Providers.swift

//: Playground - noun: a place where people can play

import UIKit

struct PriceTextProvider {

    let basePrice: Double
    let reducedPrice: Double
    let vat: Double

}

struct PriceTextRenderOptions: OptionSetType {

    let rawValue: Int

    init(rawValue: Int) {
        self.rawValue = rawValue
    }

    static let Base = PriceTextRenderOptions(rawValue: 1)
    static let Reduced = PriceTextRenderOptions(rawValue: 2)
    static let Vat = PriceTextRenderOptions(rawValue: 4)
    static let BaseAndReduced = [Base, Reduced]
    static let FullPrice = [Base, Reduced, Vat]

}

enum PriceTextContext {
    case Normal, Short
}

class PriceTextRenderer {
    
    let priceFormatter: NSNumberFormatter
    let vatFormatter: NSNumberFormatter

    init(priceFormatter: NSNumberFormatter, vatFormatter: NSNumberFormatter) {
        self.priceFormatter = priceFormatter
        self.vatFormatter = vatFormatter
    }

    func render(provider: PriceTextProvider, context: PriceTextContext, options: PriceTextRenderOptions) -> NSAttributedString {
        let attributedPrice = NSMutableAttributedString(string: "")
        let glue = context == .Normal ? "\n" : " "
        
        if let basePrice = priceFormatter.stringFromNumber(NSNumber(double: provider.basePrice)) where options.contains(.Base) {
            let a = NSAttributedString(string: basePrice, attributes: [NSForegroundColorAttributeName: UIColor.greenColor()])
            attributedPrice.appendAttributedString(a)
        }
        if let reducedPrice = priceFormatter.stringFromNumber(NSNumber(double: provider.reducedPrice)) where options.contains(.Reduced) {
            let a = NSAttributedString(string: "\(glue)\(reducedPrice)", attributes: [NSForegroundColorAttributeName: UIColor.redColor()])
            attributedPrice.appendAttributedString(a)
        }
        if let vat = vatFormatter.stringFromNumber(NSNumber(double: provider.vat)) where options.contains(.Vat) {
            let a = NSAttributedString(string: "\(glue)\(vat)")
            attributedPrice.appendAttributedString(a)
        }

        return attributedPrice
    }

}

let locale = NSLocale(localeIdentifier: "de_DE")

let priceFormatter = NSNumberFormatter()
priceFormatter.numberStyle = .CurrencyStyle
priceFormatter.locale = locale

let vatFormatter = NSNumberFormatter()
vatFormatter.numberStyle = .PercentStyle
vatFormatter.locale = locale

let renderer = PriceTextRenderer(priceFormatter: priceFormatter, vatFormatter: vatFormatter)

let provider = PriceTextProvider(basePrice: 20.00, reducedPrice: 15.00, vat: 0.19)
renderer.render(provider, context: .Normal, options: [.Base, .Reduced, .Vat])
renderer.render(provider, context: .Short, options: [.Base, .Reduced])