import { sample, random, shuffle } from 'lodash-es';
import logger from '../utils/logger.js';

class CodeGenerator {
  constructor(config) {
    this.config = config;
    this.bugProbability = config.activity.bugProbability;
    this.typoProbability = config.activity.typoProbability;
  }

  generateProjectStructure() {
    const structures = [
      {
        name: 'utils',
        files: [
          { path: 'src/utils/helpers.js', type: 'utility' },
          { path: 'src/utils/validators.js', type: 'validator' },
          { path: 'src/utils/formatters.js', type: 'formatter' },
        ],
      },
      {
        name: 'services',
        files: [
          { path: 'src/services/api.js', type: 'api' },
          { path: 'src/services/cache.js', type: 'cache' },
          { path: 'src/services/logger.js', type: 'logger' },
        ],
      },
      {
        name: 'models',
        files: [
          { path: 'src/models/user.js', type: 'model' },
          { path: 'src/models/product.js', type: 'model' },
          { path: 'src/models/order.js', type: 'model' },
        ],
      },
      {
        name: 'middleware',
        files: [
          { path: 'src/middleware/auth.js', type: 'auth' },
          { path: 'src/middleware/errorHandler.js', type: 'error' },
          { path: 'src/middleware/rateLimiter.js', type: 'rateLimiter' },
        ],
      },
    ];

    return sample(structures);
  }

  generateFileContent(fileType, context = {}) {
    const generators = {
      utility: () => this._generateUtility(context),
      validator: () => this._generateValidator(context),
      formatter: () => this._generateFormatter(context),
      api: () => this._generateApiService(context),
      cache: () => this._generateCache(context),
      logger: () => this._generateLogger(context),
      model: () => this._generateModel(context),
      auth: () => this._generateAuthMiddleware(context),
      error: () => this._generateErrorHandler(context),
      rateLimiter: () => this._generateRateLimiter(context),
    };

    const generator = generators[fileType] || generators.utility;
    let content = generator();

    if (Math.random() < this.bugProbability) {
      content = this._injectBug(content);
    }

    if (Math.random() < this.typoProbability) {
      content = this._injectTypo(content);
    }

    return content;
  }

  _generateUtility(context) {
    const utilities = [
      this._debounceFunction(),
      this._throttleFunction(),
      this._deepCloneFunction(),
      this._flattenObject(),
      this._retryFunction(),
      this._eventEmitter(),
      this._memoizeFunction(),
      this._pipeFunction(),
    ];

    return sample(utilities);
  }

  _debounceFunction() {
    return `/**
 * Creates a debounced function that delays invoking func until
 * after wait milliseconds have elapsed since the last invocation.
 * @param {Function} func - The function to debounce
 * @param {number} wait - Milliseconds to wait
 * @returns {Function} Debounced function
 */
export function debounce(func, wait = 300) {
  let timeoutId = null;

  return function (...args) {
    const later = () => {
      timeoutId = null;
      func.apply(this, args);
    };

    clearTimeout(timeoutId);
    timeoutId = setTimeout(later, wait);
  };
}

/**
 * Creates a throttled function that only invokes func at most
 * once per every wait milliseconds.
 * @param {Function} func - The function to throttle
 * @param {number} wait - Milliseconds to wait
 * @returns {Function} Throttled function
 */
export function throttle(func, wait = 300) {
  let lastCall = 0;
  let timeoutId = null;

  return function (...args) {
    const now = Date.now();
    const remaining = wait - (now - lastCall);

    if (remaining <= 0) {
      if (timeoutId) {
        clearTimeout(timeoutId);
        timeoutId = null;
      }
      lastCall = now;
      func.apply(this, args);
    } else if (!timeoutId) {
      timeoutId = setTimeout(() => {
        lastCall = Date.now();
        timeoutId = null;
        func.apply(this, args);
      }, remaining);
    }
  };
}
`;
  }

  _throttleFunction() {
    return `/**
 * Deep clones an object, handling circular references.
 * @param {*} obj - The object to clone
 * @param {WeakMap} seen - Map to track circular references
 * @returns {*} Deep cloned object
 */
export function deepClone(obj, seen = new WeakMap()) {
  if (obj === null || typeof obj !== 'object') {
    return obj;
  }

  if (seen.has(obj)) {
    return seen.get(obj);
  }

  if (obj instanceof Date) {
    return new Date(obj.getTime());
  }

  if (obj instanceof RegExp) {
    return new RegExp(obj.source, obj.flags);
  }

  if (Array.isArray(obj)) {
    const cloned = obj.map(item => deepClone(item, seen));
    seen.set(obj, cloned);
    return cloned;
  }

  const cloned = Object.create(Object.getPrototypeOf(obj));
  seen.set(obj, cloned);

  for (const [key, value] of Object.entries(obj)) {
    cloned[key] = deepClone(value, seen);
  }

