Initial Python rewrite

src.bak/main/java/com/example/util/SessionIdGenerator.java

@@ -0,0 +1,68 @@
+/*
+* Copyright 2025 Google. This software is provided as-is, without warranty or representation for any use or purpose.
+* Your use of it is subject to your agreement with Google.
+*/
+
+package com.example.util;
+
+import java.util.UUID;
+import java.util.Base64;
+
+/**
+ * A utility class for generating consistent and formatted session IDs.
+ * Centralizing ID generation ensures all parts of the application use the same
+ * logic and format.
+ */
+public final class SessionIdGenerator {
+
+    // Private constructor to prevent instantiation of the utility class.
+    private SessionIdGenerator() {}
+
+    /**
+     * Generates a standard, version 4 (random) UUID as a string.
+     * This is the most common and robust approach for general-purpose unique IDs.
+     * The UUID is a 36-character string with hyphens (e.g., "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx").
+     *
+     * @return a new, randomly generated UUID string.
+     */
+    public static String generateStandardSessionId() {
+        return UUID.randomUUID().toString();
+    }
+
+    /**
+     * Generates a more compact session ID by removing the hyphens from a standard UUID.
+     * This is useful for contexts where a shorter or URL-friendly ID is needed.
+     *
+     * @return a 32-character UUID string without hyphens.
+     */
+    public static String generateCompactSessionId() {
+        return UUID.randomUUID().toString().replace("-", "");
+    }
+
+    /**
+     * Generates a base64-encoded, URL-safe session ID from a UUID.
+     * This provides a very compact, yet robust, representation of the UUID.
+     * It's ideal for use in URLs, cookies, or other contexts where size matters.
+     *
+     * @return a new, base64-encoded UUID string.
+     */
+    public static String generateUrlSafeSessionId() {
+        UUID uuid = UUID.randomUUID();
+        byte[] uuidBytes = toBytes(uuid);
+        return Base64.getUrlEncoder().withoutPadding().encodeToString(uuidBytes);
+    }
+    
+    // Helper method to convert UUID to a byte array
+    private static byte[] toBytes(UUID uuid) {
+        long mostSignificantBits = uuid.getMostSignificantBits();
+        long leastSignificantBits = uuid.getLeastSignificantBits();
+        byte[] bytes = new byte[16];
+        for (int i = 0; i < 8; i++) {
+            bytes[i] = (byte) (mostSignificantBits >>> (8 * (7 - i)));
+        }
+        for (int i = 0; i < 8; i++) {
+            bytes[8 + i] = (byte) (leastSignificantBits >>> (8 * (7 - i)));
+        }
+        return bytes;
+    }
+}