file1.js

var hyperdb = require('hyperdb')
var hindex = require('hyperdb-index-level')
var level = require('level')
var ram = require('random-access-memory')

var db = hyperdb(ram, { valueEncoding: 'json' })
var lvl = level('./index')
var idx = hindex(db, lvl, processor)

var alice = hyperdb(ram, { valueEncoding: 'json' })
var bob = hyperdb(ram, { valueEncoding: 'json' })

// imagine alice/bob/db have all been replicted + authorized to each other

// by default, let's say 'db' (creator of the first db) is the only one with
// admin perms
// db.put('role/' + db.local.key.toString('hex'), 'admin')   // <- implicit

alice.put('role/' + db.local.key.toString('hex'), 'admin')

// then db decides to auth alice and mute bob
db.put('role/' + alice.local.key.toString('hex'), 'admin')
db.put('role/' + bob.local.key.toString('hex'), 'mute')

// the processor function below will process these in causal order

function processor (node, next) {
  if (node.key.startsWith('role/')) {
    var key = node.key.split('/')[1]
    var role = node.value
    var authorKey = db.local.key  // TODO: lookup how to derive this from the hyperdb node

    // check if the author is allowed to make permission edits
    lvl.get(authorKey, function (err, authorRole) {
      if ((err && err.notFound) || authorRole !== 'admin') return  // ignore the node
      lvl.put(key, role, next)
    })
  }
}

function getRole (key, cb) {
  idx.ready(function () {
    lvl.get(key, cb)
  })
}

// getRole(alice.local.key, function (err, role) { ... }