// ── Admin · Rust · Permissions ────────────────────────────────────────────
//
// The authoring surface for R2. Everything here writes to the site's own tables
// and marks the affected servers dirty; nothing here talks to a game. The push
// is `permSync.js`'s loop, which is deliberate — a form that wrote to six game
// hosts inside the request would fail differently for each of them and have no
// honest status code to answer with.
//
// **The one exception is "sync now"**, which runs the loop's pass for one server
// and waits for it. It exists because an operator who has just changed something
// wants to see it land, and because waiting thirty seconds to find out that a
// server is unreachable is a bad way to learn it.
//
// Every write logs an activity row. These rows decide who may do what inside
// somebody's game server, which is the one thing on this module's admin tier
// more consequential than the sidecar credential.

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

const db = require('../../model/permissions/permissions.db')
const model = require('../../model/permissions/permissions.model')
const permSync = require('../../permSync')
const servers = require('../../model/servers/servers.model')

const log = core.logger('admin:permissions')

/** Everything the screen renders: groups, grants, drift, the catalogue, per-server state. */
async function overview(req, res) {
  try {
    res.json(await model.overview())
  } catch (err) {
    log.error('failed to read the permission model', { error: err.message })
    res.status(500).json({ message: 'Failed to read the permission model' })
  }
}

/**
 * Create or update a group.
 *
 * The permission list is part of the same write, because that is how the form
 * edits it: a group and what it carries are one idea on the screen, and two
 * requests would leave a group briefly carrying the wrong set.
 */
async function putGroup(req, res) {
  const name = model.normaliseName(req.params.name)
  const scope = String(req.body.scope || model.FLEET)

  try {
    if (scope !== model.FLEET && !(await knownServer(scope))) {
      return res.status(400).json({ message: 'That scope names no configured server' })
    }

    const previous = await db.getGroup(name)

    await db.upsertGroup({
      name,
      title: String(req.body.title || name),
      rank: Number(req.body.rank) || 0,
      scope,
    })

    const permissions = [...new Set((req.body.permissions || []).map(model.normaliseName))].filter(Boolean)
    await db.setGroupPermissions(name, permissions)

    // Both scopes: a group that moved from one server to another has to be
    // retired from where it was as well as applied where it now is, and only the
    // old scope knows the first half.
    await db.markDirty(scope)
    if (previous && previous.scope !== scope) await db.markDirty(previous.scope)

    await core.activity.log({
      req,
      action: previous ? 'rust.perm.group.update' : 'rust.perm.group.create',
      detail: { group: name, scope, permissions: permissions.length },
    })

    return res.status(204).end()
  } catch (err) {
    log.error('failed to save a group', { group: name, error: err.message })
    return res.status(500).json({ message: 'Failed to save that group' })
  }
}

async function deleteGroup(req, res) {
  const name = model.normaliseName(req.params.name)

  try {
    const existing = await db.getGroup(name)
    if (!existing) return res.status(404).json({ message: 'No such group' })

    await db.deleteGroup(name)
    await db.markDirty(existing.scope)

    await core.activity.log({ req, action: 'rust.perm.group.delete', detail: { group: name } })

    return res.status(204).end()
  } catch (err) {
    log.error('failed to delete a group', { group: name, error: err.message })
    return res.status(500).json({ message: 'Failed to delete that group' })
  }
}

async function addMember(req, res) {
  const name = model.normaliseName(req.params.name)

  try {
    const group = await db.getGroup(name)
    if (!group) return res.status(404).json({ message: 'No such group' })

    const userId = await resolveUser(req.body)
    if (!userId) return res.status(404).json({ message: 'No account on this site has that name' })

    await db.addGroupMember(name, userId, req.user ? req.user.id : null)
    await db.markDirty(group.scope)

    await core.activity.log({
      req,
      action: 'rust.perm.member.add',
      detail: { group: name, userId },
    })

    return res.status(204).end()
  } catch (err) {
    // A user id that names nobody fails on the foreign key rather than on a
    // check of our own: the row is the constraint, and one round trip is
    // cheaper than two.
    log.error('failed to add a member', { group: name, userId, error: err.message })
    return res.status(400).json({ message: 'That account could not be added to the group' })
  }
}

async function removeMember(req, res) {
  const name = model.normaliseName(req.params.name)
  const userId = Number(req.params.userId)

  try {
    const group = await db.getGroup(name)
    if (!group) return res.status(404).json({ message: 'No such group' })

    const removed = await db.removeGroupMember(name, userId)
    if (!removed) return res.status(404).json({ message: 'That account is not in the group' })

    await db.markDirty(group.scope)
    await core.activity.log({
      req,
      action: 'rust.perm.member.remove',
      detail: { group: name, userId },
    })

    return res.status(204).end()
  } catch (err) {
    log.error('failed to remove a member', { group: name, userId, error: err.message })
    return res.status(500).json({ message: 'Failed to remove that account from the group' })
  }
}

