WWDC/ConfCore/SessionsResponseAdapter.swift

//
//  SessionsResponseAdapter.swift
//  WWDC
//
//  Created by Guilherme Rambo on 21/02/17.
//  Copyright © 2017 Guilherme Rambo. All rights reserved.
//

import Foundation
import SwiftyJSON

private enum SessionResponseKeys: String, JSONSubscriptType {
    case events, sessions
    
    var jsonKey: JSONKey {
        return JSONKey.key(rawValue)
    }
}

final class SessionsResponseAdapter: Adapter {
    
    typealias InputType = JSON
    typealias OutputType = SessionsResponse
    
    func adapt(_ input: JSON) -> Result<SessionsResponse, AdapterError> {
        guard let eventsJson = input[SessionResponseKeys.events].array else {
            return .error(.missingKey(SessionResponseKeys.events))
        }
        
        guard let sessionsJson = input[SessionResponseKeys.sessions].array else {
            return .error(.missingKey(SessionResponseKeys.sessions))
        }
        
        guard case .success(let events) = EventsJSONAdapter().adapt(eventsJson) else {
            return .error(.invalidData)
        }
        
        guard case .success(let sessions) = SessionsJSONAdapter().adapt(sessionsJson) else {
            return .error(.invalidData)
        }
        
        guard case .success(let assets) = SessionAssetsJSONAdapter().adapt(sessionsJson) else {
            return .error(.invalidData)
        }
        
        var trackNames = Set<String>()
        
        sessions.forEach { session in
            guard !trackNames.contains(session.trackName) else { return }
            trackNames.insert(session.trackName)
        }
        
        let tracks: [Track] = trackNames.map { name in
            let track = Track()
            
            track.name = name
            
            return track
        }
        
        let response = SessionsResponse(events: events, sessions: sessions, assets: assets.flatMap({$0}), tracks: tracks)
        
        return .success(response)
    }
    
}