From db95a4bc681797ef4c952950c76fc797044473d5 Mon Sep 17 00:00:00 2001
From: Kelson Warner <kelson.warner@amplitude.com>
Date: Thu, 8 Oct 2020 12:33:58 -0700
Subject: [PATCH] AMP-30334 add base 36 generator

---
 .../amplitude/identitymanager/Identity.java   | 18 +++++---------
 .../identitymanager/IdentityManager.java      |  2 +-
 .../identitymanager/IdentityUtils.java        | 24 +++++++++++++++++++
 3 files changed, 31 insertions(+), 13 deletions(-)
 create mode 100644 src/main/java/com/amplitude/identitymanager/IdentityUtils.java

diff --git a/src/main/java/com/amplitude/identitymanager/Identity.java b/src/main/java/com/amplitude/identitymanager/Identity.java
index 82d74706..d4e229ee 100644
--- a/src/main/java/com/amplitude/identitymanager/Identity.java
+++ b/src/main/java/com/amplitude/identitymanager/Identity.java
@@ -1,26 +1,20 @@
 package com.amplitude.identitymanager;
 
-import android.util.Log;
-
 public class Identity {
     private String _userId;
     private String _deviceId;
 
-    private void logIdentityWarning(String message) {
-        Log.w(Identity.class.getName(), message);
-    }
-
     public String initializeDeviceId(String deviceId) {
-        if (deviceId == null) {
+        if (_deviceId == null) {
             String deviceIdToUse = "";
             if (deviceId.length() > 0) {
                 deviceIdToUse = deviceId;
             } else {
-                deviceIdToUse = "generateBase36Id";
+                deviceIdToUse = IdentityUtils.generateBase36Id();
             }
             _deviceId = deviceIdToUse;
         } else {
-            logIdentityWarning("Cannot set device ID twice for same identity. Skipping operation.");
+            IdentityUtils.logIdentityWarning("Cannot set device ID twice for same identity. Skipping operation.");
         }
 
         return deviceId;
@@ -28,9 +22,9 @@ public String initializeDeviceId(String deviceId) {
 
     public String initializeDeviceId() {
         if (_deviceId == null) {
-            _deviceId = "generateBase36Id";
+            _deviceId = IdentityUtils.generateBase36Id();
         } else {
-            logIdentityWarning("Cannot set device ID twice for same identity. Skipping operation.");
+            IdentityUtils.logIdentityWarning("Cannot set device ID twice for same identity. Skipping operation.");
         }
 
         return _deviceId;
@@ -38,7 +32,7 @@ public String initializeDeviceId() {
 
     public String getDeviceId() {
         if (_deviceId == null) {
-            logIdentityWarning("Did not detect device ID; generating one for this instance.");
+            IdentityUtils.logIdentityWarning("Did not detect device ID; generating one for this instance.");
             return initializeDeviceId();
         } else {
             return _deviceId;
diff --git a/src/main/java/com/amplitude/identitymanager/IdentityManager.java b/src/main/java/com/amplitude/identitymanager/IdentityManager.java
index 8edd31bc..c5225d9d 100644
--- a/src/main/java/com/amplitude/identitymanager/IdentityManager.java
+++ b/src/main/java/com/amplitude/identitymanager/IdentityManager.java
@@ -26,4 +26,4 @@ public Identity getInstance() {
             return identityToSet;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/main/java/com/amplitude/identitymanager/IdentityUtils.java b/src/main/java/com/amplitude/identitymanager/IdentityUtils.java
new file mode 100644
index 00000000..0351f6a0
--- /dev/null
+++ b/src/main/java/com/amplitude/identitymanager/IdentityUtils.java
@@ -0,0 +1,24 @@
+package com.amplitude.identitymanager;
+
+import android.util.Log;
+
+public class IdentityUtils {
+    static private final int device_id_length = 25;
+    static private final String base_36_char_set = "abcdefghijklmnopqrstuvwxyz0123456789";
+    static private final int base_36_radix = 36;
+
+    static void logIdentityWarning(String message) {
+        Log.w(Identity.class.getName(), message);
+    }
+
+    static String generateBase36Id() {
+        String stringBuilder = "";
+        for (int idx = 0; idx < device_id_length; idx++) {
+            double randomIdx = Math.floor(Math.random() * base_36_radix);
+            char nextChar = base_36_char_set.charAt((int)randomIdx);
+            stringBuilder += nextChar;
+        }
+
+        return stringBuilder;
+    }
+}