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

module.exports = (sequelize, DataTypes) => {
  const QuizAnswer = sequelize.define('QuizAnswer', {
    id: {
      type: DataTypes.CHAR(36),
      primaryKey: true,
      defaultValue: () => uuidv4(),
      allowNull: false,
      comment: 'UUID primary key'
    },
    quizSessionId: {
      type: DataTypes.CHAR(36),
      allowNull: false,
      field: 'quiz_session_id',
      validate: {
        notEmpty: {
          msg: 'Quiz session ID is required'
        },
        isUUID: {
          args: 4,
          msg: 'Quiz session ID must be a valid UUID'
        }
      },
      comment: 'Foreign key to quiz_sessions table'
    },
    questionId: {
      type: DataTypes.CHAR(36),
      allowNull: false,
      field: 'question_id',
      validate: {
        notEmpty: {
          msg: 'Question ID is required'
        },
        isUUID: {
          args: 4,
          msg: 'Question ID must be a valid UUID'
        }
      },
      comment: 'Foreign key to questions table'
    },
    selectedOption: {
      type: DataTypes.STRING(255),
      allowNull: false,
      field: 'selected_option',
      validate: {
        notEmpty: {
          msg: 'Selected option is required'
        }
      },
      comment: 'The option selected by the user'
    },
    isCorrect: {
      type: DataTypes.BOOLEAN,
      allowNull: false,
      field: 'is_correct',
      comment: 'Whether the selected answer was correct'
    },
    pointsEarned: {
      type: DataTypes.INTEGER.UNSIGNED,
      allowNull: false,
      defaultValue: 0,
      field: 'points_earned',
      validate: {
        min: {
          args: [0],
          msg: 'Points earned must be non-negative'
        }
      },
      comment: 'Points earned for this answer'
    },
    timeTaken: {
      type: DataTypes.INTEGER.UNSIGNED,
      allowNull: false,
      defaultValue: 0,
      field: 'time_taken',
      validate: {
        min: {
          args: [0],
          msg: 'Time taken must be non-negative'
        }
      },
      comment: 'Time taken to answer in seconds'
    },
    answeredAt: {
      type: DataTypes.DATE,
      allowNull: false,
      defaultValue: DataTypes.NOW,
      field: 'answered_at',
      comment: 'When the question was answered'
    }
  }, {
    tableName: 'quiz_answers',
    timestamps: true,
    underscored: true,
    indexes: [
      {
        fields: ['quiz_session_id'],
        name: 'idx_quiz_answers_session_id'
      },
      {
        fields: ['question_id'],
        name: 'idx_quiz_answers_question_id'
      },
      {
        fields: ['quiz_session_id', 'question_id'],
        unique: true,
        name: 'idx_quiz_answers_session_question_unique'
      },
      {
        fields: ['is_correct'],
        name: 'idx_quiz_answers_is_correct'
      },
      {
        fields: ['answered_at'],
        name: 'idx_quiz_answers_answered_at'
      }
    ]
  });

  // Associations
  QuizAnswer.associate = (models) => {
    QuizAnswer.belongsTo(models.QuizSession, {
      foreignKey: 'quizSessionId',
      as: 'quizSession'
    });
    QuizAnswer.belongsTo(models.Question, {
      foreignKey: 'questionId',
      as: 'question'
    });
  };

  return QuizAnswer;
};