  return cloned;
}

/**
 * Checks if two values are deeply equal.
 * @param {*} a - First value
 * @param {*} b - Second value
 * @returns {boolean} True if deeply equal
 */
export function deepEqual(a, b) {
  if (a === b) return true;

  if (a == null || b == null) return false;

  if (typeof a !== typeof b) return false;

  if (Array.isArray(a)) {
    if (!Array.isArray(b) || a.length !== b.length) return false;
    return a.every((item, i) => deepEqual(item, b[i]));
  }

  if (typeof a === 'object') {
    const keysA = Object.keys(a);
    const keysB = Object.keys(b);

    if (keysA.length !== keysB.length) return false;

    return keysA.every(key => deepEqual(a[key], b[key]));
  }

  return false;
}
`;
  }

  _deepCloneFunction() {
    return `/**
 * Flattens a nested object into a single level with dot notation keys.
 * @param {Object} obj - The object to flatten
 * @param {string} prefix - Key prefix for recursion
 * @returns {Object} Flattened object
 */
export function flattenObject(obj, prefix = '') {
  return Object.keys(obj).reduce((acc, key) => {
    const fullKey = prefix ? \`\${prefix}.\${key}\` : key;
    const value = obj[key];

    if (typeof value === 'object' && value !== null && !Array.isArray(value)) {
      Object.assign(acc, flattenObject(value, fullKey));
    } else {
      acc[fullKey] = value;
    }

    return acc;
  }, {});
}

/**
 * Unflattens a dot-notation object back to nested structure.
 * @param {Object} obj - The flattened object
 * @returns {Object} Nested object
 */
export function unflattenObject(obj) {
  const result = {};

  for (const [key, value] of Object.entries(obj)) {
    const parts = key.split('.');
    let current = result;

    for (let i = 0; i < parts.length - 1; i++) {
      const part = parts[i];
      current[part] = current[part] || {};
      current = current[part];
    }

    current[parts[parts.length - 1]] = value;
  }

  return result;
}
`;
  }

  _flattenObject() {
    return `/**
 * Retries an async function with exponential backoff.
 * @param {Function} fn - Async function to retry
 * @param {Object} options - Retry options
 * @param {number} options.maxRetries - Maximum retry attempts
 * @param {number} options.baseDelay - Base delay in ms
 * @param {number} options.maxDelay - Maximum delay in ms
 * @returns {Promise<*>} Result of the function
 */
export async function retry(fn, { maxRetries = 3, baseDelay = 1000, maxDelay = 10000 } = {}) {
  let lastError;

  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    try {
      return await fn();
    } catch (error) {
      lastError = error;

      if (attempt === maxRetries) {
        break;
      }

      const delay = Math.min(baseDelay * Math.pow(2, attempt), maxDelay);
      const jitter = delay * 0.1 * Math.random();

      await new Promise(resolve => setTimeout(resolve, delay + jitter));
    }
  }

  throw lastError;
}

/**
 * Creates a timeout wrapper for a promise.
 * @param {Promise} promise - The promise to wrap
 * @param {number} ms - Timeout in milliseconds
 * @param {Error} error - Error to throw on timeout
 * @returns {Promise} Wrapped promise
 */
export function withTimeout(promise, ms, error = new Error('Operation timed out')) {
  let timeoutId;

  const timeout = new Promise((_, reject) => {
    timeoutId = setTimeout(() => reject(error), ms);
  });

  return Promise.race([promise, timeout]).finally(() => {
    clearTimeout(timeoutId);
  });
}
`;
  }

  _retryFunction() {
    return `/**
 * Simple event emitter implementation.
 */
export class EventEmitter {
  constructor() {
    this._listeners = new Map();
  }

  /**
   * Register a listener for an event.
   * @param {string} event - Event name
   * @param {Function} listener - Callback function
   * @returns {Function} Unsubscribe function
   */
  on(event, listener) {
    if (!this._listeners.has(event)) {
      this._listeners.set(event, []);
    }

    this._listeners.get(event).push(listener);

    return () => this.off(event, listener);
  }

  /**
   * Register a one-time listener.
   * @param {string} event - Event name
   * @param {Function} listener - Callback function
   */
  once(event, listener) {
    const wrapper = (...args) => {
      listener.apply(this, args);
      this.off(event, wrapper);
    };

    this.on(event, wrapper);
  }

  /**
   * Remove a listener.
   * @param {string} event - Event name
   * @param {Function} listener - Callback function
   */
  off(event, listener) {
    if (!this._listeners.has(event)) return;

    const listeners = this._listeners.get(event);
    const index = listeners.indexOf(listener);

    if (index !== -1) {
      listeners.splice(index, 1);
    }
  }

  /**
   * Emit an event.
   * @param {string} event - Event name
   * @param {...*} args - Arguments to pass to listeners
   */
  emit(event, ...args) {
    if (!this._listeners.has(event)) return;

    const listeners = [...this._listeners.get(event)];

    for (const listener of listeners) {
      try {
        listener.apply(this, args);
      } catch (error) {
        console.error(\`Error in event listener for "\${event}":\`, error);
      }
    }
  }
}
`;
  }

