/**
 * JSON-LD Helper Utilities for Next.js
 * 
 * Following Next.js best practices for structured data:
 * - Sanitizes output to prevent XSS attacks
 * - Uses TypeScript with schema-dts for type safety
 * - Implements proper escaping of < characters
 */

import { WithContext, Thing } from 'schema-dts'

/**
 * Safely stringify JSON-LD data with XSS protection
 * Replaces < with \u003c to prevent script injection
 */
export function safeJsonLdStringify(data: WithContext<Thing> | any): string {
  return JSON.stringify(data).replace(/</g, '\\u003c')
}

/**
 * Creates a JSON-LD script tag props object
 * Use with dangerouslySetInnerHTML in Next.js components
 * 
 * @example
 * ```tsx
 * <script
 *   type="application/ld+json"
 *   dangerouslySetInnerHTML={createJsonLdScriptProps(jsonLd)}
 * />
 * ```
 */
export function createJsonLdScriptProps(data: WithContext<Thing> | any) {
  return {
    __html: safeJsonLdStringify(data)
  }
}

/**
 * Type guard to check if data is valid JSON-LD
 */
export function isValidJsonLd(data: any): data is WithContext<Thing> {
  return (
    typeof data === 'object' &&
    data !== null &&
    '@context' in data &&
    '@type' in data
  )
}

/**
 * Merge multiple JSON-LD objects into a graph
 * Useful when you need to include multiple structured data types on one page
 */
export function mergeJsonLd(...items: Array<WithContext<Thing>>): { '@context': string; '@graph': any[] } {
  return {
    '@context': 'https://schema.org',
    '@graph': items.map(item => {
      const { '@context': _, ...rest } = item as any
      return rest
    })
  }
}