// Public · Teams — the anonymous read surface (TEAMS.md §2.11).
//
// Every handler here is a projection over core's own tables; nothing calls the
// module. A Team page must render while the shard is down, showing a roster
// marked stale, because that is what the projection is for.

const teams = require('../../../model/teams/teams.model')
const teamActivity = require('../../../model/teams/teamActivity.model')
const teamPrefs = require('../../../model/teams/teamNotify.model')
const unsubscribeToken = require('../../../utils/unsubscribeToken')

const log = require('../../../utils/logger')('teams')

const fail = (res, err, what) => {
  log.error(`public teams: ${what} failed`, { message: err.message })
  return res.status(500).json({ message: 'Internal Server Error' })
}

async function listTeams(req, res) {
  try {
    const limit = Math.min(Number.parseInt(req.query.limit, 10) || 50, 200)
    const offset = Math.max(Number.parseInt(req.query.offset, 10) || 0, 0)
    return res.json(await teams.listPublic({ limit, offset }))
  } catch (err) {
    return fail(res, err, 'list')
  }
}

async function getTeam(req, res) {
  try {
    const team = await teams.getPublic(req.params.slug)
    // A hidden Team is indistinguishable from a missing one here, deliberately:
    // "absent from every public surface" includes not confirming it exists.
    if (!team) return res.status(404).json({ message: 'Team not found' })
    return res.json(team)
  } catch (err) {
    return fail(res, err, 'get')
  }
}

/**
 * One Team, named the way the calling MODULE names it (§3.4 as amended).
 *
 * The one route that exists purely so a module's page can find core's Team
 * without holding core's identifiers. Both parameters come from the path and the
 * module id is MATCHED, not trusted: `external_id` is unique only within a
 * module, so scoping the lookup is what stops one module reading another's Team
 * by guessing a serial.
 */
async function getTeamByExternalId(req, res) {
  try {
    const team = await teams.getPublicByExternalId(req.params.moduleId, req.params.externalId)
    if (!team) return res.status(404).json({ message: 'Team not found' })
    return res.json(team)
  } catch (err) {
    return fail(res, err, 'by-external')
  }
}

/**
 * The roster, projected for whoever is asking (§3.3).
 *
 * The viewer is described to the module rather than handed over: it gets the
 * caller's id and role, which is what a rung decision turns on, and not the user
 * row — a module has `ctx.users.getById` if it needs more, and passing the whole
 * record here would make every column of `users` part of this contract.
 */
async function getRoster(req, res) {
  try {
    const viewer = req.user ? { userId: req.user.id, role: req.user.role } : null
    const roster = await teams.rosterPublic(req.params.slug, viewer)
    if (!roster) return res.status(404).json({ message: 'Team not found' })
    return res.json(roster)
  } catch (err) {
    return fail(res, err, 'roster')
  }
}

/**
 * A Team's activity feed (§4.3).
 *
 * The only handler in this tier that reads `req.user`, and it reads nothing else
 * from the caller about what they may see: `limit` and `offset` are page
 * controls, and the visibility filter is resolved from the session alone. A
 * request parameter naming its own visibility is the bug the ENUM exists to
 * prevent, so there is deliberately no way to ask for one.
 *
 * The cap is 100 rather than the index's 200 — every row carries a summary and an
 * opaque payload, so a page of these is much larger than a page of Teams.
 */
async function getActivity(req, res) {
  try {
    const limit = Math.min(Math.max(Number.parseInt(req.query.limit, 10) || 50, 1), 100)
    const offset = Math.max(Number.parseInt(req.query.offset, 10) || 0, 0)
    const feed = await teamActivity.feedFor(req.params.slug, req.user ? req.user.id : null, { limit, offset })
    if (!feed) return res.status(404).json({ message: 'Team not found' })
    return res.json(feed)
  } catch (err) {
    return fail(res, err, 'activity')
  }
}

/**
 * POST /public/teams/unsubscribe/:token — one-click unsubscribe (TEAMS.md §6.4).
 *
 * **The one write in this tier, and it is unauthenticated on purpose.** A person
 * reading their mail is not logged into the site, and an unsubscribe that first
 * demands a login is an unsubscribe most people do not complete. The token is what
 * stands in for the session, and the capability it carries is deliberately the
 * narrowest one that does the job: set `muted` for ONE (user, Team) pair. It reads
 * nothing, cannot un-mute, and names no other Team.
 *
 * **Always 200, whatever the token was.** A response that distinguished a valid
 * token from a forged one would turn this into an oracle for which (user, Team)
 * pairs exist, on an endpoint with no session behind it. The page says "you will
 * not receive further emails about this team" either way, which is true either way.
 *
 * Reached two ways with the same effect: a mail client's RFC 8058 one-click POST
 * (the `List-Unsubscribe-Post` header), and the site's own /unsubscribe page,
 * which POSTs here after a human clicks the link in the body.
 */
async function unsubscribe(req, res) {
  const claim = unsubscribeToken.verify(req.params.token)
  if (claim) {
    try {
      await teamPrefs.mute(claim.userId, claim.teamId)
    } catch (err) {
      // Logged, not surfaced. A failed write here is worth an operator's
      // attention and is not worth telling an anonymous caller about — and a 500
      // would make a mail client retry a request it should not repeat.
      log.error('unsubscribe', err)
    }
  }
  return res.json({ ok: true })
}

/**
 * GET on the same path — for a mail client that shows the `List-Unsubscribe` URL
 * as a link and has no one-click support.
 *
 * Redirects to the site's own page rather than acting, because a GET must not
 * mutate: a link prefetcher or a mail client's link scanner would otherwise
 * silently mute Teams nobody asked to leave. The page it lands on does the POST
 * once a human is looking at it.
 */
function unsubscribeLanding(req, res) {
  const base = (process.env.APP_BASE_URL || 'http://localhost:5173').replace(/\/+$/, '')
  return res.redirect(302, `${base}/unsubscribe/${encodeURIComponent(req.params.token)}`)
}

module.exports = { listTeams, getTeam, getTeamByExternalId, getRoster, getActivity, unsubscribe, unsubscribeLanding }