CREATE TABLE IF NOT EXISTS `user_notifications` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `recipient_user_id` INT UNSIGNED NOT NULL,
  `tenant_id` INT UNSIGNED NULL,
  `type` VARCHAR(60) NOT NULL,
  `title` VARCHAR(255) NOT NULL,
  `body` VARCHAR(500) NULL,
  `link` VARCHAR(500) NULL,
  `data` JSON NULL,
  `dedupe_fingerprint` CHAR(64) NULL,
  `dedupe_bucket` INT UNSIGNED NULL,
  `dedupe_until` DATETIME NULL DEFAULT NULL,
  `is_read` TINYINT(1) NOT NULL DEFAULT 0,
  `read_at` DATETIME NULL DEFAULT NULL,
  `created` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  KEY `idx_un_recipient_read_created` (`recipient_user_id`, `is_read`, `created` DESC),
  KEY `idx_un_recipient_created` (`recipient_user_id`, `created` DESC),
  KEY `idx_un_tenant_created` (`tenant_id`, `created` DESC),
  KEY `idx_un_cleanup` (`is_read`, `read_at`),
  UNIQUE KEY `uniq_un_dedupe_bucket` (`recipient_user_id`, `dedupe_fingerprint`, `dedupe_bucket`),
  CONSTRAINT `fk_un_recipient` FOREIGN KEY (`recipient_user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_un_tenant` FOREIGN KEY (`tenant_id`) REFERENCES `tenants` (`id`) ON DELETE SET NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

ALTER TABLE `user_notifications`
  ADD COLUMN IF NOT EXISTS `dedupe_fingerprint` CHAR(64) NULL AFTER `data`,
  ADD COLUMN IF NOT EXISTS `dedupe_bucket` INT UNSIGNED NULL AFTER `dedupe_fingerprint`,
  ADD COLUMN IF NOT EXISTS `dedupe_until` DATETIME NULL DEFAULT NULL AFTER `dedupe_bucket`;

CREATE UNIQUE INDEX IF NOT EXISTS `uniq_un_dedupe_bucket`
  ON `user_notifications` (`recipient_user_id`, `dedupe_fingerprint`, `dedupe_bucket`);