'use strict';

/** @type {import('sequelize-cli').Migration} */
module.exports = {
  async up (queryInterface, Sequelize) {
    console.log('Creating questions table...');
    
    await queryInterface.createTable('questions', {
      id: {
        type: Sequelize.CHAR(36),
        primaryKey: true,
        allowNull: false,
        comment: 'UUID primary key'
      },
      category_id: {
        type: Sequelize.CHAR(36),
        allowNull: false,
        references: {
          model: 'categories',
          key: 'id'
        },
        onUpdate: 'CASCADE',
        onDelete: 'RESTRICT',
        comment: 'Foreign key to categories table'
      },
      created_by: {
        type: Sequelize.CHAR(36),
        allowNull: true,
        references: {
          model: 'users',
          key: 'id'
        },
        onUpdate: 'CASCADE',
        onDelete: 'SET NULL',
        comment: 'User who created the question (admin)'
      },
      question_text: {
        type: Sequelize.TEXT,
        allowNull: false,
        comment: 'The question text'
      },
      question_type: {
        type: Sequelize.ENUM('multiple', 'trueFalse', 'written'),
        allowNull: false,
        defaultValue: 'multiple',
        comment: 'Type of question'
      },
      options: {
        type: Sequelize.JSON,
        allowNull: true,
        comment: 'Answer options for multiple choice (JSON array)'
      },
      correct_answer: {
        type: Sequelize.STRING(255),
        allowNull: false,
        comment: 'Correct answer (index for multiple choice, true/false for boolean)'
      },
      explanation: {
        type: Sequelize.TEXT,
        allowNull: true,
        comment: 'Explanation for the correct answer'
      },
      difficulty: {
        type: Sequelize.ENUM('easy', 'medium', 'hard'),
        allowNull: false,
        defaultValue: 'medium',
        comment: 'Question difficulty level'
      },
      points: {
        type: Sequelize.INTEGER,
        allowNull: false,
        defaultValue: 10,
        comment: 'Points awarded for correct answer'
      },
      time_limit: {
        type: Sequelize.INTEGER,
        allowNull: true,
        comment: 'Time limit in seconds (optional)'
      },
      keywords: {
        type: Sequelize.JSON,
        allowNull: true,
        comment: 'Search keywords (JSON array)'
      },
      tags: {
        type: Sequelize.JSON,
        allowNull: true,
        comment: 'Tags for categorization (JSON array)'
      },
      visibility: {
        type: Sequelize.ENUM('public', 'registered', 'premium'),
        allowNull: false,
        defaultValue: 'registered',
        comment: 'Who can see this question'
      },
      guest_accessible: {
        type: Sequelize.BOOLEAN,
        allowNull: false,
        defaultValue: false,
        comment: 'Whether guests can access this question'
      },
      is_active: {
        type: Sequelize.BOOLEAN,
        allowNull: false,
        defaultValue: true,
        comment: 'Question active status'
      },
      times_attempted: {
        type: Sequelize.INTEGER,
        allowNull: false,
        defaultValue: 0,
        comment: 'Number of times question was attempted'
      },
      times_correct: {
        type: Sequelize.INTEGER,
        allowNull: false,
        defaultValue: 0,
        comment: 'Number of times answered correctly'
      },
      created_at: {
        type: Sequelize.DATE,
        allowNull: false,
        defaultValue: Sequelize.literal('CURRENT_TIMESTAMP')
      },
      updated_at: {
        type: Sequelize.DATE,
        allowNull: false,
        defaultValue: Sequelize.literal('CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP')
      }
    }, {
      charset: 'utf8mb4',
      collate: 'utf8mb4_unicode_ci',
      engine: 'InnoDB'
    });

    // Add indexes
    await queryInterface.addIndex('questions', ['category_id'], {
      name: 'idx_questions_category_id'
    });

    await queryInterface.addIndex('questions', ['created_by'], {
      name: 'idx_questions_created_by'
    });

    await queryInterface.addIndex('questions', ['question_type'], {
      name: 'idx_questions_question_type'
    });

    await queryInterface.addIndex('questions', ['difficulty'], {
      name: 'idx_questions_difficulty'
    });

    await queryInterface.addIndex('questions', ['visibility'], {
      name: 'idx_questions_visibility'
    });

    await queryInterface.addIndex('questions', ['guest_accessible'], {
      name: 'idx_questions_guest_accessible'
    });

    await queryInterface.addIndex('questions', ['is_active'], {
      name: 'idx_questions_is_active'
    });

    await queryInterface.addIndex('questions', ['created_at'], {
      name: 'idx_questions_created_at'
    });

    // Composite index for common query patterns
    await queryInterface.addIndex('questions', ['category_id', 'is_active', 'difficulty'], {
      name: 'idx_questions_category_active_difficulty'
    });

    await queryInterface.addIndex('questions', ['is_active', 'guest_accessible'], {
      name: 'idx_questions_active_guest'
    });

    // Full-text search index
    await queryInterface.sequelize.query(
      'CREATE FULLTEXT INDEX idx_questions_fulltext ON questions(question_text, explanation)'
    );

    console.log('✅ Questions table created successfully with indexes and full-text search');
  },

  async down (queryInterface, Sequelize) {
    console.log('Dropping questions table...');
    await queryInterface.dropTable('questions');
    console.log('✅ Questions table dropped successfully');
  }
};