'use strict';

module.exports = {
  async up(queryInterface, Sequelize) {
    await queryInterface.addColumn('quiz_attempts', '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.',
    });

    await queryInterface.addColumn('quiz_attempts', 'passing_score', {
      type:         Sequelize.INTEGER,
      allowNull:    true,
      comment:      'Snapshot of the required passing score at the time of submission.',
    });

    await queryInterface.addColumn('quiz_attempts', '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.',
    });

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

  async down(queryInterface) {
    await queryInterface.removeIndex('quiz_attempts', 'idx_qa_course_id');
    await queryInterface.removeColumn('quiz_attempts', 'course_id');
    await queryInterface.removeColumn('quiz_attempts', 'passing_score');
    await queryInterface.removeColumn('quiz_attempts', 'attempt_number');
  },
};