Romanize.js

/**
 * Created by gschizas on 17/9/2014.
 */

function romanizeText(greekText) {
    var simpleTranslationGreek = "άβδέζήιίϊΐκλνξόπρσςτυύϋΰφωώ";
    var simpleTranslationLatin = "avdeziiiiiklnxoprsstyyyyfoo";
    var digraphTranslationGreek = "θχψ";
    var digraphTranslationLatin = "thchps";
    var digraphYpsilonGreek = "αεη";
    var digraphYpsilonLatin = "aei";
    var digraphYpsilonBeta = "βγδζλμνραάεέηήιίϊΐοόυύϋΰωώ";
    var digraphYpsilonPhi = "θκξπστφχψ";

    var result = "";
    var cursor = 0;
    var letter, newLetter, previousLetter, nextLetter, thirdLetter;
    var isUpper, isUpper2;
    while (cursor < greekText.length) {
        letter = greekText.charAt(cursor);
        previousLetter = (cursor > 0) ? greekText.charAt(cursor - 1) : "";
        nextLetter = (cursor < greekText.length - 1) ? greekText.charAt(cursor + 1) : "";
        thirdLetter = (cursor < greekText.length - 2) ? greekText.charAt(cursor + 2) : "";

        isUpper = (letter.toUpperCase() == letter);
        isUpper2 = (nextLetter.toUpperCase() == nextLetter);
        letter = letter.toLowerCase();
        previousLetter = previousLetter.toLowerCase();
        nextLetter = nextLetter.toLowerCase();
        thirdLetter = thirdLetter.toLowerCase();

        if (simpleTranslationGreek.indexOf(letter) >= 0) {
            newLetter = simpleTranslationLatin.charAt(simpleTranslationGreek.indexOf(letter));
        }
        else if (digraphTranslationGreek.indexOf(letter) >= 0) {
            var diphthong_index = digraphTranslationGreek.indexOf(letter);
            newLetter = digraphTranslationLatin.substr(diphthong_index * 2, 2);
        }
        else if (digraphYpsilonGreek.indexOf(letter) >= 0) {
            newLetter = digraphYpsilonLatin.charAt(digraphYpsilonGreek.indexOf(letter));
            if (nextLetter == "υ" || nextLetter == "ύ") {
                if (digraphYpsilonBeta.indexOf(thirdLetter) >= 0) {
                    newLetter += "v";
                    cursor++;
                }
                else if (digraphYpsilonPhi.indexOf(thirdLetter) >= 0) {
                    newLetter += "f";
                    cursor++;
                }
            }
        }
        else if (letter == "γ") {
            if (nextLetter == "γ") {
                newLetter = "ng";
                cursor++;
            }
            else if (nextLetter == "ξ") {
                newLetter = "nx";
                cursor++;
            }
            else if (nextLetter == "χ") {
                newLetter = "nch";
                cursor++;
            }
            else {
                newLetter = "g";
            }
        }
        else if (letter == "μ") {
            if (nextLetter == "π") {
                if (previousLetter.trim() == "" || thirdLetter.trim() == "") {
                    newLetter = "b";
                    cursor++;
                }
                else {
                    newLetter = "mp";
                    cursor++;
                }
            }
            else {
                newLetter = "m";
            }
        }
        else if (letter == "ο") {
            newLetter = "o";
            if (nextLetter == "υ" || nextLetter == "ύ") {
                newLetter += "u";
                cursor++;
            }
        }
        else {
            newLetter = letter;
        }

        if (isUpper) {
            newLetter = newLetter.charAt(0).toUpperCase() +
                (isUpper2 ? newLetter.substring(1).toUpperCase() : newLetter.substring(1).toLowerCase());
        }

        result += newLetter;
        cursor++;
    }
    return result;
}