-- Teacher lesson submissions and immutable video candidates.
-- Requires 20260909_curriculum_publication_identity.sql.

CREATE TABLE IF NOT EXISTS `teacher_submissions` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `uuid` CHAR(36) NOT NULL,
  `teacher_id` BIGINT UNSIGNED NOT NULL,
  `curriculum_lesson_id` BIGINT UNSIGNED NOT NULL,
  `status` ENUM('draft','uploading','review','published','withdrawn','archived') NOT NULL DEFAULT 'draft',
  `current_published_video_version_id` BIGINT UNSIGNED NULL,
  `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uq_teacher_submission_uuid` (`uuid`),
  UNIQUE KEY `uq_teacher_curriculum_submission` (`teacher_id`,`curriculum_lesson_id`),
  KEY `idx_submission_lesson_status` (`curriculum_lesson_id`,`status`),
  CONSTRAINT `fk_submission_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teachers` (`id`) ON DELETE RESTRICT,
  CONSTRAINT `fk_submission_curriculum_lesson` FOREIGN KEY (`curriculum_lesson_id`) REFERENCES `curriculum_lessons` (`id`) ON DELETE RESTRICT
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE IF NOT EXISTS `video_versions` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `uuid` CHAR(36) NOT NULL,
  `teacher_submission_id` BIGINT UNSIGNED NOT NULL,
  `version_number` INT UNSIGNED NOT NULL,
  `status` ENUM('draft','uploading','review','rejected','published','superseded','withdrawn') NOT NULL DEFAULT 'draft',
  `replaces_video_version_id` BIGINT UNSIGNED NULL,
  `source_lesson_id` BIGINT UNSIGNED NULL,
  `upload_audit_id` BIGINT UNSIGNED NULL,
  `content_sha256` CHAR(64) NULL,
  `review_report_json` JSON NULL,
  `published_at` TIMESTAMP NULL DEFAULT NULL,
  `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uq_video_version_uuid` (`uuid`),
  UNIQUE KEY `uq_submission_version` (`teacher_submission_id`,`version_number`),
  KEY `idx_video_version_status` (`teacher_submission_id`,`status`),
  CONSTRAINT `fk_video_version_submission` FOREIGN KEY (`teacher_submission_id`) REFERENCES `teacher_submissions` (`id`) ON DELETE RESTRICT,
  CONSTRAINT `fk_video_version_replacement` FOREIGN KEY (`replaces_video_version_id`) REFERENCES `video_versions` (`id`) ON DELETE RESTRICT
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

ALTER TABLE `teacher_submissions`
  ADD CONSTRAINT `fk_submission_current_version`
  FOREIGN KEY (`current_published_video_version_id`) REFERENCES `video_versions` (`id`) ON DELETE RESTRICT;

CREATE TABLE IF NOT EXISTS `submission_idempotency_keys` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `teacher_id` BIGINT UNSIGNED NOT NULL,
  `operation` VARCHAR(64) NOT NULL,
  `idempotency_key` VARCHAR(128) NOT NULL,
  `request_sha256` CHAR(64) NOT NULL,
  `response_json` JSON NULL,
  `http_status` SMALLINT UNSIGNED NULL,
  `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uq_submission_idempotency` (`teacher_id`,`operation`,`idempotency_key`),
  CONSTRAINT `fk_submission_idempotency_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teachers` (`id`) ON DELETE RESTRICT
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- Rollback: preserve submissions and versions. Withdraw affected publications;
-- do not drop records that may be referenced by student progress or review data.