// ── What the five commands share (phase 16, R11) ───────────────────────────
//
// Registered with `api.registerSlashCommands` (MODULE_API 1.6.0). The handlers
// run in the WEBSITE process: core pulls the definitions over its internal API to
// the bot and dispatches each call back here. Nothing in these files knows what
// Discord is — a handler is handed an `actor` and returns an envelope.
//
// ── The two privacy rules (D127) ──────────────────────────────────────────
//
//  1. **A refusal is private.** Core already delivers an `ephemeral` answer as a
//     private follow-up; `refuse()` below is the one way these files say no, and
//     it always sets the flag.
//  2. **An answer narrower than `public` is private too.** Core has no reverse
//     case: an answer WITHOUT the flag is posted to the channel the command was
//     run in, where everybody reads it. So a moderator running `/online` in a
//     public channel must get the names privately, or the names they may see are
//     published to everyone who may not. That is the leak module-uo's `/guild`
//     has (D132, Module-uo#46), and every answer here decides it explicitly.
//
// ── Three seconds (`HANDLER_TIMEOUT_MS`) ──────────────────────────────────
//
// Every answer reads this module's own tables. **No command asks a sidecar**: a
// game that is slow to answer would cost the reply, and the tables already hold
// the last thing each server said.

const core = require('../core')
const servers = require('../model/servers/servers.model')
const visibility = require('../model/visibility/visibility.model')

/**
 * Where the caller sits on the presence ladder.
 *
 * An UNLINKED caller is `public`, answered directly. Handing `visibility.viewer`
 * a synthetic request with no user would make it fall through to
 * `getUserFromRequest`, which expects real cookies (module-uo's phase 3 bug). A
 * linked caller is handed over as `{ user }`, which `viewer` reads first and then
 * re-reads from the account row — so a banned or demoted account is judged by
 * what it is now, not by what core resolved.
 */
async function levelFor(actor) {
  if (!actor || actor.userId == null) return 'public'
  return visibility.viewerLevel({ user: { id: actor.userId, role: actor.role } })
}

/** The viewer shape `model/clans` takes: `{ userId, role }` or null. */
const viewerOf = (actor) => (actor && actor.userId != null ? { userId: actor.userId, role: actor.role || null } : null)

/** Every answer that says no. Private, always (D127 rule 1). */
const refuse = (text) => ({ text, ephemeral: true })

/** An absolute link to a page on the site. */
const pageUrl = (path) => `${core.baseUrl}${path}`

const serverUrl = (server) => pageUrl(`/rust/servers/${encodeURIComponent(server.id)}`)

/**
 * Which server a `server` option names, among `list`.
 *
 * An exact id, then an exact name (case-insensitive), then a unique prefix of
 * either. Servers are added at runtime and `choices` are fixed at load, so this
 * is free text matched here. A wrong-server answer is worse than "say which one",
 * so two prefix matches are ambiguous rather than a guess.
 *
 * Answers `{ server }`, `{ all }` (no option and more than one server),
 * `{ none }` (no servers at all), `{ ambiguous }` or `{ missing }`.
 */
function pickServer(list, option) {
  if (!list.length) return { none: true }
  const wanted = typeof option === 'string' ? option.trim().toLowerCase() : ''
  if (!wanted) return list.length === 1 ? { server: list[0] } : { all: list }

  const byId = list.find((s) => s.id.toLowerCase() === wanted)
  if (byId) return { server: byId }
  const byName = list.filter((s) => s.name.toLowerCase() === wanted)
  if (byName.length === 1) return { server: byName[0] }

  const prefix = list.filter((s) => s.id.toLowerCase().startsWith(wanted) || s.name.toLowerCase().startsWith(wanted))
  if (prefix.length === 1) return { server: prefix[0] }
  if (prefix.length > 1) return { ambiguous: prefix }
  return { missing: option.trim() }
}

