// ── This module's fill for core's `site.footer.status` slot ───────────────
//
// R13, and the contract is MODULE_API.md §3.7. Core owns the position in the
// footer's info row and the separator around it, and passes `linkStyle` so the
// row stays visually one row. **The label, the destination, the data and whether
// anything renders at all are this component's** — that is the whole division,
// and it is why the slot is named for a place rather than for a meaning.
//
// ── The live count, and what it costs ─────────────────────────────────────
//
// The org lead chose a live count ("3 servers · 42 online") over a static link,
// so this fetches. Be clear-eyed about where it fetches from: core renders
// `SiteFooter` inside `PublicLayout`, and every public page renders
// `PublicLayout` ITSELF (§3.3) — so this component mounts once per public page
// view, not once per session. Every public page on the site therefore carries one
// `/public/rust/servers` request, including pages that have nothing to do with
// Rust.
//
// Two things keep that honest rather than merely cheap:
//
//  • **It renders NOTHING until it has an answer, and nothing again if the
//    request fails.** An unfilled slot renders nothing and core's `wrap` takes
//    the separator with it, so a failed fetch degrades to exactly the footer an
//    instance with no module installed has. A spinner in a footer would be worse
//    than silence on every page of the site.
//  • **It never polls.** One request per page view is a cost; a timer in the
//    footer of every page would be a different kind of thing entirely.
//
// If that per-page request ever shows up in an operator's logs as a problem, the
// fix is a short-lived module-scope cache here — the decision to keep the number
// live stays intact, and nothing else on the site has to change.

import { useEffect, useState } from 'react'
import { Link } from 'react-router-dom'
import api from '../api.js'

export default function FooterStatus({ linkStyle }) {
  const [summary, setSummary] = useState(null)

  useEffect(() => {
    let live = true

    api.servers
      .list()
      .then(({ servers }) => {
        if (!live) return
        // `online` already accounts for staleness — the model refuses to let a
        // row that has not been written in five minutes claim a server is up —
        // so this is a sum, not a judgement.
        setSummary({
          servers: servers.length,
          players: servers.reduce((total, server) => total + (server.online ? server.players : 0), 0),
        })
      })
      // Silence, deliberately. This is the footer of every page on the site; a
      // module that cannot reach its own API has nothing to say there.
      .catch(() => {})

    return () => {
      live = false
    }
  }, [])

  if (!summary || summary.servers === 0) return null

  return (
    <Link to="/rust" style={linkStyle}>
      {summary.servers === 1 ? '1 server' : `${summary.servers} servers`}
      {' · '}
      {summary.players === 1 ? '1 online' : `${summary.players} online`}
    </Link>
  )
}