UserInteractionFetcher.swift

//
//  UserInteractionFetcher.swift
//  Instagrowth
//
//  Created by Zachary Shakked on 1/17/16.
//  Copyright © 2016 Zachary Shakked. All rights reserved.
//

import UIKit
import AFNetworking

enum UserInteractionType {
    case Likes
    case Comments
}

class UserInteractionFetcher : NSObject {
    let postSummaries : [PostSummary]
    let accessToken : String
    
    private var likes : [Like] = []
    private lazy var likesQueue : NSOperationQueue = NSOperationQueue()
    private var likesCompletion : ((Bool, [Like]) -> (Void))?
    
    private var comments : [Comment] = []
    private lazy var commentsQueue : NSOperationQueue = NSOperationQueue()
    private var commentsCompletion : ((Bool, [Comment]) -> (Void))?
    
    init(postSummaries: [PostSummary], accessToken: String) {
        self.postSummaries = postSummaries
        self.accessToken = accessToken
        super.init()
    }
    
    func fetchLikes(completion: (Bool, [Like]) -> (Void)) {
        likesCompletion = completion
        var operations : [NSOperation] = []
        
        for postSummary in postSummaries {
            let request : NSURLRequest = userInteractionRequest(.Likes, postSummary: postSummary)
            
            let operation = AFHTTPRequestOperation(request: request)
            operation.responseSerializer = AFJSONResponseSerializer()
            operation.setCompletionBlockWithSuccess({ (operations, result) -> Void in
                guard let datas = result["data"] as? [NSDictionary] else { return }
                self.likes += Like.parse(datas, postSummary: postSummary)
            }, failure: { (operations, error) -> Void in
                completion(false, [])
            })
            
            operations.append(operation)
        }
        
        likesQueue.addOperations(operations, waitUntilFinished: false)
        likesQueue.addObserver(self, forKeyPath: "operations", options: NSKeyValueObservingOptions.init(rawValue: 0), context: nil)
    }
    
    func fetchComments(completion: (Bool, [Comment]) -> (Void)) {
        commentsCompletion = completion
        var operations : [NSOperation] = []
        
        for postSummary in postSummaries {
            let request : NSURLRequest = userInteractionRequest(.Comments, postSummary: postSummary)
            let operation = AFHTTPRequestOperation(request: request)
            operation.responseSerializer = AFJSONResponseSerializer()
            operation.setCompletionBlockWithSuccess({ (operations, result) -> Void in
                guard let datas = result["data"] as? [NSDictionary] else { return }
                self.comments += Comment.parse(datas, postSummary: postSummary)
                }, failure: { (operations, error) -> Void in
                    completion(false, [])
            })
            
            operations.append(operation)
        }
        
        commentsQueue.addOperations(operations, waitUntilFinished: false)
        commentsQueue.addObserver(self, forKeyPath: "operations", options: NSKeyValueObservingOptions.init(rawValue: 0), context: nil)
    }
    
    override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
        guard let queue = object as? NSOperationQueue else {
            return
        }
        if queue.operationCount == 0 && queue == commentsQueue {
            commentsCompletion?(true, self.comments ?? [])
            
        } else if queue.operationCount == 0 && queue == likesQueue {
            likesCompletion?(true, self.likes ?? [])
        }
    }
    
    
    private func userInteractionRequest(type: UserInteractionType, postSummary: PostSummary) -> NSURLRequest {
        let params = "/media/\(postSummary.id)/\(type == .Likes ? "likes" : "comments")|access_token=\(accessToken)"
        let sig = HMAC.signWithKey(UserSettings.InstagramClientSecret(), usingData: params)
        let baseURL = type == .Likes ? postSummary.likesURL.absoluteString : postSummary.commentsURL.absoluteString
        let paramters = "?access_token=\(accessToken)&sig=\(sig)"
        let url = NSURL(string: "\(baseURL)\(paramters)")!
        let request = NSMutableURLRequest(URL: url)
        request.HTTPMethod = "GET"
        return request
    }
    
}