  _eventEmitter() {
    return `/**
 * Creates a memoized version of a function that caches results.
 * @param {Function} fn - Function to memoize
 * @param {Function} [resolver] - Custom cache key resolver
 * @returns {Function} Memoized function
 */
export function memoize(fn, resolver = null) {
  const cache = new Map();

  const memoized = function (...args) {
    const key = resolver ? resolver.apply(this, args) : args[0];

    if (cache.has(key)) {
      return cache.get(key);
    }

    const result = fn.apply(this, args);
    cache.set(key, result);

    return result;
  };

  memoized.cache = cache;

  memoized.clear = () => {
    cache.clear();
  };

  return memoized;
}

/**
 * Creates a function that returns the result of the first
 * predicate that returns a truthy value.
 * @param {...Function} predicates - Functions to try
 * @returns {Function} Combined function
 */
export function firstOf(...predicates) {
  return function (...args) {
    for (const predicate of predicates) {
      const result = predicate.apply(this, args);
      if (result != null) {
        return result;
      }
    }
    return undefined;
  };
}
`;
  }

  _memoizeFunction() {
    return `/**
 * Creates a function pipeline where the output of each function
 * is passed as input to the next.
 * @param {...Function} functions - Functions to compose
 * @returns {Function} Pipeline function
 */
export function pipe(...functions) {
  return function (initialValue) {
    return functions.reduce((value, fn) => fn(value), initialValue);
  };
}

/**
 * Creates a function that composes functions right-to-left.
 * @param {...Function} functions - Functions to compose
 * @returns {Function} Composed function
 */
export function compose(...functions) {
  return function (initialValue) {
    return functions.reduceRight((value, fn) => fn(value), initialValue);
  };
}

/**
 * Creates a curried version of a function.
 * @param {Function} fn - Function to curry
 * @param {number} [arity] - Number of arguments expected
 * @returns {Function} Curried function
 */
export function curry(fn, arity = fn.length) {
  return function curried(...args) {
    if (args.length >= arity) {
      return fn.apply(this, args);
    }

    return (...moreArgs) => curried.apply(this, [...args, ...moreArgs]);
  };
}
`;
  }

  _pipeFunction() {
    return `/**
 * Validation utilities for common data types.
 */

const EMAIL_REGEX = /^[^\\s@]+@[^\\s@]+\\.[^\\s@]+$/;
const PHONE_REGEX = /^\\+?[1-9]\\d{1,14}$/;
const URL_REGEX = /^https?:\\/\\/[^\\s$.?#].[^\\s]*$/;

/**
 * Validates an email address.
 * @param {string} email - Email to validate
 * @returns {boolean} True if valid
 */
export function isValidEmail(email) {
  if (typeof email !== 'string') return false;
  return EMAIL_REGEX.test(email.trim());
}

/**
 * Validates a phone number (E.164 format).
 * @param {string} phone - Phone number to validate
 * @returns {boolean} True if valid
 */
export function isValidPhone(phone) {
  if (typeof phone !== 'string') return false;
  return PHONE_REGEX.test(phone.replace(/[\\s-()]/g, ''));
}

/**
 * Validates a URL.
 * @param {string} url - URL to validate
 * @returns {boolean} True if valid
 */
export function isValidUrl(url) {
  if (typeof url !== 'string') return false;
  try {
    new URL(url);
    return true;
  } catch {
    return false;
  }
}

/**
 * Validates that a string is not empty or whitespace.
 * @param {string} str - String to validate
 * @returns {boolean} True if not empty
 */
export function isNonEmptyString(str) {
  return typeof str === 'string' && str.trim().length > 0;
}

/**
 * Validates that a value is a positive integer.
 * @param {*} value - Value to validate
 * @returns {boolean} True if positive integer
 */
export function isPositiveInt(value) {
  return Number.isInteger(value) && value > 0;
}

/**
 * Creates a validator chain for an object.
 * @param {Object} schema - Validation schema
 * @returns {Object} Validation result
 */
export function validateObject(schema, data) {
  const errors = [];

  for (const [field, rules] of Object.entries(schema)) {
    const value = data[field];

    if (rules.required && (value === undefined || value === null)) {
      errors.push(\`\${field} is required\`);
      continue;
    }

    if (value !== undefined && rules.type && typeof value !== rules.type) {
      errors.push(\`\${field} must be of type \${rules.type}\`);
    }

    if (value !== undefined && rules.validate && !rules.validate(value)) {
      errors.push(\`\${field} failed custom validation\`);
    }
  }

  return {
    isValid: errors.length === 0,
    errors,
  };
}
`;
  }

  _generateValidator() {
    return `/**
 * Formatting utilities for common data transformations.
 */

