'use strict';

module.exports = {
  async up(queryInterface, Sequelize) {
    await queryInterface.createTable('course_units', {
      course_unit_id: { type: Sequelize.BIGINT, primaryKey: true, autoIncrement: true },
      course_id:      { type: Sequelize.BIGINT, allowNull: false, references: { model: 'courses', key: 'course_id' }, onDelete: 'CASCADE' },
      unit_id:        { type: Sequelize.BIGINT, allowNull: false, references: { model: 'units',   key: 'unit_id'   }, onDelete: 'CASCADE' },
      order_index:    { type: Sequelize.INTEGER, allowNull: false, defaultValue: 0 },
      createdBy:      { type: Sequelize.BIGINT, allowNull: true },
      updatedBy:      { type: Sequelize.BIGINT, allowNull: true },
      createdAt:      { type: Sequelize.DATE, allowNull: false, defaultValue: Sequelize.literal('CURRENT_TIMESTAMP') },
      updatedAt:      { type: Sequelize.DATE, allowNull: false, defaultValue: Sequelize.literal('CURRENT_TIMESTAMP') },
    });

    await queryInterface.addIndex('course_units', { fields: ['course_id', 'unit_id'], unique: true, name: 'uq_course_units_course_unit' });
    await queryInterface.addIndex('course_units', { fields: ['course_id'],   name: 'idx_course_units_course_id' });
    await queryInterface.addIndex('course_units', { fields: ['unit_id'],     name: 'idx_course_units_unit_id' });
    await queryInterface.addIndex('course_units', { fields: ['order_index'], name: 'idx_course_units_order' });
  },

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