IceCream.swift

/*
    Copyright (C) 2016 Apple Inc. All Rights Reserved.
    See LICENSE.txt for this sample’s licensing information
    
    Abstract:
    Defines the `IceCream` struct that represents a complete or partially built ice cream.
*/

import Foundation
import Messages

struct IceCream {
    // MARK: Properties
    
    var base: Base?
    
    var scoops: Scoops?
    
    var topping: Topping?

    var isComplete: Bool {
        return base != nil && scoops != nil && topping != nil
    }
}



/**
 Extends `IceCream` to be able to be represented by and created with an array of
 `NSURLQueryItem`s.
 */
extension IceCream {
    // MARK: Computed properties
    
    var queryItems: [URLQueryItem] {
        var items = [URLQueryItem]()
        
        if let part = base {
            items.append(part.queryItem)
        }
        if let part = scoops {
            items.append(part.queryItem)
        }
        if let part = topping {
            items.append(part.queryItem)
        }
        
        return items
    }
    
    // MARK: Initialization
    
    init?(queryItems: [URLQueryItem]) {
        var base: Base?
        var scoops: Scoops?
        var topping: Topping?
        
        for queryItem in queryItems {
            guard let value = queryItem.value else { continue }
            
            if let decodedPart = Base(rawValue: value), queryItem.name == Base.queryItemKey {
                base = decodedPart
            }
            if let decodedPart = Scoops(rawValue: value), queryItem.name == Scoops.queryItemKey {
                scoops = decodedPart
            }
            if let decodedPart = Topping(rawValue: value), queryItem.name == Topping.queryItemKey {
                topping = decodedPart
            }
        }
        
        guard let decodedBase = base else { return nil }
        
        self.base = decodedBase
        self.scoops = scoops
        self.topping = topping
    }
}



/**
 Extends `IceCream` to be able to be created with the contents of an `MSMessage`.
 */
extension IceCream {
    init?(message: MSMessage?) {
        guard let messageURL = message?.url else { return nil }
        guard let urlComponents = NSURLComponents(url: messageURL, resolvingAgainstBaseURL: false), let queryItems = urlComponents.queryItems else { return nil }
        
        self.init(queryItems: queryItems)
    }
}



/**
 Extends `IceCream` to make it `Equatable`.
 */
extension IceCream: Equatable {}

func ==(lhs: IceCream, rhs: IceCream) -> Bool {
    return lhs.base == rhs.base && lhs.scoops == rhs.scoops && lhs.topping == rhs.topping
}