State of the art real-time verbal output transformer written in Swift

SpeechTransformer.swift

//
//  SpeechTransformer.swift
//  SpeechTransformer
//
//  Created by Justin Kaufman 2/2/20.
//  Copyright © 2020 Justin Kaufman. All rights reserved.
//

import Foundation

// [1] Create an instance of SpeechTransformer
let transformer = SpeechTransformer(
  speaker: Speaker(name: "Justin"), 
  filters: [SWAGFilter()]
)

// [2] Become awesome
transformer.activate()

/// State of the art real-time verbal output transformer
class SpeechTransformer {
    private let speaker: Speaker
    private let filters: [SpeechFilter]
    private var isActive: Bool = false { 
    	didSet { filters.forEach { $0.toggle(isActive) } } 
    }

    init(speaker: Speaker, filters: [SpeechFilter]) {
        filters.forEach { $0.install(to: speaker) }
        self.filters = filters
    }

    func activate() { isActive = true }
    func deactivate() { isActive = false }
}

struct Speaker { 
    let name: String 
}

protocol SpeechFilter {
    var description: String { get }
    func output(for phrase: String) -> String
    func toggle(_ isOn: Bool)
    func install(to speaker: Speaker)
}

/// Scientific wild-ass guess (SWAG) transformer plugin
struct SWAGFilter: SpeechFilter {
    let description: String = "Improves the terrible estimate about to be uttered"
    private static let redFlags: [String] = ["hours", "minutes", "seconds", "today"]
    private var isOn: Bool = false

    func output(for phrase: String) -> String {
        /// Is this thing on?
        guard isOn else { return phrase }

        /// Speaker compatibility validation check
        guard SWAGFilter.redFlags.filter({ phrase.contains($0) }).isEmpty else {
            fatalError("Speaker requires more a powerful filter; try `NEWBFilter`?")
        }

        return phrase
            .replacingOccurrences(of: "easy", with: "time consuming")
            .replacingOccurrences(of: "soon", with: "in time")
            .replacingOccurrences(of: " years", with: "+ years")
            .replacingOccurrences(of: " months", with: "+ months to a year")
            .replacingOccurrences(of: " weeks", with: "+ months")
            .replacingOccurrences(of: " days", with: "+ weeks")
    }

    func toggle(_ isOn: Bool) { self.isOn = isOn }
    func install(to speaker: Speaker) { // TODO: Add brain injection code here }
}