/**
 * Input Sanitization Utilities
 * Protects against XSS, prompt injection, and other injection attacks
 */

import createDOMPurify from 'dompurify'
import {JSDOM} from 'jsdom'

const window = new JSDOM('').window
const DOMPurify = createDOMPurify(window as any)

// DOMPurify config for strict sanitization
const PURIFY_CONFIG = {
  ALLOWED_TAGS: [], // No HTML tags allowed
  ALLOWED_ATTR: [], // No attributes allowed
  KEEP_CONTENT: true // Keep text content
}

/**
 * Sanitize user input to remove HTML/JS
 * Use for: Issue comments, PR descriptions, user-generated content
 */
export const sanitizeHTML = (input: string): string => {
  if (!input) return ''
  return DOMPurify.sanitize(input, PURIFY_CONFIG)
}

/**
 * Escape special regex characters
 * Use for: Preventing regex injection
 */
export const escapeRegex = (input: string): string => {
  return input.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')
}

/**
 * Escape shell command arguments
 * Use for: Preventing command injection in exec calls
 */
export const escapeShellArg = (arg: string): string => {
  // Remove null bytes and escape quotes
  return arg.replace(/\x00/g, '').replace(/["'`]/g, '')
}

/**
 * Sanitize AI prompt input
 * Prevents prompt injection attacks
 */
export const sanitizePrompt = (input: string): string => {
  if (!input) return ''
  
  // Remove common prompt injection patterns
  const dangerousPatterns = [
    /ignore previous instructions/gi,
    /disregard (the|all|any) (above|previous|prior)/gi,
    /system prompt/gi,
    /you are now/gi,
    /new instructions/gi,
    /===END.*===/gi, // Pattern markers
    /<\|endoftext\|>/gi, // GPT end markers
    /\[SYSTEM\]/gi,
    /\[INSTRUCTION\]/gi,
    /\[PROMPT\]/gi
  ]
  
  let sanitized = input
  for (const pattern of dangerousPatterns) {
    sanitized = sanitized.replace(pattern, '[REDACTED]')
  }
  
  // Also apply HTML sanitization
  return sanitizeHTML(sanitized)
}

/**
 * Sanitize filename/path input
 * Prevents path traversal attacks
 */
export const sanitizePath = (input: string): string => {
  if (!input) return ''
  
  // Remove path traversal patterns
  return input
    .replace(/\.\./g, '') // Remove parent directory references
    .replace(/^[\/\\]/, '') // Remove leading slashes
    .replace(/\x00/g, '') // Remove null bytes
}

/**
 * Validate and sanitize webhook payload
 */
export const sanitizeWebhookPayload = (payload: any): any => {
  if (typeof payload !== 'object' || payload === null) {
    return payload
  }
  
  const sanitized: any = {}
  
  for (const [key, value] of Object.entries(payload)) {
    if (typeof value === 'string') {
      // Sanitize string values
      sanitized[key] = sanitizeHTML(value)
    } else if (typeof value === 'object' && value !== null) {
      // Recursively sanitize nested objects
      sanitized[key] = sanitizeWebhookPayload(value)
    } else {
      // Keep primitives as-is
      sanitized[key] = value
    }
  }
  
  return sanitized
}

/**
 * Rate limiting helper for sanitization
 * Prevents ReDoS attacks on regex sanitization
 */
export const safeSanitize = (
  input: string,
  sanitizer: (s: string) => string,
  maxLength = 100000
): string => {
  if (!input) return ''
  
  // Truncate very long inputs to prevent ReDoS
  const truncated = input.length > maxLength 
    ? input.substring(0, maxLength) + '... [truncated]' 
    : input
  
  return sanitizer(truncated)
}