'use strict';

module.exports = {
  async up(queryInterface, Sequelize) {
    await queryInterface.createTable('quiz_attempts', {
      attempt_id:      { type: Sequelize.BIGINT, primaryKey: true, autoIncrement: true },
      uuid:            { type: Sequelize.UUID, defaultValue: Sequelize.UUIDV4, unique: true },
      user_id:         { type: Sequelize.BIGINT, allowNull: false, references: { model: 'users', key: 'user_id' }, onDelete: 'CASCADE' },
      quiz_id:         { type: Sequelize.BIGINT, allowNull: true, references: { model: 'unit_quizzes',       key: 'quiz_id'       }, onDelete: 'SET NULL' },
      assessment_id:   { type: Sequelize.BIGINT, allowNull: true, references: { model: 'course_assessments', key: 'assessment_id' }, onDelete: 'SET NULL' },
      answers:         { type: Sequelize.JSONB, allowNull: false, defaultValue: {} },
      total_points:    { type: Sequelize.INTEGER, allowNull: false, defaultValue: 0 },
      earned_points:   { type: Sequelize.INTEGER, allowNull: false, defaultValue: 0 },
      score:           { type: Sequelize.INTEGER, allowNull: false, defaultValue: 0 },
      passed:          { type: Sequelize.BOOLEAN, allowNull: false, defaultValue: false },
      attempt_number:  {
        type:         Sequelize.INTEGER,
        allowNull:    false,
        defaultValue: 1,
        comment:      '1-based counter per user + quiz (or user + assessment). Derived at insert time from prior attempt count.',
      },
      passing_score:   {
        type:      Sequelize.INTEGER,
        allowNull: true,
        comment:   'Snapshot of the required passing score at the time of submission.',
      },
      course_id:       {
        type:       Sequelize.BIGINT,
        allowNull:  true,
        references: { model: 'courses', key: 'course_id' },
        onDelete:   'SET NULL',
        comment:    'Denormalized course reference for fast per-course attempt queries.',
      },
      createdAt:       { type: Sequelize.DATE, allowNull: false },
      updatedAt:       { type: Sequelize.DATE, allowNull: false },
    });

    await queryInterface.addIndex('quiz_attempts', ['user_id']);
    await queryInterface.addIndex('quiz_attempts', ['quiz_id']);
    await queryInterface.addIndex('quiz_attempts', ['assessment_id']);
    await queryInterface.addIndex('quiz_attempts', { fields: ['course_id'], name: 'idx_qa_course_id' });
  },

  async down(queryInterface) {
    await queryInterface.dropTable('quiz_attempts');
  },
};