_fee ADD INDEX idx_ar_detail_fee_order (detail_id, fee_no, detail_fee_id)',
    'SELECT 1');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;