/**
 * URL normalization for fetch-based curl/wget subsets (scheme guessing like CLI tools).
 * Flag support matrix: ../CLI_PARITY.md
 */

/** curl-style default (see https://everything.curl.dev/http/modify/user-agent.html); not a real libcurl build version. */
export const DEFAULT_CURL_USER_AGENT = 'curl/8.14.1'

/** GNU wget-style default (many builds use Wget/VERSION (linux-gnu)). */
export const DEFAULT_WGET_USER_AGENT = 'Wget/1.25.0 (linux-gnu)'

/** True if the string is usable by our fetch stack without guessing a scheme. */
export function isSupportedFetchUrl(s) {
  return (
    /^https?:\/\//i.test(s) || s.startsWith('data:') || s.startsWith('file://')
  )
}

/**
 * If there is no http(s)/data/file scheme, prepend http:// for host-like URLs (wget default).
 * Protocol-relative //host → https://host. Leaves other schemes (ftp:, mailto:, …) unchanged.
 * Does not rewrite `-`, ./ ../, or absolute /paths (not treated as remote URLs).
 */
export function normalizeFetchUrl(s) {
  const t = String(s)
  if (isSupportedFetchUrl(t)) return t
  if (t.startsWith('//')) return 'https:' + t
  if (/^[a-zA-Z][a-zA-Z0-9+.-]*:/.test(t)) return t
  if (t === '-') return t
  if (t.startsWith('/') || t.startsWith('./') || t.startsWith('../')) return t
  return 'http://' + t
}

/**
 * Default local filename from URL path (last segment, or index.html for directory URLs).
 * Matches wget/curl -O-style naming for simple cases.
 * @param {string} urlString
 */
export function defaultFetchSaveName(urlString) {
  try {
    const u = new URL(urlString)
    let p = u.pathname || '/'
    if (p.endsWith('/') || p === '/' || p === '') return 'index.html'
    const parts = p.split('/').filter(Boolean)
    const base = parts[parts.length - 1]
    return base && base.length > 0 ? base : 'index.html'
  } catch {
    return 'index.html'
  }
}