import fs from 'node:fs';
import path from 'node:path';

const LOCAL_HOST_PATTERN = /^(localhost|127\.0\.0\.1|\[::1\]|192\.168\.|10\.|100\.)/i;

export function resolvePublicRequestOrigin({ hostHeader = '', forwardedProto = '', protocol = 'http' } = {}) {
  const host = String(hostHeader ?? '').split(',')[0].trim();
  if (!host) return '';
  const fwdProto = String(forwardedProto ?? '').split(',')[0].trim();
  const isLocalHost = LOCAL_HOST_PATTERN.test(host);
  const resolvedProtocol = isLocalHost ? fwdProto || protocol || 'http' : 'https';
  return `${resolvedProtocol}://${host}`;
}

export function buildPublishedHtmlViewContext({
  origin = '',
  requestPath = '',
  filePath = '',
  thumbnailPngPathForSvg = (value) => value,
  fileExists = fs.existsSync,
} = {}) {
  const cleanPath = String(requestPath ?? '').split('?')[0].split('#')[0];
  const servedName = path.basename(String(filePath ?? ''));
  const urlLast = decodeURIComponent(cleanPath.split('/').filter(Boolean).pop() ?? '');
  const isImplicitIndex = urlLast.toLowerCase() !== servedName.toLowerCase();
  const pageUrl = !origin
    ? ''
    : `${origin}${isImplicitIndex && !cleanPath.endsWith('/') ? `${cleanPath}/` : cleanPath}`;
  const pageDirUrl = !origin
    ? ''
    : isImplicitIndex
      ? `${origin}${cleanPath.endsWith('/') ? cleanPath : `${cleanPath}/`}`
      : `${origin}${cleanPath.slice(0, cleanPath.lastIndexOf('/') + 1)}`;

  let fallbackImageUrl = '';
  const svgSibling = String(filePath ?? '').replace(/\.[^./]+$/, '.thumbnail.svg');
  if (pageDirUrl && fileExists(svgSibling)) {
    const pngName = path.basename(thumbnailPngPathForSvg(svgSibling));
    fallbackImageUrl = `${pageDirUrl}${pngName}`;
  }

  return {
    origin,
    cleanPath,
    pageUrl,
    pageDirUrl,
    fallbackImageUrl,
  };
}

export const mindspacePublicPageContextInternals = {
  LOCAL_HOST_PATTERN,
};