Metaphone Spanish

MetaphoneSpanish.swift

import Foundation

class MetaphoneSpanish {
    private class func stringAt(_ string: String, _ start: Int, _ length: Int, _ list: [String]) -> Bool {
        if start < 0 || start >= string.count {
            return false
        }

        let substring = string[string.index(string.startIndex, offsetBy: start)..<string.index(string.startIndex, offsetBy: start+length)]

        for expr in list {
            if substring.contains(expr) {
                return true
            }
        }

        return false
    }

    private class func isVowel(_ string: String, _ position: Int) -> Bool {
        let character = string[string.index(string.startIndex, offsetBy: position)]
        return ["A", "E", "I", "O", "U"].contains(String(character))
    }

    private class func translateCharacters(_ string: String) -> String {
        let translated: [String: String] = [
            "á": "A",
            "ch": "X",
            "ç": "S",
            "é": "E",
            "í": "I",
            "ó": "O",
            "ú": "U",
            "ñ": "NY",
            "gü": "W",
            "ü": "U",
            "b": "V",
            // "z": "S",
            "ll": "Y"
        ]

        var result = string
        for (key, value) in translated {
            result = result.replacingOccurrences(of: key, with: value)
        }

        return result
    }

    func metaphone(_ string: String, _ phonemes: Int = 0) -> String {
        var metaKey = ""
        var currentPos = 0
        var originalString = string + "    "

        originalString = MetaphoneSpanish.translateCharacters(originalString)
        originalString = originalString.uppercased()

        while phonemes == 0 || metaKey.count < phonemes {
            if currentPos >= originalString.count {
                break
            }

            let currentChar = originalString[originalString.index(originalString.startIndex, offsetBy: currentPos)]

            if MetaphoneSpanish.isVowel(originalString, currentPos) && currentPos == 0 {
                metaKey += String(currentChar)
                currentPos += 1
            } else {
                let singleSoundChars = ["D", "F", "J", "K", "M", "N", "P", "T", "V", "L", "Y"]
                if MetaphoneSpanish.stringAt(originalString, currentPos, 1, singleSoundChars) {
                    metaKey += String(currentChar)

                    if originalString[originalString.index(originalString.startIndex, offsetBy: currentPos + 1)] == currentChar {
                        currentPos += 2
                    } else {
                        currentPos += 1
                    }
                } else {
                    if currentChar == "C" {
                        if originalString[originalString.index(originalString.startIndex, offsetBy: currentPos + 1)] == "C" {
                            metaKey += "X"
                            currentPos += 2
                        } else if MetaphoneSpanish.stringAt(originalString, currentPos, 2, ["CE", "CI"]) {
                            metaKey += "Z"
                            currentPos += 2
                        } else {
                            metaKey += "K"
                            currentPos += 1
                        }
                    } else if currentChar == "G" {
                        if MetaphoneSpanish.stringAt(originalString, currentPos, 2, ["GE", "GI"]) {
                            metaKey += "J"
                            currentPos += 2
                        } else {
                            metaKey += "G"
                            currentPos += 1
                        }
                    } else if currentChar == "H" {
                        if MetaphoneSpanish.isVowel(originalString, currentPos + 1) {
                            metaKey += String(originalString[originalString.index(originalString.startIndex, offsetBy: currentPos + 1)])
                            currentPos += 2
                        } else {
                            metaKey += "H"
                            currentPos += 1
                        }
                    } else if currentChar == "Q" {
                        if originalString[originalString.index(originalString.startIndex, offsetBy: currentPos + 1)] == "U" {
                            currentPos += 2
                        } else {
                            currentPos += 1
                        }
                        metaKey += "K"
                    } else if currentChar == "W" {
                        metaKey += "U"
                        currentPos += 1
                    } else if currentChar == "R" {
                        currentPos += 1
                        metaKey += "R"
                    } else if currentChar == "S" {
                        if !MetaphoneSpanish.isVowel(originalString, currentPos + 1) && currentPos == 0 {
                            metaKey += "ES"
                            currentPos += 1
                        } else {
                            currentPos += 1
                            metaKey += "S"
                        }
                    } else if currentChar == "Z" {
                        currentPos += 1
                        metaKey += "Z"
                    } else if currentChar == "X" {
                        if !MetaphoneSpanish.isVowel(originalString, currentPos + 1)
                            && originalString.count > 1
                            && currentPos == 0 {
                            metaKey += "EX"
                            currentPos += 1
                        } else {
                            metaKey += "X"
                            currentPos += 1
                        }
                    } else {
                        currentPos += 1
                    }
                }
            }
        }

        metaKey = metaKey.trimmingCharacters(in: .whitespacesAndNewlines)
        return metaKey
    }
}

// Example usage:
let metaphoneSpanish = MetaphoneSpanish()
let metaphoneKey = metaphoneSpanish.metaphone("El Parlamento Europeo acaba de dar un espaldarazo"" ")
print(metaphoneKey)