-- Keep AIHR tenant identifiers compatible with the framework tenant contract.
-- This migration derives the target charset/collation from sys_oss.tenant_id,
-- preserves each AIHR tenant_id column's nullability/default/comment, and is idempotent.

DROP PROCEDURE IF EXISTS aihr_align_tenant_collation;

DELIMITER $$

CREATE PROCEDURE aihr_align_tenant_collation()
BEGIN
  DECLARE done int DEFAULT 0;
  DECLARE target_charset varchar(64);
  DECLARE target_collation varchar(64);
  DECLARE current_table varchar(64);
  DECLARE current_type text;
  DECLARE current_nullable varchar(3);
  DECLARE current_default text;
  DECLARE current_comment text;

  DECLARE tenant_columns CURSOR FOR
    SELECT table_name, column_type, is_nullable, column_default, column_comment
      FROM information_schema.columns
     WHERE table_schema = DATABASE()
       AND LEFT(table_name, 5) = 'aihr_'
       AND column_name = 'tenant_id'
       AND collation_name <> target_collation
     ORDER BY table_name;
  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

  SELECT character_set_name, collation_name
    INTO target_charset, target_collation
    FROM information_schema.columns
   WHERE table_schema = DATABASE()
     AND table_name = 'sys_oss'
     AND column_name = 'tenant_id'
   LIMIT 1;

  IF target_charset IS NULL OR target_collation IS NULL THEN
    SIGNAL SQLSTATE '45000'
      SET MESSAGE_TEXT = 'sys_oss.tenant_id charset/collation contract is missing';
  END IF;

  OPEN tenant_columns;
  align_loop: LOOP
    FETCH tenant_columns
      INTO current_table, current_type, current_nullable, current_default, current_comment;
    IF done = 1 THEN
      LEAVE align_loop;
    END IF;

    SET @aihr_tenant_ddl = CONCAT(
      'ALTER TABLE `', REPLACE(current_table, '`', '``'),
      '` MODIFY COLUMN `tenant_id` ', current_type,
      ' CHARACTER SET `', REPLACE(target_charset, '`', '``'),
      '` COLLATE `', REPLACE(target_collation, '`', '``'), '`',
      IF(current_nullable = 'YES', ' NULL', ' NOT NULL'),
      IF(current_default IS NULL, '', CONCAT(' DEFAULT ', QUOTE(current_default))),
      ' COMMENT ', QUOTE(COALESCE(current_comment, ''))
    );
    PREPARE aihr_tenant_statement FROM @aihr_tenant_ddl;
    EXECUTE aihr_tenant_statement;
    DEALLOCATE PREPARE aihr_tenant_statement;
  END LOOP;
  CLOSE tenant_columns;
END$$

DELIMITER ;

CALL aihr_align_tenant_collation();
DROP PROCEDURE aihr_align_tenant_collation;