-- ==============================================================================
-- SAQEL PLATFORM (منصة صَقِل) - PRIMARY DATABASE SCHEMA (MySQL 8.4+)
-- Complete Production Database Definition
-- ==============================================================================

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ------------------------------------------------------------------------------
-- DROP ALL EXISTING TABLES IN REVERSE ORDER TO PREVENT FOREIGN KEY CONFLICTS
DROP TABLE IF EXISTS `student_question_answers`;
DROP TABLE IF EXISTS `exam_attempts`;
DROP TABLE IF EXISTS `question_options`;
DROP TABLE IF EXISTS `questions`;
DROP TABLE IF EXISTS `exams`;
DROP TABLE IF EXISTS `quizzes`;
DROP TABLE IF EXISTS `chat_messages`;
DROP TABLE IF EXISTS `otp_verifications`;
DROP TABLE IF EXISTS `user_devices`;
DROP TABLE IF EXISTS `voice_notes`;
DROP TABLE IF EXISTS `lesson_progress`;
DROP TABLE IF EXISTS `progress`;
DROP TABLE IF EXISTS `lessons`;
DROP TABLE IF EXISTS `courses`;
DROP TABLE IF EXISTS `subjects`;
DROP TABLE IF EXISTS `teacher_profiles`;
DROP TABLE IF EXISTS `guardian_student`;
DROP TABLE IF EXISTS `users`;
DROP TABLE IF EXISTS `schools`;

-- ------------------------------------------------------------------------------
-- 1. Table: schools (المدارس والجهات الشريكة - B2B مثل الثقافة العسكرية)
-- ------------------------------------------------------------------------------
CREATE TABLE `schools` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `uuid` CHAR(36) NOT NULL,
  `name` VARCHAR(255) NOT NULL,
  `code` VARCHAR(50) NOT NULL UNIQUE,
  `type` ENUM('military_culture', 'private', 'public', 'center') NOT NULL DEFAULT 'private',
  `director_name` VARCHAR(255) DEFAULT NULL,
  `phone` VARCHAR(50) DEFAULT NULL,
  `city` VARCHAR(100) DEFAULT 'Amman',
  `is_active` TINYINT(1) NOT NULL DEFAULT 1,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_schools_uuid` (`uuid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 2. Table: users (المستخدمون الموحدون - طلاب، معلمون، أولياء أمور، إدارة)
-- ------------------------------------------------------------------------------
CREATE TABLE `users` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `uuid` CHAR(36) NOT NULL,
  `full_name` TEXT NOT NULL,
  `phone_number` TEXT NOT NULL,
  `phone_hash` VARCHAR(64) NOT NULL,
  `password_hash` VARCHAR(255) DEFAULT NULL,
  `role` ENUM('student', 'guardian', 'teacher', 'school_admin', 'super_admin') NOT NULL DEFAULT 'student',
  `school_id` BIGINT UNSIGNED DEFAULT NULL,
  `grade_level` VARCHAR(50) DEFAULT 'tawjihi_2007',
  `stream` ENUM('scientific', 'literary', 'vocational', 'general') DEFAULT 'scientific',
  `token_version` INT UNSIGNED NOT NULL DEFAULT 1,
  `status` ENUM('active', 'pending_otp', 'suspended') NOT NULL DEFAULT 'pending_otp',
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_users_uuid` (`uuid`),
  KEY `idx_users_phone_hash` (`phone_hash`),
  KEY `idx_users_school_id` (`school_id`),
  CONSTRAINT `fk_users_school` FOREIGN KEY (`school_id`) REFERENCES `schools` (`id`) ON DELETE SET NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 3. Table: guardian_student (ربط أولياء الأمور بالأبناء - N:M)
-- ------------------------------------------------------------------------------
CREATE TABLE `guardian_student` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `guardian_id` BIGINT UNSIGNED NOT NULL,
  `student_id` BIGINT UNSIGNED NOT NULL,
  `relationship_type` ENUM('father', 'mother', 'brother', 'guardian') NOT NULL DEFAULT 'father',
  `is_verified` TINYINT(1) NOT NULL DEFAULT 0,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_guardian_student_unique` (`guardian_id`, `student_id`),