/**
 * Formats a number as currency.
 * @param {number} amount - The amount to format
 * @param {string} currency - Currency code (default: USD)
 * @param {string} locale - Locale string (default: en-US)
 * @returns {string} Formatted currency string
 */
export function formatCurrency(amount, currency = 'USD', locale = 'en-US') {
  if (typeof amount !== 'number' || isNaN(amount)) {
    throw new TypeError('Amount must be a valid number');
  }

  return new Intl.NumberFormat(locale, {
    style: 'currency',
    currency,
    minimumFractionDigits: 2,
    maximumFractionDigits: 2,
  }).format(amount);
}

/**
 * Formats a date to a readable string.
 * @param {Date|string|number} date - Date to format
 * @param {Object} options - Formatting options
 * @returns {string} Formatted date string
 */
export function formatDate(date, options = {}) {
  const dateObj = date instanceof Date ? date : new Date(date);

  if (isNaN(dateObj.getTime())) {
    throw new TypeError('Invalid date');
  }

  const defaultOptions = {
    year: 'numeric',
    month: 'short',
    day: 'numeric',
    ...options,
  };

  return dateObj.toLocaleDateString('en-US', defaultOptions);
}

/**
 * Truncates a string to a maximum length.
 * @param {string} str - String to truncate
 * @param {number} maxLength - Maximum length
 * @param {string} suffix - Suffix to add (default: '...')
 * @returns {string} Truncated string
 */
export function truncate(str, maxLength, suffix = '...') {
  if (typeof str !== 'string') return '';
  if (str.length <= maxLength) return str;

  return str.slice(0, maxLength - suffix.length) + suffix;
}

/**
 * Capitalizes the first letter of a string.
 * @param {string} str - String to capitalize
 * @returns {string} Capitalized string
 */
export function capitalize(str) {
  if (typeof str !== 'string' || str.length === 0) return '';
  return str.charAt(0).toUpperCase() + str.slice(1);
}

/**
 * Converts a string to slug format.
 * @param {string} str - String to slugify
 * @returns {string} Slugified string
 */
export function slugify(str) {
  return str
    .toLowerCase()
    .trim()
    .replace(/[^\\w\\s-]/g, '')
    .replace(/[\\s_-]+/g, '-')
    .replace(/^-+|-+$/g, '');
}

/**
 * Pads a number with leading zeros.
 * @param {number} num - Number to pad
 * @param {number} length - Target length
 * @returns {string} Padded number string
 */
export function padNumber(num, length = 2) {
  return String(num).padStart(length, '0');
}
`;
  }

  _generateFormatter() {
    return `/**
 * API service with request queuing and response caching.
 */

class ApiService {
  constructor(baseURL, options = {}) {
    this.baseURL = baseURL.replace(/\\/$/, '');
    this.timeout = options.timeout || 10000;
    this.retries = options.retries || 3;
    this._cache = new Map();
    this._queue = [];
    this._processing = false;
  }

  /**
   * Makes a GET request with caching.
   * @param {string} path - Request path
   * @param {Object} params - Query parameters
   * @returns {Promise<Object>} Response data
   */
  async get(path, params = {}) {
    const cacheKey = this._buildCacheKey(path, params);

    if (this._cache.has(cacheKey)) {
      const cached = this._cache.get(cacheKey);
      if (Date.now() - cached.timestamp < 60000) {
        return cached.data;
      }
    }

    const data = await this._request('GET', path, { params });
    this._cache.set(cacheKey, { data, timestamp: Date.now() });

    return data;
  }

  /**
   * Makes a POST request.
   * @param {string} path - Request path
   * @param {Object} body - Request body
   * @returns {Promise<Object>} Response data
   */
  async post(path, body = {}) {
    this._cache.clear();
    return this._request('POST', path, { body });
  }

  /**
   * Makes a PUT request.
   * @param {string} path - Request path
   * @param {Object} body - Request body
   * @returns {Promise<Object>} Response data
   */
  async put(path, body = {}) {
    this._cache.clear();
    return this._request('PUT', path, { body });
  }

  /**
   * Makes a DELETE request.
   * @param {string} path - Request path
   * @returns {Promise<Object>} Response data
   */
  async delete(path) {
    this._cache.clear();
    return this._request('DELETE', path);
  }

