'use strict';

// Generalizes `products` from Course-only (`course_id`) to a polymorphic
// target (`purchasable_type` + `purchasable_id`) so standalone Units and
// Lessons can also be sold individually, alongside plan-tier gating — see
// utils/purchasable.util.js for the resolver used by every consumer.
//
// purchasable_type is STRING + explicit CHECK, not a real ENUM (CockroachDB
// can't create a new enum type via addColumn the way createTable can — same
// caveat as 20270101000076-add-assets-transcode-status.js).
//
// Dropping `course_id` also drops its FK (`onDelete: 'CASCADE'` from
// 20270101000019-create-products.js) — referential integrity across the three
// possible targets is now enforced at the application layer only, same as
// course_purchases.product_id already is today.
//
// Touches a table with live production rows (real courses have real
// products/course_purchases). NOT auto-run — test against a local/staging
// copy of the DB first; do not execute against the shared dev/prod database
// without explicit confirmation.
module.exports = {
  async up(queryInterface, Sequelize) {
    await queryInterface.addColumn('products', 'purchasable_type', {
      type: Sequelize.STRING(10),
      allowNull: false,
      defaultValue: 'course',
    });

    await queryInterface.addConstraint('products', {
      fields: ['purchasable_type'],
      type: 'check',
      name: 'check_products_purchasable_type',
      where: { purchasable_type: { [Sequelize.Op.in]: ['course', 'unit', 'lesson'] } },
    });

    await queryInterface.addColumn('products', 'purchasable_id', {
      type: Sequelize.BIGINT,
      allowNull: true, // filled by the backfill below, then locked to NOT NULL
    });

    await queryInterface.sequelize.query(`
      UPDATE products SET purchasable_type = 'course', purchasable_id = course_id;
    `);

    await queryInterface.changeColumn('products', 'purchasable_id', {
      type: Sequelize.BIGINT,
      allowNull: false,
    });

    await queryInterface.removeIndex('products', ['course_id']);
    await queryInterface.removeColumn('products', 'course_id');

    await queryInterface.addIndex('products', ['purchasable_type', 'purchasable_id'], {
      name: 'products_purchasable_type_id',
    });
  },

  async down(queryInterface, Sequelize) {
    await queryInterface.removeIndex('products', 'products_purchasable_type_id');

    await queryInterface.addColumn('products', 'course_id', {
      type: Sequelize.BIGINT,
      allowNull: true,
    });

    await queryInterface.sequelize.query(`
      UPDATE products SET course_id = purchasable_id WHERE purchasable_type = 'course';
    `);

    await queryInterface.changeColumn('products', 'course_id', {
      type: Sequelize.BIGINT,
      allowNull: false,
    });

    await queryInterface.addIndex('products', ['course_id']);

    await queryInterface.removeColumn('products', 'purchasable_id');
    await queryInterface.removeConstraint('products', 'check_products_purchasable_type');
    await queryInterface.removeColumn('products', 'purchasable_type');
  },
};