tranco.server.ts

/**
 * Tranco List API utility
 * https://tranco-list.eu/
 *
 * Tranco is a research-grade ranking of the top 1M websites,
 * combining data from Alexa, Majestic, Umbrella, and Quantcast.
 * Lower rank = more popular (1 = most popular)
 */

interface TrancoRankResponse {
  domain: string
  ranks: Array<{
    date: string
    rank: number
  }>
}

/**
 * Extract the root domain from a URL
 * e.g., "https://app.example.com/page" -> "example.com"
 */
export function extractDomain(url: string): string | null {
  try {
    const parsed = new URL(url)
    const hostname = parsed.hostname.toLowerCase()

    // Remove www. prefix
    const withoutWww = hostname.replace(/^www\./, '')

    // For simple cases, just return the hostname
    // This handles most cases like "example.com", "sub.example.com"
    const parts = withoutWww.split('.')

    // Handle common TLDs (simplified)
    if (parts.length >= 2) {
      // Check for two-part TLDs like .co.uk, .com.au
      const lastTwo = parts.slice(-2).join('.')
      const twoPartTlds = [
        'co.uk',
        'com.au',
        'co.nz',
        'co.jp',
        'com.br',
        'co.in',
      ]
      if (twoPartTlds.includes(lastTwo) && parts.length >= 3) {
        return parts.slice(-3).join('.')
      }
      // Standard case: return last two parts
      return parts.slice(-2).join('.')
    }

    return withoutWww
  } catch {
    return null
  }
}

/**
 * Fetch the Tranco rank for a domain
 * Returns the most recent rank, or null if not in top 1M
 */
export async function getTrancoRank(url: string): Promise<number | null> {
  const domain = extractDomain(url)
  if (!domain) {
    return null
  }

  try {
    const response = await fetch(
      `https://tranco-list.eu/api/ranks/domain/${encodeURIComponent(domain)}`,
      {
        headers: {
          Accept: 'application/json',
        },
      },
    )

    if (!response.ok) {
      console.error(`Tranco API error: ${response.status}`)
      return null
    }

    const data: TrancoRankResponse = await response.json()

    // Return the most recent rank (first in array)
    if (data.ranks && data.ranks.length > 0) {
      return data.ranks[0].rank
    }

    return null
  } catch (error) {
    console.error('Tranco API fetch error:', error)
    return null
  }
}