// ── Public · Rust — the handlers ──────────────────────────────────────────
//
// Thin on purpose: read the request, call a model, answer. Everything worth
// testing is in the model, which needs no express and no database to test.
//
// **A handler must not throw past express.** Core mounts this router inside its
// own tier router, so an unhandled rejection here reaches core's error handler
// and answers 500 — survivable, but it means an operator sees core blamed for a
// fault in this module. Catch, log through `core.logger` (so the line carries the
// module id), and answer something honest.

const core = require('../../core')

const clans = require('../../model/clans/clans.model')
const events = require('../../model/events/events.model')
const map = require('../../model/map/map.model')
const mapDb = require('../../model/map/map.db')
const mapLive = require('../../mapLive')
const servers = require('../../model/servers/servers.model')
const visibility = require('../../model/visibility/visibility.model')

const log = core.logger('public')

/**
 * Marks a response as depending on who asked.
 *
 * Three routes below answer differently for a moderator and for a stranger, and
 * a shared cache in front of the site that stored the moderator's answer would
 * hand the roll call to the next anonymous visitor. `private` keeps it out of
 * every cache but the viewer's own; `Vary` says why, for any cache that reads it.
 */
function perViewer(res) {
  res.set('Cache-Control', 'private, no-store')
  res.vary('Cookie')
  res.vary('Authorization')
}

async function listServers(req, res) {
  try {
    res.json({ servers: await servers.listPublic() })
  } catch (err) {
    log.error('failed to read the server list', { error: err.message })
    res.status(500).json({ message: 'Failed to read the server list' })
  }
}

/**
 * One server, or a 404.
 *
 * **The 404 is the feature.** Everything else under `/servers/:id` answers an
 * empty list for a server that does not exist — an unknown id has no events, no
 * leaderboard and nobody online, and each of those is a perfectly good answer to
 * the question it was asked. Only this route can tell the page that the server
 * itself is not there, which is what stops `/rust/servers/typo` rendering as a
 * quiet server with nothing to say.
 */
async function getServer(req, res) {
  try {
    const server = await servers.getPublic(req.params.id)
    if (!server) {
      res.status(404).json({ message: 'No such server' })
      return
    }
    res.json({ server })
  } catch (err) {
    log.error('failed to read a server', { server: req.params.id, error: err.message })
    res.status(500).json({ message: 'Failed to read the server' })
  }
}

/**
 * The killfeed, and everything else public that happened on one server.
 *
 * **`admin` is not passed, and that is the whole security posture of this
 * handler.** `events.recent` takes the viewer explicitly and defaults to the
 * public allowlist, so the way to leak an IP address from here is to add an
 * argument rather than to forget one.
 *
 * `presence` is resolved per request from the operator's setting. Below it, the
 * feed carries only what names nobody — a wipe, a start, a shutdown — and says
 * so with `presenceHidden`, so a page can explain a quiet feed instead of
 * implying a quiet server.
 */
async function listEvents(req, res) {
  try {
    const presence = await visibility.canSeePresence(req, req.params.id)
    perViewer(res)
    res.json({
      events: await events.recent({
        serverId: req.params.id,
        presence: presence.visible,
        kind: req.query.kind,
        wipeId: req.query.wipe || null,
        limit: req.query.limit,
      }),
      presenceHidden: !presence.visible,
      presenceAudience: presence.required,
    })
  } catch (err) {
    log.error('failed to read events', { server: req.params.id, error: err.message })
    res.status(500).json({ message: 'Failed to read events' })
  }
}

async function listLeaderboard(req, res) {
  try {
    const presence = await visibility.canSeePresence(req, req.params.id)
    perViewer(res)
    res.json({
      leaderboard: await events.leaderboard({
        serverId: req.params.id,
        wipeId: req.query.wipe || null,
        sort: req.query.sort,
        limit: req.query.limit,
        presence: presence.visible,
      }),
    })
  } catch (err) {
    log.error('failed to read the leaderboard', { server: req.params.id, error: err.message })
    res.status(500).json({ message: 'Failed to read the leaderboard' })
  }
}

async function listWipes(req, res) {
  try {
    res.json({ wipes: await events.wipes(req.params.id) })
  } catch (err) {
    log.error('failed to read wipes', { server: req.params.id, error: err.message })
    res.status(500).json({ message: 'Failed to read wipes' })
  }
}

