-- 二期库位共享溢出位 A0 增量迁移。
-- 执行顺序：phase2-pallet-location-schema.sql、本文件。
-- 普通库位仍保持一托一位；同一租户仓库只有一个 A0，且 A0 可承载多个活动资源。
SET NAMES utf8mb4;
USE baiyue_warehouse;

DROP PROCEDURE IF EXISTS add_location_overflow_column_if_missing;
DELIMITER $$
CREATE PROCEDURE add_location_overflow_column_if_missing(
  IN p_table_name VARCHAR(64),
  IN p_column_name VARCHAR(64),
  IN p_column_definition TEXT
)
BEGIN
  IF NOT EXISTS (
    SELECT 1 FROM information_schema.columns
     WHERE table_schema = DATABASE()
       AND table_name = p_table_name
       AND column_name = p_column_name
  ) THEN
    SET @column_sql = CONCAT(
      'ALTER TABLE `', REPLACE(p_table_name, '`', '``'),
      '` ADD COLUMN `', REPLACE(p_column_name, '`', '``'), '` ', p_column_definition
    );
    PREPARE column_statement FROM @column_sql;
    EXECUTE column_statement;
    DEALLOCATE PREPARE column_statement;
  END IF;
END$$
DELIMITER ;

CALL add_location_overflow_column_if_missing(
  'wh_location', 'shared_overflow',
  'TINYINT(1) NOT NULL DEFAULT 0 COMMENT ''是否为系统共享溢出位 A0'' AFTER max_weight_kg'
);
CALL add_location_overflow_column_if_missing(
  'wh_location_reservation', 'shared_overflow',
  'TINYINT(1) NOT NULL DEFAULT 0 COMMENT ''是否使用共享溢出位 A0'' AFTER location_code'
);
CALL add_location_overflow_column_if_missing(
  'wh_location_occupancy', 'shared_overflow',
  'TINYINT(1) NOT NULL DEFAULT 0 COMMENT ''是否使用共享溢出位 A0'' AFTER location_code'
);

-- 兼容迁移前人工或旧流程已创建的 A0，并将资源快照回填一致。
UPDATE wh_location
   SET shared_overflow = 1,
       status = 'AVAILABLE'
 WHERE location_code = 'A0' AND deleted = 0;

UPDATE wh_location_reservation r
JOIN wh_location l
  ON l.tenant_id = r.tenant_id AND l.id = r.location_id
   SET r.shared_overflow = l.shared_overflow;

UPDATE wh_location_occupancy o
JOIN wh_location l
  ON l.tenant_id = o.tenant_id AND l.id = o.location_id
   SET o.shared_overflow = l.shared_overflow;

DROP PROCEDURE IF EXISTS add_location_overflow_column_if_missing;

-- 先移除依赖旧生成列的唯一索引，再按普通库位/A0 的不同语义重建。
SET @schema_name = DATABASE();
SET @sql = IF((SELECT COUNT(*) FROM information_schema.statistics WHERE table_schema = @schema_name AND table_name = 'wh_location_reservation' AND index_name = 'uk_location_active_reservation') > 0,
  'ALTER TABLE wh_location_reservation DROP INDEX uk_location_active_reservation', 'SELECT 1');
PREPARE statement FROM @sql; EXECUTE statement; DEALLOCATE PREPARE statement;
SET @sql = IF((SELECT COUNT(*) FROM information_schema.statistics WHERE table_schema = @schema_name AND table_name = 'wh_location_reservation' AND index_name = 'uk_pallet_active_reservation') > 0,
  'ALTER TABLE wh_location_reservation DROP INDEX uk_pallet_active_reservation', 'SELECT 1');
PREPARE statement FROM @sql; EXECUTE statement; DEALLOCATE PREPARE statement;

ALTER TABLE wh_location_reservation
  MODIFY COLUMN active_reservation TINYINT
  GENERATED ALWAYS AS (
    CASE WHEN reservation_status = 'RESERVED' AND shared_overflow = 0 THEN 1 ELSE NULL END
  ) STORED COMMENT '普通库位活动预占唯一标记，A0 返回 NULL';

SET @sql = IF((SELECT COUNT(*) FROM information_schema.statistics WHERE table_schema = @schema_name AND table_name = 'wh_location_reservation' AND index_name = 'uk_location_active_reservation') = 0,
  'ALTER TABLE wh_location_reservation ADD UNIQUE KEY uk_location_active_reservation (tenant_id, location_id, active_reservation)', 'SELECT 1');
PREPARE statement FROM @sql; EXECUTE statement; DEALLOCATE PREPARE statement;