/**
 * Grant one permission to one person.
 *
 * `source` is fixed at `admin` here and is not accepted from the body: the
 * column exists so phase 13's event actions can write their own rows through the
 * same table, and a route that let a caller choose would make "who gave this"
 * unanswerable the first time somebody passed the wrong string.
 */
async function addGrant(req, res) {
  const permission = model.normaliseName(req.body.permission)
  const scope = String(req.body.scope || model.FLEET)
  let userId = null

  try {
    if (scope !== model.FLEET && !(await knownServer(scope))) {
      return res.status(400).json({ message: 'That scope names no configured server' })
    }

    userId = await resolveUser(req.body)
    if (!userId) return res.status(404).json({ message: 'No account on this site has that name' })

    const { inserted } = await db.insertGrant({
      userId,
      permission,
      scope,
      source: 'admin',
      note: req.body.note ? String(req.body.note).slice(0, 255) : null,
      grantedBy: req.user ? req.user.id : null,
    })

    if (inserted) {
      await db.markDirty(scope)
      await core.activity.log({
        req,
        action: 'rust.perm.grant',
        detail: { userId, permission, scope },
      })
    }

    return res.status(inserted ? 201 : 200).json({ granted: inserted })
  } catch (err) {
    log.error('failed to grant', { userId, permission, error: err.message })
    return res.status(400).json({ message: 'That permission could not be granted' })
  }
}

async function removeGrant(req, res) {
  const id = Number(req.params.id)

  try {
    const grant = await db.getGrant(id)
    if (!grant) return res.status(404).json({ message: 'No such grant' })

    await db.deleteGrant(id)
    await db.markDirty(grant.scope)

    await core.activity.log({
      req,
      action: 'rust.perm.revoke',
      detail: { userId: grant.userId, permission: grant.permission, scope: grant.scope },
    })

    return res.status(204).end()
  } catch (err) {
    log.error('failed to revoke a grant', { grant: id, error: err.message })
    return res.status(500).json({ message: 'Failed to remove that grant' })
  }
}

/**
 * Adopt a hand edit: the site records it as its own.
 *
 * It is only possible for a `grant` whose Steam id belongs to a website account,
 * and the refusal says so — because the alternative is authoring privilege
 * against a game account no person on this site holds, which is precisely the
 * thing D28 decided not to do.
 */
async function adoptDrift(req, res) {
  const id = Number(req.params.id)

  try {
    const row = await db.getDrift(id)
    if (!row) return res.status(404).json({ message: 'No such drift' })

    if (row.kind !== 'grant' && row.kind !== 'member') {
      return res.status(400).json({
        message: 'Only a grant or a membership can be adopted. A permission on a group is edited on the group itself.',
      })
    }

    const holder = await holderOf(row.subject)

    if (!holder) {
      return res.status(409).json({
        message:
          'That Steam account is not linked to any account on this site, so there is nobody to author this against. Revoke it instead, or ask the player to link.',
      })
    }

    if (row.kind === 'grant') {
      await db.insertGrant({
        userId: holder.userId,
        permission: row.object,
        scope: row.serverId,
        source: 'adopted',
        note: 'Adopted from a hand edit',
        grantedBy: req.user ? req.user.id : null,
      })
    } else {
      const group = await db.getGroup(row.object)
      if (!group) return res.status(409).json({ message: 'That group is not authored on this site' })

      await db.addGroupMember(row.object, holder.userId, req.user ? req.user.id : null)
    }

