// What core's Team activity feed SAYS, separated from how it renders
// (docs/website/TEAMS.md §4.3).
//
// Core renders this feed into a slot a MODULE declares on its own page, because
// Teams is a contract primitive and not a surface: core owns the feed, its
// visibility rules and its wording; the module owns the page and the vocabulary
// around it. So this file is deliberately narrow — the roster and index
// presentation that once lived here went with the core Team pages, to whichever
// module renders them.
//
// Plain JS with tests, following lib/teamAdmin.js. Worth splitting for the same
// reason it was there: a feed that is filtered, or a projection that is stale,
// has to say so in words, and getting that wording right is logic rather than
// markup.

const MINUTE = 60_000
const HOUR = 60 * MINUTE
const DAY = 24 * HOUR

/** "just now" / "14 minutes ago" / "3 hours ago" / "2 days ago". */
export function relativeTime(when, now = Date.now()) {
  if (!when) return null
  const ms = now - new Date(when).getTime()
  if (!Number.isFinite(ms)) return null
  if (ms < MINUTE) return 'just now'
  if (ms < HOUR) {
    const n = Math.floor(ms / MINUTE)
    return `${n} ${n === 1 ? 'minute' : 'minutes'} ago`
  }
  if (ms < DAY) {
    const n = Math.floor(ms / HOUR)
    return `${n} ${n === 1 ? 'hour' : 'hours'} ago`
  }
  const n = Math.floor(ms / DAY)
  return `${n} ${n === 1 ? 'day' : 'days'} ago`
}

/**
 * How a public surface describes the projection's freshness (§2.4).
 *
 * Distinct from `teamAdmin.freshnessOf`, which is worded for an operator
 * debugging a sync. A visitor needs one sentence about whether what they are
 * looking at is current, and specifically must never be shown an unconfirmed
 * empty projection as though it were a confirmed empty shard.
 */
export function freshnessNote(sync = {}, now = Date.now()) {
  // Nothing supplies Teams here, so there is nothing to be stale ABOUT. A
  // deployment with no game module is not a broken one.
  if (!sync.configured) return null
  if (!sync.lastSyncAt) return { tone: 'warn', text: 'Not yet confirmed against the game.' }
  const ago = relativeTime(sync.lastSyncAt, now)
  if (sync.stale) return { tone: 'warn', text: `Last confirmed ${ago} — the game may have moved on.` }
  return { tone: 'idle', text: `Last confirmed ${ago}.` }
}

/**
 * Group feed items into days, newest first, preserving order within a day (§4.3).
 *
 * Keyed by local calendar date rather than by a UTC slice: "yesterday" is a
 * property of where the reader is sitting, and a shard's evening raid landing at
 * 00:30 UTC belongs on the day the players experienced it.
 */
export function groupByDay(items = [], locale = undefined) {
  const days = []
  const byKey = new Map()
  for (const item of items) {
    const date = new Date(item.occurredAt)
    if (Number.isNaN(date.getTime())) continue
    const key = `${date.getFullYear()}-${date.getMonth()}-${date.getDate()}`
    if (!byKey.has(key)) {
      const day = {
        key,
        label: date.toLocaleDateString(locale, { year: 'numeric', month: 'long', day: 'numeric' }),
        items: [],
      }
      byKey.set(key, day)
      days.push(day)
    }
    byKey.get(key).items.push(item)
  }
  return days
}

/**
 * What to say under a feed that has been filtered.
 *
 * Only when there is something to say: a caller who saw everything is told
 * nothing, and an anonymous caller is invited to sign in rather than simply
 * informed that entries exist which they cannot have.
 *
 * The wording avoids core's own noun. The reader is looking at a page the module
 * titled — a guild, a clan — and "this Team" would be core's vocabulary leaking
 * onto a surface that deliberately does not use it.
 */
export function activityScopeNote(feed = {}, signedIn = false) {
  if (feed.scope !== 'public') return null
  return signedIn
    ? 'Some entries are visible to members only.'
    : 'Sign in as a member to see the members-only entries.'
}