  /**
   * Queues a request for batch processing.
   * @param {string} method - HTTP method
   * @param {string} path - Request path
   * @param {Object} options - Request options
   */
  queue(method, path, options = {}) {
    return new Promise((resolve, reject) => {
      this._queue.push({ method, path, options, resolve, reject });

      if (!this._processing) {
        this._processQueue();
      }
    });
  }

  async _processQueue() {
    this._processing = true;

    while (this._queue.length > 0) {
      const batch = this._queue.splice(0, 5);

      await Promise.allSettled(
        batch.map(({ method, path, options, resolve, reject }) =>
          this._request(method, path, options)
            .then(resolve)
            .catch(reject)
        )
      );
    }

    this._processing = false;
  }

  async _request(method, path, options = {}) {
    const url = new URL(path, this.baseURL);

    if (options.params) {
      Object.entries(options.params).forEach(([key, value]) => {
        if (value !== undefined) url.searchParams.append(key, value);
      });
    }

    const controller = new AbortController();
    const timeoutId = setTimeout(() => controller.abort(), this.timeout);

    try {
      const response = await fetch(url.toString(), {
        method,
        headers: { 'Content-Type': 'application/json' },
        body: options.body ? JSON.stringify(options.body) : undefined,
        signal: controller.signal,
      });

      if (!response.ok) {
        throw new Error(\`HTTP \${response.status}: \${response.statusText}\`);
      }

      return response.json();
    } finally {
      clearTimeout(timeoutId);
    }
  }

  _buildCacheKey(path, params) {
    return \`\${path}?\${JSON.stringify(params)}\`;
  }

  clearCache() {
    this._cache.clear();
  }
}

export default ApiService;
`;
  }

  _generateApiService() {
    return `/**
 * In-memory cache with TTL and size limits.
 */
class Cache {
  constructor(options = {}) {
    this._store = new Map();
    this._maxSize = options.maxSize || 1000;
    this._defaultTTL = options.defaultTTL || 300000; // 5 minutes
  }

  /**
   * Gets a value from cache.
   * @param {string} key - Cache key
   * @returns {*|null} Cached value or null
   */
  get(key) {
    const entry = this._store.get(key);

    if (!entry) return null;

    if (entry.expiry < Date.now()) {
      this._store.delete(key);
      return null;
    }

    entry.lastAccessed = Date.now();
    return entry.value;
  }

  /**
   * Sets a value in cache.
   * @param {string} key - Cache key
   * @param {*} value - Value to cache
   * @param {number} [ttl] - Time to live in ms
   */
  set(key, value, ttl = this._defaultTTL) {
    if (this._store.size >= this._maxSize) {
      this._evictOldest();
    }

    this._store.set(key, {
      value,
      expiry: Date.now() + ttl,
      createdAt: Date.now(),
      lastAccessed: Date.now(),
    });
  }

  /**
   * Deletes a value from cache.
   * @param {string} key - Cache key
   * @returns {boolean} True if key existed
   */
  delete(key) {
    return this._store.delete(key);
  }

  /**
   * Checks if a key exists and is not expired.
   * @param {string} key - Cache key
   * @returns {boolean} True if key exists
   */
  has(key) {
    return this.get(key) !== null;
  }

  /**
   * Gets or computes a value.
   * @param {string} key - Cache key
   * @param {Function} computeFn - Function to compute value
   * @param {number} [ttl] - Time to live in ms
   * @returns {*} Cached or computed value
   */
  async getOrCompute(key, computeFn, ttl = this._defaultTTL) {
    const cached = this.get(key);
    if (cached !== null) return cached;

    const value = await computeFn();
    this.set(key, value, ttl);

    return value;
  }

  /**
   * Clears all expired entries.
   * @returns {number} Number of entries removed
   */
  prune() {
    const now = Date.now();
    let removed = 0;

    for (const [key, entry] of this._store.entries()) {
      if (entry.expiry < now) {
        this._store.delete(key);
        removed++;
      }
    }

    return removed;
  }

  /**
   * Clears the entire cache.
   */
  clear() {
    this._store.clear();
  }

  /**
   * Gets cache statistics.
   * @returns {Object} Cache stats
   */
  getStats() {
    const now = Date.now();
    let expired = 0;
    let active = 0;

    for (const entry of this._store.values()) {
      if (entry.expiry < now) {
        expired++;
      } else {
        active++;
      }
    }

    return {
      total: this._store.size,
      active,
      expired,
      maxSize: this._maxSize,
    };
  }

  _evictOldest() {
    let oldestKey = null;
    let oldestTime = Infinity;

    for (const [key, entry] of this._store.entries()) {
      if (entry.lastAccessed < oldestTime) {
        oldestTime = entry.lastAccessed;
        oldestKey = key;
      }
    }

    if (oldestKey) {
      this._store.delete(oldestKey);
    }
  }
}

export default Cache;
`;
  }

  _generateCache() {
    return `/**
 * Structured logger with levels and output formatting.
 */

const LEVELS = {
  debug: 0,
  info: 1,
  warn: 2,
  error: 3,
};

class Logger {
  constructor(options = {}) {
    this.level = LEVELS[options.level] ?? LEVELS.info;
    this.prefix = options.prefix || '';
    this.output = options.output || console;
  }

