'use strict';

const { v4: uuidv4 } = require('uuid');

module.exports = {
  async up(queryInterface, Sequelize) {
    // Add UUID column to tasks table (without unique constraint initially)
    await queryInterface.addColumn('tasks', 'uuid', {
      type: Sequelize.UUID,
      allowNull: true
    });

    // Backfill existing tasks with UUIDs
    const tasks = await queryInterface.sequelize.query(
      'SELECT id FROM tasks WHERE uuid IS NULL',
      { type: Sequelize.QueryTypes.SELECT }
    );

    for (const task of tasks) {
      const uuid = uuidv4();
      await queryInterface.sequelize.query(
        'UPDATE tasks SET uuid = ? WHERE id = ?',
        { replacements: [uuid, task.id] }
      );
    }

    // Add unique index for UUID
    await queryInterface.addIndex('tasks', ['uuid'], {
      unique: true,
      name: 'tasks_uuid_unique'
    });
  },

  async down(queryInterface, Sequelize) {
    // Remove index first
    await queryInterface.removeIndex('tasks', 'tasks_uuid_unique');
    
    // Remove UUID column
    await queryInterface.removeColumn('tasks', 'uuid');
  }
};