KeywordsMinifier used for Minify ASO app

KeywordsMinifier.swift

//
//  KeywordsMinifier.swift
//  MinifyASO
//
//  Created by Damjan Dabo on 19.12.22.
//

import Foundation

/// Used for Minify ASO app https://apps.apple.com/us/app/minify-aso-duplicate-keywords/id1660632226
struct KeywordsMinifier {

    // MARK: - Private properties

    private static let charsToSeparateBy: CharacterSet = [".", ",", "!", "?", " ", "\n"]

    // MARK: - Public funcs

    static func minifyKeywords(
        fromInput input: String,
        keywordsToExclude: String
    ) -> String {
        let minifiedKeywordsList = minifiedKeywordsList(
            input: input,
            keywordsToExclude: keywordsToExclude)
        return (minifiedKeywordsList ?? []).joined(separator: ",")
    }

    // MARK: - Private funcs

    private static func minifiedKeywordsList(input: String, keywordsToExclude: String) -> [String]? {
        let words = input
            .lowercased()
            .components(separatedBy: charsToSeparateBy)
            .filter({!$0.isEmpty})

        print("With duplicates:\n\(words)")

        let removedPlurals = words
            .map { word in
                guard !("ios").contains(word) else { return word }

                if word.last == "s" {
                    let removedSWord = word.dropLast()

                    if removedSWord.last == "e" {
                        return String(removedSWord.dropLast())
                    } else {
                        return String(removedSWord)
                    }

                } else {
                    return word
                }
            }

        guard let uniqueOrdered = Array(NSOrderedSet(array: removedPlurals)) as? Array<String> else {
            print("Error")
            return nil
        }

        let keywordsToExcludeWords = keywordsToExclude
            .lowercased()
            .components(separatedBy: charsToSeparateBy)
            .filter({!$0.isEmpty})

        let removedStopWords = uniqueOrdered
            .filter { !stopWords.contains($0) }
            .filter { !keywordsToExcludeWords.contains($0) }

        return removedStopWords
    }

    private static var stopWords: [String] {
        /// from https://appfigures.com/resources/guides/keyword-optimization-app-store-connect#4-eliminate-stop-words
        let stopWordsInput = """
        a, about, above, after, again, against, all, am, an, and, any, app, are, aren't, as, at, be, because, been, before, being, below, between, both, but, by, can't, cannot, could, couldn't, did, didn't, do, does, doesn't, doing, don't, down, during, each, few, for, from, further, had, hadn't, has, hasn't, have, haven't, having, he, he'd, he'll, he's, her, here, here's, hers, herself, him, himself, his, how, how's, i, i'd, i'll, i'm, i've, if, in, into, is, isn't, it, it's, its, itself, let's, me, more, most, mustn't, my, myself, no, nor, not, of, off, on, once, only, or, other, ought, our, ours, ourselves, out, over, own, same, shan't, she, she'd, she'll, she's, should, shouldn't, so, some, such, than, that, that's, the, their, theirs, them, themselves, then, there, there's, these, they, they'd, they'll, they're, they've, this, those, through, to, too, under, until, up, very, was, wasn't, we, we'd, we'll, we're, we've, were, weren't, what, what's, when, when's, where, where's, which, while, who, who's, whom, why, why's, with, won't, would, wouldn't, you, you'd, you'll, you're, you've, your, yours, yourself, yourselves
        """

        return stopWordsInput
            .lowercased()
            .components(separatedBy: charsToSeparateBy)
            .filter({!$0.isEmpty})
    }
}