  KEY `idx_guardian_student_student` (`student_id`),
  CONSTRAINT `fk_gs_guardian` FOREIGN KEY (`guardian_id`) REFERENCES `users` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_gs_student` FOREIGN KEY (`student_id`) REFERENCES `users` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 4. Table: teacher_profiles (ملفات المعلمين ونسب الأرباح)
-- ------------------------------------------------------------------------------
CREATE TABLE `teacher_profiles` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `user_id` BIGINT UNSIGNED NOT NULL,
  `bio` TEXT DEFAULT NULL,
  `specialization` VARCHAR(150) NOT NULL,
  `revenue_share_pct` DECIMAL(5,2) NOT NULL DEFAULT 45.00,
  `contract_type` ENUM('exclusive', 'non_exclusive') NOT NULL DEFAULT 'exclusive',
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_teacher_user` (`user_id`),
  CONSTRAINT `fk_teacher_user` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 5. Table: subjects (المواد التعليمية)
-- ------------------------------------------------------------------------------
CREATE TABLE `subjects` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(150) NOT NULL,
  `code` VARCHAR(50) NOT NULL UNIQUE,
  `stream` ENUM('scientific', 'literary', 'common') NOT NULL DEFAULT 'common',
  `is_active` TINYINT(1) NOT NULL DEFAULT 1,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 6. Table: courses (الدورات التدريبية)
-- ------------------------------------------------------------------------------
CREATE TABLE `courses` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `uuid` CHAR(36) NOT NULL,
  `subject_id` BIGINT UNSIGNED NOT NULL,
  `teacher_id` BIGINT UNSIGNED NOT NULL,
  `title` VARCHAR(255) NOT NULL,
  `description` TEXT DEFAULT NULL,
  `semester` ENUM('first', 'second', 'full_year', 'intensive') NOT NULL DEFAULT 'first',
  `price_jod` DECIMAL(8,2) NOT NULL DEFAULT 35.00,
  `thumbnail_url` VARCHAR(500) DEFAULT NULL,
  `is_published` TINYINT(1) NOT NULL DEFAULT 0,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_courses_uuid` (`uuid`),
  KEY `idx_courses_subject` (`subject_id`),
  KEY `idx_courses_teacher` (`teacher_id`),
  CONSTRAINT `fk_courses_subject` FOREIGN KEY (`subject_id`) REFERENCES `subjects` (`id`) ON DELETE RESTRICT,
  CONSTRAINT `fk_courses_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `users` (`id`) ON DELETE RESTRICT
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 7. Table: lessons (الدروس والفيديوهات المربوطة بـ Bunny Stream)
-- ------------------------------------------------------------------------------
CREATE TABLE `lessons` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `course_id` BIGINT UNSIGNED NOT NULL,
  `title` VARCHAR(255) NOT NULL,
  `sequence_order` INT UNSIGNED NOT NULL DEFAULT 1,
  `bunny_video_id` VARCHAR(100) NOT NULL,
  `duration_seconds` INT UNSIGNED NOT NULL DEFAULT 0,
  `is_free_preview` TINYINT(1) NOT NULL DEFAULT 0,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  KEY `idx_lessons_course` (`course_id`),
  CONSTRAINT `fk_lessons_course` FOREIGN KEY (`course_id`) REFERENCES `courses` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 8. Table: exams (الامتحانات الشاملة: درس، وحدة، فصل، ومحاكاة وزاري)
-- ------------------------------------------------------------------------------
CREATE TABLE `exams` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `uuid` CHAR(36) NOT NULL,
  `course_id` BIGINT UNSIGNED NOT NULL,
  `lesson_id` BIGINT UNSIGNED DEFAULT NULL,
  `created_by_id` BIGINT UNSIGNED DEFAULT NULL,
  `creator_type` ENUM('teacher', 'ai_adaptive', 'ministry_standard') NOT NULL DEFAULT 'teacher',
  `scope` ENUM('in_video_checkpoint', 'lesson_exam', 'unit_exam', 'semester_final') NOT NULL DEFAULT 'lesson_exam',
