From e586c7e03df1ad2d64fcbab14aa2cd8e37c0e1f0 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Sun, 19 Jul 2015 01:28:18 -0700
Subject: [PATCH] inverseEncode

---
 Enigma/Components.swift | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Enigma/Components.swift b/Enigma/Components.swift
index 710f171..6e3ef7b 100644
--- a/Enigma/Components.swift
+++ b/Enigma/Components.swift
@@ -17,6 +17,7 @@ enum EncoderError: ErrorType {
 
 protocol Encoder {
     func encode(c: Character) throws -> Character
+    func inverseEncode(c: Character) throws -> Character
 }
 
 
@@ -54,6 +55,14 @@ class FixedRotor: Cryptor, Encoder {
             throw EncoderError.InvalidCharacter(ch: c)
         }
     }
+
+    func inverseEncode(c: Character) throws -> Character {
+        if let offset = series.indexOf(c) {
+            return FixedRotor.alphabet[offset]
+        } else {
+            throw EncoderError.InvalidCharacter(ch: c)
+        }
+    }
 }
 
 
@@ -109,6 +118,14 @@ class Rotor: FixedRotor {
             throw EncoderError.InvalidCharacter(ch: c)
         }
     }
+
+    override func inverseEncode(c: Character) throws -> Character {
+        if let offset = series.indexOf(c) {
+            return Rotor.alphabet[(offset + ringPosition + position) % Rotor.alphabet.count]
+        } else {
+            throw EncoderError.InvalidCharacter(ch: c)
+        }
+    }
 }
 
 
@@ -162,4 +179,8 @@ class Plugboard: Cryptor, Encoder {
             throw EncoderError.InvalidCharacter(ch: c)
         }
     }
+
+    func inverseEncode(c: Character) throws -> Character {
+        return try encode(c)
+    }
 }
\ No newline at end of file