From 560e9adf198dee5f5206ecdb024bf61be88d35ce Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Laurent=20Tr=C3=A9guier?= <laurent.treguier@fyreplace.app>
Date: Sun, 15 Sep 2024 19:30:22 +0200
Subject: [PATCH] Make user tint more random

---
 .../java/app/fyreplace/api/data/User.java     | 21 +++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/main/java/app/fyreplace/api/data/User.java b/src/main/java/app/fyreplace/api/data/User.java
index 07ec1f4..22dde63 100644
--- a/src/main/java/app/fyreplace/api/data/User.java
+++ b/src/main/java/app/fyreplace/api/data/User.java
@@ -15,6 +15,7 @@
 import jakarta.ws.rs.NotAuthorizedException;
 import jakarta.ws.rs.core.SecurityContext;
 import java.awt.Color;
+import java.security.MessageDigest;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Arrays;
@@ -22,7 +23,7 @@
 import java.util.Set;
 import java.util.UUID;
 import java.util.stream.Collectors;
-import java.util.zip.CRC32;
+import lombok.SneakyThrows;
 import org.eclipse.microprofile.openapi.annotations.media.Schema;
 import org.hibernate.annotations.OnDelete;
 import org.hibernate.annotations.OnDeleteAction;
@@ -154,11 +155,12 @@ public boolean getBlocked() {
         return Block.count("source = ?1 and target = ?2", currentUser, this) > 0;
     }
 
+    @SneakyThrows
     @Schema(required = true, pattern = "^#[A-F0-9]{6}$")
     public String getTint() {
-        final var crc = new CRC32();
-        crc.update(username.getBytes());
-        final var hue = (float) (crc.getValue() / Math.pow(2, 32));
+        final var md5 = MessageDigest.getInstance("MD5");
+        final var digest = md5.digest(username.getBytes());
+        final var hue = bytesToFloat(digest);
         final var h = hue * 6;
         final var variance = (h - (float) Math.floor(h)) * 0.25f;
         final var brightness = (int) h % 2 == 0 ? 1f - variance : 0.75f + variance;
@@ -261,6 +263,17 @@ public static User getFromSecurityContext(final SecurityContext context, @Nullab
         return user;
     }
 
+    private static float bytesToFloat(byte[] bytes) {
+        final var bytesToUse = Math.min(bytes.length, Long.BYTES);
+        var result = 0L;
+
+        for (var i = 0; i < bytesToUse; i++) {
+            result = (result << Byte.SIZE) | (bytes[i] & 0xFF);
+        }
+
+        return (float)Math.abs((double)result / Long.MAX_VALUE);
+    }
+
     public enum Rank {
         CITIZEN,
         MODERATOR,