/** The refusal for each way `pickServer` can fail to name exactly one server. */
function pickRefusal(picked, { needOne = false } = {}) {
  const names = (list) => list.map((s) => `${s.name} (\`${s.id}\`)`).join(', ')
  if (picked.none) return refuse('No Rust servers are set up on this site yet.')
  if (picked.missing) return refuse(`No server matches “${picked.missing}”.`)
  if (picked.ambiguous) return refuse(`Several servers match: ${names(picked.ambiguous)}. Name one.`)
  if (needOne && picked.all) return refuse(`Which server? This site follows ${names(picked.all)}.`)
  return null
}

/** Every enabled server, as the public shape. */
const listServers = (now = Date.now()) => servers.listPublic(now)

// ── Time, in words ────────────────────────────────────────────────────────
//
// Plain text, not a platform's timestamp markup: the envelope is platform-
// agnostic (§7.1), and a second platform would print `<t:…>` literally. So an
// instant is written in UTC, with how far away it is beside it — the relative
// part is the one every reader can use without converting.

const UTC_FORMAT = new Intl.DateTimeFormat('en-GB', {
  timeZone: 'UTC',
  weekday: 'short',
  day: 'numeric',
  month: 'short',
  hour: '2-digit',
  minute: '2-digit',
  hourCycle: 'h23',
})

function relative(ms, now = Date.now()) {
  const diff = ms - now
  const abs = Math.abs(diff)
  const unit = (n, word) => `${n} ${word}${n === 1 ? '' : 's'}`
  let span
  if (abs < 60_000) span = 'less than a minute'
  else if (abs < 3_600_000) span = unit(Math.round(abs / 60_000), 'minute')
  else if (abs < 172_800_000) span = unit(Math.round(abs / 3_600_000), 'hour')
  else span = unit(Math.round(abs / 86_400_000), 'day')
  return diff >= 0 ? `in ${span}` : `${span} ago`
}

/** `Thu 1 Oct, 18:00 UTC (in 6 days)`, or null for no instant. */
function when(value, now = Date.now()) {
  if (!value) return null
  const ms = value instanceof Date ? value.getTime() : Date.parse(value)
  if (Number.isNaN(ms)) return null
  return `${UTC_FORMAT.format(ms).replace(/,? (\d\d:\d\d)$/, ', $1')} UTC (${relative(ms, now)})`
}

/** Just the distance: `3 days ago`. */
function ago(value, now = Date.now()) {
  if (!value) return null
  const ms = value instanceof Date ? value.getTime() : Date.parse(value)
  return Number.isNaN(ms) ? null : relative(ms, now)
}

const SOURCES = {
  forced: 'the monthly forced wipe',
  rule: 'the server’s own schedule',
  once: 'rescheduled by the operator',
}

/** The next wipe in words, with what decided it — or `null` for no schedule. */
function nextWipeText(server, now = Date.now()) {
  const next = server.nextWipe
  if (!next) return null
  return `${when(next.at, now)} — ${SOURCES[next.source] || next.source}`
}

/** Players, as a number out of the maximum, for a server that is up. */
const playerCount = (server) => (server.maxPlayers ? `${server.players}/${server.maxPlayers}` : String(server.players))

/**
 * Cut a list of lines to fit one embed field (1 024 characters) and a count,
 * ending in "and N more" when it had to cut.
 */
function fitLines(lines, { max = lines.length, limit = 1000 } = {}) {
  const kept = []
  let length = 0
  for (const line of lines.slice(0, max)) {
    if (length + line.length + 1 > limit - 20) break
    kept.push(line)
    length += line.length + 1
  }
  const rest = lines.length - kept.length
  return rest > 0 ? `${kept.join('\n')}\nand ${rest} more` : kept.join('\n')
}

module.exports = {
  levelFor,
  viewerOf,
  refuse,
  pageUrl,
  serverUrl,
  pickServer,
  pickRefusal,
  listServers,
  relative,
  when,
  ago,
  nextWipeText,
  playerCount,
  fitLines,
}