Network.swift

//
//  Network.swift
//  ACArticle
//
//  Created by Zhida Cheng on 7/6/16.
//  Copyright © 2016 Zhida Cheng. All rights reserved.
//

import Foundation

struct ArticleInList{
    let title:          String
    let authorName:     String
    let authorAvatar:   String
    let cover:          String
    let commentCount:   Int
    static func decode(j: AnyObject) -> ArticleInList?{
        guard let 
            title        = j["title"]               as? String, 
            authorName   = j["user"]??["username"]  as? String,
            authorAvatar = j["user"]??["userImg"]   as? String,
            cover        = j["cover"]               as? String,
            commentCount = j["comments"]            as? Int
        else {return nil}
        
        return ArticleInList(title: title, authorName:authorName, authorAvatar:authorAvatar, cover:cover, commentCount:commentCount)
    }
}

//API Value Type

struct ACFunAPI{
    static let base = URL(string:"http://api.aixifan.com")!
    static let headers = [
        "deviceType":    "0",
        "platform":      "1",
        "productId":     "2000",
        "Content-Type":  "application/json"
    ]
    
    enum ArticleCategory: Int{
        case home    = 110
        case emotion = 73
        case anime   = 74
        case manga   = 75
        case game    = 164
    }
    
    enum ResourceType{
        case articles(category: ArticleCategory) 
    }
    
}

//API Methods

extension ACFunAPI {
    static func resourceURL(type: ResourceType) -> URL?{
        switch type{
        case .articles(let category):
            let urlString = "searches/channel?sort=4&pageNo=2&pageSize=20&channelIds=\(category.rawValue)"
            return URL(string: urlString, relativeTo: self.base)
        }
        
    }
    
    static func request(type: ResourceType, callback: (Any) -> Void) {
        // Common Network Operations
        
        // 1. URL Settings
        guard let url = resourceURL(type: type) else {return}
        var request = URLRequest(url: url)
        
        request.httpMethod = "GET"
        headers.forEach{ (h,v) in request.addValue(v, forHTTPHeaderField: h)}
        
        // 2. Task Setting
        
        let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
            guard error == nil else {print(error); return}
            guard let data = data else {return}
            
            do {
                let dictFromJson = try JSONSerialization.jsonObject(with: data, options: [])
                // 4. Parse Raw JSON
                guard let data = dictFromJson["data"] else {return}
                guard let values = data!["list"] else {return}
                print(values)
                
                // 5. Parse to Native Struct
                let articleList = values.map{j in 
                    return ArticleInList.decode(j: j)
                }
                
                print(articleList)
                //callback(dictFromJson)
            } catch {
                print(error)
            }
        }
        
        // 3. Start Task
        task.resume()
        
    }
}