import sanitizeHtml from 'sanitize-html';

const allowedTags = [
  'p', 'br', 'h2', 'h3', 'h4',
  'strong', 'em', 'u', 's',
  'ul', 'ol', 'li', 'blockquote', 'a',
  'figure', 'figcaption', 'img',
  'table', 'thead', 'tbody', 'tfoot', 'tr', 'th', 'td'
];

const blockTags = /<\/?(?:p|h[2-4]|ul|ol|li|blockquote|br|figure|figcaption|table|thead|tbody|tfoot|tr|th|td)\b[^>]*>/gi;

function escapeHtml(value) {
  return String(value)
    .replaceAll('&', '&amp;')
    .replaceAll('<', '&lt;')
    .replaceAll('>', '&gt;')
    .replaceAll('"', '&quot;')
    .replaceAll("'", '&#39;');
}

function decodeTextEntities(value) {
  const named = { amp: '&', lt: '<', gt: '>', quot: '"', apos: "'", '#39': "'", nbsp: ' ' };
  const codePoint = (code, radix) => {
    const parsed = Number.parseInt(code, radix);
    return Number.isInteger(parsed) && parsed >= 0 && parsed <= 0x10ffff && !(parsed >= 0xd800 && parsed <= 0xdfff)
      ? String.fromCodePoint(parsed)
      : '�';
  };
  return String(value)
    .replace(/&#x([0-9a-f]+);/gi, (_, code) => codePoint(code, 16))
    .replace(/&#(\d+);/g, (_, code) => codePoint(code, 10))
    .replace(/&(amp|lt|gt|quot|apos|#39|nbsp);/gi, (_, name) => named[name.toLowerCase()]);
}

export function sanitizeNoticeContent(value) {
  const source = String(value ?? '').trim().slice(0, 20000);
  return sanitizeHtml(source, {
    allowedTags,
    allowedAttributes: {
      a: ['href', 'target', 'rel'],
      figure: ['class'],
      img: ['src', 'alt'],
      th: ['colspan', 'rowspan'],
      td: ['colspan', 'rowspan']
    },
    allowedClasses: {
      figure: [
        'image', 'table', 'image-style-inline', 'image-style-block', 'image-style-side',
        'image-style-align-left', 'image-style-align-right',
        'image-style-block-align-left', 'image-style-block-align-right'
      ]
    },
    allowedSchemes: ['http', 'https', 'mailto', 'tel'],
    allowProtocolRelative: false,
    transformTags: {
      a(tagName, attributes) {
        const safeAttributes = {};
        if (attributes.href) safeAttributes.href = attributes.href;
        if (attributes.target === '_blank') safeAttributes.target = '_blank';
        safeAttributes.rel = 'noopener noreferrer';
        return { tagName, attribs: safeAttributes };
      },
      img(tagName, attributes) {
        const safeAttributes = {};
        if (/^https?:\/\//i.test(attributes.src || '')) safeAttributes.src = attributes.src;
        if (attributes.alt) safeAttributes.alt = attributes.alt;
        return { tagName, attribs: safeAttributes };
      }
    }
  });
}

export function noticePlainText(value) {
  const sanitized = sanitizeNoticeContent(value).replace(blockTags, ' ');
  const withoutTags = sanitizeHtml(sanitized, { allowedTags: [], allowedAttributes: {} });
  return decodeTextEntities(withoutTags).replace(/\s+/g, ' ').trim();
}

export function noticeContentHtml(value) {
  const source = String(value ?? '').trim();
  if (!source) return '';
  if (!/<\/?(?:p|h[2-4]|strong|em|u|s|ul|ol|li|blockquote|a|br|figure|figcaption|img|table|thead|tbody|tfoot|tr|th|td)\b/i.test(source)) {
    return source
      .split(/\r?\n{2,}/)
      .map(paragraph => `<p>${escapeHtml(paragraph).replace(/\r?\n/g, '<br>')}</p>`)
      .join('');
  }
  return sanitizeNoticeContent(source);
}

export function noticeForClient(notice) {
  return { ...notice, content: sanitizeNoticeContent(notice.content), contentHtml: noticeContentHtml(notice.content) };
}