  /**
   * Creates a child logger with additional prefix.
   * @param {string} prefix - Child prefix
   * @returns {Logger} Child logger
   */
  child(prefix) {
    return new Logger({
      level: Object.keys(LEVELS).find(k => LEVELS[k] === this.level),
      prefix: this.prefix ? \`\${this.prefix}:\${prefix}\` : prefix,
      output: this.output,
    });
  }

  debug(message, ...args) {
    this._log('debug', message, args);
  }

  info(message, ...args) {
    this._log('info', message, args);
  }

  warn(message, ...args) {
    this._log('warn', message, args);
  }

  error(message, ...args) {
    this._log('error', message, args);
  }

  _log(level, message, args) {
    if (LEVELS[level] < this.level) return;

    const timestamp = new Date().toISOString();
    const prefix = this.prefix ? \`[\${this.prefix}]\` : '';
    const formatted = \`\${timestamp} \${level.toUpperCase().padEnd(5)} \${prefix} \${message}\`;

    const method = level === 'error' ? 'error' : level === 'warn' ? 'warn' : 'log';
    this.output[method](formatted, ...args);
  }
}

export default Logger;
`;
  }

  _generateLogger() {
    return `/**
 * User model with validation and serialization.
 */
class User {
  constructor(data) {
    this.id = data.id || crypto.randomUUID();
    this.email = data.email;
    this.name = data.name;
    this.role = data.role || 'user';
    this.createdAt = data.createdAt || new Date();
    this.updatedAt = new Date();
    this.isActive = data.isActive ?? true;
  }

  /**
   * Validates user data.
   * @param {Object} data - User data
   * @returns {{valid: boolean, errors: string[]}} Validation result
   */
  static validate(data) {
    const errors = [];

    if (!data.email || typeof data.email !== 'string') {
      errors.push('Email is required and must be a string');
    } else if (!/^[^\\s@]+@[^\\s@]+\\.[^\\s@]+$/.test(data.email)) {
      errors.push('Invalid email format');
    }

    if (!data.name || typeof data.name !== 'string' || data.name.trim().length < 2) {
      errors.push('Name is required and must be at least 2 characters');
    }

    if (data.role && !['admin', 'user', 'moderator'].includes(data.role)) {
      errors.push('Role must be admin, user, or moderator');
    }

    return { valid: errors.length === 0, errors };
  }

  /**
   * Updates user properties.
   * @param {Object} updates - Properties to update
   */
  update(updates) {
    const allowedFields = ['name', 'email', 'role', 'isActive'];

    for (const [key, value] of Object.entries(updates)) {
      if (allowedFields.includes(key)) {
        this[key] = value;
      }
    }

    this.updatedAt = new Date();
  }

  /**
   * Checks if user has a specific role.
   * @param {string} role - Role to check
   * @returns {boolean} True if user has role
   */
  hasRole(role) {
    const roleHierarchy = { user: 0, moderator: 1, admin: 2 };
    return (roleHierarchy[this.role] ?? 0) >= (roleHierarchy[role] ?? 0);
  }

  /**
   * Serializes user to JSON-safe object.
   * @returns {Object} Serialized user
   */
  toJSON() {
    return {
      id: this.id,
      email: this.email,
      name: this.name,
      role: this.role,
      isActive: this.isActive,
      createdAt: this.createdAt.toISOString(),
      updatedAt: this.updatedAt.toISOString(),
    };
  }
}

export default User;
`;
  }

  _generateModel() {
    return `/**
 * Authentication middleware with token validation.
 */

const TOKEN_EXPIRY = 3600000; // 1 hour

/**
 * Creates an authentication middleware.
 * @param {Object} options - Middleware options
 * @returns {Function} Auth middleware
 */
export function createAuthMiddleware(options = {}) {
  const secret = options.secret || process.env.JWT_SECRET;
  const excludedPaths = options.excludedPaths || ['/health', '/api/public'];

  if (!secret) {
    throw new Error('JWT_SECRET is required for auth middleware');
  }

  return async function authMiddleware(req, res, next) {
    if (excludedPaths.some(path => req.url.startsWith(path))) {
      return next();
    }

    const authHeader = req.headers.authorization;

    if (!authHeader || !authHeader.startsWith('Bearer ')) {
      return res.writeHead(401, { 'Content-Type': 'application/json' })
        .end(JSON.stringify({ error: 'Missing or invalid authorization header' }));
    }

    const token = authHeader.slice(7);

    try {
      const payload = await verifyToken(token, secret);

      if (payload.exp && payload.exp < Date.now()) {
        throw new Error('Token expired');
      }

      req.user = payload;
      next();
    } catch (error) {
      return res.writeHead(401, { 'Content-Type': 'application/json' })
        .end(JSON.stringify({ error: 'Invalid or expired token' }));
    }
  };
}

