negator

/*Enumeratee to manage writing to the file writer. Mapping any errors to Left*/
type ErrorOrActivity = Either[Error,Activity]
    
def fileWriting: Enumeratee[Activity, ErrorOrActivity] = {        
    
    /* writeToFile returns a Promise, but the Enumeratee type constraint 
     * does not expect a Promise. flatMap will return an 
     * Enumeratee[Activity,ErrorOrActivity] given a function from Activity 
     * to Promise[ErrorOrActivity].
     */

negator

/*
* Flatten an enumerator of enumerators of some type into an enumerator of some type
*/
def flatten[T](enumerator: Enumerator[Enumerator[T]]): Enumerator[T] = new Enumerator[T] {
    def step[A](it: Iteratee[T, A])(in: Input[Enumerator[T]]): Iteratee[Enumerator[T], Iteratee[T, A]] = {
        in match {
            case Input.EOF   => Done(Iteratee.flatten(it.feed(Input.EOF)), Input.EOF)
            case Input.Empty => Cont(step(it))
            case Input.El(e) => {
                val promise = e |>> Cont(removeEof(it))

negator

val posts:Enumerator[List[Post]] = pagingEnumerator(postsUrl) map parseToPostList
/* parseToPostList does exactly that. Creates a list of Post objects from json*/

val activities:Enumerator[Enumerator[Activity]] = posts.map{ 
    postList =>    
        Enumerator.apply(postList:_*) map buildActivity
}

negator

type CommentsOrLikes = Either[Comments, Likes]

def buildActivity(post: Post): Promise[Activity] = {

    val likeUrl = LIKE_URL % (post.id, target.token)
    val commentsUrl = COMMENT_URL % (post.id, target.token)

    /*Construct paging enumerators, mapping each value to either Left or Right*/
    val comments = pagingEnumerator(commentsUrl).map(Left.apply) 
    val likes = pagingEnumerator(likeUrl).map(Right.apply) 

negator

import play.api.libs.ws._
import play.api.libs.iteratee._

def pagingEnumerator(url:String):Enumerator[JsValue]={ 	
  	var maybeNextUrl = Some(url) //Next url to fetch	
	Enumerator.fromCallback[JsValue] ( retriever = {
        val maybeResponsePromise = 
            maybeNextUrl map { nextUrl=>	        		                           
                WS.url(nextUrl).get.map { reponse =>
                    val json = response.json

negator

import play.api.libs.ws._
import play.api.libs.json._
import scalaz._
import Scalaz._
import java.net.{ URL => JavaUrl }


/* This class makes url manipulation a piece of cake (dark chocolate). It also includes Play WS request generation.
   Requires scalaz6 and Play 2.0.4
   Examples: