'use strict';

/** @type {import('sequelize-cli').Migration} */
module.exports = {
  async up(queryInterface, Sequelize) {
    await queryInterface.createTable('quiz_session_questions', {
      id: {
        type: Sequelize.CHAR(36),
        primaryKey: true,
        allowNull: false,
        comment: 'UUID primary key'
      },
      quiz_session_id: {
        type: Sequelize.CHAR(36),
        allowNull: false,
        references: {
          model: 'quiz_sessions',
          key: 'id'
        },
        onUpdate: 'CASCADE',
        onDelete: 'CASCADE',
        comment: 'Foreign key to quiz_sessions table'
      },
      question_id: {
        type: Sequelize.CHAR(36),
        allowNull: false,
        references: {
          model: 'questions',
          key: 'id'
        },
        onUpdate: 'CASCADE',
        onDelete: 'CASCADE',
        comment: 'Foreign key to questions table'
      },
      question_order: {
        type: Sequelize.INTEGER.UNSIGNED,
        allowNull: false,
        comment: 'Order of question in the quiz (1-based)'
      },
      created_at: {
        type: Sequelize.DATE,
        allowNull: false,
        defaultValue: Sequelize.literal('CURRENT_TIMESTAMP'),
        comment: 'Record creation timestamp'
      },
      updated_at: {
        type: Sequelize.DATE,
        allowNull: false,
        defaultValue: Sequelize.literal('CURRENT_TIMESTAMP'),
        comment: 'Record last update timestamp'
      }
    }, {
      charset: 'utf8mb4',
      collate: 'utf8mb4_unicode_ci',
      comment: 'Junction table linking quiz sessions with questions'
    });

    // Add indexes
    await queryInterface.addIndex('quiz_session_questions', ['quiz_session_id'], {
      name: 'idx_qsq_session_id'
    });

    await queryInterface.addIndex('quiz_session_questions', ['question_id'], {
      name: 'idx_qsq_question_id'
    });

    await queryInterface.addIndex('quiz_session_questions', ['question_order'], {
      name: 'idx_qsq_question_order'
    });

    // Unique composite index to prevent duplicate questions in same session
    await queryInterface.addIndex('quiz_session_questions', ['quiz_session_id', 'question_id'], {
      name: 'idx_qsq_session_question',
      unique: true
    });

    console.log('✅ Quiz session questions junction table created with 5 fields and 4 indexes');
  },

  async down(queryInterface, Sequelize) {
    await queryInterface.dropTable('quiz_session_questions');
    console.log('✅ Quiz session questions table dropped');
  }
};