import sanitizeHtml from 'sanitize-html'

const ALLOWED_REL_VALUES = new Set(['nofollow', 'noopener', 'noreferrer'])

const ALLOWED_URL_PROTOCOLS = new Set(['http:', 'https:', 'mailto:', 'tel:'])

const URL_KEYS = new Set(['href', 'url', 'externalUrl'])

const RICH_TEXT_OPTIONS: sanitizeHtml.IOptions = {
  allowedTags: [
    'a',
    'b',
    'blockquote',
    'br',
    'code',
    'em',
    'h1',
    'h2',
    'h3',
    'h4',
    'h5',
    'h6',
    'hr',
    'i',
    'li',
    'ol',
    'p',
    'pre',
    's',
    'span',
    'strong',
    'u',
    'ul',
  ],
  allowedAttributes: {
    '*': ['class', 'title'],
    'a': ['href', 'target', 'rel'],
  },
  allowedSchemes: ['http', 'https', 'mailto', 'tel'],
  allowProtocolRelative: true,
  disallowedTagsMode: 'discard',
  nonTextTags: [
    'script',
    'style',
    'textarea',
    'option',
    'iframe',
    'object',
    'embed',
    'form',
    'svg',
    'math',
  ],
  transformTags: {
    a: (tagName, attribs) => {
      if (attribs.target !== undefined && !['_blank', '_self'].includes(attribs.target)) {
        delete attribs.target
      }
      if (attribs.rel !== undefined) {
        const rel = attribs.rel
          .split(/\s+/)
          .filter((value) => ALLOWED_REL_VALUES.has(value))
          .join(' ')
        if (rel) attribs.rel = rel
        else delete attribs.rel
      }
      if (attribs.target === '_blank') attribs.rel = 'noopener noreferrer'
      return { tagName, attribs }
    },
  },
}

export function sanitizeRichText(value: string) {
  return sanitizeHtml(value, RICH_TEXT_OPTIONS)
}

export function sanitizeUrl(value: string) {
  try {
    const parsed = new URL(value, 'https://relative.invalid')
    return ALLOWED_URL_PROTOCOLS.has(parsed.protocol) ? value : ''
  } catch {
    return ''
  }
}

export function sanitizePayload(value: unknown, key = ''): unknown {
  if (typeof value === 'string') {
    return URL_KEYS.has(key) ? sanitizeUrl(value) : sanitizeRichText(value)
  }

  if (Array.isArray(value)) return value.map((item) => sanitizePayload(item))

  if (value && typeof value === 'object') {
    return Object.fromEntries(
      Object.entries(value).map(([childKey, childValue]) => [
        childKey,
        sanitizePayload(childValue, childKey),
      ])
    )
  }

  return value
}