// ── `/clan name [server]` — one clan, and its roster where the caller may see it
//
// D50 deferred it here. A clan's name, colour, score and member count are public
// (D58); its ROSTER — who is in it and which of them is on — sits behind the
// roster audience (D48), which defaults to the clan's own members plus staff.
//
// The roster decision is `clans.getForViewer`'s, the same function the web page
// and core's `projectRoster` use, so the three cannot disagree about who may
// look. What this file adds is D127: **a roster shown to anything short of a
// `public` audience goes to the caller alone**, never to the channel.

const c = require('./common')
const clans = require('../model/clans/clans.model')

/** The candidates an ambiguous name lists. */
const CANDIDATES = 10

/**
 * Every clan on the servers searched, with the server each came from, and the
 * servers whose clan board cannot be trusted right now.
 */
async function gather(servers) {
  const boards = await Promise.all(servers.map(async (s) => ({ server: s, ...(await clans.listForServer(s.id)) })))
  return {
    rows: boards.flatMap((b) => b.clans.map((clan) => ({ clan, server: b.server }))),
    unreadable: boards.filter((b) => !b.board.supported || !b.board.fresh).map((b) => b.server),
  }
}

/** An exact name (case-insensitive), then a unique prefix. */
function find(rows, wanted) {
  const needle = wanted.trim().toLowerCase()
  const exact = rows.filter((r) => r.clan.name.toLowerCase() === needle)
  if (exact.length === 1) return { hit: exact[0] }
  if (exact.length > 1) return { ambiguous: exact }
  const prefix = rows.filter((r) => r.clan.name.toLowerCase().startsWith(needle))
  if (prefix.length === 1) return { hit: prefix[0] }
  if (prefix.length > 1) return { ambiguous: prefix }
  return {}
}

function memberLine(m) {
  const tags = [m.leader ? 'leader' : null, m.online ? 'online' : null].filter(Boolean)
  return `${m.name || 'Unknown player'}${tags.length ? ` (${tags.join(', ')})` : ''}`
}

async function handler({ options, actor }) {
  const wanted = options && typeof options.name === 'string' ? options.name.trim() : ''
  if (!wanted) return c.refuse('Name a clan.')

  const picked = c.pickServer(await c.listServers(), options.server)
  const refusal = c.pickRefusal(picked)
  if (refusal) return refusal
  const searched = picked.server ? [picked.server] : picked.all

  const { rows, unreadable } = await gather(searched)
  const { hit, ambiguous } = find(rows, wanted)

  if (ambiguous) {
    const list = ambiguous.slice(0, CANDIDATES).map((r) => (searched.length > 1 ? `${r.clan.name} on ${r.server.name}` : r.clan.name))
    return c.refuse(`Several clans match “${wanted}”: ${list.join(', ')}${ambiguous.length > CANDIDATES ? ', …' : ''}`)
  }
  if (!hit) {
    // A board that is missing, stale or unsupported proves nothing about a clan
    // it does not list. Saying "no such clan" from it would be a guess presented
    // as a fact.
    if (unreadable.length) {
      return c.refuse(
        `No clan called “${wanted}” is on the boards that can be read right now. ` +
          `The clan list for ${unreadable.map((s) => s.name).join(', ')} is not available, so it may be there.`,
      )
    }
    return c.refuse(`No clan called “${wanted}”.`)
  }

  const answer = await clans.getForViewer(hit.clan.externalId, c.viewerOf(actor))
  if (!answer) return c.refuse(`No clan called “${wanted}”.`)
  const { clan, roster } = answer

  const fields = [
    { name: 'Score', value: String(clan.score), inline: true },
    { name: 'Members', value: clan.maxMembers ? `${clan.memberCount}/${clan.maxMembers}` : String(clan.memberCount), inline: true },
    { name: 'Server', value: clan.serverName || hit.server.name, inline: true },
  ]
  if (clan.color) fields.push({ name: 'Colour', value: clan.color, inline: true })

  const base = { title: clan.name, url: c.pageUrl(`/rust/clans/${encodeURIComponent(clan.externalId)}`), fields }
  if (!roster.visible || !roster.members.length) return base

  // Leaders first, then whoever is on, then everyone else — the order a person
  // looking for "who can I talk to" wants.
  const members = [...roster.members].sort(
    (a, b) => Number(b.leader) - Number(a.leader) || Number(b.online) - Number(a.online) || String(a.name).localeCompare(String(b.name)),
  )
  fields.push({ name: 'Roster', value: c.fitLines(members.map(memberLine)), inline: false })

  // D127 and D48 together: a roster the whole site may see may be posted; any
  // narrower one is for the caller.
  return { ...base, ephemeral: roster.audience !== 'public' }
}

module.exports = {
  name: 'clan',
  description: 'A clan on a Rust server — score and members, and its roster where you may see it',
  options: [
    { name: 'name', type: 'string', description: 'Clan name, or the start of it', required: true },
    { name: 'server', type: 'string', description: 'Server name or id (every server when left out)', required: false },
  ],
  access: 'everyone',
  handler,
}