Routing based on the accept header

accept-router.js

'use strict'

const assert = require('assert')
const Router = require('find-my-way')
const semver = require('semver')

function AcceptRouter (opts) {
  if (!(this instanceof AcceptRouter)) {
    return new AcceptRouter(opts)
  }

  this.opts = opts
  this.accepts = {}
}

AcceptRouter.prototype.on = function on (method, path, version, handler, store) {
  assert(semver.valid(version), 'The version should be a semver compatible string')
  if (!this.hasRouter(version)) {
    this.accepts[version] = Router(this.opts)
    this.accepts[version].on(method, path, handler, store)
  } else {
    this.accepts[version].on(method, path, handler, store)
  }
}

AcceptRouter.prototype.getRouter = function getVersion (version) {
  const versions = Object.keys(this.accepts)
  for (var i = 0, len = versions.length; i < len; i++) {
    if (semver.satisfies(versions[i], version)) {
      return this.accepts[versions[i]]
    }
  }
  return null
}

AcceptRouter.prototype.hasRouter = function getVersion (version) {
  const versions = Object.keys(this.accepts)
  for (var i = 0, len = versions.length; i < len; i++) {
    if (semver.satisfies(versions[i], version)) {
      return true
    }
  }
  return false
}

AcceptRouter.prototype.lookup = function lookup (req, res) {
  var version = req.headers['accept-version']
  if (!this.validVersion(version)) {
    res.statusCode = 400
    return res.end('Invalid version')
  }
  var router = this.getRouter(version)
  if (router === null) {
    res.statusCode = 400
    res.end(`Version '${version}' is not supported`)
  } else {
    router.lookup(req, res)
  }
}

AcceptRouter.prototype.validVersion = function validVersion (version) {
  try {
    semver.validRange(version)
    return true
  } catch (e) {}

  try {
    semver.valid(version)
    return true
  } catch (e) {}

  return false
}

module.exports = AcceptRouter