From 42920810c93c909029ccab5a96686d20c3253d91 Mon Sep 17 00:00:00 2001
From: Christoffer Tews <chris@vukee.com>
Date: Tue, 10 May 2016 14:00:46 +0200
Subject: [PATCH] Save split group membership

---
 CTSplitTest/CTSplitTest.swift | 54 +++++++++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/CTSplitTest/CTSplitTest.swift b/CTSplitTest/CTSplitTest.swift
index 574f7ef..1b5bc51 100644
--- a/CTSplitTest/CTSplitTest.swift
+++ b/CTSplitTest/CTSplitTest.swift
@@ -10,30 +10,80 @@ import Foundation
 
 struct CTSplitTest {
 
+    // Typealias
     typealias SplitGroup = () -> Void
 
-    func runABTest(distribution:[Double]=[0.5,0.5], groupA:ReferralGroup?, groupB:ReferralGroup?) {
-        let rnd = self._randomNumber(probabilities: distribution)
+    // Constants
+    let kSplitGroupKey = "splitGroup"
+    let kGroupA = "groupA"
+    let kGroupB = "groupB"
+    let kGroupC = "groupC"
+
+    func runABTest(distribution:[Double]=[0.5,0.5], groupA:SplitGroup?, groupB:SplitGroup?) {
+        let membership = _getGroupMembership()
 
+        guard membership == nil else {
+            if membership == kGroupA {
+                groupA?()
+            } else {
+                groupB?()
+            }
+
+            return
+        }
+
+        let rnd = self._randomNumber(probabilities: distribution)
         if rnd == 0 {
+            _saveGroupMembership(kGroupA)
             groupA?()
         } else {
+            _saveGroupMembership(kGroupB)
             groupB?()
         }
     }
 
     func runABCTest(groupA groupA:SplitGroup?, groupB:SplitGroup?, groupC:SplitGroup?) {
+        let membership = _getGroupMembership()
+        guard membership == nil else {
+            if membership == kGroupA {
+                groupA?()
+            } else if membership == kGroupB {
+                groupB?()
+            } else {
+                groupC?()
+            }
+
+            return
+        }
+
         let rnd = self._randomNumber(probabilities: [0.33, 0.33, 0,33])
 
         if rnd == 0 {
+            _saveGroupMembership(kGroupA)
             groupA?()
         } else if rnd == 1 {
+            _saveGroupMembership(kGroupB)
             groupB?()
         } else {
+            _saveGroupMembership(kGroupC)
             groupC?()
         }
     }
 
+    private func _getGroupMembership() -> String? {
+        let defaults = NSUserDefaults.standardUserDefaults()
+        let membership = defaults.objectForKey(kSplitGroupKey) as? String
+
+        return membership
+    }
+
+    private func _saveGroupMembership(group:String) {
+        let defaults = NSUserDefaults.standardUserDefaults()
+        defaults.setObject(group, forKey: kSplitGroupKey)
+        defaults.synchronize()
+    }
+
+
     /**
      * Create a random number with distribution
      * E.g. randomNumber([0.5,0.5]) generate a 0 or 1 with 50-50 split