module.exports = whoami

var url = require('url')
var assert = require('assert')

function whoami (uri, params, cb) {
  assert(typeof uri === 'string', 'must pass registry URI to whoami')
  assert(params && typeof params === 'object', 'must pass params to whoami')
  assert(typeof cb === 'function', 'must pass callback to whoami')

  var auth = params.auth
  assert(auth && typeof auth === 'object', 'must pass auth to whoami')

  if (auth.username) return process.nextTick(cb.bind(this, null, auth.username))

  this.request(url.resolve(uri, '-/whoami'), { auth: auth }, function (er, userdata) {
    if (er) return cb(er)

    cb(null, userdata.username)
  })
}