    // Already in the game, so it is already pushed — recorded as such rather
    // than left for the next sync to "apply". Without this the row would be
    // desired-but-not-pushed, which is a state the loop would happily write
    // again and the game would report as already correct: harmless, and a lie in
    // the one table that exists to say what this site put there.
    await db.addPushed(row.serverId, [{ kind: row.kind, subject: row.subject, object: row.object }])
    await db.deleteDrift(id)
    await db.markDirty(row.serverId)

    await core.activity.log({
      req,
      action: 'rust.perm.drift.adopt',
      detail: { server: row.serverId, kind: row.kind, subject: row.subject, object: row.object },
    })

    return res.status(204).end()
  } catch (err) {
    log.error('failed to adopt drift', { drift: id, error: err.message })
    return res.status(500).json({ message: 'Failed to adopt that change' })
  }
}

/**
 * Revoke a hand edit.
 *
 * Queued rather than sent: the server may be down, and an instruction that is
 * dropped because a game host was restarting is exactly the behaviour a site
 * claiming to be the author of record must not have. The next successful sync
 * carries it and the queue row goes.
 */
async function revokeDrift(req, res) {
  const id = Number(req.params.id)

  try {
    const row = await db.getDrift(id)
    if (!row) return res.status(404).json({ message: 'No such drift' })

    await db.queueRevocation({
      serverId: row.serverId,
      kind: row.kind,
      subject: row.subject,
      object: row.object,
      requestedBy: req.user ? req.user.id : null,
    })

    await db.deleteDrift(id)
    await db.markDirty(row.serverId)

    await core.activity.log({
      req,
      action: 'rust.perm.drift.revoke',
      detail: { server: row.serverId, kind: row.kind, subject: row.subject, object: row.object },
    })

    return res.status(202).json({ queued: true })
  } catch (err) {
    log.error('failed to queue a revocation', { drift: id, error: err.message })
    return res.status(500).json({ message: 'Failed to queue that revocation' })
  }
}

/** Run the loop's pass now, for one server or for all of them, and report what happened. */
async function syncNow(req, res) {
  const serverId = req.body && req.body.serverId ? String(req.body.serverId) : null

  try {
    if (serverId && !(await knownServer(serverId))) {
      return res.status(404).json({ message: 'No such server' })
    }

    await db.markDirty(serverId || model.FLEET)
    await permSync.tick({ force: serverId })

    await core.activity.log({
      req,
      action: 'rust.perm.sync',
      detail: { server: serverId || 'all' },
    })

    const state = await model.overview()
    return res.json({ servers: state.servers, drift: state.drift })
  } catch (err) {
    log.error('a forced sync failed', { server: serverId, error: err.message })
    return res.status(500).json({ message: 'Failed to run the sync' })
  }
}

/** Every permission name any configured server has registered, with which ones know it. */
async function catalogue(req, res) {
  try {
    const rows = await db.listCatalogue()
    res.json({ permissions: groupCatalogue(rows) })
  } catch (err) {
    log.error('failed to read the catalogue', { error: err.message })
    res.status(500).json({ message: 'Failed to read the permission catalogue' })
  }
}

function groupCatalogue(rows) {
  const byPermission = new Map()

  for (const row of rows) {
    if (!byPermission.has(row.permission)) byPermission.set(row.permission, [])
    byPermission.get(row.permission).push(row.serverId)
  }

  return [...byPermission.entries()]
    .map(([permission, serverIds]) => ({ permission, servers: serverIds }))
    .sort((a, b) => a.permission.localeCompare(b.permission))
}

/**
 * The user id a write is about, from either an id or a username.
 *
 * The form sends a name, because a form that made an operator type a numeric id
 * would be a form nobody could use. The id form stays accepted because the
 * client already holds one on the panel inside core's user page, and looking a
 * name back up from it would be a round trip to answer a question it has
 * already answered.
 */
async function resolveUser(body) {
  if (body.userId) return Number(body.userId)
  if (!body.username) return null

  const user = await db.findUserByUsername(String(body.username).trim())
  return user ? user.id : null
}

/** Whether a scope names a server row. A disabled server still counts — it exists. */
async function knownServer(id) {
  const rows = await servers.listForAdmin()
  return rows.some((row) => row.id === id)
}

/** The website account that holds a Steam id, or null. */
async function holderOf(steamId) {
  const links = await db.listLinks()
  return links.find((link) => link.steamId === steamId) || null
}

module.exports = {
  overview,
  putGroup,
  deleteGroup,
  addMember,
  removeMember,
  addGrant,
  removeGrant,
  adoptDrift,
  revokeDrift,
  syncNow,
  catalogue,
}