Georgify.java

import java.util.HashMap;
import java.util.Map;

public class Georgify {
    private static final Map<Character, String> NEIGHBOR_KEYS;

    static {
        NEIGHBOR_KEYS = new HashMap<>(26);
        // Top row
        NEIGHBOR_KEYS.put('q', "wa");
        NEIGHBOR_KEYS.put('w', "qase");
        NEIGHBOR_KEYS.put('e', "wsdr");
        NEIGHBOR_KEYS.put('r', "edft");
        NEIGHBOR_KEYS.put('t', "rfgy");
        NEIGHBOR_KEYS.put('y', "tghu");
        NEIGHBOR_KEYS.put('u', "yhji");
        NEIGHBOR_KEYS.put('i', "ujko");
        NEIGHBOR_KEYS.put('o', "iklp");
        NEIGHBOR_KEYS.put('p', "ol");
        // Middle row
        NEIGHBOR_KEYS.put('a', "qwsz");
        NEIGHBOR_KEYS.put('s', "wazxde");
        NEIGHBOR_KEYS.put('d', "esxcfr");
        NEIGHBOR_KEYS.put('f', "rdcvgt");
        NEIGHBOR_KEYS.put('g', "tfvbhy");
        NEIGHBOR_KEYS.put('h', "ygbnju");
        NEIGHBOR_KEYS.put('j', "uhnmki");
        NEIGHBOR_KEYS.put('k', "ijmlo");
        NEIGHBOR_KEYS.put('l', "okp");
        // Bottom row
        NEIGHBOR_KEYS.put('z', "asx");
        NEIGHBOR_KEYS.put('x', "zsdc");
        NEIGHBOR_KEYS.put('c', "xdfv");
        NEIGHBOR_KEYS.put('v', "cfgb");
        NEIGHBOR_KEYS.put('b', "vghn");
        NEIGHBOR_KEYS.put('n', "bhjm");
        NEIGHBOR_KEYS.put('m', "njk");
    }

    private static int randomInt(int upper) {
        return (int)(Math.random() * upper);
    }

    private static char neighborLetter(char input) {
        String replacementKeys = NEIGHBOR_KEYS.get(input);
        int index = randomInt(replacementKeys.length());
        return replacementKeys.charAt(index);
    }

    private static String misspellDelete(String word) {
        int index = randomInt(word.length());
        return word.substring(0, index) + word.substring(index + 1);
    }

    private static String misspellInsert(String word) {
        int index = randomInt(word.length());
        char newChar = neighborLetter(word.charAt(index));
        if (Math.random() < 0.5) index++;
        return word.substring(0, index) + newChar + word.substring(index);
    }

    private static String misspellSwap(String word) {
        int index = randomInt(word.length() - 1);
        char c1 = word.charAt(index);
        char c2 = word.charAt(index + 1);
        return word.substring(0, index) + c2 + c1 + word.substring(index + 2);
    }

    private static String misspellDuplicate(String word) {
        int index = randomInt(word.length());
        char c = word.charAt(index);
        return word.substring(0, index) + c + c + word.substring(index + 1);
    }

    private static String misspellReplace(String word) {
        int index = randomInt(word.length());
        char newChar = neighborLetter(word.charAt(index));
        return word.substring(0, index) + newChar + word.substring(index + 1);
    }

    public static String georgify(String word) {
        if (word.length() <= 1) {
            return word;
        }

        if (Math.random() < 0.7) {
            // Spelled correctly 70% of the time
            return word;
        }

        double rnd = Math.random();
        if (rnd < 0.1) {
            // 10%
            return misspellDelete(word);
        } else if (rnd < 0.2) {
            // 10%
            return misspellInsert(word);
        } else if (rnd < 0.3) {
            // 10%
            return misspellSwap(word);
        } else if (rnd < 0.65) {
            // 35%
            return misspellDuplicate(word);
        } else {
            // 35%
            return misspellReplace(word);
        }
    }
}