'use strict';

module.exports = {
  async up(queryInterface, Sequelize) {
    await queryInterface.createTable('unit_lessons', {
      unit_lesson_id: { type: Sequelize.BIGINT, primaryKey: true, autoIncrement: true },
      unit_id:        { type: Sequelize.BIGINT, allowNull: false, references: { model: 'units',   key: 'unit_id'   }, onDelete: 'CASCADE' },
      lesson_id:      { type: Sequelize.BIGINT, allowNull: false, references: { model: 'lessons', key: 'lesson_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('unit_lessons', { fields: ['unit_id', 'lesson_id'], unique: true, name: 'uq_unit_lessons_unit_lesson' });
    await queryInterface.addIndex('unit_lessons', { fields: ['unit_id'],     name: 'idx_unit_lessons_unit_id' });
    await queryInterface.addIndex('unit_lessons', { fields: ['lesson_id'],   name: 'idx_unit_lessons_lesson_id' });
    await queryInterface.addIndex('unit_lessons', { fields: ['order_index'], name: 'idx_unit_lessons_order' });
  },

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