/**
 * Who is on the server right now — or, below the operator's audience, how many.
 *
 * The count stays public: it is already on the server list and in the footer,
 * and a number names nobody. The names do not, by default (the org lead's rule,
 * `model/visibility`). A hidden answer is still a 200 with the same shape — an
 * empty `players` array — plus `hidden` and `count`, so a client that predates
 * the flag renders an empty list rather than breaking, and a current one can say
 * "12 online" instead of "nobody".
 */
async function listOnline(req, res) {
  try {
    const presence = await visibility.canSeePresence(req, req.params.id)
    perViewer(res)

    if (!presence.visible) {
      const server = await servers.getPublic(req.params.id)
      res.json({
        players: [],
        hidden: true,
        count: server ? server.players : 0,
        audience: presence.required,
      })
      return
    }

    const players = await events.online(req.params.id)
    res.json({ players, hidden: false, count: players.length, audience: presence.required })
  } catch (err) {
    log.error('failed to read presence', { server: req.params.id, error: err.message })
    res.status(500).json({ message: 'Failed to read who is online' })
  }
}

/**
 * Who is asking, as core describes a viewer to `projectRoster`: `{ userId, role }`
 * or null. Only the id is trusted — `model/clans` re-reads the row — so a token
 * that cannot be decoded is simply nobody.
 */
function viewerOf(req) {
  try {
    const claimed = req.user || core.auth.getUserFromRequest(req)
    if (!claimed || claimed.id == null) return null
    return { userId: claimed.id, role: claimed.role || null }
  } catch (err) {
    return null
  }
}

/**
 * One server's clans (D58): name, colour, score and member count, best first.
 *
 * Public at every setting, because none of it names a player. `board` says
 * whether the list can be trusted — a server whose plugin predates protocol 6,
 * or whose clans the bridge cannot read, answers an empty list AND the reason,
 * so the tab can say "unavailable" rather than "no clans".
 */
async function listClans(req, res) {
  try {
    res.json(await clans.listForServer(req.params.id))
  } catch (err) {
    log.error('failed to read clans', { server: req.params.id, error: err.message })
    res.status(500).json({ message: 'Failed to read clans' })
  }
}

/**
 * One clan, and its roster when the viewer is inside the roster audience (D48).
 *
 * The same decision core's `projectRoster` makes, from the same function, so
 * this page and core's roster cannot disagree about who may look. Below the
 * audience the clan is still described — its name and its count are public —
 * and `roster.visible` is false with no names at all.
 */
async function getClan(req, res) {
  try {
    const answer = await clans.getForViewer(req.params.externalId, viewerOf(req))
    perViewer(res)
    if (!answer) {
      res.status(404).json({ message: 'No such clan' })
      return
    }
    res.json(answer)
  } catch (err) {
    log.error('failed to read a clan', { clan: req.params.externalId, error: err.message })
    res.status(500).json({ message: 'Failed to read the clan' })
  }
}

// ── The map (phase 14) ────────────────────────────────────────────────────

/**
 * One server's map: the picture's address, the geometry to draw it with, the
 * monuments when the viewer may see the world layer, and **which layers this
 * viewer gets and who gets the others** — the §23.3 shape, where a hidden layer
 * says who can see it and never what it holds.
 *
 * A server that has never described its map answers `picture: null` and
 * `geometry: null`, and the page says the map is not available yet. A server
 * whose game has no picture answers geometry and no picture, and the page draws
 * the layers on a plain background (D109).
 */
async function getMap(req, res) {
  try {
    const server = await servers.getPublic(req.params.id)
    if (!server) {
      res.status(404).json({ message: 'No such server' })
      return
    }

    const [row, acc] = await Promise.all([mapDb.getMeta(req.params.id), map.access(req, req.params.id)])
    perViewer(res)

