Tasks/backend/models/Category.js

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

module.exports = (sequelize, DataTypes) => {
  const Category = sequelize.define('Category', {
    id: {
      type: DataTypes.CHAR(36),
      primaryKey: true,
      defaultValue: () => uuidv4(),
      allowNull: false,
      comment: 'UUID primary key'
    },
    name: {
      type: DataTypes.STRING(100),
      allowNull: false,
      unique: {
        msg: 'Category name already exists'
      },
      validate: {
        notEmpty: {
          msg: 'Category name cannot be empty'
        },
        len: {
          args: [2, 100],
          msg: 'Category name must be between 2 and 100 characters'
        }
      },
      comment: 'Category name'
    },
    slug: {
      type: DataTypes.STRING(100),
      allowNull: false,
      unique: {
        msg: 'Category slug already exists'
      },
      validate: {
        notEmpty: {
          msg: 'Slug cannot be empty'
        },
        is: {
          args: /^[a-z0-9]+(?:-[a-z0-9]+)*$/,
          msg: 'Slug must be lowercase alphanumeric with hyphens only'
        }
      },
      comment: 'URL-friendly slug'
    },
    description: {
      type: DataTypes.TEXT,
      allowNull: true,
      comment: 'Category description'
    },
    icon: {
      type: DataTypes.STRING(255),
      allowNull: true,
      comment: 'Icon URL or class'
    },
    color: {
      type: DataTypes.STRING(20),
      allowNull: true,
      validate: {
        is: {
          args: /^#[0-9A-F]{6}$/i,
          msg: 'Color must be a valid hex color (e.g., #FF5733)'
        }
      },
      comment: 'Display color (hex format)'
    },
    isActive: {
      type: DataTypes.BOOLEAN,
      allowNull: false,
      defaultValue: true,
      field: 'is_active',
      comment: 'Category active status'
    },
    guestAccessible: {
      type: DataTypes.BOOLEAN,
      allowNull: false,
      defaultValue: false,
      field: 'guest_accessible',
      comment: 'Whether guests can access this category'
    },
    
    // Statistics
    questionCount: {
      type: DataTypes.INTEGER,
      allowNull: false,
      defaultValue: 0,
      field: 'question_count',
      validate: {
        min: 0
      },
      comment: 'Total number of questions in this category'
    },
    quizCount: {
      type: DataTypes.INTEGER,
      allowNull: false,
      defaultValue: 0,
      field: 'quiz_count',
      validate: {
        min: 0
      },
      comment: 'Total number of quizzes taken in this category'
    },
    
    // Display order
    displayOrder: {
      type: DataTypes.INTEGER,
      allowNull: false,
      defaultValue: 0,
      field: 'display_order',
      comment: 'Display order (lower numbers first)'
    }
  }, {
    sequelize,
    modelName: 'Category',
    tableName: 'categories',
    timestamps: true,
    underscored: true,
    indexes: [
      {
        unique: true,
        fields: ['name']
      },
      {
        unique: true,
        fields: ['slug']
      },
      {
        fields: ['is_active']
      },
      {
        fields: ['guest_accessible']
      },
      {
        fields: ['display_order']
      },
      {
        fields: ['is_active', 'guest_accessible']
      }
    ]
  });

  // Helper function to generate slug from name
  Category.generateSlug = function(name) {
    return name
      .toLowerCase()
      .trim()
      .replace(/[^\w\s-]/g, '') // Remove special characters
      .replace(/[\s_-]+/g, '-') // Replace spaces and underscores with hyphens
      .replace(/^-+|-+$/g, ''); // Remove leading/trailing hyphens
  };

  // Instance methods
  Category.prototype.incrementQuestionCount = async function() {
    this.questionCount += 1;
    await this.save();
  };

  Category.prototype.decrementQuestionCount = async function() {
    if (this.questionCount > 0) {
      this.questionCount -= 1;
      await this.save();
    }
  };

  Category.prototype.incrementQuizCount = async function() {
    this.quizCount += 1;
    await this.save();
  };

  // Class methods
  Category.findActiveCategories = async function(includeGuestOnly = false) {
    const where = { isActive: true };
    if (includeGuestOnly) {
      where.guestAccessible = true;
    }
    return await this.findAll({
      where,
      order: [['displayOrder', 'ASC'], ['name', 'ASC']]
    });
  };

  Category.findBySlug = async function(slug) {
    return await this.findOne({
      where: { slug, isActive: true }
    });
  };

  Category.getGuestAccessibleCategories = async function() {
    return await this.findAll({
      where: {
        isActive: true,
        guestAccessible: true
      },
      order: [['displayOrder', 'ASC'], ['name', 'ASC']]
    });
  };

  Category.getCategoriesWithStats = async function() {
    return await this.findAll({
      where: { isActive: true },
      attributes: [
        'id',
        'name',
        'slug',
        'description',
        'icon',
        'color',
        'questionCount',
        'quizCount',
        'guestAccessible',
        'displayOrder'
      ],
      order: [['displayOrder', 'ASC'], ['name', 'ASC']]
    });
  };

  // Hooks
  Category.beforeValidate((category) => {
    // Auto-generate slug from name if not provided
    if (!category.slug && category.name) {
      category.slug = Category.generateSlug(category.name);
    }
    
    // Ensure UUID is set
    if (!category.id) {
      category.id = uuidv4();
    }
  });

  Category.beforeCreate((category) => {
    // Ensure slug is generated even if validation was skipped
    if (!category.slug && category.name) {
      category.slug = Category.generateSlug(category.name);
    }
  });

  Category.beforeUpdate((category) => {
    // Regenerate slug if name changed
    if (category.changed('name') && !category.changed('slug')) {
      category.slug = Category.generateSlug(category.name);
    }
  });

  // Define associations
  Category.associate = function(models) {
    // Category has many questions
    if (models.Question) {
      Category.hasMany(models.Question, {
        foreignKey: 'categoryId',
        as: 'questions'
      });
    }

    // Category has many quiz sessions
    if (models.QuizSession) {
      Category.hasMany(models.QuizSession, {
        foreignKey: 'categoryId',
        as: 'quizSessions'
      });
    }

    // Category belongs to many guest settings (for guest-accessible categories)
    if (models.GuestSettings) {
      Category.belongsToMany(models.GuestSettings, {
        through: 'guest_settings_categories',
        foreignKey: 'categoryId',
        otherKey: 'guestSettingsId',
        as: 'guestSettings'
      });
    }
  };

  return Category;
};