a small wrapper for request that does fancy things

controller-usage.coffee

ServiceProxy = require "ServiceProxy"

module.exports = (service_host) ->

  proxy1: (req, res) ->
  # using a static method...
  ServiceProxy.proxy req, res, {
                                 host: service_host
                                 onError: (err, req, res) ->
                                  res.send err, 500
                                 transformUrl: (host, url) ->
                                  # change the url as needed
                                  return host + url.replace 
                                }

  #or create a class and define options
  serviceProxy = new ServiceProxy { onError... }
  
  proxy2: (req, res) ->
    serviceProxy.proxy req, res

ServiceProxy.coffee

request = require 'request'
_ = require 'underscore'

transformUrl = (host, url) ->
  return host + url

onError = (err, req, res) ->
  res.send "an error occurred", 500

makeDefaults = (options) ->
  options ?= {}
  return {
    transformUrl: options.transformUrl || transformUrl
    onError: options.onError || onError
    host: options.host || "http://localhost"
    requestOpts: options.requestOpts || {}
  }

buildRequestObject = (req, options) ->
  {transformUrl, host, requestOpts} = options

  requestOpts = _.extend requestOpts, {
    url: transformUrl host, req.url
    method: req.method.toLowerCase()
    body: req.body
  }

handleError = (pipe, onError, req, res) ->
  pipe.on "error", (exception) ->
    onError exception, req, res

proxy = (req, res, options) ->
  options = makeDefaults options

  requestOpts = buildRequestObject req, options

  pipe = null
  if requestOpts.method == "get"
    pipe = request(requestOpts).pipe 
  else if requestOpts.method == "post" or requestOpts.method == "put"
    pipe = req.pipe(request(requestOpts)).pipe
  else
    throw new Error "I don't support this HTTP method yet!"

  handleError pipe, options.onError, req, res
  pipe res
  
class ServiceProxy
  constructor: (options) ->
    # add the properties onto us
    this = _.extend this, makeDefaults(options)

  proxy: (req, res, options) ->
    allOpts = _.extend this, options
    proxy req, res, allOpts

ServiceProxy.proxy = proxy

module.exports = ServiceProxy