  `title` VARCHAR(255) NOT NULL,
  `description` TEXT DEFAULT NULL,
  `duration_minutes` INT UNSIGNED NOT NULL DEFAULT 30,
  `timestamp_seconds` INT UNSIGNED NOT NULL DEFAULT 0,
  `rewind_on_fail_seconds` INT UNSIGNED NOT NULL DEFAULT 45,
  `passing_percentage` DECIMAL(5,2) NOT NULL DEFAULT 60.00,
  `total_points` INT UNSIGNED NOT NULL DEFAULT 100,
  `is_mandatory` TINYINT(1) NOT NULL DEFAULT 1,
  `is_published` TINYINT(1) NOT NULL DEFAULT 1,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_exams_uuid` (`uuid`),
  KEY `idx_exams_course` (`course_id`),
  KEY `idx_exams_lesson` (`lesson_id`),
  KEY `idx_exams_scope` (`scope`),
  KEY `idx_exams_creator` (`creator_type`),
  CONSTRAINT `fk_exams_course` FOREIGN KEY (`course_id`) REFERENCES `courses` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_exams_lesson` FOREIGN KEY (`lesson_id`) REFERENCES `lessons` (`id`) ON DELETE SET NULL,
  CONSTRAINT `fk_exams_creator` FOREIGN KEY (`created_by_id`) REFERENCES `users` (`id`) ON DELETE SET NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 9. Table: questions (الأسئلة والتحليل المعرفي للذكاء الاصطناعي)
-- ------------------------------------------------------------------------------
CREATE TABLE `questions` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `uuid` CHAR(36) NOT NULL,
  `exam_id` BIGINT UNSIGNED NOT NULL,
  `question_text` TEXT NOT NULL,
  `question_type` ENUM('multiple_choice', 'true_false', 'short_answer') NOT NULL DEFAULT 'multiple_choice',
  `bloom_taxonomy` ENUM('recall', 'comprehension', 'application', 'analysis') NOT NULL DEFAULT 'comprehension',
  `topic_tag` VARCHAR(150) DEFAULT NULL,
  `points` INT UNSIGNED NOT NULL DEFAULT 10,
  `explanation_text` TEXT DEFAULT NULL,
  `ai_hint` TEXT DEFAULT NULL,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_questions_uuid` (`uuid`),
  KEY `idx_questions_exam` (`exam_id`),
  KEY `idx_questions_topic` (`topic_tag`),
  CONSTRAINT `fk_questions_exam` FOREIGN KEY (`exam_id`) REFERENCES `exams` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 10. Table: question_options (خيارات الإجابة والتغذية الراجعة)
-- ------------------------------------------------------------------------------
CREATE TABLE `question_options` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `question_id` BIGINT UNSIGNED NOT NULL,
  `option_text` TEXT NOT NULL,
  `is_correct` TINYINT(1) NOT NULL DEFAULT 0,
  `feedback_text` TEXT DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `idx_options_question` (`question_id`),
  CONSTRAINT `fk_options_question` FOREIGN KEY (`question_id`) REFERENCES `questions` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 11. Table: exam_attempts (محاولات ونتائج الامتحانات وتحليل الذكاء الاصطناعي)
-- ------------------------------------------------------------------------------
CREATE TABLE `exam_attempts` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `uuid` CHAR(36) NOT NULL,
  `student_id` BIGINT UNSIGNED NOT NULL,
  `exam_id` BIGINT UNSIGNED NOT NULL,
  `attempt_number` INT UNSIGNED NOT NULL DEFAULT 1,
  `score` DECIMAL(6,2) NOT NULL DEFAULT 0.00,
  `total_score` DECIMAL(6,2) NOT NULL DEFAULT 100.00,
  `percentage` DECIMAL(5,2) NOT NULL DEFAULT 0.00,
  `status` ENUM('passed', 'failed', 'needs_remediation', 'in_progress') NOT NULL DEFAULT 'in_progress',
  `time_spent_seconds` INT UNSIGNED NOT NULL DEFAULT 0,
  `weak_topics_json` JSON DEFAULT NULL,
  `ai_diagnostic_report` TEXT DEFAULT NULL,
  `completed_at` TIMESTAMP NULL DEFAULT NULL,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_attempts_uuid` (`uuid`),
  KEY `idx_attempts_student_exam` (`student_id`, `exam_id`),
  KEY `idx_attempts_status` (`status`),
