'use strict';

// Part 1B — task_lists' tasks currently sort only by createdAt (no ordering
// column exists). Add order_index (position within the list) and is_required
// (mirrors unit_quizzes.is_required — an optional task doesn't block anything
// after it in the sequencing lock).

module.exports = {
  async up(queryInterface, Sequelize) {
    await queryInterface.addColumn('tasks', 'order_index', {
      type: Sequelize.INTEGER,
      allowNull: false,
      defaultValue: 0,
      after: 'deadline',
    });
    await queryInterface.addColumn('tasks', 'is_required', {
      type: Sequelize.BOOLEAN,
      allowNull: false,
      defaultValue: true,
      after: 'order_index',
    });

    // Backfill existing rows with a stable order matching current createdAt
    // sort, so tasks don't all collapse to order_index 0 on first use.
    await queryInterface.sequelize.query(`
      UPDATE tasks t SET order_index = sub.rn - 1
      FROM (
        SELECT task_id, ROW_NUMBER() OVER (PARTITION BY task_list_id ORDER BY "createdAt" ASC) AS rn
        FROM tasks
      ) sub
      WHERE t.task_id = sub.task_id
    `);
  },

  async down(queryInterface) {
    await queryInterface.removeColumn('tasks', 'is_required');
    await queryInterface.removeColumn('tasks', 'order_index');
  },
};