    const hasPicture = Boolean(row && row.sha256 && Number(row.byteCount) > 0)
    res.json({
      serverId: req.params.id,
      mapKey: row ? row.mapKey : null,
      picture: hasPicture
        ? {
            path: `/public/rust/servers/${encodeURIComponent(req.params.id)}/map/image?v=${row.sha256}`,
            source: row.source,
            fetchedAt: row.fetchedAt ? new Date(row.fetchedAt).toISOString() : null,
          }
        : null,
      geometry: map.geometryOf(row),
      ...(acc.layers.world.visible ? { monuments: map.monumentsOf(row) } : {}),
      layers: acc.layers,
      // `signedIn` is what lets the page offer "link your Steam account" to the
      // person who can act on it, and not to a visitor who has no account at all.
      mates: { visible: acc.mates.visible, on: acc.mates.on, linked: acc.mates.linked, signedIn: acc.level !== 'public' },
      pollMs: map.POLL_MS,
    })
  } catch (err) {
    log.error('failed to read a map', { server: req.params.id, error: err.message })
    res.status(500).json({ message: 'Failed to read the map' })
  }
}

/**
 * The picture itself. **Public and immutable**: the hash is in the URL, so a
 * browser and any cache in front of the site may keep it for a year — and a
 * hash that is no longer the stored picture's is a 404, never the new bytes
 * under the old address. The picture is public at every setting (§30.5): it is
 * rendered from a seed anybody can render, and it says nothing about who plays.
 */
async function getMapImage(req, res) {
  try {
    const sha = String(req.query.v || '').toLowerCase()
    const server = /^[0-9a-f]{64}$/.test(sha) ? await servers.getPublic(req.params.id) : null
    const bytes = server ? await mapDb.getBytes(req.params.id, sha) : null

    if (!bytes) {
      res.set('Cache-Control', 'no-store')
      res.status(404).json({ message: 'No such picture' })
      return
    }

    res.set('Cache-Control', 'public, max-age=31536000, immutable')
    res.set('Content-Type', 'image/jpeg')
    res.set('X-Content-Type-Options', 'nosniff')
    res.send(Buffer.isBuffer(bytes) ? bytes : Buffer.from(bytes))
  } catch (err) {
    log.error('failed to read a map picture', { server: req.params.id, error: err.message })
    res.status(500).json({ message: 'Failed to read the map picture' })
  }
}

/**
 * What moves, **projected for this viewer on the server** (§30.2). A layer the
 * viewer may not see is absent from the answer — not empty, absent — and
 * `mates` carries their own position and their online clan mates when they are
 * entitled to it (D115, D117). Positions come from `mapLive`'s five-second
 * cache, so any number of viewers cost one ask of the game (D111).
 *
 * A game that does not answer is `live: false` with a reason, a 200: the page
 * keeps the picture and says positions are unavailable.
 */
async function getMapLive(req, res) {
  try {
    const server = await servers.getForCalling(req.params.id)
    if (!server) {
      res.status(404).json({ message: 'No such server' })
      return
    }

    const acc = await map.access(req, req.params.id)
    perViewer(res)

    const anyLayer = map.LAYERS.some((l) => acc.layers[l].visible) || acc.mates.visible
    if (!anyLayer) {
      res.json({ live: true, layers: acc.layers })
      return
    }

    const answer = await mapLive.live(server)
    if (!answer.ok) {
      res.json({ live: false, reason: answer.status, layers: acc.layers })
      return
    }

    const ids = await map.mateIdsFor(req.params.id, acc)
    res.json({ live: true, layers: acc.layers, ...map.project(answer.data, acc, ids) })
  } catch (err) {
    log.error('failed to read live map positions', { server: req.params.id, error: err.message })
    res.status(500).json({ message: 'Failed to read the map' })
  }
}

module.exports = {
  listServers,
  getServer,
  listEvents,
  listLeaderboard,
  listWipes,
  listOnline,
  listClans,
  getClan,
  getMap,
  getMapImage,
  getMapLive,
}