  CONSTRAINT `fk_attempts_student` FOREIGN KEY (`student_id`) REFERENCES `users` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_attempts_exam` FOREIGN KEY (`exam_id`) REFERENCES `exams` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 12. Table: student_question_answers (تفاصيل إجابات الطالب على كل سؤال)
-- ------------------------------------------------------------------------------
CREATE TABLE `student_question_answers` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `attempt_id` BIGINT UNSIGNED NOT NULL,
  `student_id` BIGINT UNSIGNED NOT NULL,
  `question_id` BIGINT UNSIGNED NOT NULL,
  `selected_option_id` BIGINT UNSIGNED DEFAULT NULL,
  `text_answer` TEXT DEFAULT NULL,
  `is_correct` TINYINT(1) NOT NULL DEFAULT 0,
  `points_awarded` DECIMAL(5,2) NOT NULL DEFAULT 0.00,
  `time_spent_seconds` INT UNSIGNED NOT NULL DEFAULT 0,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  KEY `idx_sqa_attempt` (`attempt_id`),
  KEY `idx_sqa_student_question` (`student_id`, `question_id`),
  CONSTRAINT `fk_sqa_attempt` FOREIGN KEY (`attempt_id`) REFERENCES `exam_attempts` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_sqa_student` FOREIGN KEY (`student_id`) REFERENCES `users` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_sqa_question` FOREIGN KEY (`question_id`) REFERENCES `questions` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_sqa_option` FOREIGN KEY (`selected_option_id`) REFERENCES `question_options` (`id`) ON DELETE SET NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 13. Table: student_mastery_analytics (مؤشر الفهم التراكمي والجاهزية للوزاري)
-- ------------------------------------------------------------------------------
CREATE TABLE `student_mastery_analytics` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `student_id` BIGINT UNSIGNED NOT NULL,
  `course_id` BIGINT UNSIGNED NOT NULL,
  `subject_id` BIGINT UNSIGNED NOT NULL,
  `mastery_percentage` DECIMAL(5,2) NOT NULL DEFAULT 0.00,
  `tawjihi_readiness_score` DECIMAL(5,2) NOT NULL DEFAULT 0.00,
  `lessons_completed_count` INT UNSIGNED NOT NULL DEFAULT 0,
  `exams_passed_count` INT UNSIGNED NOT NULL DEFAULT 0,
  `exams_total_count` INT UNSIGNED NOT NULL DEFAULT 0,
  `weak_concepts_summary` TEXT DEFAULT NULL,
  `ai_recommendations` TEXT DEFAULT NULL,
  `guardian_last_notified_at` TIMESTAMP NULL DEFAULT NULL,
  `updated_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_mastery_student_course` (`student_id`, `course_id`),
  KEY `idx_mastery_subject` (`subject_id`),
  CONSTRAINT `fk_mastery_student` FOREIGN KEY (`student_id`) REFERENCES `users` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_mastery_course` FOREIGN KEY (`course_id`) REFERENCES `courses` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_mastery_subject` FOREIGN KEY (`subject_id`) REFERENCES `subjects` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 11. Table: lesson_progress (سجل متابعة ونبض المشاهدة)
-- ------------------------------------------------------------------------------
CREATE TABLE `lesson_progress` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `user_id` BIGINT UNSIGNED NOT NULL,
  `lesson_id` BIGINT UNSIGNED NOT NULL,
  `last_watched_second` INT UNSIGNED NOT NULL DEFAULT 0,
  `max_watched_second` INT UNSIGNED NOT NULL DEFAULT 0,
  `completion_pct` DECIMAL(5,2) NOT NULL DEFAULT 0.00,
  `is_completed` TINYINT(1) NOT NULL DEFAULT 0,
  `updated_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_user_lesson_progress` (`user_id`, `lesson_id`),
  KEY `idx_progress_lesson` (`lesson_id`),
  CONSTRAINT `fk_progress_user` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_progress_lesson` FOREIGN KEY (`lesson_id`) REFERENCES `lessons` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 12. Table: voice_notes (الملاحظات الصوتية والتفريغ الذكي)
