'use strict';

/** @type {import('sequelize-cli').Migration} */
module.exports = {
  async up(queryInterface, Sequelize) {
    await queryInterface.createTable('quiz_answers', {
      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'
      },
      selected_option: {
        type: Sequelize.STRING(255),
        allowNull: false,
        comment: 'The option selected by the user'
      },
      is_correct: {
        type: Sequelize.BOOLEAN,
        allowNull: false,
        comment: 'Whether the selected answer was correct'
      },
      points_earned: {
        type: Sequelize.INTEGER.UNSIGNED,
        allowNull: false,
        defaultValue: 0,
        comment: 'Points earned for this answer'
      },
      time_taken: {
        type: Sequelize.INTEGER.UNSIGNED,
        allowNull: false,
        defaultValue: 0,
        comment: 'Time taken to answer in seconds'
      },
      answered_at: {
        type: Sequelize.DATE,
        allowNull: false,
        defaultValue: Sequelize.literal('CURRENT_TIMESTAMP'),
        comment: 'When the question was answered'
      },
      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: 'Stores individual answers given during quiz sessions'
    });

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

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

    await queryInterface.addIndex('quiz_answers', ['is_correct'], {
      name: 'idx_quiz_answers_is_correct'
    });

    await queryInterface.addIndex('quiz_answers', ['answered_at'], {
      name: 'idx_quiz_answers_answered_at'
    });

    // Composite index for session + question (unique constraint)
    await queryInterface.addIndex('quiz_answers', ['quiz_session_id', 'question_id'], {
      name: 'idx_quiz_answers_session_question',
      unique: true
    });

    console.log('✅ Quiz answers table created successfully with 9 fields and 5 indexes');
  },

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