class Caesar {
    static encrypt(s, key) {
        var offset = key % 26
        if (offset == 0) return s
        var chars = List.filled(s.count, 0)
        for (i in 0...s.count) {
            var c = s[i].bytes[0]
            var d = c
            if (c >= 65 && c <= 90) { // 'A' to 'Z'
                d = c + offset
                if (d > 90) d = d - 26
            } else if (c >= 97 && c <= 122) {  // 'a' to 'z'
                d = c + offset
                if (d > 122) d = d - 26
            }
            chars[i] = d
        }
        return chars.reduce("") { |acc, c| acc + String.fromByte(c) }
    }

    static decrypt(s, key) { encrypt(s, 26 - key) }
}

var encoded = Caesar.encrypt("Bright vixens jump; dozy fowl quack.", 8)
System.print(encoded)
System.print(Caesar.decrypt(encoded, 8))