-- ------------------------------------------------------------------------------
CREATE TABLE `voice_notes` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `uuid` CHAR(36) NOT NULL,
  `user_id` BIGINT UNSIGNED NOT NULL,
  `lesson_id` BIGINT UNSIGNED NOT NULL,
  `timestamp_seconds` INT UNSIGNED NOT NULL DEFAULT 0,
  `audio_url` VARCHAR(500) NOT NULL,
  `transcript_text` TEXT DEFAULT NULL,
  `ai_summary` TEXT DEFAULT NULL,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_voice_notes_uuid` (`uuid`),
  KEY `idx_voice_notes_user_lesson` (`user_id`, `lesson_id`),
  CONSTRAINT `fk_vn_user` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_vn_lesson` FOREIGN KEY (`lesson_id`) REFERENCES `lessons` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 13. Table: user_devices (بصمة الأجهزة المربوطة بالجلسات)
-- ------------------------------------------------------------------------------
CREATE TABLE `user_devices` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `user_id` BIGINT UNSIGNED NOT NULL,
  `device_fingerprint` VARCHAR(64) NOT NULL,
  `device_name` VARCHAR(150) DEFAULT NULL,
  `platform` ENUM('android', 'ios', 'windows', 'macos', 'web') NOT NULL,
  `is_active` TINYINT(1) NOT NULL DEFAULT 1,
  `last_active_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_user_device_fingerprint` (`user_id`, `device_fingerprint`),
  CONSTRAINT `fk_ud_user` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 14. Table: otp_verifications (رموز التحقق عبر منصة صقل)
-- ------------------------------------------------------------------------------
CREATE TABLE `otp_verifications` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `phone_hash` VARCHAR(64) NOT NULL,
  `otp_code_hash` VARCHAR(255) NOT NULL,
  `attempts` INT UNSIGNED NOT NULL DEFAULT 0,
  `is_used` TINYINT(1) NOT NULL DEFAULT 0,
  `expires_at` TIMESTAMP NOT NULL,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  KEY `idx_otp_phone_hash` (`phone_hash`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

-- ------------------------------------------------------------------------------
-- 15. Table: chat_messages (المحادثات المباشرة بين الطلاب والمعلمين)
-- ------------------------------------------------------------------------------
CREATE TABLE `chat_messages` (
  `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
  `uuid` CHAR(36) NOT NULL,
  `sender_id` BIGINT UNSIGNED NOT NULL,
  `receiver_id` BIGINT UNSIGNED NOT NULL,
  `course_id` BIGINT UNSIGNED DEFAULT NULL,
  `lesson_id` BIGINT UNSIGNED DEFAULT NULL,
  `message` TEXT NOT NULL,
  `message_type` ENUM('text', 'voice', 'image', 'file') NOT NULL DEFAULT 'text',
  `media_url` VARCHAR(500) DEFAULT NULL,
  `is_read` TINYINT(1) NOT NULL DEFAULT 0,
  `read_at` TIMESTAMP NULL DEFAULT NULL,
  `created_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `idx_chat_messages_uuid` (`uuid`),
  KEY `idx_chat_sender_receiver` (`sender_id`, `receiver_id`),
  KEY `idx_chat_receiver_unread` (`receiver_id`, `is_read`),
  KEY `idx_chat_course` (`course_id`),
  KEY `idx_chat_created_at` (`created_at`),
  CONSTRAINT `fk_chat_sender` FOREIGN KEY (`sender_id`) REFERENCES `users` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_chat_receiver` FOREIGN KEY (`receiver_id`) REFERENCES `users` (`id`) ON DELETE CASCADE,
  CONSTRAINT `fk_chat_course` FOREIGN KEY (`course_id`) REFERENCES `courses` (`id`) ON DELETE SET NULL,
  CONSTRAINT `fk_chat_lesson` FOREIGN KEY (`lesson_id`) REFERENCES `lessons` (`id`) ON DELETE SET NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

SET FOREIGN_KEY_CHECKS = 1;