From ec1dd0d77be2224334ccb91a275836400fde508d Mon Sep 17 00:00:00 2001
From: Rohitesh Dutta <rohitesh.dutta@wingify.com>
Date: Tue, 21 Nov 2023 22:01:54 +0530
Subject: [PATCH] fix(MEG): Issues with Advanced implementation of MEG

---
 CHANGELOG.md                         |  6 +++++
 composer.json                        |  2 +-
 src/Core/VariationDecider.php        | 33 ++++++++++++----------------
 src/Utils/ImpressionBuilder.php      |  2 +-
 tests/Core/MutuallyExclusiveTest.php |  8 ++++---
 5 files changed, 27 insertions(+), 24 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c43aac9..b83bfb1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.66.0] - 2023-11-21
+
+### Fixed
+
+- Fixed issue with Advanced implementation of MEG
+
 ## [1.65.0] - 2023-11-09
 
 ### Fixed
diff --git a/composer.json b/composer.json
index 031ee65..decdfca 100644
--- a/composer.json
+++ b/composer.json
@@ -9,7 +9,7 @@
     "description": "VWO server side sdk",
     "require": {
         "monolog/monolog": "^1.0 || ^2.0",
-        "ramsey/uuid": "^3.8 || ^4.4",
+        "ramsey/uuid": "^3.8 || ^4.0",
         "justinrainbow/json-schema": "^5.2",
         "vwo/vwo-sdk-log-messages": ">=0.10.0"
     },
diff --git a/src/Core/VariationDecider.php b/src/Core/VariationDecider.php
index 8d808d7..2bd6217 100644
--- a/src/Core/VariationDecider.php
+++ b/src/Core/VariationDecider.php
@@ -487,35 +487,30 @@ private static function findWinnerCampaign($userId, $eligibleCampaigns, $megAlgo
                 // If winnerCampaign not found through Priority, then go for weighted Random distribution and for that,
                 // Store the list of campaigns (participatingCampaigns) out of eligibleCampaigns and their corresponding weights which are present in weightage distribution array (wt) in 2 different lists
                 if ($winnerCampaign == null) {
-                    $weights = array();
                     $partipatingCampaignList = array();
 
                     for ($i = 0; $i < count($eligibleCampaigns); $i++) {
                         $campaignId = $eligibleCampaigns[$i]['id'];
                         if (isset($wt[$campaignId])) {
-                            $weights[] = $wt[$campaignId];
+                            // Add weight to the campaign
+                            $eligibleCampaigns[$i]['weight'] = $wt[$campaignId];
+                            
                             $partipatingCampaignList[] = $eligibleCampaigns[$i];
                         }
                     }
 
-                    /*
-                    * Finding winner campaign using weighted random distribution :
-                    1. Calculate the sum of all weights
-                    2. Generate a random number between 0 and the weight sum:
-                    3. Iterate over the weights array and subtract each weight from the random number until the random number becomes negative. The corresponding ith value is the required value
-                    4. Set the ith campaign as WinnerCampaign
+                    /* Finding winner campaign using weighted Distibution :
+                    1. Re-distribute the traffic by assigning range values for each camapign in particaptingCampaignList 
+                    2. Calculate bucket value for the given userId and groupId
+                    3. Get the winnerCampaign by checking the Start and End Bucket Allocations of each campaign
                     */
-                    $weightSum = array_sum($weights);
-                    $randomNumber = rand(1, $weightSum);
-
-                    $sum = 0;
-                    for ($i = 0; $i < count($weights); $i++) {
-                        $sum += $weights[$i];
-                        if ($randomNumber < $sum) {
-                            $winnerCampaign = $partipatingCampaignList[$i];
-                            break;
-                        }
-                    }
+
+                    //Allocate new range for campaigns
+                        $eligibleCampaigns = Bucketer::addRangesToCampaigns($partipatingCampaignList);
+                    //Now retrieve the campaign from the modified_campaign_for_whitelisting
+                        list($bucketVal, $hashValue) = Bucketer::getBucketVal($userId, [], false, true);
+                        
+                    $winnerCampaign = Bucketer::getCampaignUsingRange($bucketVal, $eligibleCampaigns);
                 }
 
                 return $winnerCampaign;
diff --git a/src/Utils/ImpressionBuilder.php b/src/Utils/ImpressionBuilder.php
index 5f12894..04a9d7b 100644
--- a/src/Utils/ImpressionBuilder.php
+++ b/src/Utils/ImpressionBuilder.php
@@ -31,7 +31,7 @@ class ImpressionBuilder
     /**
      * sdk version for api hit
      */
-    const SDK_VERSION = '1.65.0';
+    const SDK_VERSION = '1.66.0';
     /**
      * sdk langauge for api hit
      */
diff --git a/tests/Core/MutuallyExclusiveTest.php b/tests/Core/MutuallyExclusiveTest.php
index 2897530..0310a73 100644
--- a/tests/Core/MutuallyExclusiveTest.php
+++ b/tests/Core/MutuallyExclusiveTest.php
@@ -429,7 +429,8 @@ public function testWinnerCampaignIsNotTheCalledCampaignAfterRandomWeightageDist
 
         $winners = 0;
         for ($i = 0; $i < $iterations; $i++) {
-            $variation = $vwoInstance->getVariationName($campaignKey, 'George');
+            $userId = "user" . $i;
+            $variation = $vwoInstance->getVariationName($campaignKey, $userId);
             if ($variation != null) {
                 $winners = $winners + 1;
             }
@@ -464,8 +465,9 @@ public function testWinnerCampaignFoundThroughWeightage()
 
         $winners = 0;
         for ($i = 0; $i < $iterations; $i++) {
-            $variation = $vwoInstance->getVariationName($campaignKey, 'George');
-            $winners = $variation == 'Control' ? $winners + 1 : $winners;
+            $userId = "user" . $i;
+            $variation = $vwoInstance->getVariationName($campaignKey, $userId);
+            $winners = $variation != null ? $winners + 1 : $winners;
         }
 
         $actualRatio = $winners / $iterations;