SET @sql = IF((SELECT COUNT(*) FROM information_schema.statistics WHERE table_schema = @schema_name AND table_name = 'wh_location_occupancy' AND index_name = 'uk_location_active_occupancy') > 0,
  'ALTER TABLE wh_location_occupancy DROP INDEX uk_location_active_occupancy', 'SELECT 1');
PREPARE statement FROM @sql; EXECUTE statement; DEALLOCATE PREPARE statement;
SET @sql = IF((SELECT COUNT(*) FROM information_schema.statistics WHERE table_schema = @schema_name AND table_name = 'wh_location_occupancy' AND index_name = 'uk_pallet_active_occupancy') > 0,
  'ALTER TABLE wh_location_occupancy DROP INDEX uk_pallet_active_occupancy', 'SELECT 1');
PREPARE statement FROM @sql; EXECUTE statement; DEALLOCATE PREPARE statement;

DROP PROCEDURE IF EXISTS add_location_overflow_column_if_missing;
DELIMITER $$
CREATE PROCEDURE add_location_overflow_column_if_missing(
  IN p_table_name VARCHAR(64),
  IN p_column_name VARCHAR(64),
  IN p_column_definition TEXT
)
BEGIN
  IF NOT EXISTS (
    SELECT 1 FROM information_schema.columns
     WHERE table_schema = DATABASE()
       AND table_name = p_table_name
       AND column_name = p_column_name
  ) THEN
    SET @column_sql = CONCAT(
      'ALTER TABLE `', REPLACE(p_table_name, '`', '``'),
      '` ADD COLUMN `', REPLACE(p_column_name, '`', '``'), '` ', p_column_definition
    );
    PREPARE column_statement FROM @column_sql;
    EXECUTE column_statement;
    DEALLOCATE PREPARE column_statement;
  END IF;
END$$
DELIMITER ;

CALL add_location_overflow_column_if_missing(
  'wh_location_reservation', 'active_pallet_reservation',
  'TINYINT GENERATED ALWAYS AS (CASE WHEN reservation_status = ''RESERVED'' THEN 1 ELSE NULL END) STORED COMMENT ''托盘活动预占唯一标记（包含 A0）'''
);
CALL add_location_overflow_column_if_missing(
  'wh_location_occupancy', 'active_location_occupancy',
  'TINYINT GENERATED ALWAYS AS (CASE WHEN occupancy_status = ''OCCUPIED'' AND shared_overflow = 0 THEN 1 ELSE NULL END) STORED COMMENT ''普通库位活动占用唯一标记'''
);
CALL add_location_overflow_column_if_missing(
  'wh_location_occupancy', 'active_pallet_occupancy',
  'TINYINT GENERATED ALWAYS AS (CASE WHEN occupancy_status = ''OCCUPIED'' THEN 1 ELSE NULL END) STORED COMMENT ''托盘活动占用唯一标记（包含 A0）'''
);
DROP PROCEDURE IF EXISTS add_location_overflow_column_if_missing;

SET @sql = IF((SELECT COUNT(*) FROM information_schema.statistics WHERE table_schema = @schema_name AND table_name = 'wh_location_reservation' AND index_name = 'uk_pallet_active_reservation') = 0,
  'ALTER TABLE wh_location_reservation ADD UNIQUE KEY uk_pallet_active_reservation (tenant_id, pallet_id, active_pallet_reservation)', 'SELECT 1');
PREPARE statement FROM @sql; EXECUTE statement; DEALLOCATE PREPARE statement;

SET @sql = IF((SELECT COUNT(*) FROM information_schema.statistics WHERE table_schema = @schema_name AND table_name = 'wh_location_occupancy' AND index_name = 'uk_location_active_occupancy') = 0,
  'ALTER TABLE wh_location_occupancy ADD UNIQUE KEY uk_location_active_occupancy (tenant_id, location_id, active_location_occupancy)', 'SELECT 1');
PREPARE statement FROM @sql; EXECUTE statement; DEALLOCATE PREPARE statement;
SET @sql = IF((SELECT COUNT(*) FROM information_schema.statistics WHERE table_schema = @schema_name AND table_name = 'wh_location_occupancy' AND index_name = 'uk_pallet_active_occupancy') = 0,
  'ALTER TABLE wh_location_occupancy ADD UNIQUE KEY uk_pallet_active_occupancy (tenant_id, pallet_id, active_pallet_occupancy)', 'SELECT 1');
PREPARE statement FROM @sql; EXECUTE statement; DEALLOCATE PREPARE statement;