/**
 * Verifies a JWT token (simplified implementation).
 * @param {string} token - JWT token
 * @param {string} secret - Signing secret
 * @returns {Object} Token payload
 */
async function verifyToken(token, secret) {
  const parts = token.split('.');

  if (parts.length !== 3) {
    throw new Error('Invalid token format');
  }

  const payload = JSON.parse(Buffer.from(parts[1], 'base64').toString());
  return payload;
}

/**
 * Checks if user has required permissions.
 * @param {string[]} requiredPermissions - Required permissions
 * @returns {Function} Permission check middleware
 */
export function requirePermissions(requiredPermissions) {
  return function (req, res, next) {
    if (!req.user) {
      return res.writeHead(401).end('Unauthorized');
    }

    const userPermissions = req.user.permissions || [];
    const hasPermission = requiredPermissions.every(p => userPermissions.includes(p));

    if (!hasPermission) {
      return res.writeHead(403).end('Insufficient permissions');
    }

    next();
  };
}
`;
  }

  _generateAuthMiddleware() {
    return `/**
 * Centralized error handler for HTTP services.
 */

class AppError extends Error {
  constructor(message, statusCode = 500, code = 'INTERNAL_ERROR') {
    super(message);
    this.name = 'AppError';
    this.statusCode = statusCode;
    this.code = code;
    this.isOperational = true;

    Error.captureStackTrace(this, this.constructor);
  }
}

/**
 * Creates an error handling middleware.
 * @returns {Function} Error handler
 */
export function createErrorHandler() {
  return function errorHandler(err, req, res, next) {
    if (err.name === 'AppError') {
      return sendError(res, err.statusCode, err.code, err.message);
    }

    if (err.name === 'ValidationError') {
      return sendError(res, 400, 'VALIDATION_ERROR', err.message);
    }

    if (err.name === 'UnauthorizedError') {
      return sendError(res, 401, 'UNAUTHORIZED', 'Authentication required');
    }

    console.error('Unhandled error:', err);

    return sendError(
      res,
      500,
      'INTERNAL_ERROR',
      process.env.NODE_ENV === 'production'
        ? 'An unexpected error occurred'
        : err.message
    );
  };
}

/**
 * Wraps an async route handler to catch errors.
 * @param {Function} handler - Route handler
 * @returns {Function} Wrapped handler
 */
export function asyncHandler(handler) {
  return function (req, res, next) {
    Promise.resolve(handler(req, res, next)).catch(next);
  };
}

function sendError(res, statusCode, code, message) {
  res.writeHead(statusCode, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({
    success: false,
    error: { code, message },
  }));
}

export { AppError };
`;
  }

  _generateErrorHandler() {
    return `/**
 * Rate limiter using sliding window algorithm.
 */
class RateLimiter {
  constructor(options = {}) {
    this.windowMs = options.windowMs || 60000; // 1 minute
    this.maxRequests = options.maxRequests || 100;
    this._requests = new Map();
  }

  /**
   * Checks if a request is allowed.
   * @param {string} key - Identifier (IP, user ID, etc.)
   * @returns {{allowed: boolean, remaining: number, resetAt: number}}
   */
  isAllowed(key) {
    const now = Date.now();
    const windowStart = now - this.windowMs;

    if (!this._requests.has(key)) {
      this._requests.set(key, []);
    }

    const timestamps = this._requests.get(key);

    // Remove expired timestamps
    while (timestamps.length > 0 && timestamps[0] <= windowStart) {
      timestamps.shift();
    }

    const remaining = this.maxRequests - timestamps.length;

    if (remaining <= 0) {
      return {
        allowed: false,
        remaining: 0,
        resetAt: timestamps[0] + this.windowMs,
      };
    }

    timestamps.push(now);

    return {
      allowed: true,
      remaining: remaining - 1,
      resetAt: now + this.windowMs,
    };
  }

  /**
   * Creates middleware function for HTTP servers.
   * @param {Function} [keyFn] - Function to extract key from request
   * @returns {Function} Rate limit middleware
   */
  middleware(keyFn = (req) => req.ip || req.socket.remoteAddress) {
    return (req, res, next) => {
      const key = keyFn(req);
      const result = this.isAllowed(key);

      res.setHeader('X-RateLimit-Limit', this.maxRequests);
      res.setHeader('X-RateLimit-Remaining', Math.max(0, result.remaining));
      res.setHeader('X-RateLimit-Reset', result.resetAt);

      if (!result.allowed) {
        res.writeHead(429, { 'Content-Type': 'application/json' });
        return res.end(JSON.stringify({
          error: 'Too Many Requests',
          retryAfter: Math.ceil((result.resetAt - Date.now()) / 1000),
        }));
      }

      next();
    };
  }

  /**
   * Resets rate limit for a specific key.
   * @param {string} key - Identifier to reset
   */
  reset(key) {
    this._requests.delete(key);
  }

  /**
   * Clears all rate limit data.
   */
  clear() {
    this._requests.clear();
  }
}

export default RateLimiter;
`;
  }

  _generateRateLimiter() {
    return `/**
 * Rate limiter using sliding window algorithm.
 */
class RateLimiter {
  constructor(options = {}) {
    this.windowMs = options.windowMs || 60000;
    this.maxRequests = options.maxRequests || 100;
    this._requests = new Map();
  }

  isAllowed(key) {
    const now = Date.now();
    const windowStart = now - this.windowMs;

    if (!this._requests.has(key)) {
      this._requests.set(key, []);
    }

    const timestamps = this._requests.get(key);

    while (timestamps.length > 0 && timestamps[0] <= windowStart) {
      timestamps.shift();
    }

    const remaining = this.maxRequests - timestamps.length;

    if (remaining <= 0) {
      return {
        allowed: false,
        remaining: 0,
        resetAt: timestamps[0] + this.windowMs,
      };
    }

    timestamps.push(now);

    return {
      allowed: true,
      remaining: remaining - 1,
      resetAt: now + this.windowMs,
    };
  }

  middleware(keyFn = (req) => req.ip) {
    return (req, res, next) => {
      const key = keyFn(req);
      const result = this.isAllowed(key);

      res.setHeader('X-RateLimit-Limit', this.maxRequests);
      res.setHeader('X-RateLimit-Remaining', Math.max(0, result.remaining));

      if (!result.allowed) {
        res.writeHead(429, { 'Content-Type': 'application/json' });
        return res.end(JSON.stringify({ error: 'Too Many Requests' }));
      }

      next();
    };
  }

  reset(key) {
    this._requests.delete(key);
  }

  clear() {
    this._requests.clear();
  }
}

export default RateLimiter;
`;
  }

  _injectBug(content) {
    const bugTypes = [
      () => content.replace(/===/g, '==').replace(/!==/g, '!='),
      () => content.replace(/return null;/g, 'return undefined;'),
      () => content.replace(/const /g, 'let ').split('\n').slice(0, -3).join('\n') + '\n' + content.split('\n').slice(-3).join('\n'),
      () => content.replace(/\.length/g, '.lenght'),
      () => content.replace(/JSON.parse/g, 'JSON.parase'),
    ];

    return sample(bugTypes)();
  }

  _injectTypo(content) {
    const typoTypes = [
      () => content.replace(/function /g, 'funciton '),
      () => content.replace(/parameter/g, 'paramter'),
      () => content.replace(/callback/g, 'callbak'),
      () => content.replace(/response/g, 'resposne'),
      () => content.replace(/undefined/g, 'undefiend'),
    ];

    return sample(typoTypes)();
  }

  generateTestFile(filePath, codeContent) {
    const fileName = filePath.split('/').pop().replace('.js', '');

    return `import { describe, it, expect } from '@jest/globals';
import * as module from '../${fileName}.js';

describe('${fileName}', () => {
  it('should export expected functions', () => {
    const exports = Object.keys(module);
    expect(exports.length).toBeGreaterThan(0);
  });

  it('should handle edge cases', () => {
    expect(() => module).not.toThrow();
  });
});
`;
  }

  generateCommitMessageForFile(filePath, fileType) {
    const messages = {
      utility: [
        `feat: add ${filePath.split('/').pop().replace('.js', '')} utility functions`,
        `feat(utils): implement reusable helper functions`,
      ],
      validator: [
        `feat: add input validation utilities`,
        `feat(validation): add data validation helpers`,
      ],
      formatter: [
        `feat: add formatting and transformation utilities`,
        `feat(formatting): implement data formatters`,
      ],
      api: [
        `feat: implement API service with caching`,
        `feat(api): add HTTP client with request queuing`,
      ],
      cache: [
        `feat: add in-memory cache with TTL support`,
        `feat(cache): implement LRU cache implementation`,
      ],
      logger: [
        `feat: add structured logging utility`,
        `feat(logging): implement leveled logger`,
      ],
      model: [
        `feat: add data model with validation`,
        `feat(model): implement ${filePath.split('/').pop().replace('.js', '')} entity`,
      ],
      auth: [
        `feat: add authentication middleware`,
        `feat(auth): implement token-based auth`,
      ],
      error: [
        `feat: add centralized error handling`,
        `feat(errors): implement error handler middleware`,
      ],
      rateLimiter: [
        `feat: add rate limiting middleware`,
        `feat(rate-limit): implement sliding window rate limiter`,
      ],
    };

    return sample(messages[fileType] || messages.utility);
  }
}

export default CodeGenerator;